/*
 * Tencent is pleased to support the open source community by making
 * 蓝鲸智云 - 配置平台 (BlueKing - CMDB) available.
 * Copyright (C) 2025 Tencent. All rights reserved.
 * Licensed under the MIT License (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at http://opensource.org/licenses/MIT
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on
 * an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND,
 * either express or implied. See the License for the
 * specific language governing permissions and limitations under the License.
 * We undertake not to change the open source license (MIT license) applicable
 * to the current version of the project delivered to anyone in the future.
 */

// Package rest framework
package rest

import (
	"context"
	"log/slog"
	"net/http"
	"time"
)

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

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

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

// Handle Composable HTTP Handlers using generics
func Handle[Req, Resp any](fn UnaryFunc[Req, Resp]) 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)
		}()

		// 反序列化
		in, err := decodeReq[Req](r)
		if err != nil {
			slog.Error("handle decode request failed", "err", err)
			APIError(err).Render(w, r)
			return
		}

		// 参数校验
		if err = validateReq(r.Context(), in); err != nil {
			slog.Error("validate req failed", "err", err)
			APIError(err).Render(w, r)
			return
		}

		out, err := fn(r.Context(), in)
		if err != nil {
			APIError(err).Render(w, r)
			return
		}
		APIOK(out).Render(w, r)
	}
	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[Req any](fn StreamFunc[Req]) 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)
		}()

		// 反序列化
		in, err := decodeReq[Req](r)
		if err != nil {
			slog.Error("handle decode stream request failed", "err", err)
			APIError(err).Render(w, r)
			return
		}

		// 参数校验
		if err = validateReq(r.Context(), in); err != nil {
			slog.Error("validate stream req failed", "err", err)
			APIError(err).Render(w, r)
			return
		}

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

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

// 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" req:"offset,in=query" validate:"gte=0"`
	Limit  int `json:"limit" req:"limit,in=query" 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"`
}