/*
 *  2ooM: The Master of Orion II Reverse Engineering Project
 *  Library for working with LBX archive files.
 *  Copyright © 2006-2010, 2013-2014 Nick Bowler
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it 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.
 *
 *  This program 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
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */
#include <config.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <assert.h>

#include "pack.h"
#include "misc.h"
#include "error.h"
#include "lbx.h"

#define LBX_MAGIC    0x0000fead
#define LBX_HDR_SIZE 8

struct lbx_priv {
	struct lbx pub;

	char *name;

	const struct lbx_file_ops *fops;
	int (*dtor)(void *handle);
	void *f;

	struct lbx_file_state *last_file;

	unsigned long offsets[FLEXIBLE_ARRAY_MEMBER];
};

struct lbx_file_state {
	unsigned long base, limit, offset;
	struct lbx_priv *lbx;
	int eof;
};

static struct lbx_priv *lbx_init(unsigned char *hdr)
{
	unsigned short nfiles  = unpack_16_le(hdr+0);
	unsigned long  magic   = unpack_32_le(hdr+2);
	unsigned short version = unpack_16_le(hdr+6);
	struct lbx_priv *lbx;

	if (magic != LBX_MAGIC) {
		lbx_error_raise(LBX_EMAGIC);
		return NULL;
	}

	lbx = malloc(sizeof *lbx + sizeof lbx->offsets[0] * (nfiles+1));
	if (!lbx) {
		lbx_error_raise(LBX_ENOMEM);
		return NULL;
	}

	*lbx = (struct lbx_priv) {
		.pub = { .nfiles = nfiles, },
	};

	return lbx;
}

static char *str_dup(const char *s)
{
	char *buf;

	buf = malloc(strlen(s)+1);
	if (buf)
		strcpy(buf, s);
	return buf;
}

struct lbx *lbx_open(void *f, const struct lbx_file_ops *fops,
                     int (*destructor)(void *), const char *name)
{
	unsigned char hdr_buf[LBX_HDR_SIZE];
	struct lbx_priv *lbx = NULL;
	char *dupname = NULL;

	dupname = str_dup(name);
	if (!dupname) {
		lbx_error_raise(LBX_ENOMEM);
		goto err;
	}

	if (fops->read(hdr_buf, sizeof hdr_buf, f) != sizeof hdr_buf) {
		if (fops->eof(f))
			lbx_error_raise(LBX_EEOF);
		goto err;
	}

	lbx = lbx_init(hdr_buf);
	if (!lbx)
		goto err;

	lbx->name = dupname;
	lbx->dtor = destructor;
	lbx->fops = fops;
	lbx->f    = f;

	for (unsigned i = 0; i <= lbx->pub.nfiles; i++) {
		unsigned char buf[4];

		if (fops->read(buf, sizeof buf, f) != sizeof buf) {
			if (fops->eof(f))
				lbx_error_raise(LBX_EEOF);
			goto err;
		}

		lbx->offsets[i] = unpack_32_le(buf);
	}

	return &lbx->pub;
err:
	free(dupname);
	free(lbx);
	return NULL;
}

static int file_close(void *f)
{
	return fclose((FILE *)f);
}

static int pipe_close(void *f)
{
	struct lbx_pipe_state *p = f;
	int rc;

	rc = fclose(p->f);
	free(p);
	return rc;
}

static char *last_component(const char *name)
{
	char *c;

	/* TODO: Handle other path separators. */
	c = strrchr(name, '/');
	if (!c)
		return (char *)name;
	return c+1;
}

struct lbx *lbx_fopen(const char *file)
{
	const char *name = last_component(file);
	struct lbx_pipe_state *p;
	FILE *f;

	f = fopen(file, "rb");
	if (!f) {
		lbx_error_raise(-errno);
		return NULL;
	}

	if (fseek(f, 0, SEEK_CUR) == 0)
		return lbx_open(f, &lbx_default_fops, file_close, name);

	p = malloc(sizeof *p);
	if (!p) {
		lbx_error_raise(LBX_ENOMEM);
		fclose(f);
		return NULL;
	}

	*p = (struct lbx_pipe_state) { .f = f };
	return lbx_open(p, &lbx_pipe_fops, pipe_close, name);
}

int lbx_file_stat(struct lbx *pub, unsigned fileno, struct lbx_statbuf *buf)
{
	struct lbx_priv *lbx = (struct lbx_priv *)pub;
	static char str[256]; /* FIXME */

	if (fileno >= lbx->pub.nfiles) {
		lbx_error_raise(LBX_EINVAL);
		buf->name = NULL;
		return -1;
	}

	snprintf(str, sizeof str, "%s.%03u", lbx->name, fileno);
	buf->name = str;
	buf->size = lbx->offsets[fileno+1] - lbx->offsets[fileno];
	return 0;
}

int lbx_close(struct lbx *pub)
{
	struct lbx_priv *lbx = (struct lbx_priv *)pub;
	int rc = 0;

	if (lbx && lbx->dtor)
		rc = lbx->dtor(lbx->f);
	free(lbx->name);
	free(lbx);

	return rc;
}

struct lbx_file_state *lbx_file_open(struct lbx *pub, unsigned fileno)
{
	struct lbx_priv *lbx = (struct lbx_priv *)pub;
	struct lbx_file_state *state;

	if (fileno >= lbx->pub.nfiles) {
		lbx_error_raise(LBX_EINVAL);
		return NULL;
	}

	lbx->last_file = NULL;
	if (lbx->fops->seek(lbx->f, lbx->offsets[fileno], SEEK_SET) != 0) {
		return NULL;
	}

	state = malloc(sizeof *state);
	if (!state) {
		lbx_error_raise(LBX_ENOMEM);
		return NULL;
	}

	*state = (struct lbx_file_state) {
		.base  = lbx->offsets[fileno],
		.limit = lbx->offsets[fileno+1] - lbx->offsets[fileno],
		.lbx   = lbx,
	};

	lbx->last_file = state;
	return state;
}

size_t lbx_file_read(struct lbx_file_state *f, void *buf, size_t n)
{
	const struct lbx_file_ops *fops = f->lbx->fops;
	size_t want = MIN(n, f->limit - f->offset);
	size_t rc;

	if (f != f->lbx->last_file) {
		f->lbx->last_file = NULL;
		if (fops->seek(f->lbx->f, f->base + f->limit, SEEK_SET) != 0)
			return 0;
		f->lbx->last_file = f;
	}

	rc = fops->read(buf, want, f->lbx->f);
	f->offset += rc;

	if (rc < want) {
		if (fops->eof(f->lbx->f))
			lbx_error_raise(LBX_EEOF);
	} else if (rc < n) {
		f->eof = 1;
	}

	return rc;
}

int lbx_file_seek(struct lbx_file_state *f, long offset, int whence)
{
	const struct lbx_file_ops *fops = f->lbx->fops;
	unsigned long pos;

	switch (whence) {
	case SEEK_CUR:
		pos = f->offset + offset;
		break;
	case SEEK_SET:
		pos = offset;
		break;
	case SEEK_END:
		pos = f->limit + offset;
		break;
	default:
		lbx_error_raise(LBX_EINVAL);
		return -1;
	}

	if (pos > f->limit) {
		lbx_error_raise(LBX_EINVAL);
		return -1;
	}

	f->lbx->last_file = NULL;
	if (fops->seek(f->lbx->f, f->base + pos, SEEK_SET) != 0)
		return -1;

	f->offset = pos;
	f->lbx->last_file = f;
	f->eof = 0;

	return 0;
}

long lbx_file_tell(struct lbx_file_state *f)
{
	return f->offset;
}

int lbx_file_eof(struct lbx_file_state *f)
{
	return f->eof;
}

void lbx_file_close(struct lbx_file_state *f)
{
	if (f->lbx->last_file == f)
		f->lbx->last_file = NULL;
	free(f);
}