package main

import (
	"encoding/json"
	"fmt"
	"os"
)

type Command struct {
	Name        string
	Description string
	Action      func([]string) (string, error)
	Arguments   []string
	IsVarargs   bool
}

var commands = []Command{
	{
		Name:        "install",
		Description: "Install one or more mod archives into modman",
		Arguments:   []string{"game name", "archive path"},
		IsVarargs:   true,

		Action: func(arguments []string) (string, error) {
			var argumentCount = len(arguments)

			if argumentCount == 0 {
				return "", fmt.Errorf("expected game name")
			}

			var modsToInstall = arguments[1:]
			var installedMods = []string{}

			if gameError := WithGame(arguments[0], func(game *Game) error {
				var installed, installError = game.InstallMods(modsToInstall)

				if installError != nil {
					return installError
				}

				installedMods = installed

				return nil
			}); gameError != nil {
				return "", gameError
			}

			return fmt.Sprint(len(installedMods), " of ", len(modsToInstall), " installed"), nil
		},
	},

	{
		Name:        "remove",
		Description: "Remove one or more mods from modman",
		Arguments:   []string{"game name", "mod name"},
		IsVarargs:   true,

		Action: func(arguments []string) (string, error) {
			var argumentCount = len(arguments)

			if argumentCount == 0 {
				return "", fmt.Errorf("expected game name")
			}

			var modsToRemove = arguments[1:]
			var removedMods = []string{}

			if gameError := WithGame(arguments[0], func(game *Game) error {
				var removed, removeError = game.RemoveMods(modsToRemove)

				if removeError != nil {
					return removeError
				}

				removedMods = removed

				return nil
			}); gameError != nil {
				return "", gameError
			}

			return fmt.Sprint(len(removedMods), " of ", len(removedMods), " removed"), nil
		},
	},

	{
		Name:        "rename",
		Description: "Rename a mod within modman",
		Arguments:   []string{"game name", "mod name", "new name"},
		IsVarargs:   false,

		Action: func(arguments []string) (string, error) {
			if len(arguments) != 3 {
				return "", fmt.Errorf("expected game name followed by mod name and new name")
			}

			if gameError := WithGame(arguments[0], func(game *Game) error {
				if removeError := game.RenameMod(arguments[1], arguments[2]); removeError != nil {
					return removeError
				}

				return nil
			}); gameError != nil {
				return "", gameError
			}

			return "", nil
		},
	},

	{
		Name:        "manifest",
		Description: "Retrieve a manifest of all installed mods",
		Arguments:   []string{"game name", "format"},
		IsVarargs:   false,

		Action: func(arguments []string) (string, error) {
			if len(arguments) != 2 {
				return "", fmt.Errorf("expected game name followed by format")
			}

			var modManifest = ""

			if gameError := WithGame(arguments[0], func(game *Game) error {
				var format = arguments[1]
				var formatter, formatterExists = formatters[format]

				if !(formatterExists) {
					return fmt.Errorf("unsupported format: `%s`", format)
				}

				var formattedManifest, formatError = formatter(game.Mods)

				if formatError != nil {
					return formatError
				}

				// TODO: Reconsider if always casting formatted data to string for output is a good
				// idea.
				modManifest = string(formattedManifest)

				return nil
			}); gameError != nil {
				return "", gameError
			}

			return modManifest, nil
		},
	},

	{
		Name:        "deploy",
		Description: "Deploy all installed and enabled mods",
		Arguments:   []string{"game name"},
		IsVarargs:   false,

		Action: func(arguments []string) (string, error) {
			// TODO: Implement.
			return "", fmt.Errorf("not implemented")
		},
	},
}

var formatters = map[string]func(any) ([]byte, error){
	"json": func(data any) ([]byte, error) {
		var marshalledJson, marshalError = json.Marshal(data)

		if marshalError != nil {
			return nil, marshalError
		}

		return marshalledJson, nil
	},
}

func main() {
	var argCount = len(os.Args)

	if argCount == 1 {
		fmt.Println("Modman v0.1")
		fmt.Println("Enter one of the following commands following modman:")

		for i := range commands {
			var command = commands[i]

			fmt.Print("\t", command.Name)

			for j := range command.Arguments {
				fmt.Print(" [", command.Arguments[j], "]")
			}

			if command.IsVarargs {
				fmt.Println("...")
			} else {
				fmt.Println()
			}
		}

		return
	}

	var commandName = os.Args[1]

	for i := range commands {
		var command = commands[i]

		if command.Name == commandName {
			var response, actionError = command.Action(os.Args[2:])

			if actionError != nil {
				fmt.Fprintln(os.Stderr, actionError.Error())
				os.Exit(1)
			}

			if len(response) != 0 {
				fmt.Println(response)
			}

			return
		}
	}

	fmt.Fprintf(os.Stderr, "unknown command: `%s`\n", commandName)
}