/*
NAME
  rtsp_test.go

DESCRIPTION
  rtsp_test.go provides a test to check functionality provided in rtsp.go.

AUTHORS
  Saxon A. Nelson-Milton <saxon@ausocean.org>

LICENSE
  This is Copyright (C) 2019 the Australian Ocean Lab (AusOcean).

  It is free software: you can redistribute it and/or modify them
  under the terms of the GNU General Public License as published by the
  Free Software Foundation, either version 3 of the License, or (at your
  option) any later version.

  It is distributed in the hope that it will be useful, but WITHOUT
  ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
  for more details.

  You should have received a copy of the GNU General Public License
  in gpl.txt.  If not, see http://www.gnu.org/licenses.
*/
package rtsp

import (
	"errors"
	"fmt"
	"io"
	"net"
	"net/url"
	"strings"
	"testing"
	"time"
	"unicode"
)

// The max request size we should get in bytes.
const maxRequest = 1024

// TestMethods checks that we can correctly form requests for each of the RTSP
// methods supported in the rtsp pkg. This test also checks that communication
// over a TCP connection is performed correctly.
func TestMethods(t *testing.T) {
	const dummyURL = "rtsp://admin:admin@192.168.0.50:8554/CH001.sdp"
	url, err := url.Parse(dummyURL)
	if err != nil {
		t.Fatalf("could not parse dummy address, failed with err: %v", err)
	}

	// tests holds tests which consist of a function used to create and write a
	// request of a particular method, and also the expected request bytes
	// to be received on the server side. The bytes in these tests have been
	// obtained from a valid RTSP communication cltion..
	tests := []struct {
		method   func(c *Client) (*Response, error)
		expected []byte
	}{
		{
			method: func(c *Client) (*Response, error) {
				req, err := NewRequest("DESCRIBE", c.nextCSeq(), url, nil)
				if err != nil {
					return nil, err
				}
				req.Header.Add("Accept", "application/sdp")
				return c.Do(req)
			},
			expected: []byte{
				0x44, 0x45, 0x53, 0x43, 0x52, 0x49, 0x42, 0x45, 0x20, 0x72, 0x74, 0x73,
				0x70, 0x3a, 0x2f, 0x2f, 0x61, 0x64, 0x6d, 0x69, 0x6e, 0x3a, 0x61, 0x64,
				0x6d, 0x69, 0x6e, 0x40, 0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38, 0x2e,
				0x30, 0x2e, 0x35, 0x30, 0x3a, 0x38, 0x35, 0x35, 0x34, 0x2f, 0x43, 0x48,
				0x30, 0x30, 0x31, 0x2e, 0x73, 0x64, 0x70, 0x20, 0x52, 0x54, 0x53, 0x50,
				0x2f, 0x31, 0x2e, 0x30, 0x0d, 0x0a, 0x43, 0x53, 0x65, 0x71, 0x3a, 0x20,
				0x32, 0x0d, 0x0a, 0x41, 0x63, 0x63, 0x65, 0x70, 0x74, 0x3a, 0x20, 0x61,
				0x70, 0x70, 0x6c, 0x69, 0x63, 0x61, 0x74, 0x69, 0x6f, 0x6e, 0x2f, 0x73,
				0x64, 0x70, 0x0d, 0x0a, 0x0d, 0x0a,
			},
		},
		{
			method: func(c *Client) (*Response, error) {
				req, err := NewRequest("OPTIONS", c.nextCSeq(), url, nil)
				if err != nil {
					return nil, err
				}
				return c.Do(req)
			},
			expected: []byte{
				0x4f, 0x50, 0x54, 0x49, 0x4f, 0x4e, 0x53, 0x20, 0x72, 0x74, 0x73, 0x70,
				0x3a, 0x2f, 0x2f, 0x61, 0x64, 0x6d, 0x69, 0x6e, 0x3a, 0x61, 0x64, 0x6d,
				0x69, 0x6e, 0x40, 0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38, 0x2e, 0x30,
				0x2e, 0x35, 0x30, 0x3a, 0x38, 0x35, 0x35, 0x34, 0x2f, 0x43, 0x48, 0x30,
				0x30, 0x31, 0x2e, 0x73, 0x64, 0x70, 0x20, 0x52, 0x54, 0x53, 0x50, 0x2f,
				0x31, 0x2e, 0x30, 0x0d, 0x0a, 0x43, 0x53, 0x65, 0x71, 0x3a, 0x20, 0x31,
				0x0d, 0x0a, 0x0d, 0x0a,
			},
		},
		{
			method: func(c *Client) (*Response, error) {
				u, err := url.Parse(dummyURL + "/track1")
				if err != nil {
					return nil, err
				}

				req, err := NewRequest("SETUP", c.nextCSeq(), u, nil)
				if err != nil {
					return nil, err
				}
				req.Header.Add("Transport", fmt.Sprintf("RTP/AVP;unicast;client_port=%d-%d", 6870, 6871))

				return c.Do(req)
			},
			expected: []byte{
				0x53, 0x45, 0x54, 0x55, 0x50, 0x20, 0x72, 0x74, 0x73, 0x70, 0x3a, 0x2f,
				0x2f, 0x61, 0x64, 0x6d, 0x69, 0x6e, 0x3a, 0x61, 0x64, 0x6d, 0x69, 0x6e,
				0x40, 0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38, 0x2e, 0x30, 0x2e, 0x35,
				0x30, 0x3a, 0x38, 0x35, 0x35, 0x34, 0x2f, 0x43, 0x48, 0x30, 0x30, 0x31,
				0x2e, 0x73, 0x64, 0x70, 0x2f, 0x74, 0x72, 0x61, 0x63, 0x6b, 0x31, 0x20,
				0x52, 0x54, 0x53, 0x50, 0x2f, 0x31, 0x2e, 0x30, 0x0d, 0x0a, 0x54, 0x72,
				0x61, 0x6e, 0x73, 0x70, 0x6f, 0x72, 0x74, 0x3a, 0x20, 0x52, 0x54, 0x50,
				0x2f, 0x41, 0x56, 0x50, 0x3b, 0x75, 0x6e, 0x69, 0x63, 0x61, 0x73, 0x74,
				0x3b, 0x63, 0x6c, 0x69, 0x65, 0x6e, 0x74, 0x5f, 0x70, 0x6f, 0x72, 0x74,
				0x3d, 0x36, 0x38, 0x37, 0x30, 0x2d, 0x36, 0x38, 0x37, 0x31, 0x0d, 0x0a,
				0x43, 0x53, 0x65, 0x71, 0x3a, 0x20, 0x33, 0x0d, 0x0a, 0x0d, 0x0a,
			},
		},
		{
			method: func(c *Client) (*Response, error) {
				req, err := NewRequest("PLAY", c.nextCSeq(), url, nil)
				if err != nil {
					return nil, err
				}
				req.Header.Add("Session", "00000021")

				return c.Do(req)
			},
			expected: []byte{
				0x50, 0x4c, 0x41, 0x59, 0x20, 0x72, 0x74, 0x73, 0x70, 0x3a, 0x2f, 0x2f,
				0x61, 0x64, 0x6d, 0x69, 0x6e, 0x3a, 0x61, 0x64, 0x6d, 0x69, 0x6e, 0x40,
				0x31, 0x39, 0x32, 0x2e, 0x31, 0x36, 0x38, 0x2e, 0x30, 0x2e, 0x35, 0x30,
				0x3a, 0x38, 0x35, 0x35, 0x34, 0x2f, 0x43, 0x48, 0x30, 0x30, 0x31, 0x2e,
				0x73, 0x64, 0x70, 0x20, 0x52, 0x54, 0x53, 0x50, 0x2f, 0x31, 0x2e, 0x30,
				0x0d, 0x0a, 0x43, 0x53, 0x65, 0x71, 0x3a, 0x20, 0x34, 0x0d, 0x0a, 0x53,
				0x65, 0x73, 0x73, 0x69, 0x6f, 0x6e, 0x3a, 0x20, 0x30, 0x30, 0x30, 0x30,
				0x30, 0x30, 0x32, 0x31, 0x0d, 0x0a, 0x0d, 0x0a,
			},
		},
	}

	const serverAddr = "rtsp://localhost:8005"
	const retries = 10

	clientErr := make(chan error)
	serverErr := make(chan error)
	done := make(chan struct{})

	// This routine acts as the server.
	go func() {
		l, err := net.Listen("tcp", strings.TrimLeft(serverAddr, "rtsp://"))
		if err != nil {
			serverErr <- errors.New(fmt.Sprintf("server could not listen, error: %v", err))
		}

		conn, err := l.Accept()
		if err != nil {
			serverErr <- errors.New(fmt.Sprintf("server could not accept connection, error: %v", err))
		}

		buf := make([]byte, maxRequest)
		var n int
		for i, test := range tests {
		loop:
			for {
				n, err = conn.Read(buf)
				err, ok := err.(net.Error)

				switch {
				case err == nil:
					break loop
				case err == io.EOF:
				case ok && err.Timeout():
				default:
					serverErr <- errors.New(fmt.Sprintf("server could not read conn, error: %v", err))
					return
				}
			}

			// Write a dummy response, client won't care.
			conn.Write([]byte{'\n'})

			want := test.expected
			got := buf[:n]
			if !equal(got, want) {
				serverErr <- errors.New(fmt.Sprintf("unexpected result for test: %v. \nGot: %v\n Want: %v\n", i, got, want))
			}
		}
		close(done)
	}()

	// This routine acts as the client.
	go func() {
		var clt *Client
		var err error

		// Keep trying to connect to server.
		// TODO: use generalised retry utility when available.
		for retry := 0; ; retry++ {
			clt, err = NewClient(serverAddr)
			if err == nil {
				break
			}

			if retry > retries {
				clientErr <- errors.New(fmt.Sprintf("client could not connect to server, error: %v", err))
			}
			time.Sleep(10 * time.Millisecond)
		}

		for i, test := range tests {
			_, err = test.method(clt)
			if err != nil && err != io.EOF && err != errSmallResponse {
				clientErr <- errors.New(fmt.Sprintf("error request for: %v err: %v", i, err))
			}
		}
	}()

	// We check for errors or a done signal from the server and client routines.
	for {
		select {
		case err := <-clientErr:
			t.Fatalf("client error: %v", err)
		case err := <-serverErr:
			t.Fatalf("server error: %v", err)
		case <-done:
			return
		default:
		}
	}
}

// equal checks that the got slice is considered equivalent to the want slice,
// neglecting unimportant differences such as order of items in header and the
// CSeq number.
func equal(got, want []byte) bool {
	const eol = "\r\n"
	gotParts := strings.Split(strings.TrimRight(string(got), eol), eol)
	wantParts := strings.Split(strings.TrimRight(string(want), eol), eol)
	gotParts, ok := rmSeqNum(gotParts)
	if !ok {
		return false
	}
	wantParts, ok = rmSeqNum(wantParts)
	if !ok {
		return false
	}
	for _, gotStr := range gotParts {
		for i, wantStr := range wantParts {
			if gotStr == wantStr {
				wantParts = append(wantParts[:i], wantParts[i+1:]...)
			}
		}
	}
	return len(wantParts) == 0
}

// rmSeqNum removes the CSeq number from a string in []string that contains it.
// If a CSeq field is not found nil and false is returned.
func rmSeqNum(s []string) ([]string, bool) {
	for i, _s := range s {
		if strings.Contains(_s, "CSeq") {
			s[i] = strings.TrimFunc(s[i], func(r rune) bool { return unicode.IsNumber(r) })
			return s, true
		}
	}
	return nil, false
}