package main

import (
	"context"
	"errors"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"os"
	"os/signal"
	"strings"
	"syscall"
	"time"

	"git.lzcwy.cn/zhengchiliu/zt-online-game-backend/global"
	"git.lzcwy.cn/zhengchiliu/zt-online-game-backend/internal/mysqlmodel"
	"git.lzcwy.cn/zhengchiliu/zt-online-game-backend/internal/routers"
	"git.lzcwy.cn/zhengchiliu/zt-online-game-backend/pkg/cos"
	"git.lzcwy.cn/zhengchiliu/zt-online-game-backend/pkg/setting"
	"github.com/gin-gonic/gin"
	"gopkg.in/natefinch/lumberjack.v2"
)

func init() {
	if err := setupSetting(); err != nil {
		panic(err)
	}

	if err := setupSlogLogger(); err != nil {
		panic(err)
	}

	if err := setupMysqlEngine(); err != nil {
		panic(err)
	}

	setupCosClient()
}

func main() {
	gin.SetMode(global.ServerSetting.RunMode)

	router := routers.NewRouter()

	s := &http.Server{
		Addr:         ":" + global.ServerSetting.HttpPort,
		Handler:      router,
		ReadTimeout:  time.Duration(global.ServerSetting.ReadTimeout) * time.Second,
		WriteTimeout: time.Duration(global.ServerSetting.WriteTimeout) * time.Second,

		// 限制http请求头的大小为1MB
		MaxHeaderBytes: 1 << 20,
	}

	// 后台启动 HTTP 服务；启动失败（如端口占用）通过 channel 反馈主流程，避免进程「假存活」。
	serverErr := make(chan error, 1)
	go func() {
		if err := s.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			serverErr <- err
		}
	}()
	slog.Info("server started", "port", global.ServerSetting.HttpPort)

	// 等待退出信号或服务启动错误。
	quit := make(chan os.Signal, 1)
	signal.Notify(quit, syscall.SIGINT, syscall.SIGTERM)

	select {
	case <-quit:
		slog.Info("shutting down server...")
	case err := <-serverErr:
		slog.Error("http server start failed", "error", err)
	}

	// 优雅关闭：等待在途请求处理完成，超时 5 秒强制退出。
	shutdownCtx, shutdownCancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer shutdownCancel()
	if err := s.Shutdown(shutdownCtx); err != nil {
		slog.Error("http server shutdown error", "error", err)
	}

	slog.Info("server exited")
}

// setupSetting 加载 configs/config.yaml 各配置段到 global，并完成必填校验与默认值兜底。
//
// 注意：Redis 段只读取不建连接（本轮不接入缓存），保留读取是为了配置结构完整、
// 后续启用缓存时无需改动此处顺序。
func setupSetting() error {
	s, err := setting.NewSetting()
	if err != nil {
		return err
	}

	if err := s.ReadSection("Server", &global.ServerSetting); err != nil {
		return err
	}
	if err := s.ReadSection("Log", &global.LogSetting); err != nil {
		return err
	}
	if err := s.ReadSection("Mysql", &global.MysqlSetting); err != nil {
		return err
	}
	if err := s.ReadSection("Redis", &global.RedisSetting); err != nil {
		return err
	}
	if err := s.ReadSection("JWT", &global.JWTSetting); err != nil {
		return err
	}
	if err := s.ReadSection("Upload", &global.UploadSetting); err != nil {
		return err
	}
	if err := s.ReadSection("Cos", &global.CosSetting); err != nil {
		return err
	}
	if err := s.ReadSection("WechatMini", &global.WechatMiniSetting); err != nil {
		return err
	}
	if err := s.ReadSection("WS", &global.WSSetting); err != nil { // 读取 WS 配置段到全局变量
		return err // 读取或反序列化失败直接返回，启动阶段 panic 暴露问题
	}

	// ===== 必填校验：缺失即启动失败，避免运行期才发现配置错误 =====
	if global.ServerSetting == nil {
		return errors.New("server config section is missing")
	}
	if global.LogSetting == nil {
		return errors.New("log config section is missing")
	}
	if global.MysqlSetting == nil || global.MysqlSetting.DBName == "" {
		return errors.New("mysql config section is missing or db name is empty")
	}
	if global.JWTSetting == nil || global.JWTSetting.SecretKey == "" {
		return errors.New("jwt secret key must not be empty")
	}
	if global.JWTSetting.AccessTokenExpire <= 0 || global.JWTSetting.RefreshTokenExpire <= 0 {
		return errors.New("jwt token expire must be positive")
	}

	// ===== 默认值兜底：可选段缺失时给安全默认，避免下游 nil 解引用 =====
	if global.UploadSetting == nil {
		global.UploadSetting = &setting.UploadSettingS{}
	}
	if global.UploadSetting.MaxSizeMB <= 0 {
		global.UploadSetting.MaxSizeMB = 20
	}
	if global.CosSetting == nil {
		global.CosSetting = &setting.CosSettingS{}
	}
	if global.WechatMiniSetting == nil {
		global.WechatMiniSetting = &setting.WechatMiniSettingS{}
	}
	// 其余 WS 默认值（心跳/超时/限流/队列）都在 internal/wsgateway 内部兜底，这里只避免 nil 解引用。
	if global.WSSetting == nil { // 配置文件里没有 WS 段
		global.WSSetting = &setting.WSSettingS{} // 赋一个零值结构体，保证各处读取不 panic
	}

	return nil
}

// setupSlogLogger 初始化全局日志：lumberjack 按大小/天数轮转写文件，同时输出到 stdout，
// 采用 JSON 结构化格式并按配置级别过滤。
func setupSlogLogger() error {
	// 确保日志目录存在（lumberjack 不会自动创建父目录，目录缺失时文件日志会静默失效）。
	if err := os.MkdirAll(global.LogSetting.LogSavePath, 0o755); err != nil {
		return fmt.Errorf("create log dir: %w", err)
	}

	writer := &lumberjack.Logger{
		Filename:   global.LogSetting.LogSavePath + "/" + global.LogSetting.LogFileName + global.LogSetting.LogFileExt,
		MaxSize:    global.LogSetting.MaxSize,
		MaxBackups: global.LogSetting.MaxBackups,
		MaxAge:     global.LogSetting.MaxAge,
		Compress:   true,
		LocalTime:  true, // 轮转文件名时间戳使用本地时区（默认 UTC，与业务展示时区不一致）
	}

	multiWriter := io.MultiWriter(writer, os.Stdout)

	// 级别匹配忽略大小写与首尾空白，避免 "debug"/"Info " 等误配静默回落 Info。
	level := slog.LevelInfo
	unknownLevel := ""
	switch strings.ToLower(strings.TrimSpace(global.LogSetting.LogLevel)) {
	case "debug":
		level = slog.LevelDebug
	case "", "info":
		level = slog.LevelInfo
	case "warn", "warning":
		level = slog.LevelWarn
	case "error":
		level = slog.LevelError
	default:
		unknownLevel = global.LogSetting.LogLevel
	}

	slog.SetDefault(slog.New(slog.NewJSONHandler(multiWriter, &slog.HandlerOptions{
		AddSource: true,
		Level:     level,
	})))

	if unknownLevel != "" {
		slog.Warn("unknown log level in config, fallback to info", "configured", unknownLevel)
	}

	return nil
}

// setupMysqlEngine 初始化 MySQL 数据库连接。
func setupMysqlEngine() error {
	var err error
	global.MysqlEngine, err = mysqlmodel.NewMysqlEngine(global.MysqlSetting)
	if err != nil {
		return err
	}
	return nil
}

// setupCosClient 初始化腾讯云 COS 客户端（头像上传依赖）。
// 初始化失败仅告警，不阻断服务启动（上传时返回明确的业务错误）。
func setupCosClient() {
	client, err := cos.NewCosClient()
	if err != nil {
		slog.Warn("init cos client failed, upload features may fail", "error", err)
		return
	}
	global.CosClient = client
}