/*
NAME
  lex_test.go

DESCRIPTION
  lex_test.go provides tests to check validity of the Lexer found in lex.go.

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

LICENSE
  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 h265

import (
	"io"
	"testing"
)

// rtpReader provides the RTP stream.
type rtpReader struct {
	packets [][]byte
	idx     int
}

// Read implements io.Reader.
func (r *rtpReader) Read(p []byte) (int, error) {
	if r.idx == len(r.packets) {
		return 0, io.EOF
	}
	b := r.packets[r.idx]
	n := copy(p, b)
	r.idx++
	return n, nil
}

// destination holds the access units extracted during the lexing process.
type destination [][]byte

// Write implements io.Writer.
func (d *destination) Write(p []byte) (int, error) {
	t := make([]byte, len(p))
	copy(t, p)
	*d = append([][]byte(*d), t)
	return len(p), nil
}

// TestLex checks that the Lexer can correctly extract H265 access units from
// HEVC RTP stream in RTP payload format.
func TestLex(t *testing.T) {
	const rtpVer = 2

	tests := []struct {
		donl    bool
		packets [][]byte
		expect  [][]byte
	}{
		{
			donl: false,
			packets: [][]byte{
				{ // Single NAL unit.
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // NAL Data.
				},
				{ // Fragmentation (start packet).
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type49).
					0x80,             // FU header.
					0x01, 0x02, 0x03, // FU payload.
				},
				{ // Fragmentation (middle packet)
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type 49).
					0x00,             // FU header.
					0x04, 0x05, 0x06, // FU payload.
				},
				{ // Fragmentation (end packet)
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type 49).
					0x40,             // FU header.
					0x07, 0x08, 0x09, // FU payload
				},

				{ // Aggregation. Make last packet of access unit => marker bit true.
					0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x60, 0x00, // NAL header (type 49).
					0x00, 0x04, // NAL 1 size.
					0x01, 0x02, 0x03, 0x04, // NAL 1 data.
					0x00, 0x04, // NAL 2 size.
					0x01, 0x02, 0x03, 0x04, // NAL 2 data.
				},
				{ // Singla NAL
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // NAL data.
				},
				{ // Singla NAL. Make last packet of access unit => marker bit true.
					0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // NAL data.
				},
			},
			expect: [][]byte{
				// First access unit.
				{
					// NAL 1
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // NAL data.
					// NAL 2
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, // FU payload.
					0x04, 0x05, 0x06, // FU payload.
					0x07, 0x08, 0x09, // FU payload.
					// NAL 3
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, 0x04, // NAL data.
					// NAL 4
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, 0x04, // NAL 2 data
				},
				// Second access unit.
				{
					// NAL 1
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // Data.
					// NAL 2
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x01, 0x02, 0x03, 0x04, // Data.
				},
			},
		},
		{
			donl: true,
			packets: [][]byte{
				{ // Single NAL unit.
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, 0x04, // NAL Data.
				},
				{ // Fragmentation (start packet).
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type49).
					0x80,       // FU header.
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, // FU payload.
				},
				{ // Fragmentation (middle packet)
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type 49).
					0x00,       // FU header.
					0x00, 0x00, // DONL
					0x04, 0x05, 0x06, // FU payload.
				},
				{ // Fragmentation (end packet)
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x62, 0x00, // NAL header (type 49).
					0x40,       // FU header.
					0x00, 0x00, // DONL
					0x07, 0x08, 0x09, // FU payload
				},

				{ // Aggregation. Make last packet of access unit => marker bit true.
					0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x60, 0x00, // NAL header (type 49).
					0x00, 0x00, // DONL
					0x00, 0x04, // NAL 1 size.
					0x01, 0x02, 0x03, 0x04, // NAL 1 data.
					0x00,       // DOND
					0x00, 0x04, // NAL 2 size.
					0x01, 0x02, 0x03, 0x04, // NAL 2 data.
				},
				{ // Singla NAL
					0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS)
					0x00, 0x00, // DONL.
					0x01, 0x02, 0x03, 0x04, // NAL data.
				},
				{ // Singla NAL. Make last packet of access unit => marker bit true.
					0x80, 0x80, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, // RTP header.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, 0x04, // NAL data.
				},
			},
			expect: [][]byte{
				// First access unit.
				{
					// NAL 1
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, 0x04, // NAL data.
					// NAL 2
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, // FU payload.
					0x04, 0x05, 0x06, // FU payload.
					0x07, 0x08, 0x09, // FU payload.
					// NAL 3
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, 0x04, // NAL data.
					// NAL 4
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x01, 0x02, 0x03, 0x04, // NAL 2 data
				},
				// Second access unit.
				{
					// NAL 1
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, 0x04, // Data.
					// NAL 2
					0x00, 0x00, 0x00, 0x01, // Start code.
					0x40, 0x00, // NAL header (type=32 VPS).
					0x00, 0x00, // DONL
					0x01, 0x02, 0x03, 0x04, // Data.
				},
			},
		},
	}

	for testNum, test := range tests {
		r := &rtpReader{packets: test.packets}
		d := &destination{}
		err := NewLexer(test.donl).Lex(d, r, 0)
		if err != nil {
			t.Fatalf("error lexing: %v\n", err)
		}

		for i, accessUnit := range test.expect {
			for j, part := range accessUnit {
				if part != [][]byte(*d)[i][j] {
					t.Fatalf("did not get expected data for test: %v.\nGot: %v\nWant: %v\n", testNum, d, test.expect)
				}
			}
		}
	}
}