#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>
#include <limits.h>
#include <sys/stat.h>
#include "config.h"

struct DB_STR {
	char *filename;

	char **tags;
	size_t size;

	struct DB_STR *next;
};

struct UNIQ_TAGS {
	char **tags;
	size_t size;
};

char *gen_id(void) {
	char *alf = "qwertyUIOPasdfghjklQWERTASDFGHJKLZXCVBNMzxcvbnm1234567890";

	static char id[6];
	for (size_t i = 0; i < sizeof(id); i++)
		id[i] = alf[rand() % sizeof(alf)];

	id[sizeof(id) - 1] = '\0';
	return id;
}

FILE *file_open(const char *file, const char *mode) {
	FILE *fp = fopen(file, mode);
	if (fp == NULL) {
		fprintf(stderr, "8img: %s: %s\n", file, strerror(errno));
		return NULL;
	}

	return fp;
}

void copy(const char *src, const char *dst) {
	FILE *ifp = file_open(src, "r");
	if (ifp == NULL)
		exit(1);

	FILE *ofp = file_open(dst, "a");
	if (ofp == NULL) {
		fclose(ifp);
		exit(1);
	}

	char buf[4096];
	size_t ret = 0;
	while ((ret = fread(buf, sizeof(char), sizeof(buf), ifp)))
		fwrite(buf, sizeof(char), ret, ofp);

	fclose(ifp);
	fclose(ofp);
}

void add(char **list, const int size) {
	char *name = NULL;
	char new_path[PATH_MAX + 1];

	while (1) {
		name = gen_id();
		snprintf(new_path, sizeof(new_path), "%s/%s", ROOT, name);

		struct stat sb;
		if (stat(new_path, &sb) < 0)
			break;
	}

	/* Copy file */
	copy(list[0], new_path);

	/* Update db */
	FILE *fp = file_open(DB, "a");
	if (fp == NULL)
		exit(1);

	/* Write filename ,tag1,tag2... to the db */
	fprintf(fp, "%s ", name);
	for (int i = 1; i < size; i++) {
		if (strchr(list[i], ',') == NULL || strchr(list[i], ' ') == NULL)
			fprintf(fp, ",%s", list[i]);

		else
			fprintf(stderr, "8img: tag '%s' contain ',' or ' '\n", list[i]);
	}

	fputc('\n', fp);
	fclose(fp);
}

void free_db(struct DB_STR *db) {
	if (db == NULL)
		return;

	while (db != NULL) {
		struct DB_STR *i = db->next;
		if (i == NULL)
			return;

		if (db->filename != NULL)
			free(db->filename);

		if (db->tags != NULL) {
			for (size_t i = 0; i < db->size; i++)
				if (db->tags[i] != NULL)
					free(db->tags[i]);

			free(db->tags);
		}

		free(db);
		db = i;
	}
}

int append_tag(struct DB_STR *db, const char *tok, const size_t allocated) {
	if (allocated == 0) {
		db->tags = malloc(sizeof(char *) * (db->size + 1));
		if (db->tags == NULL)
			return 1;

		db->tags[0] = strdup(tok);
		if (db->tags[0] == NULL) {
			free(db->tags);
			return 1;
		}
	}

	else {
		db->tags[allocated] = strdup(tok);
		if (db->tags[allocated] == NULL)
			return 1;
	}

	return 0;
}

struct DB_STR *new_db_value(char *str) {
	struct DB_STR *db = malloc(sizeof(struct DB_STR));
	if (db == NULL)
		return NULL;


	/* Filename */
	char *tok = strtok(str, " ");
	char *ptr = strrchr(tok, '\n');
	if (ptr != NULL)
		*ptr = '\0';

	db->filename = strdup(tok);
	if (db->filename == NULL)
		goto NDV_CLOSE;


	/* Tags */
	tok = strtok(NULL, " ");
	if (tok == NULL)
		db->tags = NULL;

	else {
		ptr = strrchr(tok, '\n');
		if (ptr != NULL)
			*ptr = '\0';

		for (size_t i = 0; i < strlen(tok); i++)
			if (tok[i] == ',')
				db->size++;

		size_t allocated = 0;
		char *tok2 = strtok(tok, ",");
		while (tok2 != NULL) {
			if (append_tag(db, tok2, allocated))
				goto NDV_CLOSE;

			allocated++;
			tok2 = strtok(NULL, ",");
		}
	}


	return db;

NDV_CLOSE:
	free_db(db);
	return NULL;
}

struct DB_STR *read_db(void) {
	FILE *fp = file_open(DB, "r");
	if (fp == NULL)
		exit(1);

	int ret = 1;

	char *line = NULL;
	ssize_t bytes = 0;
	size_t n = 0;

	struct DB_STR *db = NULL;
	struct DB_STR *i = NULL;

	while ((bytes = getline(&line, &n, fp))) {
		if (bytes == -1)
			break;

		else if (bytes <= 1)
			continue;

		db = new_db_value(line);
		if (db == NULL)
			goto RDB_CLOSE;

		db->next = i;
		i = db;
	}

	ret = 0;

RDB_CLOSE:
	fclose(fp);
	if (line)
		free(line);

	if (ret) {
		free_db(db);
		fprintf(stderr, "8img: db: %s\n", strerror(errno));
	}

	return db;
}

struct DB_STR *build_html(FILE *fp, const char *file, const struct UNIQ_TAGS ut, struct DB_STR *db, const size_t page, const size_t pages) {
	fprintf(fp, "<html>\n<head>\n<link rel='stylesheet' href='%s'>\n<title>%s</title>\n</head>\n<body>\n<center>", CSS, TITLE);

	/* Tags */
	fputs("\n<a id='alltags' href='index.html'>  [all]  </a>", fp);
	for (size_t i = 0; i < ut.size; i++)
		fprintf(fp, "<a id='alltags' href='%s.html'>  [%s]  </a>", ut.tags[i], ut.tags[i]);
	fputs("\n<br><br><div id='bar'></div><br>\n", fp);

	/* Images */
	size_t images = 0;
	struct DB_STR *p = db;
	while (p != NULL) {
		struct DB_STR *i = p->next;
		if (strcmp(file, "index")) {
			char flag = 1;
			for (size_t i = 0; i < p->size; i++)
				if (!strcmp(p->tags[i], file))
					flag = 0;

			if (flag) {
				p = i;
				continue;
			}
		}

		fprintf(fp, "<a href='%s'><img src='%s' alt='%s'></a><br>", p->filename, p->filename, p->filename);
		for (size_t i = 0; i < p->size; i++)
			fprintf(fp, "<a id='tags' href='%s.html'> %s</a>", p->tags[i], p->tags[i]);

		fputs("\n<br><br><div id='bar'></div><br>\n", fp);

		p = i;
		images++;
		if (images >= POST_PER_PAGE)
			break;
	}

	for (size_t i = 0; i <= pages; i++) {
		if (i == 0) {
			if (i == page)
				fprintf(fp, "<a id='pager' href='%s.html'>(0) </a> ", file);

			else
				fprintf(fp, "<a id='pager' href='%s.html'>[0] </a> ", file);
		}

		else {
			char new_path[PATH_MAX + 1];
			snprintf(new_path, sizeof(new_path), "%s-%zu.html", file, i);

			if (i == page)
				fprintf(fp, "<a id='pager' href='%s'>(%zu) </a>", new_path, i);

			else
				fprintf(fp, "<a id='pager' href='%s'>[%zu] </a>", new_path, i);
		}

	}

	fprintf(fp, "\n</center>\n</body>\n</html>\n");
	return p;
}

void build(const char *file, const struct UNIQ_TAGS ut, struct DB_STR *db) {
	FILE *fp = NULL;

	size_t page = 0;
	size_t pages = 0;

	/* Count pages */
	size_t count = 0;
	struct DB_STR *p = db;
	while (p != NULL) {
		struct DB_STR *i = p->next;

		if (count == POST_PER_PAGE) {
			count = 0;
			pages++;
		}

		if (!strcmp(file, "index"))
			count++;

		else {
			for (size_t i = 0; i < p->size; i++)
			if (!strcmp(file, p->tags[i]))
				count++;
		}

		p = i;
	}

	p = db;
	while (1) {
		if (fp != NULL)
			fclose(fp);

		char new_path[PATH_MAX + 1];
		if (page == 0)
			snprintf(new_path, sizeof(new_path), "%s/%s.html", ROOT, file);

		else
			snprintf(new_path, sizeof(new_path), "%s/%s-%zu.html", ROOT, file, page);

		FILE *fp = file_open(new_path, "w");
		if (fp == NULL)
			return;

		p = build_html(fp, file, ut, p, page, pages);
		if (p == NULL) {
			fclose(fp);
			break;
		}

		page++;
	}
}

char **uniq(struct DB_STR *db, size_t *uniq_size) {
	char **uniq_tag = malloc(sizeof(char *));
	if (uniq_tag == NULL)
		return NULL;

	struct DB_STR *p = db;
	while (p != NULL) {
		struct DB_STR *i = p->next;

		for (size_t i = 0; i < p->size; i++) {
			if (p->tags == NULL)
				break;

			char flag = 0;
			for (size_t j = 0; j < *uniq_size; j++) {
				if (!strcmp(p->tags[i], uniq_tag[j]))
					flag = 1;
			}

			if (flag)
				continue;

			char **bckp = realloc(uniq_tag, sizeof(char *) * (*uniq_size + 1));
			if (bckp == NULL) {
				free(uniq_tag);
				return NULL;
			}

			uniq_tag = bckp;
			uniq_tag[*uniq_size] = p->tags[i];
			(*uniq_size)++;
		}

		p = i;
	}

	return uniq_tag;
}

void rebuild(void) {
	struct DB_STR *db = read_db();
	if (db == NULL)
		return;

	/* Uniq */
	size_t uniq_size = 0;
	char **uniq_tag = uniq(db, &uniq_size);
	if (uniq_tag != NULL) {
		struct UNIQ_TAGS ut = {.tags = uniq_tag, .size = uniq_size};

		for (size_t i = 0; i < uniq_size; i++)
			build(uniq_tag[i], ut, db);

		build("index", ut, db);
	}

	else
		fprintf(stderr, "8img: malloc: %s\n", strerror(errno));

	/* Close */
	if (uniq_tag != NULL)
		free(uniq_tag);

	free_db(db);
}

void help(void) {
	puts("8img [add/rebuild]:\n\tadd [img] [tag1] [tag2] [...]\n\trebuild");
	exit(0);
}

int main(int argc, char **argv) {
	if (argc < 2)
		help();

	mkdir(ROOT, 0777);
	srand(getpid());

	argv++;
	argc--;

	/* Parse args */
	if (!strcmp(argv[0], "add") && argc > 1)
		add(argv + 1, argc - 1);

	else if (!strcmp(argv[0], "rebuild"))
		rebuild();

	else
		help();
}