/*
 * strbuf.c: A simple string buffer
 *
 * Copyright (c) 2006-2008 Dennis Stosberg <dennis@stosberg.net>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License,
 * version 2 as published by the Free Software Foundation
 */

#include "strbuf.h"

static const size_t strbuf_start_sz = 128;
static const size_t strbuf_grow_sz = 128;

static void strbuf_grow(STRBUF *buf); /* enlarge a buffer by strbuf_grow_sz */

#ifdef STRBUF_CHECK
static void die(const char *format, ...) {
	va_list argp;
	va_start(argp, format);
	vfprintf(stderr, format, argp);
	va_end(argp);
	fprintf(stderr, "\n");
	exit(EXIT_FAILURE);
}

static void strbuf_check(STRBUF *buf)
{
	if (!buf)
		die("buf is null");

	if (!buf->data)
		die("buf->data is null");

	if (!(buf->opt & STRBUF_NULLOK) && strlen(buf->data) != buf->len)
		die("length mismatch. strlen says %u, len says %u",
		    (unsigned int)strlen(buf->data), buf->len);

	if (buf->len + 1 > buf->buf_sz)
		die("overlap");
}
#else
#define strbuf_check(a)
#endif

STRBUF *strbuf_new(void)
{
	STRBUF *buf = ymalloc(sizeof(STRBUF));

	buf->buf_sz = strbuf_start_sz;
	buf->data = ymalloc(strbuf_start_sz);

	buf->len = 0;
	buf->data[0] = '\0';

	buf->opt = 0;

	strbuf_check(buf);
	return buf;
}

void strbuf_free(STRBUF *buf)
{
	strbuf_check(buf);

	yfree(buf->data);
	yfree(buf);
}

void strbuf_shrink(STRBUF *buf)
{
	strbuf_check(buf);

	buf->buf_sz = buf->len + 1;
	buf->data = yrealloc(buf->data, buf->buf_sz);

	strbuf_check(buf);
}

size_t strbuf_append_n(STRBUF *buf, const char *str, size_t n)
{
	strbuf_check(buf);

	if (n == 0)
		return buf->len;

	while (buf->len + n + 1 > buf->buf_sz)
		strbuf_grow(buf);

	memcpy(buf->data + buf->len, str, n);
	buf->len += n;
	*(buf->data + buf->len) = 0;

	strbuf_check(buf);
	return buf->len;
}

size_t strbuf_append(STRBUF *buf, const char *str)
{
	return strbuf_append_n(buf, str, strlen(str));
}

const char *strbuf_get(STRBUF *buf)
{
	strbuf_check(buf);
	return buf->data;
}

size_t strbuf_len(STRBUF *buf)
{
	strbuf_check(buf);
	return buf->len;
}

int strbuf_subst(STRBUF *buf,
		 size_t start, size_t stop,
		 const char *subst)
{
	size_t len;
	size_t subst_len;
	int    diff;

	strbuf_check(buf);

	if (start > stop) {
		size_t tmp = start;
		start = stop;
		stop = tmp;
	}

	len = stop - start;
	subst_len = strlen(subst);
	diff = subst_len - len;

	if (0 > diff) {
		memcpy(buf->data + start, subst, subst_len);
		memmove(buf->data + start + subst_len, buf->data + stop,
			buf->len - stop + 1);

	} else if (0 == diff) {
		memcpy(buf->data + start, subst, subst_len);

	} else { /* 0 < diff */
		while (buf->len + diff + 1 > buf->buf_sz)
			strbuf_grow(buf);

		memmove(buf->data + start + subst_len, buf->data + stop,
			buf->len - stop + 1);
		memcpy(buf->data + start, subst, subst_len);
	}

	buf->len += diff;

	strbuf_check(buf);
	return diff;
}

size_t strbuf_append_inflate(STRBUF *buf, FILE *in)
{
	size_t len;
	z_stream strm;
	Bytef readbuf[1024];
	int z_ret;
	int nullok;

	strbuf_check(buf);

	/* save NULLOK flag */
	nullok = (buf->opt & STRBUF_NULLOK) ? 1 : 0;
	strbuf_setopt(buf, STRBUF_NULLOK);

	/* zlib init */
	strm.zalloc   = Z_NULL;
	strm.zfree    = Z_NULL;
	strm.opaque   = Z_NULL;
	strm.next_in  = Z_NULL;
	strm.avail_in = 0;

	z_ret = inflateInit2(&strm, -15);
	if (z_ret != Z_OK) {
		fprintf(stderr, "A: zlib returned error: %d\n", z_ret);
		exit(EXIT_FAILURE);
	}

	do {
		int f_err;

		strm.avail_in = (uInt)fread(readbuf, 1, sizeof(readbuf), in);

		f_err = ferror(in);
		if (f_err) {
			(void)inflateEnd(&strm);
			fprintf(stderr, "stdio error: %d\n", f_err);
			exit(EXIT_FAILURE); /* TODO: errmsg? continue? */
		}

		if (strm.avail_in == 0)
			break;

		strm.next_in = readbuf;
		do {
			size_t bytes_inflated;

			while (buf->buf_sz < buf->len + sizeof(readbuf) * 2)
				strbuf_grow(buf);

			strm.next_out  = (Bytef*)(buf->data + buf->len);
			strm.avail_out = (uInt)(buf->buf_sz - buf->len);

			z_ret = inflate(&strm, Z_SYNC_FLUSH);
			switch (z_ret) {
			case Z_NEED_DICT:
			case Z_DATA_ERROR:
			case Z_MEM_ERROR:
				(void)inflateEnd(&strm);
				fprintf(stderr, "B: zlib returned error: %d\n", z_ret);
				exit(EXIT_FAILURE);
			}

			bytes_inflated  = (buf->buf_sz - buf->len) - strm.avail_out;
			buf->len       += bytes_inflated;

		} while (strm.avail_out == 0);

	} while (z_ret != Z_STREAM_END);

	/* terminate buffer */
	if (buf->len + 1 > buf->buf_sz)
		strbuf_grow(buf);
	*(buf->data + buf->len) = '\0';

	/* restore NULLOK option */
	if (!nullok)
		strbuf_unsetopt(buf, STRBUF_NULLOK);

	strbuf_check(buf);

	len = (size_t)strm.total_out;
	(void)inflateEnd(&strm);

	if (z_ret != Z_STREAM_END) {
		fprintf(stderr, "ERR\n");
		exit(EXIT_FAILURE);
	}

	return len;
}

static void strbuf_grow(STRBUF *buf)
{
	buf->buf_sz += strbuf_grow_sz;
	buf->data = yrealloc(buf->data, buf->buf_sz);

	strbuf_check(buf);
}

STRBUF *strbuf_slurp(char *str)
{
	return strbuf_slurp_n(str, strlen(str));
}

STRBUF *strbuf_slurp_n(char *str, size_t len)
{
	STRBUF *buf = ymalloc(sizeof(STRBUF));
	buf->len = len;
	buf->buf_sz = len + 1;
	buf->data = yrealloc(str, buf->buf_sz);
	*(buf->data + len) = '\0';

	buf->opt = 0;

	return buf;
}

char *strbuf_spit(STRBUF *buf)
{
	char *data;

	strbuf_check(buf);

	strbuf_shrink(buf);
	data = buf->data;
	yfree(buf);

	return data;
}

unsigned int strbuf_crc32(STRBUF *buf)
{
	uLong crc = crc32(0L, Z_NULL, 0);
	crc = crc32(crc, (Bytef *)buf->data, buf->len);

	return (unsigned int)crc;
}

void strbuf_setopt(STRBUF *buf, enum strbuf_opt opt)
{
	buf->opt |= opt;
}

void strbuf_unsetopt(STRBUF *buf, enum strbuf_opt opt)
{
	buf->opt &= ~opt;
}