package config

import (
	"encoding/json"
	"os"
	"path/filepath"
	"runtime"
	"strings"
)

const appName = "luxtools-client"

// Config stores client configuration loaded from disk.
type Config struct {
	PathMap map[string]string `json:"path_map"`
}

// ConfigPath returns the full path to the config.json file.
func ConfigPath() (string, error) {
	dir, err := configDir()
	if err != nil {
		return "", err
	}
	return filepath.Join(dir, "config.json"), nil
}

func configDir() (string, error) {
	if dir, err := os.UserConfigDir(); err == nil && strings.TrimSpace(dir) != "" {
		return filepath.Join(dir, appName), nil
	}

	home, err := os.UserHomeDir()
	if err != nil {
		return "", err
	}

	switch runtime.GOOS {
	case "windows":
		if v := strings.TrimSpace(os.Getenv("APPDATA")); v != "" {
			return filepath.Join(v, appName), nil
		}
		return filepath.Join(home, "AppData", "Roaming", appName), nil
	case "darwin":
		return filepath.Join(home, "Library", "Application Support", appName), nil
	default:
		return filepath.Join(home, ".config", appName), nil
	}
}

// Load reads the config from disk. If the file does not exist, it returns an empty config.
func Load(path string) (Config, error) {
	cfg := Config{PathMap: map[string]string{}}

	b, err := os.ReadFile(path)
	if err != nil {
		if os.IsNotExist(err) {
			return cfg, nil
		}
		return cfg, err
	}
	if len(b) == 0 {
		return cfg, nil
	}

	if err := json.Unmarshal(b, &cfg); err != nil {
		return cfg, err
	}
	if cfg.PathMap == nil {
		cfg.PathMap = map[string]string{}
	}
	return cfg, nil
}

// Save writes the config to disk.
func Save(path string, cfg Config) error {
	if cfg.PathMap == nil {
		cfg.PathMap = map[string]string{}
	}
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	b, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(path, b, 0o644)
}