package mux

import (
	"fmt"
	"golang.org/x/time/rate"
	"net/http"
	"net/url"
	"runtime/debug"
	"time"

	"git.bvbej.com/bvbej/base-golang/pkg/color"
	"git.bvbej.com/bvbej/base-golang/pkg/env"
	"git.bvbej.com/bvbej/base-golang/pkg/errno"
	"git.bvbej.com/bvbej/base-golang/pkg/errors"
	"git.bvbej.com/bvbej/base-golang/pkg/trace"
	"github.com/gin-contrib/pprof"
	"github.com/gin-gonic/gin"
	"github.com/prometheus/client_golang/prometheus/promhttp"
	cors "github.com/rs/cors/wrapper/gin"
	"go.uber.org/multierr"
	"go.uber.org/zap"
)

const (
	_EverySize    = 1e3
	_MaxBurstSize = _EverySize * 60
)

var limiter = rate.NewLimiter(rate.Limit(_EverySize), _MaxBurstSize)

type Option func(*option)

type option struct {
	enableCors        bool
	enableRate        bool
	enablePProf       bool
	enablePrometheus  bool
	enableOpenBrowser string
	staticDirs        []string
	panicNotify       OnPanicNotify
	recordMetrics     RecordMetrics
}

type Failure struct {
	ResultCode int    `json:"result_code"` // 业务码
	ResultInfo string `json:"result_info"` // 描述信息

}

type Success struct {
	ResultCode int `json:"result_code"` // 业务码
	ResultData any `json:"result_data"` //返回数据
}

/******************************************************************************/

// OnPanicNotify 发生panic时通知用
type OnPanicNotify func(ctx Context, err any, stackInfo string)

// RecordMetrics 记录prometheus指标用
// 如果使用AliasForRecordMetrics配置了别名，uri将被替换为别名。
type RecordMetrics func(method, uri string, success bool, costSeconds float64)

// DisableTrace 禁用追踪链
func DisableTrace(ctx Context) {
	ctx.disableTrace()
}

// WithPanicNotify 设置panic时的通知回调
func WithPanicNotify(notify OnPanicNotify) Option {
	return func(opt *option) {
		opt.panicNotify = notify
		fmt.Println(color.Green("* [register panic notify]"))
	}
}

// WithRecordMetrics 设置记录prometheus记录指标回调
func WithRecordMetrics(record RecordMetrics) Option {
	return func(opt *option) {
		opt.recordMetrics = record
	}
}

// WithEnableCors 开启CORS
func WithEnableCors() Option {
	return func(opt *option) {
		opt.enableCors = true
		fmt.Println(color.Green("* [register cors]"))
	}
}

// WithEnableRate 开启限流
func WithEnableRate() Option {
	return func(opt *option) {
		opt.enableRate = true
		fmt.Println(color.Green("* [register rate]"))
	}
}

// WithStaticDir 设置静态文件目录
func WithStaticDir(dirs []string) Option {
	return func(opt *option) {
		opt.staticDirs = dirs
		fmt.Println(color.Green("* [register rate]"))
	}
}

// AliasForRecordMetrics 对请求uri起个别名，用于prometheus记录指标。
// 如：Get /user/:username 这样的uri，因为username会有非常多的情况，这样记录prometheus指标会非常的不有好。
func AliasForRecordMetrics(path string) HandlerFunc {
	return func(ctx Context) {
		ctx.setAlias(path)
	}
}

/******************************************************************************/

// RouterGroup 包装gin的RouterGroup
type RouterGroup interface {
	Group(string, ...HandlerFunc) RouterGroup
	IRoutes
}

var _ IRoutes = (*router)(nil)

// IRoutes 包装gin的IRoutes
type IRoutes interface {
	Any(string, ...HandlerFunc)
	GET(string, ...HandlerFunc)
	POST(string, ...HandlerFunc)
	DELETE(string, ...HandlerFunc)
	PATCH(string, ...HandlerFunc)
	PUT(string, ...HandlerFunc)
	OPTIONS(string, ...HandlerFunc)
	HEAD(string, ...HandlerFunc)
}

type router struct {
	group *gin.RouterGroup
}

func (r *router) Group(relativePath string, handlers ...HandlerFunc) RouterGroup {
	group := r.group.Group(relativePath, wrapHandlers(handlers...)...)
	return &router{group: group}
}

func (r *router) Any(relativePath string, handlers ...HandlerFunc) {
	r.group.Any(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) GET(relativePath string, handlers ...HandlerFunc) {
	r.group.GET(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) POST(relativePath string, handlers ...HandlerFunc) {
	r.group.POST(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) DELETE(relativePath string, handlers ...HandlerFunc) {
	r.group.DELETE(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) PATCH(relativePath string, handlers ...HandlerFunc) {
	r.group.PATCH(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) PUT(relativePath string, handlers ...HandlerFunc) {
	r.group.PUT(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) OPTIONS(relativePath string, handlers ...HandlerFunc) {
	r.group.OPTIONS(relativePath, wrapHandlers(handlers...)...)
}

func (r *router) HEAD(relativePath string, handlers ...HandlerFunc) {
	r.group.HEAD(relativePath, wrapHandlers(handlers...)...)
}

func wrapHandlers(handlers ...HandlerFunc) []gin.HandlerFunc {
	list := make([]gin.HandlerFunc, len(handlers))
	for i, handler := range handlers {
		fn := handler
		list[i] = func(c *gin.Context) {
			ctx := newContext(c)
			defer releaseContext(ctx)

			fn(ctx)
		}
	}
	return list
}

/******************************************************************************/

var _ Mux = (*mux)(nil)

type Mux interface {
	http.Handler
	Group(relativePath string, handlers ...HandlerFunc) RouterGroup
	Routes() gin.RoutesInfo
	HandlerFunc(relativePath string, handlerFunc gin.HandlerFunc)
}

type mux struct {
	engine *gin.Engine
}

func (m *mux) ServeHTTP(w http.ResponseWriter, req *http.Request) {
	m.engine.ServeHTTP(w, req)
}

func (m *mux) Group(relativePath string, handlers ...HandlerFunc) RouterGroup {
	return &router{
		group: m.engine.Group(relativePath, wrapHandlers(handlers...)...),
	}
}

func (m *mux) Routes() gin.RoutesInfo {
	return m.engine.Routes()
}

func (m *mux) HandlerFunc(relativePath string, handlerFunc gin.HandlerFunc) {
	m.engine.GET(relativePath, handlerFunc)
}

func New(logger *zap.Logger, options ...Option) (Mux, error) {
	if logger == nil {
		return nil, errors.New("logger required")
	}

	gin.SetMode(gin.ReleaseMode)
	gin.DisableBindValidation()
	newMux := &mux{
		engine: gin.New(),
	}

	fmt.Println(color.Green(fmt.Sprintf("* [register env %s]", env.Active().Value())))

	// withoutLogPaths 这些请求，默认不记录日志
	withoutTracePaths := map[string]bool{
		"/metrics":       true,
		"/favicon.ico":   true,
		"/system/health": true,
	}

	opt := new(option)
	for _, f := range options {
		f(opt)
	}

	if opt.enablePProf {
		pprof.Register(newMux.engine)
		fmt.Println(color.Green("* [register pprof]"))
	}

	if opt.enablePrometheus {
		newMux.engine.GET("/metrics", gin.WrapH(promhttp.Handler()))
		fmt.Println(color.Green("* [register prometheus]"))
	}

	if opt.enableCors {
		newMux.engine.Use(cors.AllowAll())
	}

	if opt.staticDirs != nil {
		for _, dir := range opt.staticDirs {
			newMux.engine.StaticFS(dir, gin.Dir(dir, false))
		}
	}

	// recover两次，防止处理时发生panic，尤其是在OnPanicNotify中。
	newMux.engine.Use(func(ctx *gin.Context) {
		defer func() {
			if err := recover(); err != nil {
				logger.Error("got panic", zap.String("panic", fmt.Sprintf("%+v", err)), zap.String("stack", string(debug.Stack())))
			}
		}()

		ctx.Next()
	})

	newMux.engine.Use(func(ctx *gin.Context) {
		ts := time.Now()

		newCtx := newContext(ctx)
		defer releaseContext(newCtx)

		newCtx.init()
		newCtx.setLogger(logger)

		if !withoutTracePaths[ctx.Request.URL.Path] {
			if traceId := newCtx.GetHeader(trace.Header); traceId != "" {
				newCtx.setTrace(trace.New(traceId))
			} else {
				newCtx.setTrace(trace.New(""))
			}
		}

		defer func() {
			if err := recover(); err != nil {
				stackInfo := string(debug.Stack())
				logger.Error("got panic", zap.String("panic", fmt.Sprintf("%+v", err)), zap.String("stack", stackInfo))
				newCtx.AbortWithError(errno.NewError(
					http.StatusInternalServerError,
					http.StatusInternalServerError,
					http.StatusText(http.StatusInternalServerError)),
				)

				if notify := opt.panicNotify; notify != nil {
					notify(newCtx, err, stackInfo)
				}
			}

			if ctx.Writer.Status() == http.StatusNotFound {
				return
			}

			var (
				response        any
				businessCode    int
				businessCodeMsg string
				abortErr        error
				graphResponse   any
			)

			if ctx.IsAborted() {
				for i := range ctx.Errors { // gin error
					multierr.AppendInto(&abortErr, ctx.Errors[i])
				}

				if err := newCtx.abortError(); err != nil { // customer err
					multierr.AppendInto(&abortErr, err.GetErr())
					response = err
					businessCode = err.GetBusinessCode()
					businessCodeMsg = err.GetMsg()

					if x := newCtx.Trace(); x != nil {
						newCtx.SetHeader(trace.Header, x.ID())
					}

					ctx.JSON(err.GetHttpCode(), &Failure{
						ResultCode: businessCode,
						ResultInfo: businessCodeMsg,
					})
				}
			} else {
				response = newCtx.getPayload()
				if response != nil {
					if x := newCtx.Trace(); x != nil {
						newCtx.SetHeader(trace.Header, x.ID())
					}
					ctx.JSON(http.StatusOK, response)
				}
			}

			graphResponse = newCtx.getGraphPayload()

			if opt.recordMetrics != nil {
				uri := newCtx.Path()
				if alias := newCtx.Alias(); alias != "" {
					uri = alias
				}

				opt.recordMetrics(
					newCtx.Method(),
					uri,
					!ctx.IsAborted() && ctx.Writer.Status() == http.StatusOK,
					time.Since(ts).Seconds(),
				)
			}

			var t *trace.Trace
			if x := newCtx.Trace(); x != nil {
				t = x.(*trace.Trace)
			} else {
				return
			}

			decodedURL, _ := url.QueryUnescape(ctx.Request.URL.RequestURI())

			t.WithRequest(&trace.Request{
				TTL:        "un-limit",
				Method:     ctx.Request.Method,
				DecodedURL: decodedURL,
				Header:     ctx.Request.Header,
				Body:       string(newCtx.RawData()),
			})

			var responseBody any

			if response != nil {
				responseBody = response
			}

			if graphResponse != nil {
				responseBody = graphResponse
			}

			t.WithResponse(&trace.Response{
				Header:          ctx.Writer.Header(),
				HttpCode:        ctx.Writer.Status(),
				HttpCodeMsg:     http.StatusText(ctx.Writer.Status()),
				BusinessCode:    businessCode,
				BusinessCodeMsg: businessCodeMsg,
				Body:            responseBody,
				CostSeconds:     time.Since(ts).Seconds(),
			})

			t.Success = !ctx.IsAborted() && ctx.Writer.Status() == http.StatusOK
			t.CostSeconds = time.Since(ts).Seconds()

			logger.Info("core-interceptor",
				zap.Any("method", ctx.Request.Method),
				zap.Any("path", decodedURL),
				zap.Any("http_code", ctx.Writer.Status()),
				zap.Any("business_code", businessCode),
				zap.Any("success", t.Success),
				zap.Any("cost_seconds", t.CostSeconds),
				zap.Any("trace_id", t.Identifier),
				zap.Any("trace_info", t),
				zap.Error(abortErr),
			)
		}()

		ctx.Next()
	})

	if opt.enableRate {
		newMux.engine.Use(func(ctx *gin.Context) {
			newCtx := newContext(ctx)
			defer releaseContext(newCtx)

			if !limiter.Allow() {
				newCtx.AbortWithError(errno.NewError(
					http.StatusTooManyRequests,
					http.StatusTooManyRequests,
					http.StatusText(http.StatusTooManyRequests)),
				)
				return
			}

			ctx.Next()
		})
	}

	newMux.engine.NoMethod(wrapHandlers(DisableTrace)...)
	newMux.engine.NoRoute(wrapHandlers(DisableTrace)...)
	system := newMux.Group("/system")
	{
		// 健康检查
		system.GET("/health", func(ctx Context) {
			resp := &struct {
				Timestamp   time.Time `json:"timestamp"`
				Environment string    `json:"environment"`
				Host        string    `json:"host"`
				Status      string    `json:"status"`
			}{
				Timestamp:   time.Now(),
				Environment: env.Active().Value(),
				Host:        ctx.Host(),
				Status:      "ok",
			}
			ctx.Payload(resp)
		})
	}

	return newMux, nil
}