#include <unistd.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <sys/mman.h>

struct databuffer {
	size_t len;
	char *data;
};

void db_init(struct databuffer *db) { // Initialises the db
	db->len = 0;
	db->data = malloc(1);
	db->data[0] = 0x00;
}

void db_deinit(struct databuffer *db) { // Deinitialises the db (TODO)
	//free(db->data);
}

const char *db_raw(struct databuffer *db) { // Append temporary null-terminator and returns data
	db->data = realloc(db->data, db->len + 1);
	db->data[db->len] = 0x00;
	return db->data;
}

void db_clear(struct databuffer *db) { // Reinitialises ("clears") the db
	db_deinit(db);
	db_init(db);
}

void db_append(struct databuffer *db, const struct databuffer *db_src) { // Appends db_src to db
	if (db_src->len == 0) {
		return;
	}
	db->len += db_src->len;
	db->data = realloc(db->data, db->len);
	memcpy(db->data + db->len - db_src->len, db_src->data, db_src->len);
}

void db_set(struct databuffer *db, const struct databuffer *db_src) { // Resets db to db_src
	db_clear(db);
	db_append(db, db_src);
}

const struct databuffer sized_db(const char *buffer, size_t len) { // Generates sized-size uninitialised (!!!) db
	struct databuffer thisdb;
	thisdb.data = buffer;
	thisdb.len = len;
	return thisdb;
}

const struct databuffer auto_db(const char *buffer) { // Same as above but autodetects size
	return sized_db(buffer, strlen(buffer));
}

bool db_compare(const struct databuffer *db1, const struct databuffer *db2) { // Compares two dbs
	if (db1->len != db2->len) {
		return true;
	} else {
		for (size_t it = 0; it != db1->len; it++) {
			if (db1->data[it] != db2->data[it]) {
				return false;
			}
		}
		return true;
	}
}

ssize_t db_find(const struct databuffer *db, const struct databuffer *db_src) { // Finds db_src in db, returns position or -1
	if (db->len < db_src->len) {
		return -1;
	}
	struct databuffer thisdb;
	thisdb.len = db_src->len;
	for (char *byte = db->data; byte != db->data + db->len - db_src->len + 1; byte++) {
		thisdb.data = byte;
		if (db_compare(&thisdb, db_src)) {
			return byte - db->data;
		}
	}
	return -1;
}

bool db_contains(const struct databuffer *db, const struct databuffer *db_src) { // Checks if db contains db_src
	return db_find(db, db_src) != -1;
}
bool db_startswith(const struct databuffer *db, const struct databuffer *db_src) { // Checks if db starts with db_src
	return db_find(db, db_src) == 0;
}
bool db_endswith(const struct databuffer *db, const struct databuffer *db_src) { // Checks if db ends with db_src
	if (db->len < db_src->len) {
		return false;
	}
	struct databuffer db_aligned;
	db_aligned = sized_db(db->data + db->len - db_src->len, db_src->len);
	return db_compare(&db_aligned, db_src);
}

bool db_fcheck(FILE *stream) {
	if (stream == NULL) {
		perror("Couldn't handle file");
		return false;
	} else {
		return true;
	}
}

void db_fwrite(const struct databuffer *db, FILE *output) { // writes data from db to output
	db_fcheck(output);
	fwrite(db->data, db->len, 1, output);
}

void db_fread(struct databuffer *db, FILE *input) { // Reads data from input to db
	size_t readbytes;
	struct databuffer readdb;
	char outb[16];
	db_fcheck(input);
	while (feof(input) == 0) {
		readbytes = fread(outb, 1, sizeof(outb), input);
		readdb = sized_db(outb, readbytes);
		db_append(db, &readdb);
	}
}


void db_readline(struct databuffer *db, FILE *input) { // Appends one line from input to db
	struct databuffer thisdb;
	char *buffer = NULL;
	ssize_t size = 0;
	db_fcheck(input);
	size = getline(&buffer, &size, input);
	assert(size != -1);
	thisdb = sized_db(buffer, size);
	db_append(db, &thisdb);
}

int runcmd(const char **command, bool wait_exit) { // Dumbly runs command
	fflush(stdout);
	if (fork() == 0) {
		execvp(command[0], command);
		perror(command[0]);
	}
	if (wait_exit) {
        int status;
		wait(&status);
        return status;
	} else {
        return 0;
    }
}

void db_cmdread(struct databuffer *db, const char **command) { // Appends output (stdout) of command to db
	struct databuffer thisdb;
	int stdout_backup = dup(1);
	dup2(memfd_create("pipe", 0), 1);
	runcmd(command, true);
	FILE *proc_out = fdopen(1, "r");
	fseek(proc_out, 0, SEEK_SET);
	db_fread(db, proc_out);
	close(1);
	dup2(stdout_backup, 1);
	thisdb = auto_db("\n");
	if (db_endswith(db, &thisdb)) {
		db->data[db->len - 1] = 0x00;
	}
}