/*
 *     Copyright 2020 The Dragonfly Authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

package peer

import (
	"context"
	"io"
	"net"
	"net/http/httputil"
	"time"

	"github.com/pkg/errors"

	"d7y.io/dragonfly/v2/client/clientutil"
	logger "d7y.io/dragonfly/v2/pkg/dflog"
)

type optimizedPieceDownloader struct {
}

type cancelCloser struct {
	cancel func()
	closer io.Closer
}

func (c *cancelCloser) Close() error {
	err := c.closer.Close()
	c.cancel()
	return err
}

func NewOptimizedPieceDownloader(opts ...func(*optimizedPieceDownloader) error) (PieceDownloader, error) {
	pd := &optimizedPieceDownloader{}
	for _, opt := range opts {
		if err := opt(pd); err != nil {
			return nil, err
		}
	}
	return pd, nil
}

func (o optimizedPieceDownloader) DownloadPiece(ctx context.Context, request *DownloadPieceRequest) (io.Reader, io.Closer, error) {
	logger.Debugf("download piece, addr: %s, task: %s, peer: %s, piece: %d",
		request.TaskID, request.DstAddr, request.DstPid, request.piece.PieceNum)
	// TODO get from connection pool
	conn, err := net.DialTimeout("tcp", request.DstAddr, 2*time.Second)
	if err != nil {
		panic(err)
	}
	// TODO refactor httputil.NewClientConn
	//nolint
	client := httputil.NewClientConn(conn, nil)
	// add default timeout
	ctx, cancel := context.WithTimeout(ctx, 30*time.Second)
	req := buildDownloadPieceHTTPRequest(ctx, request)

	// write request to tcp conn
	if err = client.Write(req); err != nil {
		cancel()
		return nil, nil, err
	}
	// read response header
	resp, err := client.Read(req)
	if err != nil {
		cancel()
		return nil, nil, err
	}
	if resp.ContentLength <= 0 {
		cancel()
		logger.Errorf("can not get ContentLength, addr: %s, task: %s, peer: %s, piece: %d",
			request.TaskID, request.DstAddr, request.DstPid, request.piece.PieceNum)
		return nil, nil, errors.New("can not get ContentLength")
	}
	conn, buf := client.Hijack()
	if buf.Buffered() > 0 {
		logger.Warnf("buffer size is not 0, addr: %s, task: %s, peer: %s, piece: %d",
			request.TaskID, request.DstAddr, request.DstPid, request.piece.PieceNum)
		return io.LimitReader(clientutil.BufferReader(buf, conn), resp.ContentLength),
			&cancelCloser{cancel: cancel, closer: conn}, nil
	}
	return io.LimitReader(conn, resp.ContentLength), &cancelCloser{cancel: cancel, closer: conn}, nil
}