// ITU-T H.222.0(10/2014)
// Information technology – Generic coding of moving pictures and associated audio information: Systems
// 2.4.4.3 Program association table(p65)

#include "mpeg-ts-proto.h"
#include "mpeg-util.h"
#include <assert.h>

static struct pmt_t *pat_fetch(struct pat_t *pat, uint16_t pid)
{
    unsigned int i;
    for (i = 0; i < pat->pmt_count; i++) {
        if (pat->pmts[i].pid == pid) {
            return &pat->pmts[i];
        }
    }

    if (pat->pmt_count >= sizeof(pat->pmts) / sizeof(pat->pmts[0])) {
        assert(0);
        return NULL;
    }

    // new pmt
    return &pat->pmts[pat->pmt_count++];
}

size_t pat_read(struct pat_t *pat, const uint8_t *data, size_t bytes)
{
    // Table 2-30 – Program association section(p65)

    struct pmt_t *pmt;
    uint32_t i = 0;
    uint16_t pn, pid;
//	uint32_t crc = 0;

    uint32_t table_id = data[0];
    uint32_t section_syntax_indicator = (data[1] >> 7) & 0x01;
//	uint32_t zero = (data[1] >> 6) & 0x01;
//	uint32_t reserved = (data[1] >> 4) & 0x03;
    uint32_t section_length = ((data[1] & 0x0F) << 8) | data[2];
    uint32_t transport_stream_id = (data[3] << 8) | data[4];
//	uint32_t reserved2 = (data[5] >> 6) & 0x03;
    uint32_t version_number = (data[5] >> 1) & 0x1F;
//	uint32_t current_next_indicator = data[5] & 0x01;
//	uint32_t sector_number = data[6];
//	uint32_t last_sector_number = data[7];

//	printf("PAT: %0x %0x %0x %0x %0x %0x %0x %0x\n", (unsigned int)data[0], (unsigned int)data[1], (unsigned int)data[2], (unsigned int)data[3], (unsigned int)data[4], (unsigned int)data[5], (unsigned int)data[6], (unsigned int)data[7]);

    assert(PAT_TID_PAS == table_id);
    assert(1 == section_syntax_indicator);
    if (pat->ver != version_number) {
        pat->pmt_count = 0;    // clear all pmts
    }
    pat->tsid = transport_stream_id;
    pat->ver = version_number;

    // TODO: version_number change, reload pmts
    assert(bytes >= section_length + 3); // PAT = section_length + 3
    for (i = 8; i + 4 <= section_length + 8 - 5 - 4; i += 4) { // 4:CRC, 5:follow section_length item
        pn = (data[i] << 8) | data[i + 1];
        pid = ((data[i + 2] & 0x1F) << 8) | data[i + 3];
//        printf("PAT: pn: %0x, pid: %0x\n", (unsigned int)pn, (unsigned int)pid);

        if (0 == pn) {
            continue;    // ignore NIT info
        }
        assert(pat->pmt_count <= sizeof(pat->pmts) / sizeof(pat->pmts[0]));
        pmt = pat_fetch(pat, pid);
        if (NULL == pmt) {
            continue;
        }

        pmt->pn = pn;
        pmt->pid = pid;
    }

    //assert(i+4 == bytes);
    //crc = (data[i] << 24) | (data[i+1] << 16) | (data[i+2] << 8) | data[i+3];
    //crc = mpeg_crc32(-1, data, bytes-4);
    assert(0 == mpeg_crc32(0xffffffff, data, section_length + 3));
    return 0;
}

size_t pat_write(const struct pat_t *pat, uint8_t *data)
{
    // Table 2-30 – Program association section(p65)

    uint32_t i = 0;
    uint32_t len = 0;
    uint32_t crc = 0;

    len = pat->pmt_count * 4 + 5 + 4; // 5 bytes remain header and 4 bytes crc32

    // shall not exceed 1021 (0x3FD).
    assert(len <= 1021);
    assert(len <= TS_PACKET_SIZE - 7);

    data[0] = PAT_TID_PAS;	// program association table

    // section_syntax_indicator = '1'
    // '0'
    // reserved '11'
    nbo_w16(data + 1, (uint16_t)(0xb000 | len));

    // transport_stream_id
    nbo_w16(data + 3, (uint16_t)pat->tsid);

    // reserved '11'
    // version_number 'xxxxx'
    // current_next_indicator '1'
    data[5] = (uint8_t)(0xC1 | (pat->ver << 1));

    // section_number/last_section_number
    data[6] = 0x00;
    data[7] = 0x00;

    for (i = 0; i < pat->pmt_count; i++) {
        nbo_w16(data + 8 + i * 4 + 0, (uint16_t)pat->pmts[i].pn);
        nbo_w16(data + 8 + i * 4 + 2, (uint16_t)(0xE000 | pat->pmts[i].pid));
    }

    // crc32
    crc = mpeg_crc32(0xffffffff, data, len - 1);
    //put32(data + section_length - 1, crc);
    data[len - 1 + 3] = (crc >> 24) & 0xFF;
    data[len - 1 + 2] = (crc >> 16) & 0xFF;
    data[len - 1 + 1] = (crc >> 8) & 0xFF;
    data[len - 1 + 0] = crc & 0xFF;

    return len + 3; // total length
}

struct pmt_t *pat_find(struct pat_t *pat, uint16_t pn)
{
    unsigned int i;
    for (i = 0; i < pat->pmt_count; i++) {
        if (pat->pmts[i].pn == pn) {
            return &pat->pmts[i];
        }
    }
    return NULL;
}