eon/lib/main.go

package lib

import (
	"bufio"
	"bytes"
	"errors"
	"io"
	"os"
	"strconv"
	"strings"
	"time"

	"archive/tar"
	"crypto/ed25519"
	"encoding/binary"
	"encoding/hex"
	"encoding/json"
	"net/http"
	"net/url"
	"os/exec"
	"path/filepath"

	"github.com/Masterminds/semver"
	"github.com/cespare/xxhash/v2"
	"github.com/dustin/go-humanize"
	"github.com/klauspost/compress/zstd"
)

// RemoteEPK is a struct that contains the metadata of an EPK from a remote repository
type RemoteEPK struct {
	Repository     Repository
	Name           string
	Author         string
	Description    string
	Version        semver.Version
	Architecture   string
	CompressedSize uint64
	Dependencies   []string
	Path           string
	Arch           string
	EPKHash        uint64
}

// Repository is a struct that contains the repository information
type Repository struct {
	Name        string
	URL         string
	Owner       string
	Description string
}

// SpecialFiles is a struct that contains the special files that are not to be deleted or replaced
type SpecialFiles struct {
	NoDelete  []string
	NoReplace []string
}

// Metadata is a struct that contains the metadata of the package
type Metadata struct {
	Name             string
	Description      string
	LongDescription  string
	Version          semver.Version
	Author           string
	License          string
	Architecture     string
	Dependencies     []string
	SpecialFiles     SpecialFiles
	Size             uint64
	DecompressedSize uint64
}

// EPKPreMap is a struct that contains the metadata of the EPK
type EPKPreMap struct {
	DisplayData    DisplayData
	MetadataMap    map[string]interface{}
	IsLittleEndian bool
	IsUpgrade      bool
	TarOffset      uint64
}

// DisplayData is a struct that contains the display data of the EPK
type DisplayData struct {
	Name             string
	Author           string
	Architecture     string
	Description      string
	Version          semver.Version
	Size             uint64
	DecompressedSize uint64
	Dependencies     []string
	IsDependency     bool
}

// PotentiallyNullEPKPreMap is a EPKPreMap that can be nil
type PotentiallyNullEPKPreMap struct {
	EPKPreMap *EPKPreMap
	Null      bool
}

// Log is a struct that contains the log information
type Log struct {
	Level     string
	Content   string
	Prompt    bool
	PlaySound bool
	Progress  uint64
	Total     uint64
	Overwrite bool
}

// StreamOrBytes is a struct that contains either a stream or bytes, allowing optimising for memory or speed
type StreamOrBytes struct {
	FileStream     *os.File
	RepositoryName string
	URL            string
	Bytes          []byte
	IsURL          bool
	IsRemote       bool
	IsFileStream   bool
}

// Logger is a struct that contains the functions and properties of the logger
type Logger struct {
	LogFunc           func(Log) string
	PromptSupported   bool
	ProgressSupported bool
}

// Epk is a struct that contains the metadata and the tar archive of the EPK
type Epk struct {
	Metadata   Metadata
	TarArchive []byte
}

// interfaceToStringSlice converts an interface slice to a string slice
func interfaceToStringSlice(interfaceSlice []interface{}, interfaceName string) ([]string, error) {
	// Yes, it's meant to be empty and not nil: JSON arrays are empty, not nil
	//goland:noinspection GoPreferNilSlice
	stringSlice := []string{}
	for _, interfaceValue := range interfaceSlice {
		stringValue, ok := interfaceValue.(string)
		if !ok {
			return nil, errors.New(interfaceName + " are not strings")
		}
		stringSlice = append(stringSlice, stringValue)
	}

	return stringSlice, nil
}

// ByteToFingerprint converts a byte slice to an Eon fingerprint, which is similar to a legacy-style OpenSSH fingerprint
func ByteToFingerprint(input []byte) string {
	xxHashWriter := xxhash.New()
	_, _ = xxHashWriter.Write(input)
	inputString := hex.EncodeToString(xxhash.New().Sum(nil))
	var result []string
	var previousChar rune
	for index, char := range inputString {
		if index%2 == 0 && index != 0 {
			result = append(result, string(previousChar)+string(char))
		} else {
			previousChar = char
		}
	}
	return strings.Join(result, ":")
}

// MkdirAllWithPaths mimics os.MkdirAll but returns the created directories
func MkdirAllWithPaths(path string, perm os.FileMode) ([]string, error) {
	// Make sure to return absolute paths
	absPath, err := filepath.Abs(path)
	if err != nil {
		return nil, err
	}

	// Split the path into individual directories
	var dirs []string
	currentPath := absPath
	for currentPath != "/" {
		dirs = append([]string{currentPath}, dirs...)
		currentPath = filepath.Dir(currentPath)
	}

	// Slice to hold the created directory paths
	var createdDirs []string

	// Iterate through each directory and create if not exists
	for _, dir := range dirs {
		_, err := os.Stat(dir)
		if errors.Is(err, os.ErrNotExist) {
			// Directory doesn't exist, create it
			err := os.Mkdir(dir, perm)
			if err != nil {
				return createdDirs, err
			}
			// Append created directory's absolute path
			createdDirs = append(createdDirs, dir)
		}
	}

	return createdDirs, nil
}

func preMapEpkFromBytes(metaDataBytes []byte, littleEndian bool, size uint64, offset uint64) (EPKPreMap, error) {
	// Unmarshal the JSON
	var displayDataMap map[string]interface{}
	decoder := json.NewDecoder(bytes.NewReader(metaDataBytes))
	decoder.UseNumber()
	err := decoder.Decode(&displayDataMap)
	if err != nil {
		return EPKPreMap{}, errors.New("metadata is not valid JSON")
	}

	// Declare the parsedDisplayData object
	var parsedDisplayData EPKPreMap

	// Add some of our data so that the full EPK can be mapped with less effort
	parsedDisplayData.MetadataMap = displayDataMap
	parsedDisplayData.IsLittleEndian = littleEndian
	parsedDisplayData.TarOffset = offset
	parsedDisplayData.DisplayData.Size = size

	// Map the display data
	var ok bool
	// Set the size
	sizeJSON, ok := displayDataMap["size"].(json.Number)
	if !ok {
		return EPKPreMap{}, errors.New("size is not a number")
	}
	parsedDisplayData.DisplayData.DecompressedSize, err = strconv.ParseUint(sizeJSON.String(), 10, 64)
	if err != nil {
		return EPKPreMap{}, err
	}
	// Set the name, author, version, arch, and dependencies
	parsedDisplayData.DisplayData.Name, ok = displayDataMap["name"].(string)
	if !ok {
		return EPKPreMap{}, errors.New("name is not a string")
	}
	parsedDisplayData.DisplayData.Author, ok = displayDataMap["author"].(string)
	if !ok {
		return EPKPreMap{}, errors.New("author is not a string")
	}
	versionString, ok := displayDataMap["version"].(string)
	if !ok {
		return EPKPreMap{}, errors.New("version is not a string")
	}
	versionPointer, err := semver.NewVersion(versionString)
	if err != nil {
		return EPKPreMap{}, err
	}
	parsedDisplayData.DisplayData.Version = *versionPointer
	parsedDisplayData.DisplayData.Architecture, ok = displayDataMap["arch"].(string)
	if !ok {
		return EPKPreMap{}, errors.New("arch is not a string")
	}
	dependencies, ok := displayDataMap["deps"].([]interface{})
	if !ok {
		return EPKPreMap{}, errors.New("dependencies is not an array")
	}
	parsedDisplayData.DisplayData.Dependencies, err = interfaceToStringSlice(dependencies, "dependencies")
	if err != nil {
		return EPKPreMap{}, err
	}

	return parsedDisplayData, nil
}

// ConstMapEPKMetadataOffset is the offset of the metadata in the EPK: 3 magic bytes, 1 endian byte, 8 offset bytes, 64 signature bytes, and 32 public key bytes
var ConstMapEPKMetadataOffset uint64 = 108

var ErrPreMapEPKCouldNotRead = errors.New("could not read EPK")
var ErrPreMapEPKHasNetworkStream = errors.New("network streams are not supported")
var ErrPreMapEPKHasNotGotEPK = errors.New("has not got an EPK")
var ErrPreMapEPKHasInvalidEndian = errors.New("has invalid endian")
var ErrPreMapEPKCouldNotMapJSON = errors.New("could not map metadata")

// PreMapEPK maps enough data to create the display summary of an EPK
func PreMapEPK(epkBytes StreamOrBytes, epkSize uint64) (EPKPreMap, error, error) {
	// Say that we don't support network streams
	if epkBytes.IsURL {
		return EPKPreMap{}, nil, ErrPreMapEPKHasNetworkStream
	}

	// First, we need to check if it even is a EPK by checking the first 3 magic bytes
	if epkBytes.IsFileStream {
		var magicBytes = make([]byte, 3)
		_, err := epkBytes.FileStream.ReadAt(magicBytes, 0)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotRead
		}
		if string(magicBytes) != "epk" {
			return EPKPreMap{}, nil, ErrPreMapEPKHasNotGotEPK
		}
	} else {
		if string(epkBytes.Bytes[0:3]) != "epk" {
			return EPKPreMap{}, nil, ErrPreMapEPKHasNotGotEPK
		}
	}

	// Let's determine the endian-ness of the EPK via the 3rd byte
	var littleEndian bool
	if epkBytes.IsFileStream {
		var littleEndianByte = make([]byte, 1)
		_, err := epkBytes.FileStream.ReadAt(littleEndianByte, 3)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotRead
		}
		if littleEndianByte[0] == 0x6C {
			littleEndian = true
		} else if littleEndianByte[0] == 0x62 {
			littleEndian = false
		} else {
			return EPKPreMap{}, nil, ErrPreMapEPKHasInvalidEndian
		}
	} else {
		if epkBytes.Bytes[3] == 0x6C {
			littleEndian = true
		} else if epkBytes.Bytes[3] == 0x62 {
			littleEndian = false
		} else {
			return EPKPreMap{}, nil, ErrPreMapEPKHasInvalidEndian
		}
	}

	// Now we can get the offsets of the tar archive
	var tarArchiveOffset uint64
	if epkBytes.IsFileStream {
		var tarArchiveOffsetBytes = make([]byte, 8)
		_, err := epkBytes.FileStream.ReadAt(tarArchiveOffsetBytes, 4)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotRead
		}
		if littleEndian {
			tarArchiveOffset = binary.LittleEndian.Uint64(tarArchiveOffsetBytes)
		} else {
			tarArchiveOffset = binary.BigEndian.Uint64(tarArchiveOffsetBytes)
		}
	} else {
		if littleEndian {
			tarArchiveOffset = binary.LittleEndian.Uint64(epkBytes.Bytes[4:12])
		} else {
			tarArchiveOffset = binary.BigEndian.Uint64(epkBytes.Bytes[4:12])
		}
	}

	// We don't need to validate the signature yet. We will do that when we map the full EPK, because it means
	// we have to read the entire thing, which is a waste of resources, since we only need the metadata.
	var preMapEpk EPKPreMap
	if epkBytes.IsFileStream {
		var metadataBuffer = make([]byte, tarArchiveOffset-ConstMapEPKMetadataOffset)
		_, err := epkBytes.FileStream.ReadAt(metadataBuffer, int64(ConstMapEPKMetadataOffset))
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotRead
		}
		preMapEpk, err = preMapEpkFromBytes(metadataBuffer, littleEndian, epkSize, tarArchiveOffset)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotMapJSON
		}
	} else {
		var err error
		preMapEpk, err = preMapEpkFromBytes(epkBytes.Bytes[ConstMapEPKMetadataOffset:tarArchiveOffset], littleEndian, epkSize, tarArchiveOffset)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapEPKCouldNotMapJSON
		}
	}

	return preMapEpk, nil, nil
}

var ErrPreMapRemoteEPKCouldNotCreateURL = errors.New("could not create URL")
var ErrPreMapRemoteEPKCouldNotCreateRequest = errors.New("could not create request")
var ErrPreMapRemoteEPKCouldNotSendRequest = errors.New("could not send request")
var ErrPreMapRemoteEPKCouldNotRead = errors.New("could not read EPK")
var ErrPreMapRemoteEPKCouldNotCloseConnection = errors.New("could not close connection")
var ErrPreMapRemoteEPKUnexpectedStatusCode = errors.New("unexpected status code")
var ErrPreMapEPKHasNotGotEPKMagic = errors.New("not an EPK")
var ErrPreMapRemoteEPKInvalidEndian = errors.New("invalid endian")
var ErrPreMapRemoteEPKCouldNotMapJSON = errors.New("error mapping metadata")

func PreMapRemoteEPK(remoteEPK RemoteEPK, logger *Logger) (EPKPreMap, error, error) {
	// Fetch the first 12 bytes of the EPK - this contains the magic, endian, and offset
	// We use the range header to only fetch the first 12 bytes
	packageUrl, err := url.JoinPath(remoteEPK.Repository.URL, remoteEPK.Path)
	if err != nil {
		return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotCreateURL
	}
	req, err := http.NewRequest("GET", packageUrl, nil)
	if err != nil {
		return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotCreateRequest
	}
	req.Header.Set("Range", "bytes=0-12")
	resp, err := http.DefaultClient.Do(req)
	if err != nil {
		return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotSendRequest
	}

	// Check if the status code is 206 (partial content)
	var epkHeaderBytes = make([]byte, 12)
	var rangeSupported bool
	if resp.StatusCode == 200 {
		// We have the entire file. Not great, not terrible.
		// We'll have to cut off the connection early later. To optimise things slightly, we'll reuse this connection
		// to read the metadata later.

		// I'm deadly serious about the radiation. It could cause a bit flip causing the Range header to be malformed.
		// It's amazing how many times I error handled for this, and I hope I can save someone from cancer one day.
		logger.LogFunc(Log{
			Level: "INFO",
			Content: "The server does not support range requests. The installation process will be significantly slower." +
				"Is the repository owner using python3's SimpleHTTPServer or similar? If so, please use a proper web " +
				"server like Nginx, Ailur HTTP Server, or Apache. If not, please report this to the repository owner or " +
				"check for sources of radiation around your computer.",
		})

		_, err := resp.Body.Read(epkHeaderBytes)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotRead
		}
		rangeSupported = false
	} else if resp.StatusCode == 206 {
		// Great, everything is working as expected.
		_, err := io.ReadFull(resp.Body, epkHeaderBytes)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotRead
		}
		rangeSupported = true
		// Close the connection
		err = resp.Body.Close()
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotCloseConnection
		}
	} else if resp.StatusCode == 404 {
		// Repository not found
		return EPKPreMap{}, errors.New("repository not found: " + strconv.Itoa(resp.StatusCode)), ErrPreMapRemoteEPKUnexpectedStatusCode
	} else {
		// Something went wrong
		return EPKPreMap{}, errors.New("unexpected status code: " + strconv.Itoa(resp.StatusCode)), ErrPreMapRemoteEPKUnexpectedStatusCode
	}

	// Now we verify the magic bytes
	if string(epkHeaderBytes[0:3]) != "epk" {
		return EPKPreMap{}, nil, ErrPreMapEPKHasNotGotEPKMagic
	}

	// Let's determine the endian-ness of the EPK via the 3rd byte
	var littleEndian bool
	if epkHeaderBytes[3] == 0x6C {
		littleEndian = true
	} else if epkHeaderBytes[3] == 0x62 {
		littleEndian = false
	} else {
		return EPKPreMap{}, nil, ErrPreMapRemoteEPKInvalidEndian
	}

	// Now we can get the offsets of the tar archive
	var tarArchiveOffset uint64
	if littleEndian {
		tarArchiveOffset = binary.LittleEndian.Uint64(epkHeaderBytes[4:12])
	} else {
		tarArchiveOffset = binary.BigEndian.Uint64(epkHeaderBytes[4:12])
	}

	// No signature verification for you

	// Let's fetch the display data bytes
	displayDataBytes := make([]byte, tarArchiveOffset-ConstMapEPKMetadataOffset)
	if rangeSupported {
		// Send another request to fetch the display data
		req.Header.Set("Range", "bytes=108-"+strconv.FormatUint(tarArchiveOffset-1, 10))
		resp, err = http.DefaultClient.Do(req)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotSendRequest
		}
		// Read the display data
		_, err = io.ReadFull(resp.Body, displayDataBytes)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotRead
		}
		// Close the connection
		err = resp.Body.Close()
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotCloseConnection
		}
	} else {
		// Re-use the connection to read the display data
		// The offset will move automatically because we are reading from the same connection, therefore
		// meaning that the web server will have already iterated past the header
		_, err = io.ReadFull(resp.Body, displayDataBytes)
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotRead
		}

		// You didn't have to cut me off, make out like it never happened and that we were nothing
		// All I wanted was a header part, but you just had to go and give me the whole thing
		// Now you're just some obscure web server that I used to know
		err = resp.Body.Close()
		if err != nil {
			return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotCloseConnection
		}
	}

	// Now we can map the display data
	var preMapEpk EPKPreMap
	preMapEpk, err = preMapEpkFromBytes(displayDataBytes, littleEndian, remoteEPK.CompressedSize, tarArchiveOffset)
	if err != nil {
		return EPKPreMap{}, err, ErrPreMapRemoteEPKCouldNotMapJSON
	}

	return preMapEpk, nil, nil
}

func handlePublicKeyCheck(exists bool, matchingAuthor bool, matchingFingerprint bool, publicKey []byte, author string, addFingerprintToDB func([]byte, string, bool) error, logger *Logger) error {
	if !exists {
		if logger.PromptSupported {
			response := logger.LogFunc(Log{
				Level: "WARN",
				Content: "Public key not found in database.\nthe public key fingerprint is: " + author + " " + ByteToFingerprint(publicKey) +
					"\nWould you like to trust this key (y/n)?",
				Prompt: true,
			})
			if strings.ToLower(response) == "y" {
				err := addFingerprintToDB(publicKey, author, false)
				if err != nil {
					return err
				} else {
					logger.LogFunc(Log{
						Level:   "INFO",
						Content: "Public key added to database.",
					})
				}
			} else {
				logger.LogFunc(Log{
					Level:   "INFO",
					Content: "Installation cancelled.",
				})
			}
		} else {
			logger.LogFunc(Log{
				Level: "FATAL",
				Content: "Public key not found in database.\nthe public key fingerprint is:" + author + " " + ByteToFingerprint(publicKey) +
					"\nSince non-interactive mode is enabled, the installation will not proceed.",
			})
		}
	} else if !matchingAuthor {
		if logger.PromptSupported {
			response := logger.LogFunc(Log{
				Level: "WARN",
				Content: "Public key does not match the author.\nthe public key fingerprint is: " + author + " " + ByteToFingerprint(publicKey) +
					"\nWould you like to replace the key (y/n)?",
				Prompt: true,
			})
			if strings.ToLower(response) == "y" {
				err := addFingerprintToDB(publicKey, author, true)
				if err != nil {
					return err
				} else {
					logger.LogFunc(Log{
						Level:   "INFO",
						Content: "Public key replaced in database.",
					})
				}
			} else {
				logger.LogFunc(Log{
					Level:   "FATAL",
					Content: "Installation cancelled.",
				})
			}
		} else {
			logger.LogFunc(Log{
				Level: "FATAL",
				Content: "Public key does not match the author.\nThe public key is :" + author + " " + ByteToFingerprint(publicKey) +
					"\nSince non-interactive mode is enabled, the installation will not proceed.",
			})
		}
	} else if !matchingFingerprint {
		if logger.PromptSupported {
			response := logger.LogFunc(Log{
				Level: "WARN",
				Content: "Public key fingerprint does not match the author.\nThe public key is :" + author + " " + ByteToFingerprint(publicKey) +
					"\nThis may be a security risk. To replace the key, type \"Yes, do as I say!\". Otherwise, type anything else.",
				Prompt: true,
			})
			if response == "Yes, do as I say!" {
				err := addFingerprintToDB(publicKey, author, true)
				if err != nil {
					return err
				} else {
					logger.LogFunc(Log{
						Level:   "INFO",
						Content: "Public key replaced in database.",
					})
				}
			} else {
				logger.LogFunc(Log{
					Level:   "FATAL",
					Content: "Installation cancelled.",
				})
			}
		} else {
			logger.LogFunc(Log{
				Level: "FATAL",
				Content: "Public key fingerprint does not match the author.\nthe public key fingerprint is: " + author + " " + ByteToFingerprint(publicKey) +
					"\nSince non-interactive mode is enabled, the installation will not proceed.",
			})
		}
	}

	return nil
}

var ErrFullyMapMetadataCouldNotRead = errors.New("could not read EPK")
var ErrFullyMapMetadataCouldNotJump = errors.New("could not jump to offset")
var ErrFullyMapMetadataCouldNotAddFingerprint = errors.New("could not add fingerprint")
var ErrFullyMapMetadataCouldNotGetFingerprint = errors.New("could not get fingerprint")
var ErrFullyMapMetadataHasInvalidSignature = errors.New("invalid signature")
var ErrFullyMapMetadataCouldNotMapJSON = errors.New("error mapping metadata")

// FullyMapMetadata maps an EPK file, but is significantly slower than PreMapEPK. Use PreMapEPK if you only need the display data.
// it pulls data from PreMapEPK to reduce the amount of work needed to map the EPK.
func FullyMapMetadata(epkBytes StreamOrBytes, preMap *EPKPreMap, checkFingerprintInDB func([]byte, string) (bool, bool, bool, error), addFingerprintToDB func([]byte, string, bool) error, warnUserAboutNoRange func(*Logger), logger *Logger) (*Metadata, error, error) {
	// We define the signature and public key bytes here so that we can read them later
	signature := make([]byte, 64)
	publicKey := make([]byte, 32)

	var connection io.ReadCloser
	if epkBytes.IsFileStream {
		// Before we continue, check if the signature is valid
		// To get the signature, we read from the 12th byte to the 76th byte
		_, err := epkBytes.FileStream.ReadAt(signature, 12)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}

		// To get the public key, we read from the 76th byte to the 108th byte
		_, err = epkBytes.FileStream.ReadAt(publicKey, 76)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
	} else if epkBytes.IsURL {
		// Before we continue, check if the signature is valid
		// Fetch range 12 - EOF and read them in
		req, err := http.NewRequest("GET", epkBytes.URL, nil)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
		req.Header.Set("Range", "bytes=12-")
		resp, err := http.DefaultClient.Do(req)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
		// Set the connection
		connection = resp.Body
		// Check the status code
		if resp.StatusCode == 200 {
			// Not great, not terrible.
			// We'll have to cut off the connection early later.
			// Warn the user
			warnUserAboutNoRange(logger)
			// Discard the first 12 bytes
			_, err := io.CopyN(io.Discard, connection, 12)
			if err != nil {
				return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
			}
		} else if resp.StatusCode != 206 {
			return &Metadata{}, errors.New("unexpected status code: " + strconv.Itoa(resp.StatusCode)), ErrFullyMapMetadataCouldNotRead
		}

		// Read the signature
		_, err = io.ReadFull(connection, signature)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}

		// Read the public key
		_, err = io.ReadFull(connection, publicKey)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
	} else {
		// Make signature and public key the optimised bytes
		signature = epkBytes.Bytes[12:76]
		publicKey = epkBytes.Bytes[76:108]
	}

	// Let's check for the public key in the database
	exists, matchingAuthor, matchingFingerprint, err := checkFingerprintInDB(publicKey, preMap.DisplayData.Author)
	if err != nil {
		return &Metadata{}, err, ErrFullyMapMetadataCouldNotGetFingerprint
	} else {
		err := handlePublicKeyCheck(exists, matchingAuthor, matchingFingerprint, publicKey, preMap.DisplayData.Author, addFingerprintToDB, logger)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotAddFingerprint
		}
	}

	// We need to create a new xxHash instance
	xxHash := xxhash.New()
	if epkBytes.IsFileStream {
		// Now we can verify the signature. First, we need to take the checksum of the metadata
		// Seeking is better than using ReadAt because it allows us to not have to load the entire file into memory
		_, err = epkBytes.FileStream.Seek(int64(ConstMapEPKMetadataOffset), io.SeekStart)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotJump
		}

		// Streaming bytes to the hash is more memory efficient
		_, err = epkBytes.FileStream.WriteTo(xxHash)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
		// Verify the signature (we verify the hash because it's cheaper than verifying the entire EPK)
		if !ed25519.Verify(publicKey, xxHash.Sum(nil), signature) {
			return &Metadata{}, nil, ErrFullyMapMetadataHasInvalidSignature
		}
	} else if epkBytes.IsURL {
		// Now we can verify the signature. We can just stream the rest of the EPK to the hash
		_, err = io.Copy(xxHash, connection)
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
		// You didn't have to cut me off...
		// Don't worry, we are reading to EOF anyway, no matter if we do have a non-range supported server, so we
		// (probably) won't upset the server owner.
		err = connection.Close()
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}

		// Verify the signature (we verify the hash because it's cheaper than verifying the entire EPK)
		if !ed25519.Verify(publicKey, xxHash.Sum(nil), signature) {
			return &Metadata{}, nil, ErrFullyMapMetadataHasInvalidSignature
		}
	} else {
		// We now verify the signature in one go without streaming
		_, err := xxHash.Write(epkBytes.Bytes[ConstMapEPKMetadataOffset:])
		if err != nil {
			return &Metadata{}, err, ErrFullyMapMetadataCouldNotRead
		}
		if !ed25519.Verify(publicKey, xxHash.Sum(nil), signature) {
			return &Metadata{}, nil, ErrFullyMapMetadataHasInvalidSignature
		}
	}

	// Great, the EPK is valid. Let's map the metadata.
	// We use the metadata map provided by PreMapEPK to reduce the amount of work needed to map the EPK

	// First, map SpecialFiles
	var parsedSpecialFiles SpecialFiles
	specialFilesMap, ok := preMap.MetadataMap["specialFiles"].(map[string]interface{})
	if !ok {
		return &Metadata{}, errors.New("specialFiles is not an object"), ErrFullyMapMetadataCouldNotMapJSON
	}
	noDelete, ok := specialFilesMap["noDelete"].([]interface{})
	if !ok {
		return &Metadata{}, errors.New("noDelete is not an array"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedSpecialFiles.NoDelete, err = interfaceToStringSlice(noDelete, "noDelete")
	if err != nil {
		return &Metadata{}, err, ErrFullyMapMetadataCouldNotMapJSON
	}
	noReplace, ok := specialFilesMap["noReplace"].([]interface{})
	if !ok {
		return &Metadata{}, errors.New("noReplace is not an array"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedSpecialFiles.NoReplace, err = interfaceToStringSlice(noReplace, "noReplace")
	if err != nil {
		return &Metadata{}, err, ErrFullyMapMetadataCouldNotMapJSON
	}

	// Declare the parsedMetadata object
	var parsedMetadata Metadata

	// Append parsedSpecialFiles to parsedMetadata
	parsedMetadata.SpecialFiles = parsedSpecialFiles

	// Steal some data from the PreMapEPK object
	parsedMetadata.Name = preMap.DisplayData.Name
	parsedMetadata.Version = preMap.DisplayData.Version
	parsedMetadata.Architecture = preMap.DisplayData.Architecture
	parsedMetadata.Size = preMap.DisplayData.Size
	parsedMetadata.Dependencies = preMap.DisplayData.Dependencies

	// Map the metadata
	parsedMetadata.Description, ok = preMap.MetadataMap["desc"].(string)
	if !ok {
		return &Metadata{}, errors.New("description is not a string"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedMetadata.LongDescription, ok = preMap.MetadataMap["longDesc"].(string)
	if !ok {
		return &Metadata{}, errors.New("longDesc is not a string"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedMetadata.Author, ok = preMap.MetadataMap["author"].(string)
	if !ok {
		return &Metadata{}, errors.New("author is not a string"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedMetadata.License, ok = preMap.MetadataMap["license"].(string)
	if !ok {
		return &Metadata{}, errors.New("license is not a string"), ErrFullyMapMetadataCouldNotMapJSON
	}
	decompressedSizeJSON, ok := preMap.MetadataMap["size"].(json.Number)
	if !ok {
		return &Metadata{}, errors.New("size is not a number"), ErrFullyMapMetadataCouldNotMapJSON
	}
	parsedMetadata.DecompressedSize, err = strconv.ParseUint(decompressedSizeJSON.String(), 10, 64)
	if err != nil {
		return &Metadata{}, err, ErrFullyMapMetadataCouldNotMapJSON
	}

	return &parsedMetadata, nil, nil
}

var ErrInstallEPKCouldNotCreateTempDir = errors.New("could not create temporary directory")
var ErrInstallEPKCouldNotCreateZStandardReader = errors.New("could not create ZStandard reader")
var ErrInstallEPKCouldNotDecompressTarArchive = errors.New("could not decompress tar archive")
var ErrInstallEPKCouldNotCreateDir = errors.New("could not create directory")
var ErrInstallEPKCouldNotStatDir = errors.New("could not stat directory")
var ErrInstallEPKCouldNotStatFile = errors.New("could not stat file")
var ErrInstallEPKCouldNotCreateFile = errors.New("could not create file")
var ErrInstallEPKCouldNotCloseTarReader = errors.New("could not close tar reader")
var ErrInstallEPKCouldNotStatHook = errors.New("could not stat hook")
var ErrInstallEPKCouldNotRunHook = errors.New("could not run hook")
var ErrInstallEPKCouldNotAddEPKToDB = errors.New("could not add EPK to database")
var ErrInstallEPKCouldNotRemoveTempDir = errors.New("could not remove temporary directory")

// ProgressWriter implements a writer that intercepts writes in order to log progress
type ProgressWriter struct {
	Logger *Logger
	Total  uint64
	Writer io.Writer
}

// Write writes to the ProgressWriter
func (writer *ProgressWriter) Write(p []byte) (n int, err error) {
	var byteCount uint64
	for range p {
		byteCount++
	}
	if writer.Logger.ProgressSupported {
		writer.Logger.LogFunc(Log{
			Level:     "PROGRESS",
			Progress:  byteCount,
			Total:     writer.Total,
			Overwrite: true,
		})
	} else {
		writer.Logger.LogFunc(Log{
			Level:   "INFO",
			Content: "Written " + humanize.Bytes(byteCount) + " out of " + humanize.Bytes(writer.Total),
			Prompt:  false,
		})
	}

	written, err := writer.Writer.Write(p)
	if err != nil {
		return written, err
	}

	return written, nil
}

// InstallEPK installs an EPK file
func InstallEPK(epkBytes StreamOrBytes, metadata *Metadata, preMap *EPKPreMap, addEPKToDB func(*Metadata, []string, []byte, bool, bool, uint64, uint64, string) error, logger *Logger) (string, error, error) {
	// Create the temporary directory
	tempDir, err := os.MkdirTemp("/tmp", "eon-install-")
	if err != nil {
		return tempDir, err, ErrInstallEPKCouldNotCreateTempDir
	}

	var zStandardReader *zstd.Decoder
	var connection io.ReadCloser
	if epkBytes.IsFileStream {
		// Seek to the correct position in the EPK
		_, err = epkBytes.FileStream.Seek(int64(preMap.TarOffset), io.SeekStart)
		if err != nil {
			return "", err, nil
		}

		// Create a ZStandard reader reading from the EPK
		zStandardReader, err = zstd.NewReader(epkBytes.FileStream)
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCreateZStandardReader
		}
	} else if epkBytes.IsURL {
		// Range header to the tar offset
		req, err := http.NewRequest("GET", epkBytes.URL, nil)
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCreateZStandardReader
		}
		// Set the range header
		req.Header.Set("Range", "bytes="+strconv.FormatUint(preMap.TarOffset, 10)+"-")
		// Send the request
		resp, err := http.DefaultClient.Do(req)
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCreateZStandardReader
		}
		// Set connection to the response body
		connection = resp.Body
		// Check the status code
		if resp.StatusCode == 200 {
			// Not great, is terrible in this case, we have to keep reading bytes and discarding them until we reach the offset
			// The user will have already been warned about 300 times, so we don't need to warn them again
			// God this is painful. Let's give the user a progress bar to make it less painful
			_, err := io.CopyN(&ProgressWriter{
				Logger: logger,
				Total:  preMap.TarOffset,
				Writer: io.Discard,
			}, connection, int64(preMap.TarOffset))
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotDecompressTarArchive
			}
		} else if resp.StatusCode != 206 {
			// Something went wrong
			return tempDir, errors.New("unexpected status code: " + strconv.Itoa(resp.StatusCode)), ErrInstallEPKCouldNotCreateZStandardReader
		}
		// Create a ZStandard reader reading from the EPK
		zStandardReader, err = zstd.NewReader(connection)
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCreateZStandardReader
		}
	} else {
		// Create a ZStandard reader reading from the EPKs in-memory bytes
		zStandardReader, err = zstd.NewReader(bytes.NewReader(epkBytes.Bytes[preMap.TarOffset:]))
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCreateZStandardReader
		}
	}

	// Create a tar reader reading from the ZStandard reader
	tarReader := tar.NewReader(zStandardReader)

	// Create a goroutine to see how much of the decompressed size we have decompressed
	var written uint64
	stop := make(chan bool)
	go func() {
		for {
			select {
			case <-stop:
				return
			default:
				if logger.ProgressSupported {
					logger.LogFunc(Log{
						Level:     "PROGRESS",
						Progress:  written,
						Total:     metadata.DecompressedSize,
						Overwrite: true,
					})
				} else {
					logger.LogFunc(Log{
						Level:   "INFO",
						Content: "Decompressed " + humanize.Bytes(written) + " of " + humanize.Bytes(metadata.DecompressedSize),
						Prompt:  false,
					})
					time.Sleep(1 * time.Second)
				}
			}
		}
	}()

	// Create a slice of the installed files
	var installedFiles []string

	// Iterate through the tar archive
	for {
		// Read the next header
		header, err := tarReader.Next()
		if err != nil {
			break
		}

		switch {
		// If we are done, break
		case err == io.EOF:
			break

		// If there was an error, return the error
		case err != nil:
			return tempDir, err, ErrInstallEPKCouldNotDecompressTarArchive

		// This should never happen, but if it does, we should just continue
		case header == nil:
			continue
		}

		// Get the target path
		var target string
		var isHook bool
		if strings.HasPrefix(header.Name, "root") {
			target = strings.TrimPrefix(header.Name, "root")
		} else if strings.HasPrefix(header.Name, "hooks") {
			target = filepath.Join(tempDir, header.Name)
			isHook = true
		} else {
			return tempDir, errors.New("invalid path in EPK: " + header.Name), ErrInstallEPKCouldNotDecompressTarArchive
		}

		switch header.Typeflag {
		case tar.TypeDir:
			// Check if the directory exists
			_, err := os.Stat(target)
			if err != nil {
				// If the directory does not exist, create it
				if errors.Is(err, os.ErrNotExist) {
					// All directories are 0755
					paths, err := MkdirAllWithPaths(target, 0755)
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCreateDir
					} else {
						// Check if the files are in noDelete
						for _, file := range metadata.SpecialFiles.NoDelete {
							if strings.TrimSuffix(target, "/") == strings.TrimSuffix(file, "/") {
								// This file is a special file and should not be deleted
								continue
							}
						}
						if !isHook {
							// Add the directory to the installed files
							installedFiles = append(installedFiles, target)

							// Add the paths to the installed files
							if paths != nil {
								installedFiles = append(installedFiles, paths...)
							}
						}
					}
				} else {
					return tempDir, err, ErrInstallEPKCouldNotStatDir
				}
			} else {
				// If it does exist, don't touch it
				continue
			}
		case tar.TypeReg:
			// Check if the file has anywhere to go
			_, err := os.Stat(filepath.Dir(target))
			if err != nil {
				// No, it doesn't. Create the directory
				if errors.Is(err, os.ErrNotExist) {
					// We assume 0755 for directories
					paths, err := MkdirAllWithPaths(filepath.Dir(target), 0755)
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCreateDir
					} else {
						// Check if the files are in noDelete
						for _, file := range metadata.SpecialFiles.NoDelete {
							if strings.TrimSuffix(target, "/") == strings.TrimSuffix(file, "/") {
								// This file is a special file and should not be deleted
								continue
							}
						}
						if !isHook {
							// Add the directory to the installed files
							installedFiles = append(installedFiles, filepath.Dir(target))

							// Add the paths to the installed files
							if paths != nil {
								installedFiles = append(installedFiles, paths...)
							}
						}
					}
				} else {
					return tempDir, err, ErrInstallEPKCouldNotStatDir
				}
			}

			// Check if the file already exists
			_, err = os.Stat(target)
			if err != nil {
				if errors.Is(err, os.ErrNotExist) {
					// Great, the file does not exist. Let's create it.
					file, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR|os.O_TRUNC, os.FileMode(header.Mode))
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCreateFile
					}

					writtenFile, err := io.Copy(file, tarReader)
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotDecompressTarArchive
					}

					written += uint64(writtenFile)

					err = file.Close()
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCloseTarReader
					} else {
						if !isHook {
							// Add the file to the installed files
							installedFiles = append(installedFiles, target)
						}
					}
				} else {
					return tempDir, err, ErrInstallEPKCouldNotStatFile
				}
			} else {
				// See if it's an upgrade or not
				if preMap.IsUpgrade {
					// Check if it's a special file
					for _, file := range metadata.SpecialFiles.NoReplace {
						if strings.TrimSuffix(target, "/") == strings.TrimSuffix(file, "/") {
							// This file is a special file and should not be replaced
							continue
						}
					}
				}

				// It's not special, so we can replace it
				file, err := os.OpenFile(target, os.O_CREATE|os.O_RDWR|os.O_TRUNC, os.FileMode(header.Mode))
				if err != nil {
					return tempDir, err, ErrInstallEPKCouldNotCreateFile
				}

				writtenFile, err := io.Copy(file, tarReader)
				if err != nil {
					return tempDir, err, ErrInstallEPKCouldNotDecompressTarArchive
				}

				written += uint64(writtenFile)

				err = file.Close()
				if err != nil {
					return tempDir, err, ErrInstallEPKCouldNotCloseTarReader
				} else {
					if !isHook {
						// Add the file to the installed files
						installedFiles = append(installedFiles, target)
					}
				}
			}
		case tar.TypeSymlink:
			// Check if the symlink has anywhere to go
			_, err := os.Stat(filepath.Dir(target))
			if err != nil {
				// No, it doesn't. Create the directory
				if errors.Is(err, os.ErrNotExist) {
					// We assume 0755 for directories
					paths, err := MkdirAllWithPaths(filepath.Dir(target), 0755)
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCreateDir
					} else {
						// Check if the files are in noDelete
						for _, file := range metadata.SpecialFiles.NoDelete {
							if strings.TrimSuffix(target, "/") == strings.TrimSuffix(file, "/") {
								// This file is a special file and should not be deleted
								continue
							}
						}
						if !isHook {
							// Add the directory to the installed files
							installedFiles = append(installedFiles, filepath.Dir(target))

							// Add the paths to the installed files
							if paths != nil {
								installedFiles = append(installedFiles, paths...)
							}
						}
					}
				} else {
					return tempDir, err, ErrInstallEPKCouldNotStatDir
				}
			}

			// Check if the symlink already exists
			_, err = os.Lstat(target)
			if err != nil {
				if errors.Is(err, os.ErrNotExist) {
					// Great, the symlink does not exist. Let's create it.

					err = os.Symlink(header.Linkname, target)
					if err != nil {
						return tempDir, err, ErrInstallEPKCouldNotCreateFile
					} else {
						if !isHook {
							// Add the symlink to the installed files
							installedFiles = append(installedFiles, target)
						}
					}
				} else {
					return tempDir, err, ErrInstallEPKCouldNotStatFile
				}
			} else {
				// See if it's an upgrade or not
				if preMap.IsUpgrade {
					// Check if it's a special file
					for _, file := range metadata.SpecialFiles.NoReplace {
						if strings.TrimSuffix(target, "/") == strings.TrimSuffix(file, "/") {
							// This file is a special file and should not be replaced
							continue
						}
					}
				}

				// It's not special, so we can replace it
				err = os.Remove(target)
				if err != nil {
					return tempDir, err, ErrInstallEPKCouldNotCreateFile
				}

				err = os.Symlink(header.Linkname, target)
				if err != nil {
					return tempDir, err, ErrInstallEPKCouldNotCreateFile
				} else {
					if !isHook {
						// Add the symlink to the installed files
						installedFiles = append(installedFiles, target)
					}
				}
			}
		}
	}

	zStandardReader.Close()

	// Close the connection if it's a URL
	if epkBytes.IsURL {
		err = connection.Close()
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotCloseTarReader
		}
	}

	// Now let's run the hooks
	if preMap.IsUpgrade {
		_, err := os.Stat(filepath.Join(tempDir, "hooks", "upgrade.sh"))
		if err != nil {
			if !errors.Is(err, os.ErrNotExist) {
				return tempDir, err, ErrInstallEPKCouldNotStatHook
			}
		} else {
			cmd := exec.Command("/bin/sh", filepath.Join(tempDir, "hooks", "upgrade.sh"), metadata.Version.String())
			stderr, err := cmd.StderrPipe()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
			err = cmd.Start()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
			scanner := bufio.NewScanner(stderr)
			scanner.Split(bufio.ScanWords)
			for scanner.Scan() {
				message := scanner.Text()
				logger.LogFunc(Log{
					Level:   "INFO",
					Content: message,
				})
			}
			err = cmd.Wait()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
		}
	} else {
		_, err := os.Stat(filepath.Join(tempDir, "hooks", "install.sh"))
		if err != nil {
			if !errors.Is(err, os.ErrNotExist) {
				return tempDir, err, ErrInstallEPKCouldNotStatHook
			}
		} else {
			cmd := exec.Command("/bin/sh", filepath.Join(tempDir, "hooks", "install.sh"), metadata.Version.String())
			stderr, err := cmd.StderrPipe()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
			err = cmd.Start()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
			scanner := bufio.NewScanner(stderr)
			scanner.Split(bufio.ScanWords)
			for scanner.Scan() {
				message := scanner.Text()
				logger.LogFunc(Log{
					Level:   "INFO",
					Content: message,
				})
			}
			err = cmd.Wait()
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotRunHook
			}
		}
	}

	// Do one more double-check to make sure nothing in installedFiles is in noDelete
	for _, file := range metadata.SpecialFiles.NoDelete {
		for index, installedFile := range installedFiles {
			if strings.TrimSuffix(installedFile, "/") == strings.TrimSuffix(file, "/") {
				// Remove the file from the installed files
				installedFiles = append(installedFiles[:index], installedFiles[index+1:]...)
			}
		}
	}

	// Finally, add the EPK and remove script to the database
	file, err := os.ReadFile(filepath.Join(tempDir, "hooks", "remove.sh"))
	if err != nil {
		if !errors.Is(err, os.ErrNotExist) {
			return tempDir, err, ErrInstallEPKCouldNotAddEPKToDB
		} else {
			var err error
			if !epkBytes.IsRemote {
				err = addEPKToDB(metadata, installedFiles, []byte{}, preMap.DisplayData.IsDependency, false, metadata.Size, metadata.DecompressedSize, "Local file")
			} else {
				err = addEPKToDB(metadata, installedFiles, []byte{}, preMap.DisplayData.IsDependency, false, metadata.Size, metadata.DecompressedSize, epkBytes.RepositoryName)
			}
			if err != nil {
				return tempDir, err, ErrInstallEPKCouldNotAddEPKToDB
			}
		}
	} else {
		var err error
		if !epkBytes.IsRemote {
			err = addEPKToDB(metadata, installedFiles, file, preMap.DisplayData.IsDependency, true, metadata.Size, metadata.DecompressedSize, "Local file")
		} else {
			err = addEPKToDB(metadata, installedFiles, file, preMap.DisplayData.IsDependency, true, metadata.Size, metadata.DecompressedSize, epkBytes.RepositoryName)
		}
		if err != nil {
			return tempDir, err, ErrInstallEPKCouldNotAddEPKToDB
		}
	}

	// Remove the temporary directory
	err = os.RemoveAll(tempDir)
	if err != nil {
		return tempDir, err, ErrInstallEPKCouldNotRemoveTempDir
	}

	stop <- true
	logger.LogFunc(Log{
		Level:     "PROGRESS",
		Progress:  1,
		Total:     1,
		Overwrite: true,
	})

	return "", nil, nil
}

var ErrAddRepositoryCouldNotCreateRequest = errors.New("could not create request")
var ErrAddRepositoryCouldNotSendRequest = errors.New("could not send request")
var ErrAddRepositoryHasUnexpectedStatusCode = errors.New("unexpected status code")
var ErrAddRepositoryCouldNotReadResponse = errors.New("could not read response")
var ErrAddRepositoryHasInvalidMagic = errors.New("invalid magic")
var ErrAddRepositoryCouldNotHash = errors.New("could not write to hash")
var ErrAddRepositoryCouldNotUnmarshalMetadata = errors.New("could not unmarshal metadata")
var ErrAddRepositoryCouldNotGetFingerprint = errors.New("could not get fingerprint")
var ErrAddRepositoryCouldNotAddFingerprint = errors.New("could not add fingerprint")
var ErrAddRepositoryHasInvalidMetadata = errors.New("invalid metadata")
var ErrAddRepositoryCouldNotAddPackage = errors.New("could not add package to database")
var ErrAddRepositoryHasRepositoryExists = errors.New("repository already exists")
var ErrAddRepositoryCouldNotAddRepository = errors.New("could not add repository to database")

// AddRepository adds a repository to the database
func AddRepository(url string, addRepositoryToDB func(Repository, bool) error, getFingerprintFromDB func([]byte, string) (bool, bool, bool, error), addFingerprintToDB func([]byte, string, bool) error, addRemotePackageToDB func(RemoteEPK) error, checkRepositoryInDB func(string) (bool, error), forceReplace bool, logger *Logger) (string, error, error) {
	// First, fetch range 0-3 of /repository.erf
	// Then, check if the first 3 bytes are "eon"

	// Create the request
	magicRequest, err := http.NewRequest("GET", url+"/repository.erf", nil)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotCreateRequest
	}

	// Add the range header
	magicRequest.Header.Add("Range", "bytes=0-3")

	// Send the request
	magicResponse, err := http.DefaultClient.Do(magicRequest)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotSendRequest
	}

	// Check if the status code is 206
	var hasEntireFile bool
	if magicResponse.StatusCode != 206 {
		if magicResponse.StatusCode == 200 {
			// This web server does not support range requests, meaning we now have the entire file.
			// Mark it as such.
			hasEntireFile = true
		} else {
			return "", errors.New("status code " + strconv.Itoa(magicResponse.StatusCode)), ErrAddRepositoryHasUnexpectedStatusCode
		}
	}

	// Check the magic bytes
	var magicBytes = make([]byte, 3)
	_, err = magicResponse.Body.Read(magicBytes)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotReadResponse
	}

	// Check if the magic bytes are "eon"
	if string(magicBytes) != "eon" {
		return "", nil, ErrAddRepositoryHasInvalidMagic
	}

	// Great. We either confirmed the repository is an Eon repository or we have the entire file.
	var fullFetch *http.Response
	if !hasEntireFile {
		// Download the rest of the file
		var err error
		fullFetch, err = http.Get(url + "/repository.erf")
		if err != nil {
			return "", err, ErrAddRepositoryCouldNotSendRequest
		}
	} else {
		fullFetch = magicResponse
	}

	// Now we get the contents of the file
	contents, err := io.ReadAll(fullFetch.Body)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotReadResponse
	}

	// Verify the file's signature

	// Unmarshal the repository metadata, which is NOT the same as the EPK metadata
	var repositoryMetadata map[string]interface{}
	// We use a decoder instead of unmarshal here because we need to use JSON numbers: float64 is not enough
	var jsonDecoder = json.NewDecoder(bytes.NewReader(contents[99:]))
	jsonDecoder.UseNumber()
	err = jsonDecoder.Decode(&repositoryMetadata)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotUnmarshalMetadata
	}

	// Get the public key and signature
	signature := contents[3:67]
	publicKey := contents[67:99]

	// Look for the public key in the database
	exists, matchingAuthor, matchingFingerprint, err := getFingerprintFromDB(publicKey, repositoryMetadata["author"].(string))
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotGetFingerprint
	} else {
		err := handlePublicKeyCheck(exists, matchingAuthor, matchingFingerprint, publicKey, repositoryMetadata["author"].(string), addFingerprintToDB, logger)
		if err != nil {
			return "", err, ErrAddRepositoryCouldNotAddFingerprint
		}
	}

	// We need to create a new xxHash instance
	xxHash := xxhash.New()
	_, err = xxHash.Write(contents[99:])
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotHash
	}

	// Verify the signature
	if !ed25519.Verify(publicKey, xxHash.Sum(nil), signature) {
		return "", errors.New("invalid signature"), ErrAddRepositoryHasInvalidMetadata
	}

	// Now we can create the repository object
	var repository Repository
	var ok bool
	repository.URL = url
	repository.Name, ok = repositoryMetadata["name"].(string)
	if !ok {
		return "", errors.New("name is not a string"), ErrAddRepositoryHasInvalidMetadata
	}

	// In force replace mode, we don't check if the repository already exists and just replace it
	if !forceReplace {
		// Side quest: check if the repository already exists
		repoExists, err := checkRepositoryInDB(repository.Name)
		if err != nil {
			return "", err, ErrAddRepositoryCouldNotAddRepository
		} else if repoExists {
			return "", nil, ErrAddRepositoryHasRepositoryExists
		}
	}

	repository.Description, ok = repositoryMetadata["desc"].(string)
	if !ok {
		return "", errors.New("desc is not a string"), ErrAddRepositoryHasInvalidMetadata
	}
	repository.Owner, ok = repositoryMetadata["author"].(string)
	if !ok {
		return "", errors.New("author is not a string"), ErrAddRepositoryHasInvalidMetadata
	}

	// Write the contents of the repository to the database
	packageList, ok := repositoryMetadata["packages"].([]interface{})
	if !ok {
		return "", errors.New("packages is not an array"), ErrAddRepositoryHasInvalidMetadata
	}

	var remoteEPKs []RemoteEPK
	for _, epk := range packageList {
		epk, ok := epk.(map[string]interface{})
		if !ok {
			return "", errors.New("package is not an object"), ErrAddRepositoryHasInvalidMetadata
		}

		name, ok := epk["name"].(string)
		if !ok {
			return "", errors.New("package name is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		author, ok := epk["author"].(string)
		if !ok {
			return "", errors.New("package author is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		arch, ok := epk["arch"].(string)
		if !ok {
			return "", errors.New("package arch is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		versionString, ok := epk["version"].(string)
		if !ok {
			return "", errors.New("package version is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		versionPointer, err := semver.NewVersion(versionString)
		if err != nil {
			return "", errors.New("package version is not a valid semver version"), ErrAddRepositoryHasInvalidMetadata
		}

		sizeString, ok := epk["size"].(json.Number)
		if !ok {
			return "", errors.New("package size is not a number"), ErrAddRepositoryHasInvalidMetadata
		}

		size, err := strconv.ParseUint(sizeString.String(), 10, 64)
		if err != nil {
			return "", errors.New("package size is not a number"), ErrAddRepositoryHasInvalidMetadata
		}

		dependenciesInterface, ok := epk["deps"].([]interface{})
		if !ok {
			return "", errors.New("package dependencies is not an array"), ErrAddRepositoryHasInvalidMetadata
		}

		dependencies, err := interfaceToStringSlice(dependenciesInterface, "dependencies")
		if err != nil {
			return "", err, ErrAddRepositoryHasInvalidMetadata
		}

		hashJsonNumber, ok := epk["hash"].(json.Number)
		if !ok {
			return "", errors.New("package hash is not a number"), ErrAddRepositoryHasInvalidMetadata
		}

		var hash uint64
		hash, err = strconv.ParseUint(hashJsonNumber.String(), 10, 64)
		if err != nil {
			return "", errors.New("package hash is not a valid number"), ErrAddRepositoryHasInvalidMetadata
		}

		path, ok := epk["path"].(string)
		if !ok {
			return "", errors.New("package path is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		description, ok := epk["desc"].(string)
		if !ok {
			return "", errors.New("package description is not a string"), ErrAddRepositoryHasInvalidMetadata
		}

		remoteEPKs = append(remoteEPKs, RemoteEPK{
			Name:           name,
			Author:         author,
			Description:    description,
			Version:        *versionPointer,
			Architecture:   arch,
			CompressedSize: size,
			Dependencies:   dependencies,
			Path:           path,
			Arch:           arch,
			EPKHash:        hash,
			Repository:     repository,
		})
		if err != nil {
			return "", err, ErrAddRepositoryCouldNotAddPackage
		}
	}

	// We add packages afterward so that if there is an error, we don't have to remove the packages
	for _, epk := range remoteEPKs {
		err := addRemotePackageToDB(epk)
		if err != nil {
			return "", err, ErrAddRepositoryCouldNotAddPackage
		}
	}

	// Add the repository to the database
	err = addRepositoryToDB(repository, forceReplace)
	if err != nil {
		return "", err, ErrAddRepositoryCouldNotAddRepository
	}

	return repository.Name, nil, nil
}

var ErrRemoveRepositoryDoesNotExist = errors.New("repository does not exist")
var ErrRemoveRepositoryCouldNotFindRepository = errors.New("could not check for repository")
var ErrRemoveRepositoryCouldNotRemoveRepository = errors.New("could not remove repository")
var ErrRemoveRepositoryCouldNotRemoveRepositoryFromDB = errors.New("could not remove repository from database")

func RemoveRepository(repository string, removeRepositoryFromDB func(string) error, checkRepositoryInDB func(string) (bool, error), logger *Logger) (error, error) {
	// First check if the repository exists
	exists, err := checkRepositoryInDB(repository)
	if err != nil {
		return err, ErrRemoveRepositoryCouldNotFindRepository
	}

	if !exists {
		return nil, ErrRemoveRepositoryDoesNotExist
	}

	// Purge the download cache
	err = os.RemoveAll(filepath.Join("/var/cache/eon/repositories/", repository))
	if err != nil {
		return err, ErrRemoveRepositoryCouldNotRemoveRepository
	}

	// Remove the repository from the database
	err = removeRepositoryFromDB(repository)
	if err != nil {
		return err, ErrRemoveRepositoryCouldNotRemoveRepositoryFromDB
	}

	// Alright, we're done here.
	logger.LogFunc(Log{
		Level:   "INFO",
		Content: "Removed repository " + repository + " from the database.",
	})

	return nil, nil
}

var ErrRemoveEPKCouldNotFindEPK = errors.New("could not get EPK from database")
var ErrRemoveEPKCouldNotCreateTempFile = errors.New("could not create temporary file")
var ErrRemoveEPKCouldNotWriteTempFile = errors.New("could not write to temporary file")
var ErrRemoveEPKCouldNotRunRemoveHook = errors.New("could not run remove hook")
var ErrRemoveEPKCouldNotRemoveEPKFromDB = errors.New("could not remove EPK from database")
var ErrRemoveEPKCouldNotRemoveFiles = errors.New("could not remove files")

func RemoveEPK(name string, removeEPKFromDB func(string) error, getEPKRemoveInfoFromDB func(name string) (string, []string, error), logger *Logger) (error, error) {
	// Try to fetch the EPK from the database
	removeScript, installedPaths, err := getEPKRemoveInfoFromDB(name)
	if err != nil {
		return err, ErrRemoveEPKCouldNotFindEPK
	}

	// Save the remove script to a temporary file
	removeScriptFile, err := os.CreateTemp("", "eon-remove-*.sh")
	if err != nil {
		return err, ErrRemoveEPKCouldNotCreateTempFile
	}

	// Write the remove script to the file
	_, err = removeScriptFile.Write([]byte(removeScript))
	if err != nil {
		return err, ErrRemoveEPKCouldNotWriteTempFile
	}

	// Run the remove script
	cmd := exec.Command("/bin/sh", removeScriptFile.Name())
	stderr, err := cmd.StderrPipe()
	if err != nil {
		return err, ErrRemoveEPKCouldNotRunRemoveHook
	}

	// Start the command
	err = cmd.Start()
	if err != nil {
		return err, ErrRemoveEPKCouldNotRunRemoveHook
	}

	// Read the output
	scanner := bufio.NewScanner(stderr)
	scanner.Split(bufio.ScanWords)
	for scanner.Scan() {
		message := scanner.Text()
		logger.LogFunc(Log{
			Level:   "INFO",
			Content: message,
		})
	}

	// Close the file
	err = removeScriptFile.Close()
	if err != nil {
		return err, ErrRemoveEPKCouldNotRunRemoveHook
	}

	// Remove the EPK from the database
	err = removeEPKFromDB(name)
	if err != nil {
		return err, ErrRemoveEPKCouldNotRemoveEPKFromDB
	}

	// Remove the installed files
	for _, path := range installedPaths {
		// Check if there is anything in the paths not in installedPaths
		// If there is, we should not remove the directory
		err := filepath.Walk(path, func(path string, info os.FileInfo, err error) error {
			if err != nil {
				return err
			}

			// Check if the path is in installedPaths
			for _, installedPath := range installedPaths {
				if path == installedPath {
					return nil
				}
			}

			// If it's not, return an error
			return errors.New("path is not in installedPaths")
		})
		if err != nil {
			if errors.Is(err, errors.New("path is not in installedPaths")) {
				// The path is not in installedPaths, so we should not remove it
				continue
			} else if !errors.Is(err, os.ErrNotExist) {
				// Something else went wrong
				return err, ErrRemoveEPKCouldNotRemoveFiles
			}
		} else {
			// The path is in installedPaths, so we should remove it
			err := os.RemoveAll(path)
			if err != nil {
				if !errors.Is(err, os.ErrNotExist) {
					return err, ErrRemoveEPKCouldNotRemoveFiles
				} else {
					// The file does not exist - we must have deleted its parent directory or the user has done our job for us
					continue
				}
			}
		}
	}

	return nil, nil
}