package config

import (
	"encoding/json"
	"errors"
	"os"
	"path/filepath"
	"runtime"
	"strconv"

	"douyu_go/internal/constants"
	"douyu_go/internal/logger"
	"douyu_go/internal/types"
)

// DefaultAppPaths 收集运行时路径，支持环境变量覆盖。
// 所有相对路径会基于当前工作目录解析为绝对路径，避免打包后工作目录不同导致路径错位。
func DefaultAppPaths() types.AppPaths {
	return types.AppPaths{
		ConfigFile:  resolvePath(envOrDefault("DOUYU_CONFIG", constants.DefaultConfigFile)),
		AccountFile: resolvePath(envOrDefault("DOUYU_USERS", constants.DefaultAccountFile)),
		LogDir:      resolvePath(envOrDefault("DOUYU_LOG_DIR", constants.DefaultLogDir)),
		SuccessDir:  resolvePath(envOrDefault("DOUYU_SUCCESS_DIR", constants.DefaultSuccessDir)),
		FontFiles:   CollectFontCandidates(),
	}
}

// resolvePath 将相对路径解析为绝对路径。
func resolvePath(path string) string {
	if filepath.IsAbs(path) {
		return path
	}
	if abs, err := filepath.Abs(path); err == nil {
		return abs
	}
	return path
}

func envOrDefault(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return filepath.Clean(value)
	}
	return fallback
}

// LoadTraceConfig 读取 trace 开关；默认关闭，避免保存敏感调试数据。
func LoadTraceConfig() types.TraceConfig {
	return types.TraceConfig{
		Enabled:      isTruthyEnv("DOUYU_TRACE"),
		MaxBodyBytes: envInt("DOUYU_TRACE_MAX_BODY", 0),
	}
}

func isTruthyEnv(key string) bool {
	switch os.Getenv(key) {
	case "1", "true", "TRUE", "yes", "YES", "on", "ON":
		return true
	default:
		return false
	}
}

func envInt(key string, fallback int) int {
	raw := os.Getenv(key)
	if raw == "" {
		return fallback
	}
	value, err := strconv.Atoi(raw)
	if err != nil || value <= 0 {
		return fallback
	}
	return value
}

// defaultConfig 返回内置默认配置。
func defaultConfig() types.Config {
	return types.Config{
		TimeAPIURL:   constants.DefaultTimeAPI,
		TraceEnabled: false,
		TraceMaxBody: 0,
		LogLevel:     "info",
		Concurrency:  constants.DefaultConcurrency,
		Attempts:     constants.DefaultAttempts,
	}
}

// LoadConfig 读取配置文件；缺失时安静使用内置默认配置。
func LoadConfig(path string) types.Config {
	cfg := defaultConfig()
	if path == "" {
		path = constants.DefaultConfigFile
	}

	f, err := os.Open(path)
	if err != nil {
		if errors.Is(err, os.ErrNotExist) {
			logger.LogEvent("配置", "info", "配置加载完成: 内置默认配置")
		} else {
			logger.LogEvent("配置", "warn", "读取 %s 出错，使用内置默认配置: %v", path, err)
		}
		return cfg
	}
	defer f.Close()

	if err := json.NewDecoder(f).Decode(&cfg); err != nil {
		logger.LogEvent("配置", "warn", "解析 %s 失败，使用内置默认配置: %v", path, err)
		return defaultConfig()
	}
	if cfg.TimeAPIURL == "" {
		cfg.TimeAPIURL = constants.DefaultTimeAPI
	}
	if cfg.Concurrency <= 0 {
		cfg.Concurrency = constants.DefaultConcurrency
	}
	if cfg.Attempts <= 0 {
		cfg.Attempts = constants.DefaultAttempts
	}
	if cfg.LogLevel == "" {
		cfg.LogLevel = "info"
	}
	logger.LogEvent("配置", "success", "配置加载完成: %s", path)
	return cfg
}

// SaveConfig 将配置写入文件。
func SaveConfig(path string, cfg types.Config) error {
	if path == "" {
		path = constants.DefaultConfigFile
	}
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(path, data, 0644)
}

// CollectFontCandidates 收集常见中文字体路径，允许用 DOUYU_FONT 指定自定义字体。
func CollectFontCandidates() []string {
	candidates := []string{}
	if custom := os.Getenv("DOUYU_FONT"); custom != "" {
		candidates = append(candidates, custom)
	}
	candidates = append(candidates,
		"Microsoft Yahei.ttf",
		"Microsoft YaHei.ttf",
		"NotoSansCJKsc-Regular.otf",
		"NotoSansCJK-Regular.ttc",
	)

	switch runtime.GOOS {
	case "darwin":
		candidates = append(candidates,
			"/System/Library/Fonts/PingFang.ttc",
			"/System/Library/Fonts/Supplemental/Arial Unicode.ttf",
			"/System/Library/Fonts/Supplemental/Songti.ttc",
		)
	case "windows":
		candidates = append(candidates,
			`C:\Windows\Fonts\msyh.ttc`,
			`C:\Windows\Fonts\simhei.ttf`,
			`C:\Windows\Fonts\simsun.ttc`,
		)
	default:
		candidates = append(candidates,
			"/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.ttc",
			"/usr/share/fonts/opentype/noto/NotoSansCJK-Regular.otf",
			"/usr/share/fonts/truetype/noto/NotoSansCJK-Regular.ttc",
			"/usr/share/fonts/truetype/wqy/wqy-microhei.ttc",
			"/usr/share/fonts/truetype/dejavu/DejaVuSans.ttf",
		)
	}
	return candidates
}