#define _GNU_SOURCE
#include <stdio.h>
#include <getopt.h>
#include <stdlib.h>
#include <string.h>
#include <assert.h>

#include <unistd.h>
#include <sys/wait.h>
#include <fcntl.h>

#include "io.h"
#include "util.h"
#include "common.h"

#include "labdefs.h"

static int events_log_fd = -1;

static const char e_no_args[]  = "Error: not enough arguments\n";
static const char e_proc_num[] = "Error: number of processes should be from 1 to 10\n";

static const char e_log_write[] = "Error: failed to write event read log\n";
static const char e_log_multicast[] = "Error: failed to send multicast\n";
static const char e_log_multicast_read[] = "Error: failed to read multicast\n";

void create_message(Message *msg, MessageType type, size_t length){
	memset(msg, 0, sizeof *msg);
	msg->s_header.s_magic = MESSAGE_MAGIC;
	msg->s_header.s_type = type;
	msg->s_header.s_local_time = get_lamport_time();
	msg->s_header.s_payload_len = length;
}

int log_event(char *msg){
	assert(events_log_fd > 0 && "Called before opening log file");
	int rc = write(events_log_fd, msg, strlen(msg));
	if( rc < 0 ){
		(void)write(STDERR_FILENO, e_log_write, sizeof e_log_write);
		return 1;
	}
	return 0;
}

static void close_pipes(IOHandle *handle){
	for(int i = 0; i < handle->proc_num; i++){
		for(int j = 0; j < handle->proc_num; j++){
			if( i == j ) continue;
			if( i != handle->src_pid ){
				close(handle->channel_table[i * handle->proc_num + j].writefd);
			}
			if( j != handle->src_pid ){
				close(handle->channel_table[i * handle->proc_num + j].readfd);
			}
		}
	}
}

static int receive_all(IOHandle *handle){
	assert(handle != NULL);
	Message msg;
	for(local_id i = 1; i < handle->proc_num; i++){
		int rc = receive(handle, i, &msg);
		if( rc != 0 ){
			(void)write(STDERR_FILENO, e_log_multicast_read, sizeof e_log_multicast);
			return 1;
		}
	}
	return 0;
}

int get_proc_num_from_args(int argc, char *const argv[]) {
	if ( argc < 2 ) {
		(void)write(STDERR_FILENO, e_no_args, sizeof e_no_args);
        return -1;
    }

	int proc_num = 0;
	char *endp = NULL;
	switch ( getopt(argc, argv, "p:") ) {
		case 'p':
			proc_num = strtoul(optarg, &endp, 10);
			if ( *endp != '\0' || proc_num == 0 || proc_num > 10 ) {
				(void)write(STDERR_FILENO, e_proc_num, sizeof e_proc_num);
				return -1;
			}
			break;
		case -1: return -1;
	}
	proc_num++; // include parent id

	return proc_num;
}

int create_handle(int proc_num, IOHandle *handle) {
	Channel *channel_table = calloc(1, proc_num * proc_num * sizeof *channel_table);
	if( channel_table == NULL ) return 1;

	memset(handle, 0, sizeof *handle);
	handle->proc_num = proc_num;
	handle->channel_table = channel_table;
	handle->parent_pid = getpid();
	return 0;
}

int create_pipes(IOHandle *handle) {
	int pipes_log_fd = open(pipes_log, O_CREAT | O_WRONLY | O_TRUNC | O_APPEND, 0644);
	if( pipes_log_fd < 0 ) return 1;

	char msg[64];
	for(int32_t i = 0; i < handle->proc_num; i++){
		for(int32_t j = 0; j < handle->proc_num; j++){
			if( i == j ) continue;
			int	rc = pipe2((int*)&handle->channel_table[i * handle->proc_num + j], O_NONBLOCK | O_DIRECT);
			snprintf(msg, 64, "opened pipe(%d, %d)\n", i, j);
			int n = write(pipes_log_fd, msg, strlen(msg));
			if( n  < 0 ) return 1;
			if( rc < 0 ) return 1;
		}
	}
	return 0;
}

int spawn_childs(IOHandle *handle) {
	events_log_fd = open(events_log, O_CREAT | O_WRONLY | O_TRUNC | O_APPEND, 0644);
	if( events_log_fd < 0 ) return 1;

	int is_parent = 1;
	for(local_id pid = 1; pid < handle->proc_num; pid++){
		int sys_pid = fork();
		if( sys_pid < 0 ) return -1;
		if( sys_pid == 0 ){
			is_parent = 0;
			handle->src_pid = pid;
			break;
		}
	}

	return is_parent;
}

int parent(IOHandle *handle){
	close_pipes(handle);
	int rc = 0;
	rc = receive_all(handle);
	if( rc != 0 ) return 1;

	// Do work
	rc = parent_work(handle);
	if( rc != 0 ) return rc;

	rc = receive_all(handle);
	if( rc != 0 ) return 1;

	rc = parent_atexit(handle);
	if( rc != 0 ) return 1;

	for(local_id pid = 1; pid < handle->proc_num; pid++){
		wait(NULL);
	}
	return 0;
}

int child(IOHandle *handle, void *data) {
	close_pipes(handle);
	char log_buff[MAX_PAYLOAD_LEN];
	int rc = 0;
	Message msg;
	memset(&msg, 0, sizeof msg);
	msg.s_header.s_magic = MESSAGE_MAGIC;

	child_set_started_msg(msg.s_payload, handle, data);

	msg.s_header.s_payload_len = strlen(msg.s_payload);
	msg.s_header.s_type = STARTED;

	rc = log_event(msg.s_payload);
	if( rc != 0 ) return 1;

	rc = send_multicast(handle, &msg);
	if( rc != 0 ){
		(void)write(STDERR_FILENO, e_log_multicast, sizeof e_log_multicast);
		return 1;
	}

	rc = receive_all(handle);
	if( rc != 0 ) return 1;

	child_set_received_all_started_msg(log_buff, handle);

	rc = log_event(log_buff);
	if( rc != 0 ) return 1;

	// Do work
	rc = child_work(handle, data);
	if( rc != 0 ) return rc;

	child_set_done_msg(msg.s_payload, handle, data);
	msg.s_header.s_payload_len = strlen(msg.s_payload);
	msg.s_header.s_type = DONE;

	rc = log_event(msg.s_payload);
	if( rc != 0 ) return 1;

	rc = send_multicast(handle, &msg);
	if( rc < 0 ){
		(void)write(STDERR_FILENO, e_log_multicast, sizeof e_log_multicast);
		return 1;
	}

	rc = receive_all(handle);
	if( rc != 0 ) return 1;

	child_set_received_all_done_msg(log_buff, handle);
	rc = log_event(log_buff);
	if( rc != 0 ) return 1;

	return child_atexit(handle, data);
}