package qmc

import (
	"crypto/md5"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strconv"
	"strings"

	"git.um-react.app/um/cli/algo/common"
	"go.uber.org/zap"
)

func LoadMMKVOrDefault(path string, key string, logger *zap.Logger) (result common.QMCKeys, err error) {
	key1, err := loadMacKeysV8(logger)
	if err != nil {
		key1 = nil
		logger.Warn("LoadMMKVOrDefault: could not read QQMusic v8.8.0 keys", zap.Error(err))
	}

	key2, err := loadMacKeysV10(logger)
	if err != nil {
		key2 = nil
		logger.Warn("LoadMMKVOrDefault: could not read QQMusic v10.x keys", zap.Error(err))
	}

	userKeys := make(common.QMCKeys)
	if path != "" {
		logger.Info("Using user mmkv")
		userKeys, err = LoadMMKV(path, key, logger)
		if err != nil {
			userKeys = nil
			logger.Warn("LoadMMKVOrDefault: could not read user keys", zap.Error(err))
		}
	}

	allKeys := mergeMMKVKeys(key1, key2, userKeys)

	logger.Debug("Keys loaded", zap.Any("keys", allKeys), zap.Int("len", len(allKeys)))

	return allKeys, nil
}

func loadMacKeysV8(logger *zap.Logger) (keys common.QMCKeys, err error) {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		logger.Warn("Failed to get home dir")
		return nil, fmt.Errorf("loadMacKeysV8: failed to get home: %w", err)
	}
	p := filepath.Join(
		homeDir,
		"Library/Containers/com.tencent.QQMusicMac/Data",
		"Library/Application Support/QQMusicMac/mmkv",
		"MMKVStreamEncryptId",
	)
	if f, err := os.Stat(p); err == nil && !f.IsDir() {
		logger.Info("Using QQMusic 8.x mmkv", zap.String("mmkv", p))
		return LoadMMKV(p, "", logger)
	}
	return nil, nil
}

var _RE_UDID = regexp.MustCompile(`_\x10\(([0-9a-f]{40})_`)

func extractUdid(data []byte) (string, error) {
	match := _RE_UDID.FindSubmatch(data)
	if len(match) != 2 {
		return "", fmt.Errorf("extractUdid: could not find udid")
	}
	return string(match[1]), nil
}

func caesar(text string, shift int) string {
	var result strings.Builder

	for _, char := range []byte(text) {
		var transformed byte
		if 'A' <= char && char <= 'Z' {
			transformed = (char-'A'+byte(shift))%26 + 'A'
		} else if 'a' <= char && char <= 'z' {
			transformed = (char-'a'+byte(shift))%26 + 'a'
		} else if '0' <= char && char <= '9' {
			transformed = (char-'0'+byte(shift))%10 + '0'
		} else {
			transformed = char
		}
		result.WriteByte(transformed)
	}

	return result.String()
}

func getMmkv(udid string, id int) (name string, key string, err error) {
	str1 := caesar(udid, id+3)
	int1, err := strconv.ParseInt(udid[5:7], 16, 32)
	if err != nil {
		return "", "", fmt.Errorf("getMmkv: could not parse udid: %w", err)
	}
	int2 := 5 + (int(int1)+id)%4
	name = str1[:int2]

	int3 := id + 0xa546
	str3 := fmt.Sprintf("%s%04x", udid, int3)
	hash := md5.Sum([]byte(str3))
	key = fmt.Sprintf("%x", hash)[:16]

	return name, key, nil
}

func loadMacKeysV10(logger *zap.Logger) (common.QMCKeys, error) {
	homeDir, err := os.UserHomeDir()
	if err != nil {
		logger.Warn("Failed to get home dir")
		return nil, fmt.Errorf("loadMacKeysV10: failed to get home: %w", err)
	}
	plist_path := filepath.Join(
		homeDir,
		"Library/Preferences/com.tencent.QQMusicMac.plist",
	)
	if f, err := os.Stat(plist_path); err != nil || f.IsDir() {
		logger.Debug("loadMacKeysV10: plist not found", zap.String("plist", plist_path))
		return nil, fmt.Errorf("loadMacKeysV10: plist not found")
	}
	plist_data, err := os.ReadFile(plist_path)
	if err != nil {
		logger.Warn("loadMacKeysV10: could not read plist", zap.String("plist", plist_path), zap.Error(err))
		return nil, fmt.Errorf("loadMacKeysV10: could not read plist: %w", err)
	}
	udid, err := extractUdid(plist_data)
	if err != nil {
		logger.Warn("loadMacKeysV10: could not extract udid", zap.Error(err))
		return nil, fmt.Errorf("loadMacKeysV10: could not extract udid: %w", err)
	}
	logger.Debug("loadMacKeysV10: read udid", zap.String("udid", udid))

	mmkv_dir := filepath.Join(
		homeDir,
		"Library/Containers/com.tencent.QQMusicMac/Data/",
		"Library/Application Support/QQMusicMac/iData",
	)
	if f, err := os.Stat(mmkv_dir); err != nil || !f.IsDir() {
		logger.Debug("loadMacKeysV10: mmkv dir not found", zap.String("mmkv_dir", mmkv_dir))
		return nil, nil
	}
	mmkv_name, mmkv_key, err := getMmkv(udid, 1)
	if err != nil {
		logger.Warn("loadMacKeysV10: could not get mmkv name/key", zap.Error(err))
		return nil, fmt.Errorf("loadMacKeysV10: could not get mmkv name/key: %w", err)
	}
	mmkv_path := filepath.Join(mmkv_dir, mmkv_name)
	if f, err := os.Stat(mmkv_path); err != nil || f.IsDir() {
		logger.Debug("loadMacKeysV10: mmkv file not found", zap.String("mmkv", mmkv_path))
		return nil, nil
	}
	logger.Info("Using QQMusic 10.x mmkv", zap.String("mmkv", mmkv_path))
	keys, err := LoadMMKV(mmkv_path, mmkv_key, logger)
	if err != nil {
		logger.Warn("loadMacKeysV10: could not load mmkv", zap.String("mmkv", mmkv_path), zap.Error(err))
		return nil, fmt.Errorf("loadMacKeysV10: could not load mmkv: %w", err)
	}
	return keys, nil
}