#include <assert.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>   /* for perror() */
#include <string.h>  /* for memcpy() */
#include <stdlib.h>  /* for realloc(), free() */
#include <unistd.h>  /* for write() */

#define LM_ARRAY_LEN(ary)       (sizeof(ary)/sizeof((ary)[0]))
#define LM_CEILDIV(n, d)        ( ((n)+(d)-1) / (d) )
#define LM_NEXT_POWER_OF_2(x)   ( (x) ? 1ULL<<((sizeof(unsigned long long)*8)-__builtin_clzll(x)) : 1)
#define LM_CAT2(a, b)           a ## b
#define LM_CAT2_(a, b)          LM_CAT2(a, b)
#define assert_notreached(msg)  assert(false)

struct buf {
	uint8_t *dat;
	size_t   len;
	size_t   cap;
};

void append(struct buf *buf, void *dat, size_t len) {
	assert(buf);
	assert(len == 0 || dat);

	if (buf->len + len > buf->cap) {
		buf->cap = LM_NEXT_POWER_OF_2(buf->len + len);
		buf->dat = realloc(buf->dat, buf->cap);
		assert(buf->dat);
	}
	memcpy(&buf->dat[buf->len], dat, len);
	buf->len += len;
}

void append_u32be(struct buf *buf, uint32_t val) {
	assert(buf);

	uint8_t dat[4] = {
		(val>>(8*3))&0xFF,
		(val>>(8*2))&0xFF,
		(val>>(8*1))&0xFF,
		(val>>(8*0))&0xFF,
	};
	append(buf, dat, sizeof(dat));
}

bool xwrite(int fd, uint8_t *dat, size_t len) {
	assert(len == 0 || dat);

	for (size_t done = 0; done < len;) {
		ssize_t n = write(fd, &dat[done], len-done);
		if (n < 0) {
			perror("write");
			return true;
		}
		done += n;
	}
	return false;
}

/* NUT ************************************************************************/

/* Magic values.  *****************************************/
uint8_t nut_file_id_string[]      = "nut/multimedia container"; /* including NUL terminator */
uint8_t nut_startcode_main[]      = {'N', 'M', 0x7A, 0x56, 0x1F, 0x5F, 0x04, 0xAD };
uint8_t nut_startcode_stream[]    = {'N', 'S', 0x11, 0x40, 0x5B, 0xF2, 0xF9, 0xDB };
uint8_t nut_startcode_syncpoint[] = {'N', 'K', 0xE4, 0xAD, 0xEE, 0xCA, 0x45, 0x69 };
uint8_t nut_startcode_index[]     = {'N', 'X', 0xDD, 0x67, 0x2F, 0x23, 0xE6, 0x4E };
uint8_t nut_startcode_info[]      = {'N', 'I', 0xAB, 0x68, 0xB5, 0x96, 0xBA, 0x78 };

#define NUT_FRAMEFLAG_KEY         (1<< 0)
#define NUT_FRAMEFLAG_EOR         (1<< 1)
#define _NUT_FRAMEFLAG_2          (1<< 2)
#define NUT_FRAMEFLAG_CODED_PTS   (1<< 3)
#define NUT_FRAMEFLAG_STREAM_ID   (1<< 4)
#define NUT_FRAMEFLAG_SIZE_MSB    (1<< 5)
#define NUT_FRAMEFLAG_CHECKSUM    (1<< 6)
#define NUT_FRAMEFLAG_RESERVED    (1<< 7)
#define NUT_FRAMEFLAG_SM_DATA     (1<< 8)
#define _NUT_FRAMEFLAG_9          (1<< 9)
#define NUT_FRAMEFLAG_HEADER_IDX  (1<<10)
#define NUT_FRAMEFLAG_MATCH_TIME  (1<<11)
#define NUT_FRAMEFLAG_CODED       (1<<12)
#define NUT_FRAMEFLAG_INVALID     (1<<13)

#define NUT_MAINFLAG_BROADCAST_MODE (1<< 0)
#define NUT_MAINFLAG_PIPE_MODE      (1<< 1)

#define NUT_UNKNOWN_MATCH_TIME (1-(UINT64_C(1)<<62))

enum nut_stream_class {
	NUT_STREAMCLASS_VIDEO     = 0,
	NUT_STREAMCLASS_AUDIO     = 1,
	NUT_STREAMCLASS_SUBTITLES = 2,
	NUT_STREAMCLASS_USERDATA  = 3,
};

#define NUT_STREAMFLAG_FIXED_FPS (1<< 1)

enum nut_colorspace {
	NUT_COLORSPACE_UNKNOWN         =  0,
	NUT_COLORSPACE_ITU642_TRUNC    =  1,
	NUT_COLORSPACE_ITU709_TRUNC    =  2,
	NUT_COLORSPACE_ITU642_FULL     = 17,
	NUT_COLORSPACE_ITU709_FILL     = 18,
};

/* Basic fixed-length types.  *****************************/

void nut_append_u8(struct buf *buf, uint8_t val) {
	assert(buf);

	append(buf, &val, 1);
}

void nut_append_u32(struct buf *buf, uint32_t val) {
	assert(buf);

	append_u32be(buf, val);
}

/* Basic variable-length types.  **************************/

void nut_append_vu(struct buf *buf, uint64_t val) {
	assert(buf);

	uint8_t dat[10] = {
		0x80|((val>>(7*9))&0x7F),
		0x80|((val>>(7*8))&0x7F),
		0x80|((val>>(7*7))&0x7F),
		0x80|((val>>(7*6))&0x7F),
		0x80|((val>>(7*5))&0x7F),
		0x80|((val>>(7*4))&0x7F),
		0x80|((val>>(7*3))&0x7F),
		0x80|((val>>(7*2))&0x7F),
		0x80|((val>>(7*1))&0x7F),
		0x00|((val>>(7*0))&0x7F),
	};
	uint8_t skip = 0;
	while (dat[skip] == 0x80)
		skip++;
	append(buf, &dat[skip], sizeof(dat)-skip);
}

void nut_append_vs(struct buf *buf, int64_t val) {
	assert(buf);
	assert((val < 0 ? -val : val) <= UINT64_MAX>>1);

	uint64_t temp;
	if (val > 0)
		temp = val << 1;
	else
		temp = ((-val) << 1) | 1;
	temp--;
	nut_append_vu(buf, temp);
}

void nut_append_vb(struct buf *buf, void *dat, size_t len) {
	assert(buf);
	assert(len == 0 || dat);

	nut_append_vu(buf, len);
	append(buf, dat, len);
}

#define nut_append_vb_str(buf, str) nut_append_vb(buf, str, sizeof(str)-1)

/* Mid-level.  ********************************************/

uint32_t nut_crc32(uint8_t *dat, int len){
	assert(len == 0 || dat);

	/* "Generator polynomial is 0x104C11DB7."  */
	static const uint32_t table[16] = {
		0x00000000, 0x04C11DB7, 0x09823B6E, 0x0D4326D9,
		0x130476DC, 0x17C56B6B, 0x1A864DB2, 0x1E475005,
		0x2608EDB8, 0x22C9F00F, 0x2F8AD6D6, 0x2B4BCB61,
		0x350C9B64, 0x31CD86D3, 0x3C8EA00A, 0x384FBDBD,
	};

	/* "Starting value is zero."  */
	uint32_t crc = 0;

	while (len--) {
		crc ^= *dat++ << 24;
		crc = (crc<<4) ^ table[crc>>28];
		crc = (crc<<4) ^ table[crc>>28];
	}
	return crc;
}

void nut_append_packet(struct buf *buf, uint8_t *startcode, void *data, size_t len) {
	assert(buf);
	assert(startcode);
	assert(len == 0 || data);

	size_t packet_beg = buf->len;
	append(buf, startcode, 8);
	nut_append_vu(buf, len+4);
	if (len+4 > 4096)
		nut_append_u32(buf, nut_crc32(&buf->dat[packet_beg], buf->len - packet_beg));
	size_t data_beg = buf->len;
	append(buf, data, len);
	nut_append_u32(buf, nut_crc32(&buf->dat[data_beg], buf->len - data_beg));
}

[[gnu::nonstring]] char font[10][8*4] = {
	"   ##   "
	"  #  #  "
	"  #  #  "
	"   ##   ",

	"    #   "
	"   ##   "
	"    #   "
	"   ###  ",

	"   ##   "
	"  #  #  "
	"    #   "
	"  ####  ",

	"   ##   "
	"     #  "
	"     #  "
	"   ##   ",

	"    ##  "
	"   # #  "
	"  ####  "
	"     #  ",

	"  ####  "
	"  ###   "
	"     #  "
	"  ###   ",

	"  #     "
	"  ###   "
	"  #  #  "
	"   ##   ",

	"  ####  "
	"    #   "
	"   #    "
	"   #    ",

	"   ##   "
	"  #  #  "
	"  ####  "
	"   ##   ",

	"   ##   "
	"  #  #  "
	"   ###  "
	"     #  ",
};
static_assert(LM_ARRAY_LEN(font) == 10);
static_assert(sizeof(font[0]) == 32);