// TINYGO: The following is copied and modified from Go 1.26.2 official implementation.

// Copyright 2009 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// HTTP client. See RFC 7230 through 7235.
//
// This is the high-level Client interface.
// The low-level implementation is in transport.go.

package http

import (
	"bufio"
	"crypto/tls"
	"encoding/base64"
	"errors"
	"fmt"
	"io"
	"net"
	"net/http/internal/ascii"
	"net/url"
	"strings"
	"time"

	"golang.org/x/net/http/httpguts"
)

// A Client is an HTTP client. Its zero value ([DefaultClient]) is a
// usable client that uses [DefaultTransport].
//
// The [Client.Transport] typically has internal state (cached TCP
// connections), so Clients should be reused instead of created as
// needed. Clients are safe for concurrent use by multiple goroutines.
//
// A Client is higher-level than a [RoundTripper] (such as [Transport])
// and additionally handles HTTP details such as cookies and
// redirects.
//
// When following redirects, the Client will forward all headers set on the
// initial [Request] except:
//
//   - when forwarding sensitive headers like "Authorization",
//     "WWW-Authenticate", and "Cookie" to untrusted targets.
//     These headers will be ignored when following a redirect to a domain
//     that is not a subdomain match or exact match of the initial domain.
//     For example, a redirect from "foo.com" to either "foo.com" or "sub.foo.com"
//     will forward the sensitive headers, but a redirect to "bar.com" will not.
//   - when forwarding the "Cookie" header with a non-nil cookie Jar.
//     Since each redirect may mutate the state of the cookie jar,
//     a redirect may possibly alter a cookie set in the initial request.
//     When forwarding the "Cookie" header, any mutated cookies will be omitted,
//     with the expectation that the Jar will insert those mutated cookies
//     with the updated values (assuming the origin matches).
//     If Jar is nil, the initial cookies are forwarded without change.
type Client struct {
	// Transport specifies the mechanism by which individual
	// HTTP requests are made.
	// If nil, DefaultTransport is used.
	Transport RoundTripper

	// CheckRedirect specifies the policy for handling redirects.
	// If CheckRedirect is not nil, the client calls it before
	// following an HTTP redirect. The arguments req and via are
	// the upcoming request and the requests made already, oldest
	// first. If CheckRedirect returns an error, the Client's Get
	// method returns both the previous Response (with its Body
	// closed) and CheckRedirect's error (wrapped in a url.Error)
	// instead of issuing the Request req.
	// As a special case, if CheckRedirect returns ErrUseLastResponse,
	// then the most recent response is returned with its body
	// unclosed, along with a nil error.
	//
	// If CheckRedirect is nil, the Client uses its default policy,
	// which is to stop after 10 consecutive requests.
	CheckRedirect func(req *Request, via []*Request) error

	// Jar specifies the cookie jar.
	//
	// The Jar is used to insert relevant cookies into every
	// outbound Request and is updated with the cookie values
	// of every inbound Response. The Jar is consulted for every
	// redirect that the Client follows.
	//
	// If Jar is nil, cookies are only sent if they are explicitly
	// set on the Request.
	Jar CookieJar

	// Timeout specifies a time limit for requests made by this
	// Client. The timeout includes connection time, any
	// redirects, and reading the response body. The timer remains
	// running after Get, Head, Post, or Do return and will
	// interrupt reading of the Response.Body.
	//
	// A Timeout of zero means no timeout.
	//
	// The Client cancels requests to the underlying Transport
	// as if the Request's Context ended.
	//
	// For compatibility, the Client will also use the deprecated
	// CancelRequest method on Transport if found. New
	// RoundTripper implementations should use the Request's Context
	// for cancellation instead of implementing CancelRequest.
	Timeout time.Duration
}

// DefaultClient is the default [Client] and is used by [Get], [Head], and [Post].
var DefaultClient = &Client{}

// RoundTripper is an interface representing the ability to execute a
// single HTTP transaction, obtaining the [Response] for a given [Request].
//
// A RoundTripper must be safe for concurrent use by multiple
// goroutines.
type RoundTripper interface {
	// RoundTrip executes a single HTTP transaction, returning
	// a Response for the provided Request.
	//
	// RoundTrip should not attempt to interpret the response. In
	// particular, RoundTrip must return err == nil if it obtained
	// a response, regardless of the response's HTTP status code.
	// A non-nil err should be reserved for failure to obtain a
	// response. Similarly, RoundTrip should not attempt to
	// handle higher-level protocol details such as redirects,
	// authentication, or cookies.
	//
	// RoundTrip should not modify the request, except for
	// consuming and closing the Request's Body. RoundTrip may
	// read fields of the request in a separate goroutine. Callers
	// should not mutate or reuse the request until the Response's
	// Body has been closed.
	//
	// RoundTrip must always close the body, including on errors,
	// but depending on the implementation may do so in a separate
	// goroutine even after RoundTrip returns. This means that
	// callers wanting to reuse the body for subsequent requests
	// must arrange to wait for the Close call before doing so.
	//
	// The Request's URL and Header fields must be initialized.
	RoundTrip(*Request) (*Response, error)
}

// didTimeout is non-nil only if err != nil.
func (c *Client) send(req *Request, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {
	cookieURL := req.URL
	if req.Host != "" {
		cookieURL = cloneURL(cookieURL)
		cookieURL.Host = req.Host
	}
	if c.Jar != nil {
		for _, cookie := range c.Jar.Cookies(cookieURL) {
			req.AddCookie(cookie)
		}
	}
	resp, didTimeout, err = send(req, deadline)
	if err != nil {
		return nil, didTimeout, err
	}
	if c.Jar != nil {
		if rc := resp.Cookies(); len(rc) > 0 {
			c.Jar.SetCookies(cookieURL, rc)
		}
	}
	return resp, nil, nil
}

func (c *Client) deadline() time.Time {
	if c.Timeout > 0 {
		return time.Now().Add(c.Timeout)
	}
	return time.Time{}
}

// send issues an HTTP request.
// Caller should close resp.Body when done reading from it.
func send(req *Request, deadline time.Time) (resp *Response, didTimeout func() bool, err error) {

	// TINYGO: Removed round tripper

	if req.URL == nil {
		req.closeBody()
		return nil, alwaysFalse, errors.New("http: nil Request.URL")
	}

	if req.RequestURI != "" {
		req.closeBody()
		return nil, alwaysFalse, errors.New("http: Request.RequestURI can't be set in client requests")
	}

	// TINYGO: Removed forkReq stuff

	// Most the callers of send (Get, Post, et al) don't need
	// Headers, leaving it uninitialized. We guarantee to the
	// Transport that this has been initialized, though.
	if req.Header == nil {
		req.Header = make(Header)
	}

	if u := req.URL.User; u != nil && req.Header.Get("Authorization") == "" {
		username := u.Username()
		password, _ := u.Password()
		req.Header.Set("Authorization", "Basic "+basicAuth(username, password))
	}

	resp, err = roundTrip(req)
	if err != nil {

		// TINYGO: Remove TLS error check

		return nil, didTimeout, err
	}
	if resp == nil {
		return nil, didTimeout, fmt.Errorf("http: sendit returned a nil *Response with a nil error")
	}

	// TINYGO: Skip check for resp.Body == nil since we'll set it in roundTrip

	return resp, nil, nil
}

func roundTrip(req *Request) (*Response, error) {

	// TINYGO: This is an approximation of Transport.roudTrip()

	if req.URL == nil {
		req.closeBody()
		return nil, errors.New("http: nil Request.URL")
	}
	if req.Header == nil {
		req.closeBody()
		return nil, errors.New("http: nil Request.Header")
	}
	scheme := req.URL.Scheme
	isHTTP := scheme == "http" || scheme == "https"
	if isHTTP {
		for k, vv := range req.Header {
			if !httpguts.ValidHeaderFieldName(k) {
				req.closeBody()
				return nil, fmt.Errorf("net/http: invalid header field name %q", k)
			}
			for _, v := range vv {
				if !httpguts.ValidHeaderFieldValue(v) {
					req.closeBody()
					// Don't include the value in the error, because it may be sensitive.
					return nil, fmt.Errorf("net/http: invalid header field value for %q", k)
				}
			}
		}
	}

	// TINYGO: Skipping alternate round tripper

	if !isHTTP {
		req.closeBody()
		return nil, badStringError("unsupported protocol scheme", scheme)
	}
	if req.Method != "" && !validMethod(req.Method) {
		req.closeBody()
		return nil, fmt.Errorf("net/http: invalid method %q", req.Method)
	}
	if req.URL.Host == "" {
		req.closeBody()
		return nil, errors.New("http: no Host in request URL")
	}

	// TINYGO: From here on just brute force dial a connection,
	// TINYGO: send the request, read and return the response.
	// TINYGO: The connection is closed when resp body is closed.

	var conn net.Conn
	var err error

	host := req.Host
	missingPort := !strings.Contains(host, ":")

	switch scheme {
	case "http":
		if missingPort {
			host = host + ":80"
		}
		conn, err = net.Dial("tcp", host)
	case "https":
		if missingPort {
			host = host + ":443"
		}
		conn, err = tls.Dial("tcp", host, nil)
	}
	if err != nil {
		req.closeBody()
		return nil, err
	}

	// TINYGO: TODO handle timeouts

	writer := bufio.NewWriter(conn)
	if err = req.Write(writer); err != nil {
		req.closeBody()
		return nil, err
	}
	req.closeBody()
	if err = writer.Flush(); err != nil {
		return nil, err
	}

	req.onEOF = func() { conn.Close() }

	reader := bufio.NewReader(conn)
	return ReadResponse(reader, req)
}

// See 2 (end of page 4) https://www.ietf.org/rfc/rfc2617.txt
// "To receive authorization, the client sends the userid and password,
// separated by a single colon (":") character, within a base64
// encoded string in the credentials."
// It is not meant to be urlencoded.
func basicAuth(username, password string) string {
	auth := username + ":" + password
	return base64.StdEncoding.EncodeToString([]byte(auth))
}

// Get issues a GET to the specified URL. If the response is one of
// the following redirect codes, Get follows the redirect, up to a
// maximum of 10 redirects:
//
//	301 (Moved Permanently)
//	302 (Found)
//	303 (See Other)
//	307 (Temporary Redirect)
//	308 (Permanent Redirect)
//
// An error is returned if there were too many redirects or if there
// was an HTTP protocol error. A non-2xx response doesn't cause an
// error. Any returned error will be of type [*url.Error]. The url.Error
// value's Timeout method will report true if the request timed out.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// Get is a wrapper around DefaultClient.Get.
//
// To make a request with custom headers, use [NewRequest] and
// DefaultClient.Do.
//
// To make a request with a specified context.Context, use [NewRequestWithContext]
// and DefaultClient.Do.
func Get(url string) (resp *Response, err error) {
	return DefaultClient.Get(url)
}

// Get issues a GET to the specified URL. If the response is one of the
// following redirect codes, Get follows the redirect after calling the
// [Client.CheckRedirect] function:
//
//	301 (Moved Permanently)
//	302 (Found)
//	303 (See Other)
//	307 (Temporary Redirect)
//	308 (Permanent Redirect)
//
// An error is returned if the [Client.CheckRedirect] function fails
// or if there was an HTTP protocol error. A non-2xx response doesn't
// cause an error. Any returned error will be of type [*url.Error]. The
// url.Error value's Timeout method will report true if the request
// timed out.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// To make a request with custom headers, use [NewRequest] and [Client.Do].
//
// To make a request with a specified context.Context, use [NewRequestWithContext]
// and Client.Do.
func (c *Client) Get(url string) (resp *Response, err error) {
	req, err := NewRequest("GET", url, nil)
	if err != nil {
		return nil, err
	}
	return c.Do(req)
}

func alwaysFalse() bool { return false }

// urlErrorOp returns the (*url.Error).Op value to use for the
// provided (*Request).Method value.
func urlErrorOp(method string) string {
	if method == "" {
		return "Get"
	}
	if lowerMethod, ok := ascii.ToLower(method); ok {
		return method[:1] + lowerMethod[1:]
	}
	return method
}

// Do sends an HTTP request and returns an HTTP response, following
// policy (such as redirects, cookies, auth) as configured on the
// client.
//
// An error is returned if caused by client policy (such as
// CheckRedirect), or failure to speak HTTP (such as a network
// connectivity problem). A non-2xx status code doesn't cause an
// error.
//
// If the returned error is nil, the [Response] will contain a non-nil
// Body which the user is expected to close. If the Body is not both
// read to EOF and closed, the [Client]'s underlying [RoundTripper]
// (typically [Transport]) may not be able to re-use a persistent TCP
// connection to the server for a subsequent "keep-alive" request.
//
// The request Body, if non-nil, will be closed by the underlying
// Transport, even on errors. The Body may be closed asynchronously after
// Do returns.
//
// On error, any Response can be ignored. A non-nil Response with a
// non-nil error only occurs when CheckRedirect fails, and even then
// the returned [Response.Body] is already closed.
//
// Generally [Get], [Post], or [PostForm] will be used instead of Do.
//
// If the server replies with a redirect, the Client first uses the
// CheckRedirect function to determine whether the redirect should be
// followed. If permitted, a 301, 302, or 303 redirect causes
// subsequent requests to use HTTP method GET
// (or HEAD if the original request was HEAD), with no body.
// A 307 or 308 redirect preserves the original HTTP method and body,
// provided that the [Request.GetBody] function is defined.
// The [NewRequest] function automatically sets GetBody for common
// standard library body types.
//
// Any returned error will be of type [*url.Error]. The url.Error
// value's Timeout method will report true if the request timed out.
func (c *Client) Do(req *Request) (*Response, error) {
	if c.Transport != nil {
		return c.Transport.RoundTrip(req)
	}

	return c.do(req)
}

func (c *Client) do(req *Request) (retres *Response, reterr error) {
	if req.URL == nil {
		req.closeBody()
		return nil, &url.Error{
			Op:  urlErrorOp(req.Method),
			Err: errors.New("http: nil Request.URL"),
		}
	}
	_ = *c // panic early if c is nil; see go.dev/issue/53521

	var err error
	var didTimeout func() bool
	var resp *Response
	var deadline = c.deadline()

	// TINYGO: lots removed here, mostly handling multiple requests.
	// TINYGO: we just want simple GET, POST, etc.  In and out.

	if resp, didTimeout, err = c.send(req, deadline); err != nil {
		// c.send() always closes req.Body
		if !deadline.IsZero() && didTimeout() {
			return nil, fmt.Errorf("%s (Client.Timeout exceeded while awaiting headers)", err.Error())
		}
		return nil, err
	}

	return resp, nil
}

// Post issues a POST to the specified URL.
//
// Caller should close resp.Body when done reading from it.
//
// If the provided body is an [io.Closer], it is closed after the
// request.
//
// Post is a wrapper around DefaultClient.Post.
//
// To set custom headers, use [NewRequest] and DefaultClient.Do.
//
// See the [Client.Do] method documentation for details on how redirects
// are handled.
//
// To make a request with a specified context.Context, use [NewRequestWithContext]
// and DefaultClient.Do.
func Post(url, contentType string, body io.Reader) (resp *Response, err error) {
	return DefaultClient.Post(url, contentType, body)
}

// Post issues a POST to the specified URL.
//
// Caller should close resp.Body when done reading from it.
//
// If the provided body is an [io.Closer], it is closed after the
// request.
//
// To set custom headers, use [NewRequest] and [Client.Do].
//
// To make a request with a specified context.Context, use [NewRequestWithContext]
// and [Client.Do].
//
// See the [Client.Do] method documentation for details on how redirects
// are handled.
func (c *Client) Post(url, contentType string, body io.Reader) (resp *Response, err error) {
	req, err := NewRequest("POST", url, body)
	if err != nil {
		return nil, err
	}
	req.Header.Set("Content-Type", contentType)
	return c.Do(req)
}

// PostForm issues a POST to the specified URL, with data's keys and
// values URL-encoded as the request body.
//
// The Content-Type header is set to application/x-www-form-urlencoded.
// To set other headers, use [NewRequest] and DefaultClient.Do.
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// PostForm is a wrapper around DefaultClient.PostForm.
//
// See the [Client.Do] method documentation for details on how redirects
// are handled.
//
// To make a request with a specified [context.Context], use [NewRequestWithContext]
// and DefaultClient.Do.
func PostForm(url string, data url.Values) (resp *Response, err error) {
	return DefaultClient.PostForm(url, data)
}

// PostForm issues a POST to the specified URL,
// with data's keys and values URL-encoded as the request body.
//
// The Content-Type header is set to application/x-www-form-urlencoded.
// To set other headers, use [NewRequest] and [Client.Do].
//
// When err is nil, resp always contains a non-nil resp.Body.
// Caller should close resp.Body when done reading from it.
//
// See the [Client.Do] method documentation for details on how redirects
// are handled.
//
// To make a request with a specified context.Context, use [NewRequestWithContext]
// and Client.Do.
func (c *Client) PostForm(url string, data url.Values) (resp *Response, err error) {
	return c.Post(url, "application/x-www-form-urlencoded", strings.NewReader(data.Encode()))
}

// Head issues a HEAD to the specified URL. If the response is one of
// the following redirect codes, Head follows the redirect, up to a
// maximum of 10 redirects:
//
//	301 (Moved Permanently)
//	302 (Found)
//	303 (See Other)
//	307 (Temporary Redirect)
//	308 (Permanent Redirect)
//
// Head is a wrapper around DefaultClient.Head.
//
// To make a request with a specified [context.Context], use [NewRequestWithContext]
// and DefaultClient.Do.
func Head(url string) (resp *Response, err error) {
	return DefaultClient.Head(url)
}

// Head issues a HEAD to the specified URL. If the response is one of the
// following redirect codes, Head follows the redirect after calling the
// [Client.CheckRedirect] function:
//
//	301 (Moved Permanently)
//	302 (Found)
//	303 (See Other)
//	307 (Temporary Redirect)
//	308 (Permanent Redirect)
//
// To make a request with a specified [context.Context], use [NewRequestWithContext]
// and [Client.Do].
func (c *Client) Head(url string) (resp *Response, err error) {
	req, err := NewRequest("HEAD", url, nil)
	if err != nil {
		return nil, err
	}
	return c.Do(req)
}