/*
 *     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 (
	"context"
	"errors"
	"net/url"
)

type Request struct {
	URL    *url.URL
	Header Header
	// ctx is either the client or server context. It should only
	// be modified via copying the whole Request using WithContext.
	// It is unexported to prevent people from using Context wrong
	// and mutating the contexts held by callers of the same request.
	ctx context.Context
}

func NewRequest(rawURL string) (*Request, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, err
	}
	return &Request{
		URL:    u,
		Header: make(Header),
		ctx:    context.Background(),
	}, nil
}

func NewRequestWithHeader(rawURL string, header map[string]string) (*Request, error) {
	request, err := NewRequest(rawURL)
	if err != nil {
		return nil, err
	}
	for k, v := range header {
		request.Header.Add(k, v)
	}
	return request, nil
}

func NewRequestWithContext(ctx context.Context, rawURL string, header map[string]string) (*Request, error) {
	if ctx == nil {
		return nil, errors.New("nil Context")
	}
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, err
	}
	req := &Request{
		ctx:    ctx,
		URL:    u,
		Header: make(Header),
	}
	for k, v := range header {
		req.Header.Add(k, v)
	}
	return req, nil
}

// Context returns the request's context. To change the context, use
// WithContext.
//
// The returned context is always non-nil; it defaults to the
// background context.
//
// For outgoing client requests, the context controls cancellation.
//
// For incoming server requests, the context is canceled when the
// client's connection closes, the request is canceled (with HTTP/2),
// or when the ServeHTTP method returns.
func (r *Request) Context() context.Context {
	if r.ctx != nil {
		return r.ctx
	}
	return context.Background()
}

// WithContext returns a shallow copy of r with its context changed
// to ctx. The provided ctx must be non-nil.
//
// For outgoing client request, the context controls the entire
// lifetime of a request and its response: obtaining a connection,
// sending the request, and reading the response headers and body.
//
// To create a new request with a context, use NewRequestWithContext.
// To change the context of a request, such as an incoming request you
// want to modify before sending back out, use Request.Clone. Between
// those two uses, it's rare to need WithContext.
func (r *Request) WithContext(ctx context.Context) *Request {
	if ctx == nil {
		panic("nil context")
	}
	r2 := new(Request)
	*r2 = *r
	r2.ctx = ctx
	r2.URL = cloneURL(r.URL) // legacy behavior; TODO: try to remove. Issue 23544
	return r2
}

func cloneURL(u *url.URL) *url.URL {
	if u == nil {
		return nil
	}
	u2 := new(url.URL)
	*u2 = *u
	if u.User != nil {
		u2.User = new(url.Userinfo)
		*u2.User = *u.User
	}
	return u2
}

// Clone returns a deep copy of r with its context changed to ctx.
// The provided ctx must be non-nil.
//
// For an outgoing client request, the context controls the entire
// lifetime of a request and its response: obtaining a connection,
// sending the request, and reading the response headers and body.
func (r *Request) Clone(ctx context.Context) *Request {
	if ctx == nil {
		panic("nil context")
	}
	r2 := new(Request)
	*r2 = *r
	r2.ctx = ctx
	r2.URL = cloneURL(r.URL)
	if r.Header != nil {
		r2.Header = r.Header.Clone()
	}
	return r2
}