package httpconn

import (
	"bufio"
	"context"
	"crypto/tls"
	"errors"
	"io"
	"net"
	"net/http"
	"net/url"
	"time"

	"git.crumpington.com/public/jldb/lib/errs"
)

var ErrInvalidStatus = errors.New("invalid status")

func Dial(rawURL string) (net.Conn, error) {
	u, err := url.Parse(rawURL)
	if err != nil {
		return nil, errs.Unexpected.WithErr(err)
	}

	switch u.Scheme {
	case "https":
		return DialHTTPS(u.Host+":443", u.Path)
	case "http":
		return DialHTTP(u.Host, u.Path)
	default:
		return nil, errs.Unexpected.WithMsg("Unknown scheme: " + u.Scheme)
	}
}

func DialHTTPS(host, path string) (net.Conn, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	d := tls.Dialer{}
	conn, err := d.DialContext(ctx, "tcp", host)
	cancel()
	if err != nil {
		return nil, errs.IO.WithErr(err)
	}
	return finishDialing(conn, host, path)
}

func DialHTTPSWithIP(ip, host, path string) (net.Conn, error) {
	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	d := tls.Dialer{Config: &tls.Config{ServerName: host}}
	conn, err := d.DialContext(ctx, "tcp", ip)
	cancel()
	if err != nil {
		return nil, errs.IO.WithErr(err)
	}
	return finishDialing(conn, host, path)
}

func DialHTTP(host, path string) (net.Conn, error) {
	conn, err := net.Dial("tcp", host)
	if err != nil {
		return nil, errs.IO.WithErr(err)
	}
	return finishDialing(conn, host, path)
}

func finishDialing(conn net.Conn, host, path string) (net.Conn, error) {
	conn.SetDeadline(time.Now().Add(10 * time.Second))

	io.WriteString(conn, "CONNECT "+path+" HTTP/1.0\n")
	io.WriteString(conn, "Host: "+host+"\n\n")

	// Require successful HTTP response before using the conn.
	resp, err := http.ReadResponse(bufio.NewReader(conn), &http.Request{Method: "CONNECT"})
	if err != nil {
		conn.Close()
		return nil, errs.IO.WithErr(err)
	}

	if resp.Status != "200 OK" {
		conn.Close()
		return nil, errs.IO.WithMsg("invalid status: %s", resp.Status)
	}

	conn.SetDeadline(time.Time{})

	return conn, nil
}