/* See LICENSE file for copyright and license details. */
#include "common.h"


void
writeall(const char *s, size_t n)
{
	ssize_t r;
	while (n) {
		r = write(STDOUT_FILENO, s, n);
		if (r < 0) {
			if (errno == EINTR)
				continue;
			fprintf(stderr, "%s: write <stdout>: %s\n", argv0, strerror(errno));
			exit(1);
		}
		s = &s[r];
		n -= (size_t)r;
	}
}


void
writechar(uint_least32_t cp)
{
	char buf[4];

	if (cp < UINT32_C(0x80)) {
		buf[0] = (char)cp;
		writeall(buf, 1u);
	} else if (cp < UINT32_C(0x800)) {
		buf[0] = (char)(( cp >> 6) | 0xC0u);
		buf[1] = (char)(((cp >> 0) & 0x3Fu) | 0x80u);
		writeall(buf, 2u);
	} else if (cp < UINT32_C(0x10000)) {
		buf[0] = (char)(( cp >> 12) | 0xE0u);
		buf[1] = (char)(((cp >> 6) & 0x3Fu) | 0x80u);
		buf[2] = (char)(((cp >> 0) & 0x3Fu) | 0x80u);
		writeall(buf, 3u);
	} else if (cp < UINT32_C(0x110000)) {
		buf[0] = (char)(( cp >> 18) | 0xF0u);
		buf[1] = (char)(((cp >> 12) & 0x3Fu) | 0x80u);
		buf[2] = (char)(((cp >>  6) & 0x3Fu) | 0x80u);
		buf[3] = (char)(((cp >>  0) & 0x3Fu) | 0x80u);
		writeall(buf, 4u);
	} else {
		abort();
	}
}


int
convert(enum libcharconv_result (*conv)(const char *, size_t, size_t *, uint_least32_t *, size_t *))
{
	char *buf = NULL;
	size_t bufsize = 0;
	size_t head = 0;
	size_t tail = 0;
	ssize_t r;
	enum libcharconv_result res;
	size_t n;
	uint_least32_t *cps;
	size_t ncps;
	size_t cps_size = 16u;
	size_t i;

	cps = malloc(cps_size * sizeof(*cps));
	if (!cps) {
		fprintf(stderr, "%s: out of memory\n", argv0);
		exit(1);
	}

	for (;;) {
		if (head == bufsize) {
			if (tail) {
				memmove(&buf[0], &buf[tail], head -= tail);
				tail = 0;
			} else {
				buf = realloc(buf, bufsize += 8 << 10);
				if (!buf) {
					fprintf(stderr, "%s: out of memory\n", argv0);
					exit(1);
				}
			}
		}
		r = read(STDIN_FILENO, &buf[head], bufsize - head);
		if (r <= 0) {
			if (!r)
				break;
			if (errno == EINTR)
				continue;
			fprintf(stderr, "%s: read <stdin>: %s\n", argv0, strerror(errno));
			exit(1);
		}
		head += (size_t)r;
	conv_again:
		ncps = cps_size;
		res = (*conv)(&buf[tail], head - tail, &n, cps, &ncps);
		if (ncps > cps_size) {
			cps_size = ncps;
			cps = realloc(cps, cps_size * sizeof(*cps));
			if (!cps) {
				fprintf(stderr, "%s: out of memory\n", argv0);
				exit(1);
			}
			goto conv_again;
		}
		switch (res) {
		case LIBCHARCONV_NO_CONVERT:
			writeall(&buf[tail], n);
			tail += n;
			if (tail != head)
				goto conv_again;
			break;
		case LIBCHARCONV_CONVERTED:
			for (i = 0u; i < ncps; i++)
				writechar(cps[i]);
			tail += n;
			if (tail != head)
				goto conv_again;
			break;
		case LIBCHARCONV_INDETERMINATE:
		case LIBCHARCONV_CONVERT_IF_END:
			break;
		default:
			abort();
		}
	}

	while (tail < head) {
		ncps = cps_size;
		res = (*conv)(&buf[tail], head - tail, &n, cps, &ncps);
		if (ncps > cps_size) {
			cps_size = ncps;
			cps = realloc(cps, cps_size * sizeof(*cps));
			if (!cps) {
				fprintf(stderr, "%s: out of memory\n", argv0);
				exit(1);
			}
			continue;
		}
		switch (res) {
		case LIBCHARCONV_INDETERMINATE:
			n = head - tail;
			/* fall through */
		case LIBCHARCONV_NO_CONVERT:
			writeall(&buf[tail], n);
			tail += n;
			break;
		case LIBCHARCONV_CONVERTED:
		case LIBCHARCONV_CONVERT_IF_END:
			for (i = 0u; i < ncps; i++)
				writechar(cps[i]);
			tail += n;
			break;
		default:
			abort();
		}
	}

	if (close(STDOUT_FILENO)) {
		fprintf(stderr, "%s: write <stdout>: %s\n", argv0, strerror(errno));
		exit(1);
	}

	free(buf);
	free(cps);
	return 0;
}