package main

import (
	"archive/zip"
	"bufio"
	"fmt"
	"io"
	"io/fs"
	"os"
	"path/filepath"
	"strings"

	"sauce.pizzawednes.day/kayomn/ini-gusher"
)

func (game *Game) CleanDeployedMods() error {
	// Clean up currently deployed files first.
	for _, filePath := range game.DeployedFilePaths {
		var gameFilePath = filepath.Join(game.Path, filePath)

		if removeError := os.Remove(gameFilePath); removeError != nil {
			if !(os.IsNotExist(removeError)) {
				return removeError
			}
		}
	}

	game.DeployedFilePaths = game.DeployedFilePaths[:0]

	// Then restore all files overwritten by previously deployment.
	for _, filePath := range game.OverwrittenFilePaths {
		var backupDirPath, backupDirPathError = game.cachePath("overwritten")

		if backupDirPathError != nil {
			return backupDirPathError
		}

		if renameError := os.Rename(filepath.Join(backupDirPath, filePath),
			filepath.Join(game.Path, filePath)); renameError != nil {

			return renameError
		}
	}

	game.OverwrittenFilePaths = game.OverwrittenFilePaths[:0]

	return nil
}

func (game *Game) DeployMod(name string) error {
	var mod, exists = game.Mods[name]

	if !(exists) {
		return fmt.Errorf("mod does not exist: %s", name)
	}

	var archivePath, archivePathError = game.configPath(name)

	if archivePathError != nil {
		return archivePathError
	}

	switch mod.Format {
	case "zip":
		archivePath += ".zip"

		var zipReadCloser, zipReadCloserOpenError = zip.OpenReader(archivePath)

		if zipReadCloserOpenError != nil {
			return zipReadCloserOpenError
		}

		defer func() {
			if closeError := zipReadCloser.Close(); closeError != nil {
				panic(closeError)
			}
		}()

		for _, zipFile := range zipReadCloser.File {
			var deployPath = filepath.Join(game.Path, zipFile.Name)
			var fileMode = zipFile.Mode()

			if dirError := os.MkdirAll(filepath.Dir(deployPath), fileMode); dirError != nil {
				return dirError
			}

			if zipFile.FileInfo().IsDir() {
				// All work is done for creating a directory, rest is just for files.
				continue
			}

			var file, openFileError = os.OpenFile(
				deployPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, fileMode)

			if openFileError != nil {
				if !(os.IsExist(openFileError)) {
					return openFileError
				}

				var backupPath, backupPathError = game.cachePath("overwritten") // deployPath

				if backupPathError != nil {
					return backupPathError
				}

				backupPath = filepath.Join(backupPath, zipFile.Name)

				if dirError := os.MkdirAll(filepath.Dir(backupPath), 0755); dirError != nil {
					return dirError
				}

				if renameError := os.Rename(deployPath, backupPath); renameError != nil {
					return renameError
				}

				game.OverwrittenFilePaths = append(game.OverwrittenFilePaths, zipFile.Name)

				file, openFileError = os.OpenFile(
					deployPath, os.O_WRONLY|os.O_CREATE|os.O_EXCL, fileMode)

				if openFileError != nil {
					return openFileError
				}
			}

			var zipReadCloser, zipFileOpenError = zipFile.Open()

			if zipFileOpenError != nil {
				return zipFileOpenError
			}

			defer func() {
				if syncError := file.Sync(); syncError != nil {
					panic(syncError)
				}

				if closeError := file.Close(); closeError != nil {
					panic(closeError)
				}
			}()

			if _, copyError := io.Copy(file, zipReadCloser); copyError != nil {
				return copyError
			}

			game.DeployedFilePaths = append(game.DeployedFilePaths, zipFile.Name)
		}

	default:
		return fmt.Errorf("unsupported mod format: %s", mod.Format)
	}

	return nil
}

type Game struct {
	ID                   string
	DeployedFilePaths    []string
	OverwrittenFilePaths []string
	Mods                 map[string]Mod
	Path                 string
}

func (game *Game) InstallMod(archivePath string) error {
	var archiveBaseName = filepath.Base(archivePath)
	var archiveExtension = filepath.Ext(archiveBaseName)

	if len(archiveExtension) == 0 {
		return fmt.Errorf("unknown archive format: %s", archiveExtension)
	}

	var name = strings.TrimSuffix(archiveBaseName, archiveExtension)

	if _, exists := game.Mods[name]; exists {
		return fmt.Errorf("mod with name already exists: `%s`", name)
	}

	// Copy archive into installation directory.
	{
		var installPath, installPathError = game.configPath(name)

		if installPathError != nil {
			return installPathError
		}

		var sourceFile, sourceOpenError = os.Open(archivePath)

		if sourceOpenError != nil {
			return sourceOpenError
		}

		defer sourceFile.Close()

		var targetFile, targetCreateError = os.Create(installPath)

		if targetCreateError != nil {
			return targetCreateError
		}

		defer targetFile.Close()

		if _, copyError := io.Copy(targetFile, sourceFile); copyError != nil {
			return copyError
		}
	}

	game.Mods[name] = Mod{
		Format:  archiveExtension[1:],
		Source:  archivePath,
		Version: "",
	}

	return nil
}

func (game *Game) Load() error {
	// Read deployed files from disk.
	var deployedListPath, deployedListPathError = game.cachePath("deployed.txt")

	if deployedListPathError != nil {
		return deployedListPathError
	}

	if file, openError := os.Open(deployedListPath); openError == nil {
		defer func() {
			if closeError := file.Close(); closeError != nil {
				panic(closeError)
			}
		}()

		var scanner = bufio.NewScanner(file)

		for scanner.Scan() {
			game.DeployedFilePaths = append(game.DeployedFilePaths, scanner.Text())
		}
	} else if !(os.IsNotExist(openError)) {
		return openError
	}

	// Read overwritten files from disk.
	var overwriteDirPath, overwriteDirPathError = game.cachePath("overwritten")

	if overwriteDirPathError != nil {
		return overwriteDirPathError
	}

	if _, statError := os.Stat(overwriteDirPath); statError == nil {
		if walkError := filepath.WalkDir(overwriteDirPath, func(
			path string, dirEntry fs.DirEntry, walkError error) error {

			if walkError != nil {
				return walkError
			}

			if !(dirEntry.IsDir()) {
				game.OverwrittenFilePaths = append(game.OverwrittenFilePaths, path)
			}

			return nil
		}); walkError != nil {
			return walkError
		}
	} else if !(os.IsNotExist(statError)) {
		return statError
	}

	// Read mod info from disk.
	var modInfoPath, modInfoPathError = game.configPath("mods.ini")

	if modInfoPathError != nil {
		return modInfoPathError
	}

	if file, openError := os.Open(modInfoPath); openError == nil {
		defer func() {
			if closeError := file.Close(); closeError != nil {
				panic(closeError)
			}
		}()

		var parser = ini.NewParser(file)

		for entry := parser.Parse(); !(parser.IsEnd()); entry = parser.Parse() {
			var mod = game.Mods[entry.Section]

			switch entry.Key {
			case "format":
				mod.Format = entry.Value

			case "source":
				mod.Source = entry.Value

			case "version":
				mod.Version = entry.Value
			}

			game.Mods[entry.Section] = mod
		}

		if parserError := parser.Err(); parserError != nil {
			return parserError
		}
	} else if !(os.IsNotExist(openError)) {
		return openError
	}

	return nil
}

type Mod struct {
	Format  string
	Source  string
	Version string
}

func (game *Game) RemoveMods(names []string) error {
	for _, name := range names {
		if _, exists := game.Mods[name]; !(exists) {
			return fmt.Errorf("unknown mod: `%s`", name)
		}

		var path, pathError = game.configPath(name)

		if pathError != nil {
			return pathError
		}

		if removeError := os.RemoveAll(path); removeError != nil {
			return removeError
		}

		delete(game.Mods, name)
	}

	return nil
}

func (game *Game) RenameMod(modName string, newName string) error {
	if _, exists := game.Mods[modName]; !(exists) {
		return fmt.Errorf("no mod with that name exists")
	}

	if _, nameTaken := game.Mods[newName]; nameTaken {
		return fmt.Errorf("a mod with the new name already exists")
	}

	var modPath, modPathError = game.configPath(modName)

	if modPathError != nil {
		return modPathError
	}

	var newPath, newPathError = game.configPath(modName)

	if newPathError != nil {
		return newPathError
	}

	if renameError := os.Rename(modPath, newPath); renameError != nil {
		return renameError
	}

	var mod = game.Mods[modName]

	game.Mods[newName] = mod

	delete(game.Mods, modName)

	return nil
}

func (game *Game) Save() error {
	// Write deployed files to disk.
	var deployedListPath, deployedListPathError = game.cachePath("deployed.txt")

	if deployedListPathError != nil {
		return deployedListPathError
	}

	var deployedListFile, deployedListCreateError = os.Create(deployedListPath)

	if deployedListCreateError != nil {
		return deployedListCreateError
	}

	defer func() {
		if syncError := deployedListFile.Sync(); syncError != nil {
			panic(syncError)
		}

		if closeError := deployedListFile.Close(); closeError != nil {
			panic(closeError)
		}
	}()

	var deployedListWriter = bufio.NewWriter(deployedListFile)

	defer func() {
		if flushError := deployedListWriter.Flush(); flushError != nil {
			panic(flushError)
		}
	}()

	for _, filePath := range game.DeployedFilePaths {
		if _, writeError := deployedListWriter.WriteString(filePath); writeError != nil {
			return writeError
		}

		if writeError := deployedListWriter.WriteByte('\n'); writeError != nil {
			return writeError
		}
	}

	// Read mod info from disk.
	var modInfoPath, modInfoPathError = game.configPath("mods.ini")

	if modInfoPathError != nil {
		return modInfoPathError
	}

	var modInfoFile, modInfoCreateError = os.Create(modInfoPath)

	if modInfoCreateError != nil {
		return modInfoCreateError
	}

	defer func() {
		if closeError := modInfoFile.Close(); closeError != nil {
			panic(closeError)
		}
	}()

	var modInfoEntries = make([]ini.Entry, 0, len(game.Mods)*3)

	for name, mod := range game.Mods {
		modInfoEntries = append(modInfoEntries, ini.Entry{
			Section: name,
			Key:     "source",
			Value:   mod.Source,
		})

		modInfoEntries = append(modInfoEntries, ini.Entry{
			Section: name,
			Key:     "format",
			Value:   mod.Format,
		})

		modInfoEntries = append(modInfoEntries, ini.Entry{
			Section: name,
			Key:     "version",
			Value:   mod.Version,
		})
	}

	return ini.Write(modInfoFile, modInfoEntries)
}

func WithGame(gameName string, action func(*Game) error) error {
	var supportedGames = []string{"fallout4", "falloutnv", "skyrim"}

	for _, supportedGame := range supportedGames {
		if gameName == supportedGame {
			var game = Game{
				ID:                   supportedGame,
				OverwrittenFilePaths: make([]string, 0, 512),
				DeployedFilePaths:    make([]string, 0, 512),
				Mods:                 make(map[string]Mod),
				Path:                 "/home/kayomn/.steam/steam/steamapps/common/Fallout 4/Data",
			}

			if loadError := game.Load(); loadError != nil {
				return loadError
			}

			if actionError := action(&game); actionError != nil {
				return actionError
			}

			if saveError := game.Save(); saveError != nil {
				return saveError
			}

			return nil
		}
	}

	return fmt.Errorf("%s: game not supported", gameName)
}

func (game *Game) cachePath(path string) (string, error) {
	var dirPath, pathError = os.UserCacheDir()

	if pathError != nil {
		return "", pathError
	}

	dirPath = filepath.Join(dirPath, "modman", game.ID)

	if mkdirError := os.MkdirAll(dirPath, 0755); mkdirError != nil {
		return "", mkdirError
	}

	return filepath.Join(dirPath, path), nil
}

func (game *Game) configPath(path string) (string, error) {
	var dirPath, pathError = os.UserConfigDir()

	if pathError != nil {
		return "", pathError
	}

	dirPath = filepath.Join(dirPath, "modman", game.ID)

	if mkdirError := os.MkdirAll(dirPath, 0755); mkdirError != nil {
		return "", mkdirError
	}

	return filepath.Join(dirPath, path), nil
}