package core
import (
	"errors"
	"os"

	"github.com/BurntSushi/toml"
)

// Mod stores metadata about a mod. This is written to a TOML file for each mod.
type Mod struct {
	metaFile string      // The file for the metadata file, used as an ID
	Name     string      `toml:"name"`
	FileName string      `toml:"filename"`
	Side     string      `toml:"side,omitempty"`
	Optional bool        `toml:"optional,omitempty"`
	Download ModDownload `toml:"download"`
	// Update is a map of map of stuff, so you can store arbitrary values on string keys to define updating
	Update   map[string]map[string]interface{} `toml:"update"`
	updaters map[string]Updater
}

// ModDownload specifies how to download the mod file
type ModDownload struct {
	URL        string `toml:"url"`
	HashFormat string `toml:"hash-format"`
	Hash       string `toml:"hash"`
}

// The three possible values of Side (the side that the mod is on) are "server", "client", and "both".
const (
	ServerSide    = "server"
	ClientSide    = "client"
	UniversalSide = "both"
)

// LoadMod attempts to load a mod file from a path
func LoadMod(modFile string) (Mod, error) {
	var mod Mod
	if _, err := toml.DecodeFile(modFile, &mod); err != nil {
		return Mod{}, err
	}
	mod.updaters = make(map[string]Updater)
	// Horrible reflection library to convert to Updaters
	for k, v := range mod.Update {
		updateParser, ok := UpdateParsers[k]
		if ok {
			updater, err := updateParser.ParseUpdate(v)
			if err != nil {
				return mod, err
			}
			mod.updaters[k] = updater
		} else {
			return mod, errors.New("Update plugin " + k + " not found!")
		}
	}
	mod.metaFile = modFile
	return mod, nil
}

// SetMetaName sets the mod metadata file from a given file name (to be put in the mods folder)
func (m *Mod) SetMetaName(metaName string, flags Flags) {
	m.metaFile = ResolveMod(metaName, flags)
}

// Write saves the mod file
func (m Mod) Write() error {
	f, err := os.Create(m.metaFile)
	if err != nil {
		return err
	}
	defer f.Close()

	enc := toml.NewEncoder(f)
	// Disable indentation
	enc.Indent = ""
	return enc.Encode(m)
}