#define _DEFAULT_SOURCE
#include <errno.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/socket.h>
#include <unistd.h>
#include "common.h"
#include "daemon.h"
#include "streamer.h"

int daemon_run = 0;

// TODO: Too pedantic and verbose, replace with read_val, write_val, read_str, write_str
#define strict_read(fd, ptr, count) (read(fd, ptr, sizeof(*ptr) * count) != sizeof(*ptr) * count)
#define strict_write(fd, ptr, count) (write(fd, ptr, sizeof(*ptr) * count) != sizeof(*ptr) * count)

enum Opcode {
	OP_DAEMON,
	OP_PUSH,
	OP_POP,
	OP_TERM,
	OP_SKIP,
	OP_LIST,
	OP_PAUSE,
	OP_RESUME,
};

struct Command {
	enum Opcode opcode;
	int opindex;
	int urllen;
};

#define      write_val(fd, ptr) (write(fd, ptr, sizeof(*ptr)))
#define      read_val(fd, ptr)  (read(fd, ptr, sizeof(*ptr)))
static void  write_str (int fd, const char *str);
static char *read_str  (int fd);

// ===================================================================
// Server code
// ===================================================================

static inline int send_reply (int fd, struct StateInfo *state_info)
{
	int i;
	struct Entry *entry;

	errno = 0;
	write_val(fd, &state_info->state);
	write_str(fd, state_info->current_song);
	write_val(fd, &state_info->song_count);
	for (i = 0; i < state_info->song_count; i ++) {
		entry = &state_info->next_songs[i];
		write_val(fd, &entry->id);
		write_str(fd, entry->file);
	}

	return errno ? -1 : 0;
}

int daemon_start(int sockfd, const struct StreamerOpt *opts)
{
	Streamer *streamer;
	int connfd, new_id;
	char *url;
	struct Command msg;
	struct StateInfo state_info;
	enum State state;

	if ((streamer = streamer_init(opts)) == NULL) {
		fprintf(stderr, "Failed to allocate streamer\n");
 		return EXIT_FAILURE;
	}

	url = NULL;
	daemon_run = 1;
	while (daemon_run) {
		puts("Awaiting connection");

		/* Block and wait for another connection. accept(2) shall returns a
		 * nonnegative file descriptor on sucess, or -1 if an error occured. All
		 * error are considered fatal, except for EINTR, which is seen as an
		 * occasion to re-check whether the daemon should keep running.
		 */
		if ((connfd = accept(sockfd, NULL, NULL)) < 0) {
			if (errno == EINTR) continue;
			perror("Failed to accept connection");
			break;
		}

		if (read(connfd, &msg, sizeof(msg)) != sizeof(msg)) {
			fputs("Unexpected end of package, discarding.\n", stderr);
			close(connfd);
			continue;
		}

		switch (msg.opcode) {
			case OP_PUSH:
				if ((url = realloc(url, msg.urllen + 1)) == NULL) {
					perror("Failed to allocate URL buffer");
					break;
				}
				read(connfd, url, msg.urllen);
				url[msg.urllen] = '\0';

				new_id = streamer_push(streamer, url, msg.opindex);
				if (new_id < 0)
					fprintf(stderr, "Failed to add '%s' to the playlist: %s\n", url, strerror(errno));
				else
					printf("Pushed '%s' with id %i\n", url, new_id);
				break;

			case OP_POP:
				if (streamer_pop(streamer, msg.opindex))
					fprintf(stderr, "Failed remove entry #%i\n", msg.opindex);
				else
					printf("Succesfullt remove '%i' from the playlist\n", msg.opindex);
				break;

			case OP_TERM:
				daemon_run = 0;
				break;
			case OP_SKIP:
				streamer_skip(streamer);
				break;
			case OP_PAUSE:
				streamer_pause(streamer);
				break;
			case OP_RESUME:
				streamer_resume(streamer);
				break;
			case OP_LIST:
				state = streamer_info(streamer, &state_info);
				if (state == -1) {
					perror("Failed to reatrieve streamer info");
					break;
				}

				if (send_reply(sockfd, &state_info)) {
					perror("Failed to send back state info");
					break;
				}
				break;
			default:
				fprintf(stderr, "Ignoring unknown command code: %i\n", msg.opcode);
				break;
		}

		close(connfd);
		errno = 0;
	}
	puts("done\n");

	daemon_run = 0;
	streamer_free(streamer);
	return errno ? -1 : -0;
}


// ===================================================================
// Client code
// ===================================================================

static inline int send_command(int fd, int code, unsigned int index, int len)
{
	struct Command m;
	m.opcode = code;
	m.opindex = index;
	m.urllen = len;
	return strict_write(fd, &m, 1) ? -1 : 0;
}

int daemon_push(int fd, const char *track, unsigned int index)
{
	int len;
	char *realtrack;

	if ((realtrack = realpath(track, NULL)) == NULL)
		return -1;

	len = strlen(realtrack);
	if (send_command(fd, OP_PUSH, index, len))
		goto error;
	if (strict_write(fd, realtrack, len))
		goto error;
	free(realtrack);
	return 0;

error:
	free(realtrack);
	return -1;
}


int daemon_pop(int fd, unsigned int index)
{
	return send_command(fd, OP_POP, index, 0);
}

int daemon_skip(int fd)
{
	return send_command(fd, OP_SKIP, 0, 0);
}

int daemon_pause(int fd)
{
	return send_command(fd, OP_PAUSE, 0, 0);
}

int daemon_resume(int fd)
{
	return send_command(fd, OP_RESUME, 0, 0);
}

int daemon_kill(int fd)
{
	return send_command(fd, OP_TERM, 0, 0);
}

int daemon_query(int fd, struct StateInfo *state_info)
{
	int i, len;
	enum State state;
	struct Entry *entry;

	if (send_command(fd, OP_LIST, 0, 0))
		return -1;

	errno = 0;
	read_val(fd, &state_info->state);
	state_info->current_song = read_str(fd);
	read_val(fd, &state_info->song_count);

	state_info->next_songs = calloc(state_info->song_count, sizeof(struct Entry));
	if (state_info->next_songs == NULL) {
		free(state_info->current_song);
		return -1;
	}

	for (i = 0; i < state_info->song_count; i ++) {
		entry = &state_info->next_songs[i];
		read_val(fd, &entry->id);
		entry->file = read_str(fd);
	}

	if (errno) {
		stateinfo_free(state_info);
		return -1;
	}

	return 0;
}

static void write_str (int fd, const char *str)
{
	size_t len;
	len = strlen(str) + 1;
	write(fd, &len, sizeof(size_t));
	write(fd, str, len);
}

static char *read_str(int fd)
{
	size_t len;
	char *str;

	read(fd, &len, sizeof(size_t));
	if ((str = malloc(len)) == NULL)
		return NULL;
	read(fd, str, len);
	return str;
}