package main

import (
	"archive/zip"
	"encoding/csv"
	"fmt"
	"io"
	"os"
	"path/filepath"
	"strings"
)

type App struct {
	ConfigDirPath string
}

type Game struct {
	ID         string
	Mods       map[string]Mod
	HasUpdated bool
}

func (game *Game) InstallMods(archivePaths []string) ([]string, error) {
	var processed = 0

	for i := range archivePaths {
		var archivePath = archivePaths[i]
		var suffixIndex = strings.LastIndex(archivePath, ".")

		if suffixIndex < 0 {
			return nil, fmt.Errorf("cannot determine file type of `%s`", archivePath)
		}

		var extension = archivePath[suffixIndex+1:]
		var extractor = extractors[extension]

		if extractor == nil {
			return nil, fmt.Errorf("unsupported file type `%s`", extension)
		}

		var gamePath, pathError = game.Path()

		if pathError != nil {
			return nil, pathError
		}

		var modName = filepath.Base(archivePath[:suffixIndex])

		if extractError := extractor(archivePath, filepath.Join(
			gamePath, "mods", modName)); extractError != nil {

			return nil, extractError
		}

		game.Mods[modName] = Mod{
			IsEnabled: false,
		}

		game.HasUpdated = true
		processed += 1
	}

	return archivePaths[0:processed], nil
}

type Mod struct {
	IsEnabled bool
}

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

	for i := range supportedGames {
		var supportedGame = supportedGames[i]

		if gameName == supportedGame {
			var game = Game{
				ID:         supportedGame,
				Mods:       make(map[string]Mod),
				HasUpdated: false,
			}

			var gamePath, pathError = game.Path()

			if pathError != nil {
				return pathError
			}

			var manifestPath = filepath.Join(gamePath, "mods.csv")

			// Load manifest from disk.
			{
				var manifestFile, openError = os.Open(manifestPath)

				if openError == nil {
					defer manifestFile.Close()

					var manifestReader = csv.NewReader(manifestFile)
					var recordValues, recordError = manifestReader.Read()

					for recordValues != nil {
						if recordError != nil {
							return recordError
						}

						if len(recordValues) < 2 {
							return fmt.Errorf("could not read mod manifest data - may be corrupt")
						}

						var status = recordValues[0]
						var name = recordValues[1]

						game.Mods[name] = Mod{
							IsEnabled: status == "*",
						}

						recordValues, recordError = manifestReader.Read()
					}
				}
			}

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

			// Save manifest back to disk.
			if game.HasUpdated {
				var manifestFile, openError = os.OpenFile(manifestPath,
					os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)

				if openError != nil {
					return openError
				}

				defer manifestFile.Close()

				var manifestWriter = csv.NewWriter(manifestFile)

				for name, mod := range game.Mods {
					var status = ""

					if mod.IsEnabled {
						status = "*"
					}

					manifestWriter.Write([]string{status, name})
				}

				manifestWriter.Flush()
			}

			return nil
		}
	}

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

func (game Game) Path() (string, error) {
	var configDirPath, configError = os.UserConfigDir()

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

	return filepath.Join(configDirPath, "modman", game.ID), nil
}

func (game *Game) RemoveMods(modNames []string) ([]string, error) {
	var gamePath, pathError = game.Path()

	if pathError != nil {
		return nil, pathError
	}

	var processed = 0

	for i := range modNames {
		var modName = modNames[i]

		if removeError := os.RemoveAll(filepath.Join(gamePath, modName)); removeError != nil {
			return nil, removeError
		}

		delete(game.Mods, modName)

		game.HasUpdated = true
		processed += 1
	}

	return modNames[0:processed], nil
}

func (game *Game) RenameMod(modName string, newName string) error {
	var gamePath, pathError = game.Path()

	if pathError != nil {
		return pathError
	}

	if _, exists := game.Mods[modName]; !(exists) {
		return fmt.Errorf("no mod with that name exists")
	}

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

	if renameError := os.Rename(filepath.Join(gamePath, modName),
		filepath.Join(gamePath, newName)); renameError != nil {

		return renameError
	}

	game.Mods[newName] = game.Mods[modName]

	delete(game.Mods, modName)

	game.HasUpdated = true

	return nil
}

var extractors = map[string]func(string, string) error{
	"zip": func(archivePath string, destinationPath string) error {
		var zipReader, openReaderError = zip.OpenReader(archivePath)

		if openReaderError != nil {
			return openReaderError
		}

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

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

		for i := range zipReader.File {
			var file = zipReader.File[i]
			var fileReader, fileOpenError = file.Open()

			if fileOpenError != nil {
				return fileOpenError
			}

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

			var path = filepath.Join(destinationPath, file.Name)

			if file.FileInfo().IsDir() {
				if mkdirError := os.MkdirAll(path, file.Mode()); mkdirError != nil {
					return mkdirError
				}
			} else {
				if mkdirError := os.MkdirAll(filepath.Dir(path), file.Mode()); mkdirError != nil {
					return mkdirError
				}

				var extractedFile, fileOpenError = os.OpenFile(path,
					os.O_WRONLY|os.O_CREATE|os.O_TRUNC, file.Mode())

				if fileOpenError != nil {
					return fileOpenError
				}

				defer func() {
					if fileOpenError := extractedFile.Close(); fileOpenError != nil {
						panic(fileOpenError)
					}
				}()

				var _, copyError = io.Copy(extractedFile, fileReader)

				if copyError != nil {
					return copyError
				}
			}
		}

		return nil
	},
}