/*
 *     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 source

import (
	"fmt"
	"io"
	"net/http"
)

const (
	TimeFormat = "Mon, 02 Jan 2006 15:04:05 GMT"
)

type Response struct {
	Status        string
	StatusCode    int
	Header        Header
	Body          io.ReadCloser
	ContentLength int64
	// Validate this response is okay to transfer in p2p network, like status 200 or 206 in http is valid to do this,
	// otherwise return status code to original client
	Validate func() error
	// Temporary indecates the error whether the error is temporary, if is true, we can retry it later
	Temporary bool
}

func NewResponse(rc io.ReadCloser, opts ...func(*Response)) *Response {
	if rc == nil {
		// for custom plugin, return an error body
		rc = &errorBody{
			fmt.Errorf("empty io.ReadCloser, please check resource plugin implement")}
	}
	resp := &Response{
		Header:        make(Header),
		Status:        "OK",
		StatusCode:    http.StatusOK,
		Body:          rc,
		ContentLength: -1,
		Validate: func() error {
			return nil
		},
		Temporary: true,
	}

	for _, opt := range opts {
		opt(resp)
	}
	return resp
}

func WithStatus(code int, status string) func(*Response) {
	return func(resp *Response) {
		resp.StatusCode = code
		resp.Status = status
	}
}

func WithContentLength(length int64) func(*Response) {
	return func(resp *Response) {
		resp.ContentLength = length
	}
}

func WithHeader(header map[string]string) func(*Response) {
	return func(resp *Response) {
		for k, v := range header {
			resp.Header.Set(k, v)
		}
	}
}

func WithExpireInfo(info ExpireInfo) func(*Response) {
	return func(resp *Response) {
		if len(info.LastModified) > 0 {
			resp.Header.Set(LastModified, info.LastModified)
		}
		if len(info.ETag) > 0 {
			resp.Header.Set(ETag, info.ETag)
		}
	}
}

func WithValidate(validate func() error) func(*Response) {
	return func(resp *Response) {
		resp.Validate = validate
	}
}

func WithTemporary(temporary bool) func(*Response) {
	return func(resp *Response) {
		resp.Temporary = temporary
	}
}

func (resp *Response) ExpireInfo() ExpireInfo {
	return ExpireInfo{
		LastModified: resp.Header.Get(LastModified),
		ETag:         resp.Header.Get(ETag),
	}
}

type errorBody struct {
	error
}

func (e *errorBody) Read(p []byte) (n int, err error) {
	return 0, e.error
}

func (e *errorBody) Close() error {
	return nil
}