/*
Copyright (C) 2003-2004 Douglas Thain and the University of Wisconsin
Copyright (C) 2005- The University of Notre Dame
This software is distributed under the GNU General Public License.
See the file COPYING for details.
*/

#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include "get_line.h"
#include "hash_table.h"
#include "stringtools.h"

struct chunk {
	long pos;
	long len;
	char *logical_file_name;

	struct chunk_set *parent;

	struct chunk *next;
};

struct chunk_set {
	char *physical_file_name;
	struct chunk *head;
	struct chunk *tail;

	struct hash_table *file_table;
};

static void chunk_set_add_chunk(struct chunk_set *chunk_set, struct chunk *new_chunk)
{
	if(!chunk_set->head) {
		chunk_set->head = new_chunk;
		chunk_set->tail = new_chunk;
	} else {
		chunk_set->tail->next = new_chunk;
		chunk_set->tail = new_chunk;
	}

	hash_table_insert(chunk_set->file_table, new_chunk->logical_file_name, new_chunk);
}

static struct chunk *chunk_create(struct chunk_set *parent, char *logical_name, long pos)
{
	struct chunk *chunk = malloc(sizeof(*chunk));
	if(!chunk)
		return NULL;

	chunk->pos = pos;
	chunk->len = 0;

	chunk->logical_file_name = strdup(logical_name);

	chunk->parent = parent;
	chunk->next = NULL;

	return chunk;
}

struct chunk_set *chunk_parse_file(char *file_name, char *ln_prefix, char *fc_prefix)
{
	if(string_null_or_empty(file_name))
		return NULL;

	if(string_null_or_empty(ln_prefix) && string_null_or_empty(fc_prefix))
		return NULL;

	struct chunk_set *chunk_set = malloc(sizeof(*chunk_set));
	chunk_set->physical_file_name = strdup(file_name);
	chunk_set->head = NULL;
	chunk_set->tail = NULL;
	chunk_set->file_table = hash_table_create(0, NULL);

	struct chunk *new_chunk = NULL;

	int ln_prefix_len = 0;
	if(ln_prefix)
		ln_prefix_len = strlen(ln_prefix);
	int fc_prefix_len = 0;
	if(fc_prefix)
		fc_prefix_len = strlen(fc_prefix);

	FILE *fp = fopen(file_name, "r");
	long pos = 0;
	char *line;

	while((line = get_line(fp)) != NULL) {
		if(!string_null_or_empty(ln_prefix) && strncmp(line, ln_prefix, ln_prefix_len) == 0) {
			/* finish current chunk; begin new chunk */
			pos = ftell(fp);

			if(new_chunk) {
				new_chunk->len = pos - strlen(line) - new_chunk->pos;

				chunk_set_add_chunk(chunk_set, new_chunk);
			}

			new_chunk = chunk_create(chunk_set, line + ln_prefix_len, pos);
		} else if(fc_prefix && strncmp(line, fc_prefix, fc_prefix_len) == 0) {
			/* add to len? at any rate just continue */
			continue;
		} else if(string_null_or_empty(ln_prefix)) {
			/* finish current chunk; begin new chunk */
			pos = ftell(fp);

			if(new_chunk) {
				new_chunk->len = pos - strlen(line) - new_chunk->pos;

				chunk_set_add_chunk(chunk_set, new_chunk);
			}

			new_chunk = chunk_create(chunk_set, line + ln_prefix_len, pos);
		} else if(new_chunk) {
			/* assert string_null_or_empty(fc_prefix) and we are
			   in the middle of a chunk */

			/* add to len? at any rate just continue */
			continue;
		} else {
			/* we are before all the chunks... just ignore */
			continue;
		}
	}

	if(!chunk_set->head) {
		/* Chunks could not be parsed, so return null */
		free(chunk_set->physical_file_name);
		free(chunk_set);
		return NULL;
	}

	return chunk_set;

}

char *chunk_read(struct chunk_set *chunk_set, const char *file_name, int *size)
{
	struct chunk *the_chunk = (struct chunk *) hash_table_lookup(chunk_set->file_table, file_name);

	FILE *fp = fopen(chunk_set->physical_file_name, "r");
	fseek(fp, the_chunk->pos, SEEK_SET);

	char *content = malloc(the_chunk->len);

	size_t amt = fread(content, sizeof(*content), the_chunk->len, fp);

	if(amt != the_chunk->len && ferror(fp)) {
		/* error reading stream */
		free(content);
		return NULL;
	}

	*size = the_chunk->len;
	return content;
}

int chunk_concat(const char *new_name, char **filenames, int num_files, char *ln_prefix, char *fc_prefix)
{
	FILE *old_file, *new_file;
	char *line;

	if(string_null_or_empty(ln_prefix) && string_null_or_empty(fc_prefix))
		return 0;

	new_file = fopen(new_name, "w");
	if(!new_file)
		return 0;

	if(!ln_prefix)
		ln_prefix = "";
	if(!fc_prefix)
		fc_prefix = "";

	int i;
	for(i = 0; i < num_files; ++i) {
		char *current_file_name = filenames[i];
		old_file = fopen(current_file_name, "r");

		fprintf(new_file, "%s%s\n", ln_prefix, current_file_name);

		while((line = get_line(old_file)) != NULL)
			fprintf(new_file, "%s%s", fc_prefix, line);

		fclose(old_file);
	}

	fclose(new_file);

	return 1;
}
