package config

import (
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
)

type OverwriteMode string
type FileSelectMode string

const (
	OverwriteSkip   OverwriteMode = "skip"
	OverwriteDelete OverwriteMode = "delete"

	SelectNew FileSelectMode = "new"
	SelectAll FileSelectMode = "all"
)

type SourceFolder struct {
	Path    string `json:"path"`
	Enabled bool   `json:"enabled"`
}

type Config struct {
	ReserveFreeGB  float64        `json:"reserve_free_gb"`
	DestFolder     string         `json:"dest_folder"`
	Sources        []SourceFolder `json:"sources"`
	OverwriteMode  OverwriteMode  `json:"overwrite_mode"`
	FileSelectMode FileSelectMode `json:"file_select_mode"`
	AutoCopy       bool           `json:"auto_copy"`
}

func defaults() Config {
	return Config{
		ReserveFreeGB:  2.0,
		DestFolder:     "media",
		OverwriteMode:  OverwriteSkip,
		FileSelectMode: SelectNew,
		AutoCopy:       false,
	}
}

func Load(path string) (*Config, error) {
	data, err := os.ReadFile(path)
	if errors.Is(err, os.ErrNotExist) {
		cfg := defaults()
		return &cfg, nil
	}
	if err != nil {
		return nil, err
	}
	cfg := defaults()
	if err := json.Unmarshal(data, &cfg); err != nil {
		return nil, err
	}
	return &cfg, nil
}

func Save(path string, cfg *Config) error {
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		return err
	}
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	tmp := path + ".tmp"
	if err := os.WriteFile(tmp, data, 0o644); err != nil {
		return err
	}
	return os.Rename(tmp, path)
}

func (c *Config) Validate() error {
	if c.ReserveFreeGB < 0 {
		return errors.New("reserve_free_gb must be >= 0")
	}
	switch c.OverwriteMode {
	case OverwriteSkip, OverwriteDelete:
	default:
		return errors.New("overwrite_mode must be 'skip' or 'delete'")
	}
	switch c.FileSelectMode {
	case SelectNew, SelectAll:
	default:
		return errors.New("file_select_mode must be 'new' or 'all'")
	}
	return nil
}