package apis

import (
	"context"
	"encoding/json"
	"fmt"
	"io"
	"log/slog"
	"net/http"
	"time"

	"github.com/ggicci/httpin"
	httpin_integration "github.com/ggicci/httpin/integration"
	"github.com/go-chi/chi/v5"
	"github.com/go-chi/render"

	"git.ifooth.com/common/pkg/i18n"
)

// UnaryFunc Unary or ClientStreaming handle function
type UnaryFunc[In, Out any] func(context.Context, *In) (*Out, error)

// StreamingServer server or bidi streaming server
type StreamingServer interface {
	http.ResponseWriter
	Context() context.Context
}

// StreamFunc ServerStreaming or BidiStreaming handle function
type StreamFunc[In any] func(*In, StreamingServer) error

// Handle Composable HTTP Handlers using generics
func Handle[In any, Out any](fn UnaryFunc[In, Out]) func(w http.ResponseWriter, r *http.Request) {
	handleName := getHandleName(fn)

	f := func(w http.ResponseWriter, r *http.Request) {
		r.Header.Set("Content-Type", "application/json")
		st := time.Now()
		var err error
		defer func() {
			collectHandleMetrics(handleName, r.Method, st, err)
		}()

		in, err := decodeReq[In](r)
		if err != nil {
			slog.Error("handle decode request failed", "err", err)
			_ = render.Render(w, r, APIError(err))
			return
		}

		// 设置语言
		ctx := i18n.SetLang(r.Context(), r.Header.Get("Accept-Language"))
		ctx = context.WithValue(ctx, reqCtxKey, r)

		out, err := fn(ctx, in)
		if err != nil {
			_ = render.Render(w, r, APIError(err))
			return
		}
		_ = render.Render(w, r, APIOK(out))
	}
	return f
}

type streamingServer struct {
	http.ResponseWriter
	*http.ResponseController
	ctx context.Context
}

// Context return svr's context
func (s *streamingServer) Context() context.Context {
	return s.ctx
}

// Stream Composable HTTP Handlers using generics
func Stream[In any](fn StreamFunc[In]) func(w http.ResponseWriter, r *http.Request) {
	handleName := getHandleName(fn)

	f := func(w http.ResponseWriter, r *http.Request) {
		st := time.Now()
		var err error
		defer func() {
			collectHandleMetrics(handleName, r.Method, st, err)
		}()

		in, err := decodeReq[In](r)
		if err != nil {
			slog.Error("handle decode request failed ", "err", err)
			_ = render.Render(w, r, APIError(err))
			return
		}

		// 设置语言
		ctx := i18n.SetLang(r.Context(), r.Header.Get("Accept-Language"))
		ctx = context.WithValue(ctx, reqCtxKey, r)

		svr := &streamingServer{
			ResponseWriter:     w,
			ResponseController: http.NewResponseController(w),
			ctx:                ctx,
		}

		err = fn(in, svr)
		if err != nil {
			_ = render.Render(w, r, APIError(err))
		}
	}
	return f
}

// decodeReq ...
func decodeReq[T any](r *http.Request) (*T, error) {
	in := new(T)
	var err error

	// http.Request 直接返回
	if _, ok := any(in).(*http.Request); ok {
		return any(r).(*T), nil
	}

	// 空值不需要反序列化
	if _, ok := any(in).(*EmptyReq); ok {
		return in, nil
	}

	in, err = httpin.Decode[T](r)
	if err != nil {
		return nil, err
	}

	// Get/Delete 请求, 请求参数从url中获取
	if r.Method == http.MethodGet || r.Method == http.MethodDelete {
		return in, nil
	}

	// Post 请求等, 从body中获取
	body, err := io.ReadAll(r.Body)
	if err != nil {
		return nil, err
	}

	if err = json.Unmarshal(body, in); err != nil {
		return nil, fmt.Errorf("unmarshal json body: %s", err)
	}
	return in, nil
}

// EmptyReq 空的请求
type EmptyReq struct{}

// EmptyResp 空的返回
type EmptyResp struct{}

// PaginationReq 分页接口通用请求
type PaginationReq struct {
	Offset int `json:"offset" in:"query=offset" validate:"gte=0"`
	Limit  int `json:"limit" in:"query=limit" validate:"gte=0"`
}

// PaginationResp 分页接口通用返回
type PaginationResp[T any] struct {
	Count int64 `json:"count"`
	Items []*T  `json:"items"`
}

func init() {
	httpin_integration.UseGochiURLParam("path", chi.URLParam)
}