/* copyright (c) 2007 magnus auvinen, see licence.txt for more info */
#include <stdio.h>
#include <string.h>
#include <stdlib.h>

#include <engine/system.h>
#include <engine/config.h>
#include <engine/engine.h>
#include <engine/interface.h>

#include <engine/protocol.h>
#include <engine/snapshot.h>

#include <engine/compression.h>

#include <engine/network.h>
#include <engine/config.h>
#include <engine/packer.h>
#include <engine/datafile.h>

#include <mastersrv/mastersrv.h>

static SNAPBUILD builder;

static int64 game_start_time;
static int current_tick = 0;

static int browseinfo_gametype = -1;
static int browseinfo_progression = -1;

static int64 lastheartbeat;
static NETADDR4 master_server;

static char current_map[64];

void *snap_new_item(int type, int id, int size)
{
	dbg_assert(type >= 0 && type <=0xffff, "incorrect type");
	dbg_assert(id >= 0 && id <=0xffff, "incorrect id");
	return snapbuild_new_item(&builder, type, id, size);
}

typedef struct
{
	short next;
	short state; /* 0 = free, 1 = alloced, 2 = timed */
	int timeout_tick;
} SNAP_ID;

static const int MAX_IDS = 8*1024; /* should be lowered */
static SNAP_ID snap_ids[8*1024];
static int snap_first_free_id;
static int snap_first_timed_id;
static int snap_last_timed_id;
static int snap_id_usage;
static int snap_id_inusage;
static int snap_id_inited = 0;


enum
{
	SRVCLIENT_STATE_EMPTY = 0,
	SRVCLIENT_STATE_CONNECTING,
	SRVCLIENT_STATE_READY,
	SRVCLIENT_STATE_INGAME
};

typedef struct 
{
	int data[MAX_INPUT_SIZE];
	int pred_tick; /* tick that the client predicted for the input */
	int game_tick; /* the tick that was chosen for the input */
	int64 timeleft; /* how much time in ms there were left before this should be applied */
} CLIENT_INPUT;
	
/* */
typedef struct
{
	/* connection state info */
	int state;
	int latency;
	
	int last_acked_snapshot;
	SNAPSTORAGE snapshots;
	
	CLIENT_INPUT inputs[200]; /* TODO: handle input better */
	int current_input;
	
	char name[MAX_NAME_LENGTH];
	char clan[MAX_CLANNAME_LENGTH];
} CLIENT;

static CLIENT clients[MAX_CLIENTS];
static NETSERVER *net;

static void snap_init_id()
{
	int i;
	for(i = 0; i < MAX_IDS; i++)
	{
		snap_ids[i].next = i+1;
		snap_ids[i].state = 0;
	}
		
	snap_ids[MAX_IDS-1].next = -1;
	snap_first_free_id = 0;
	snap_first_timed_id = -1;
	snap_last_timed_id = -1;
	snap_id_usage = 0;
	snap_id_inusage = 0;
	
	snap_id_inited = 1;
}

int snap_new_id()
{
	int id;
	dbg_assert(snap_id_inited == 1, "requesting id too soon");
	
	/* process timed ids */
	while(snap_first_timed_id != -1 && snap_ids[snap_first_timed_id].timeout_tick < server_tick())
	{
		int next_timed = snap_ids[snap_first_timed_id].next;
		
		/* add it to the free list */
		snap_ids[snap_first_timed_id].next = snap_first_free_id;
		snap_ids[snap_first_timed_id].state = 0;
		snap_first_free_id = snap_first_timed_id;
		
		/* remove it from the timed list */
		snap_first_timed_id = next_timed;
		if(snap_first_timed_id == -1)
			snap_last_timed_id = -1;
			
		snap_id_usage--;
	}
	
	id = snap_first_free_id;
	dbg_assert(id != -1, "id error");
	snap_first_free_id = snap_ids[snap_first_free_id].next;
	snap_ids[id].state = 1;
	snap_id_usage++;
	snap_id_inusage++;
	return id;
}

void snap_free_id(int id)
{
	dbg_assert(snap_ids[id].state == 1, "id is not alloced");

	snap_id_inusage--;
	snap_ids[id].state = 2;
	snap_ids[id].timeout_tick = server_tick() + server_tickspeed()*5;
	snap_ids[id].next = -1;
	
	if(snap_last_timed_id != -1)
	{
		snap_ids[snap_last_timed_id].next = id;
		snap_last_timed_id = id;
	}
	else
	{
		snap_first_timed_id = id;
		snap_last_timed_id = id;
	}
}

const char *server_clientname(int client_id)
{
	if(client_id < 0 || client_id > MAX_CLIENTS || clients[client_id].state < SRVCLIENT_STATE_READY)
		return "(invalid client)";
	return clients[client_id].name;
}

void server_setclientname(int client_id, const char *name)
{
	if(client_id < 0 || client_id > MAX_CLIENTS || clients[client_id].state < SRVCLIENT_STATE_READY)
		return;
	strncpy(clients[client_id].name, name, MAX_NAME_LENGTH);
}

void server_setbrowseinfo(int game_type, int progression)
{
	browseinfo_gametype = game_type;
	browseinfo_progression = progression;
}

int server_tick()
{
	return current_tick;
}

int64 server_tick_start_time(int tick)
{
	return game_start_time + (time_freq()*tick)/SERVER_TICK_SPEED;
}

int server_tickspeed()
{
	return SERVER_TICK_SPEED;
}

int server_init()
{
	int i;
	for(i = 0; i < MAX_CLIENTS; i++)
	{
		clients[i].state = SRVCLIENT_STATE_EMPTY;
		clients[i].name[0] = 0;
		clients[i].clan[0] = 0;
		snapstorage_init(&clients[i].snapshots);
	}

	current_tick = 0;

	return 0;
}

int server_getclientinfo(int client_id, CLIENT_INFO *info)
{
	dbg_assert(client_id >= 0 && client_id < MAX_CLIENTS, "client_id is not valid");
	dbg_assert(info != 0, "info can not be null");

	if(clients[client_id].state == SRVCLIENT_STATE_INGAME)
	{
		info->name = clients[client_id].name;
		info->latency = clients[client_id].latency;
		return 1;
	}
	return 0;
}


int server_send_msg(int client_id)
{
	const MSG_INFO *info = msg_get_info();
	NETPACKET packet;
	mem_zero(&packet, sizeof(NETPACKET));
	
	packet.client_id = client_id;
	packet.data = info->data;
	packet.data_size = info->size;

	if(info->flags&MSGFLAG_VITAL)	
		packet.flags = PACKETFLAG_VITAL;
			
	if(client_id == -1)
	{
		/* broadcast */
		int i;
		for(i = 0; i < MAX_CLIENTS; i++)
			if(clients[i].state == SRVCLIENT_STATE_INGAME)
			{
				packet.client_id = i;
				netserver_send(net, &packet);
			}
	}
	else
		netserver_send(net, &packet);
	return 0;
}

static void server_do_snap()
{
	int i, k;
	mods_presnap();

	for(i = 0; i < MAX_CLIENTS; i++)
	{
		if(clients[i].state == SRVCLIENT_STATE_INGAME)
		{
			char data[MAX_SNAPSHOT_SIZE];
			char deltadata[MAX_SNAPSHOT_SIZE];
			char compdata[MAX_SNAPSHOT_SIZE];
			int snapshot_size;
			int crc;
			static SNAPSHOT emptysnap;
			SNAPSHOT *deltashot = &emptysnap;
			int deltashot_size;
			int delta_tick = -1;
			int input_predtick = -1;
			int64 timeleft = 0;
			int deltasize;

			snapbuild_init(&builder);
			mods_snap(i);

			/* finish snapshot */
			snapshot_size = snapbuild_finish(&builder, data);
			crc = snapshot_crc((SNAPSHOT*)data);

			/* remove old snapshos */
			/* keep 1 seconds worth of snapshots */
			snapstorage_purge_until(&clients[i].snapshots, current_tick-SERVER_TICK_SPEED);
			
			/* save it the snapshot */
			snapstorage_add(&clients[i].snapshots, current_tick, time_get(), snapshot_size, data);
			
			/* find snapshot that we can preform delta against */
			emptysnap.data_size = 0;
			emptysnap.num_items = 0;
			
			{
				deltashot_size = snapstorage_get(&clients[i].snapshots, clients[i].last_acked_snapshot, 0, &deltashot);
				if(deltashot_size >= 0)
					delta_tick = clients[i].last_acked_snapshot;
			}
			
			for(k = 0; k < 200; k++) /* TODO: do this better */
			{
				if(clients[i].inputs[k].game_tick == current_tick)
				{
					timeleft = clients[i].inputs[k].timeleft;
					input_predtick = clients[i].inputs[k].pred_tick;
					break;
				}
			}
			
			/* create delta */
			deltasize = snapshot_create_delta(deltashot, (SNAPSHOT*)data, deltadata);
			
			if(deltasize)
			{
				/* compress it */
				unsigned char intdata[MAX_SNAPSHOT_SIZE];
				int intsize = intpack_compress(deltadata, deltasize, intdata);
				int snapshot_size = zerobit_compress(intdata, intsize, compdata);
				const int max_size = MAX_SNAPSHOT_PACKSIZE;
				int numpackets = (snapshot_size+max_size-1)/max_size;
				int n, left;

				(void)numpackets;

				for(n = 0, left = snapshot_size; left; n++)
				{
					int chunk = left < max_size ? left : max_size;
					left -= chunk;

					msg_pack_start_system(NETMSG_SNAP, 0);
					msg_pack_int(current_tick);
					msg_pack_int(current_tick-delta_tick); /* compressed with */
					msg_pack_int(input_predtick);
					msg_pack_int((timeleft*1000)/time_freq());
					msg_pack_int(crc);
					msg_pack_int(chunk);
					msg_pack_raw(&compdata[n*max_size], chunk);
					msg_pack_end();
					server_send_msg(i);
				}
			}
			else
			{
				msg_pack_start_system(NETMSG_SNAPEMPTY, 0);
				msg_pack_int(current_tick);
				msg_pack_int(current_tick-delta_tick); /* compressed with */
				msg_pack_int(input_predtick);
				msg_pack_int((timeleft*1000)/time_freq());
				msg_pack_end();
				server_send_msg(i);
			}
		}
	}

	mods_postsnap();
}


static int new_client_callback(int cid, void *user)
{
	int i;
	clients[cid].state = SRVCLIENT_STATE_CONNECTING;
	clients[cid].name[0] = 0;
	clients[cid].clan[0] = 0;
	
	/* reset input */
	for(i = 0; i < 200; i++)
	{
		clients[cid].inputs[i].game_tick = -1;
		clients[cid].inputs[i].pred_tick = -1;
	}
	clients[cid].current_input = 0;
	
	snapstorage_purge_all(&clients[cid].snapshots);
	clients[cid].last_acked_snapshot = -1;
	return 0;
}

static int del_client_callback(int cid, void *user)
{
	clients[cid].state = SRVCLIENT_STATE_EMPTY;
	clients[cid].name[0] = 0;
	clients[cid].clan[0] = 0;
	snapstorage_purge_all(&clients[cid].snapshots);
	
	mods_client_drop(cid);
	return 0;
}


static void server_send_map(int cid)
{
	msg_pack_start_system(NETMSG_MAP, MSGFLAG_VITAL);
	msg_pack_string(config.sv_map, 0);
	msg_pack_end();
	server_send_msg(cid);
}
	
static void server_send_heartbeat()
{
	NETPACKET packet;
	packet.client_id = -1;
	packet.address = master_server;
	packet.flags = PACKETFLAG_CONNLESS;
	packet.data_size = sizeof(SERVERBROWSE_HEARTBEAT);
	packet.data = SERVERBROWSE_HEARTBEAT;
	netserver_send(net, &packet);
}

static void server_process_client_packet(NETPACKET *packet)
{
	int cid = packet->client_id;
	int sys;
	int msg = msg_unpack_start(packet->data, packet->data_size, &sys);
	if(sys)
	{
		/* system message */
		if(msg == NETMSG_INFO)
		{
			char version[64];
			const char *password;
			strncpy(version, msg_unpack_string(), 64);
			if(strcmp(version, mods_net_version()) != 0)
			{
				/* OH FUCK! wrong version, drop him */
				char reason[256];
				sprintf(reason, "wrong version. server is running %s.", mods_net_version());
				netserver_drop(net, cid, reason);
				return;
			}
			
			strncpy(clients[cid].name, msg_unpack_string(), MAX_NAME_LENGTH);
			strncpy(clients[cid].clan, msg_unpack_string(), MAX_CLANNAME_LENGTH);
			password = msg_unpack_string();
			
			if(config.password[0] != 0 && strcmp(config.password, password) != 0)
			{
				/* wrong password */
				netserver_drop(net, cid, "wrong password");
				return;
			}
			
			server_send_map(cid);
		}
		else if(msg == NETMSG_READY)
		{
			if(clients[cid].state == SRVCLIENT_STATE_CONNECTING)
			{
				dbg_msg("server", "player is ready. cid=%x", cid);
				clients[cid].state = SRVCLIENT_STATE_READY;
				mods_connected(cid);
			}
		}
		else if(msg == NETMSG_ENTERGAME)
		{
			if(clients[cid].state != SRVCLIENT_STATE_INGAME)
			{
				dbg_msg("server", "player as entered the game. cid=%x", cid);
				clients[cid].state = SRVCLIENT_STATE_INGAME;
				mods_client_enter(cid);
			}
		}
		else if(msg == NETMSG_INPUT)
		{
			int tick, size, i;
			CLIENT_INPUT *input;
			int64 tagtime;

			clients[cid].last_acked_snapshot = msg_unpack_int();
			if(snapstorage_get(&clients[cid].snapshots, clients[cid].last_acked_snapshot, &tagtime, 0) >= 0)
				clients[cid].latency = (int)(((time_get()-tagtime)*1000)/time_freq());
			
			tick = msg_unpack_int();
			size = msg_unpack_int();
			
			input = &clients[cid].inputs[clients[cid].current_input];
			input->timeleft = server_tick_start_time(tick)-time_get();
			input->pred_tick = tick;
			
			if(tick <= server_tick())
			{
				/* TODO: how should we handle this */
				dbg_msg("server", "input got in late for=%d cur=%d", tick, server_tick());
				tick = server_tick()+1;
			}

			input->game_tick = tick;
			
			for(i = 0; i < size/4; i++)
				input->data[i] = msg_unpack_int();
				
			clients[cid].current_input++;
			clients[cid].current_input %= 200;
		}
		else if(msg == NETMSG_CMD)
		{
			const char *pw = msg_unpack_string();
			const char *cmd = msg_unpack_string();
			if(config.rcon_password[0] != 0 && strcmp(pw, config.rcon_password) == 0)
			{
				dbg_msg("server", "cid=%d rcon='%s'", cid, cmd);
				config_set(cmd);
			}
		}
		else
		{
			dbg_msg("server", "strange message cid=%d msg=%d data_size=%d", cid, msg, packet->data_size);
		}
	}
	else
	{
		/* game message */
		mods_message(msg, cid);
	}
}

static void server_send_serverinfo(NETADDR4 *addr)
{
	NETPACKET packet;
	PACKER p;
	char buf[128];

	/* count the players */	
	int c = 0;
	int i;
	for(i = 0; i < MAX_CLIENTS; i++)
	{
		if(clients[i].state != SRVCLIENT_STATE_EMPTY)
			c++;
	}
	
	packer_reset(&p);
	packer_add_raw(&p, SERVERBROWSE_INFO, sizeof(SERVERBROWSE_INFO));
	packer_add_string(&p, mods_net_version(), 32);
	packer_add_string(&p, config.sv_name, 64);
	packer_add_string(&p, config.sv_map, 32);

	/* gametype */
	sprintf(buf, "%d", browseinfo_gametype);
	packer_add_string(&p, buf, 2);

	/* flags */
	i = 0;
	if(strlen(config.password))
		i |= 1;
	sprintf(buf, "%d", i);
	packer_add_string(&p, buf, 2);

	/* progression */
	sprintf(buf, "%d", browseinfo_progression);
	packer_add_string(&p, buf, 4);
	
	sprintf(buf, "%d", c); packer_add_string(&p, buf, 3);  /* num players */
	sprintf(buf, "%d", netserver_max_clients(net)); packer_add_string(&p, buf, 3); /* max players */

	for(i = 0; i < MAX_CLIENTS; i++)
	{
		if(clients[i].state != SRVCLIENT_STATE_EMPTY)
		{
			packer_add_string(&p, clients[i].name, 48);  /* player name */
			packer_add_string(&p, "0", 6); /* score */
		}
	}
	
	
	packet.client_id = -1;
	packet.address = *addr;
	packet.flags = PACKETFLAG_CONNLESS;
	packet.data_size = packer_size(&p);
	packet.data = packer_data(&p);
	netserver_send(net, &packet);
}


static void server_send_fwcheckresponse(NETADDR4 *addr)
{
	NETPACKET packet;
	packet.client_id = -1;
	packet.address = *addr;
	packet.flags = PACKETFLAG_CONNLESS;
	packet.data_size = sizeof(SERVERBROWSE_FWRESPONSE);
	packet.data = SERVERBROWSE_FWRESPONSE;
	netserver_send(net, &packet);
}

static void server_pump_network()
{
	NETPACKET packet;

	netserver_update(net);
	
	/* process packets */
	while(netserver_recv(net, &packet))
	{
		if(packet.client_id == -1)
		{
			/* stateless */
			if(packet.data_size == sizeof(SERVERBROWSE_GETINFO) &&
				memcmp(packet.data, SERVERBROWSE_GETINFO, sizeof(SERVERBROWSE_GETINFO)) == 0)
			{
				server_send_serverinfo(&packet.address);
			}
			else if(packet.data_size == sizeof(SERVERBROWSE_FWCHECK) &&
				memcmp(packet.data, SERVERBROWSE_FWCHECK, sizeof(SERVERBROWSE_FWCHECK)) == 0)
			{
				server_send_fwcheckresponse(&packet.address);
			}
			else if(packet.data_size == sizeof(SERVERBROWSE_FWOK) &&
				memcmp(packet.data, SERVERBROWSE_FWOK, sizeof(SERVERBROWSE_FWOK)) == 0)
			{
				if(config.debug)
					dbg_msg("server", "no firewall/nat problems detected");
			}
			else if(packet.data_size == sizeof(SERVERBROWSE_FWERROR) &&
				memcmp(packet.data, SERVERBROWSE_FWERROR, sizeof(SERVERBROWSE_FWERROR)) == 0)
			{
				dbg_msg("server", "ERROR: the master server reports that clients can not connect to this server.");
				dbg_msg("server", "ERROR: configure your firewall/nat to let trough udp on port %d.", config.sv_port);
			}
		}
		else
			server_process_client_packet(&packet);
	}
}

static int server_load_map(const char *mapname)
{
	DATAFILE *df;
	char buf[512];
	sprintf(buf, "data/maps/%s.map", mapname);
	df = datafile_load(buf);
	if(!df)
		return 0;
		
	strcpy(current_map, mapname);
	map_set(df);
	return 1;
}


static int server_run()
{
	NETADDR4 bindaddr;

	net_init(); /* For Windows compatibility. */
	
	snap_init_id();

	/* load map */
	if(!server_load_map(config.sv_map))
	{
		dbg_msg("server", "failed to load map. mapname='%s'", config.sv_map);
		return -1;
	}
	
	/* start server */
	if(strlen(config.sv_bindaddr) && net_host_lookup(config.sv_bindaddr, config.sv_port, &bindaddr) != 0)
	{
		/* sweet! */
	}
	else
	{
		mem_zero(&bindaddr, sizeof(bindaddr));
		bindaddr.port = config.sv_port;
	}
	
	net = netserver_open(bindaddr, config.sv_max_clients, 0);
	if(!net)
	{
		dbg_msg("server", "couldn't open socket. port might already be in use");
		return -1;
	}
	
	netserver_set_callbacks(net, new_client_callback, del_client_callback, 0);
	
	dbg_msg("server", "server name is '%s'", config.sv_name);
	dbg_msg("server", "masterserver is '%s'", config.masterserver);
	if(net_host_lookup(config.masterserver, MASTERSERVER_PORT, &master_server) != 0)
	{
		/* TODO: fix me */
		/*master_server = netaddr4(0, 0, 0, 0, 0); */
	}

	mods_init();
	dbg_msg("server", "version %s", mods_net_version());

	/* start game */
	{
		int64 time_per_heartbeat = time_freq() * 30;
		int64 reporttime = time_get();
		int reportinterval = 3;
	
		int64 simulationtime = 0;
		int64 snaptime = 0;
		int64 networktime = 0;
		int64 totaltime = 0;
		
		lastheartbeat = 0;
		game_start_time = time_get();
	
		if(config.debug)
			dbg_msg("server", "baseline memory usage %dk", mem_allocated()/1024);

		while(1)
		{
			int64 t = time_get();
			/* load new map TODO: don't poll this */
			if(strcmp(config.sv_map, current_map) != 0)
			{
				/* load map */
				if(server_load_map(config.sv_map))
				{
					int c;
					
					/* new map loaded */
					mods_shutdown();
					
					for(c = 0; c < MAX_CLIENTS; c++)
					{
						if(clients[c].state == SRVCLIENT_STATE_EMPTY)
							continue;
						
						server_send_map(c);
						clients[c].state = SRVCLIENT_STATE_CONNECTING;
						clients[c].last_acked_snapshot = -1;
						snapstorage_purge_all(&clients[c].snapshots);
					}
					
					mods_init();
					game_start_time = time_get();
					current_tick = 0;
				}
				else
				{
					dbg_msg("server", "failed to load map. mapname='%s'", config.sv_map);
					config_set_sv_map(&config, current_map);
				}
			}
			
			if(t > server_tick_start_time(current_tick+1))
			{
				current_tick++;
				
				/* apply new input */
				{
					int c, i;
					for(c = 0; c < MAX_CLIENTS; c++)
					{
						if(clients[c].state == SRVCLIENT_STATE_EMPTY)
							continue;
						for(i = 0; i < 200; i++)
						{
							if(clients[c].inputs[i].game_tick == server_tick())
							{
								mods_client_input(c, clients[c].inputs[i].data);
								break;
							}
						}
					}
				}
				
				/* progress game */
				{
					int64 start = time_get();
					mods_tick();
					simulationtime += time_get()-start;
				}
	
				/* snap game */
				if(config.sv_bandwidth_mode == 0 ||
					(config.sv_bandwidth_mode == 1 && current_tick%2) ||
					(config.sv_bandwidth_mode == 2 && (current_tick%3) == 0 ))
				/* if(current_tick&1) */
				{
					int64 start = time_get();
					server_do_snap();
					snaptime += time_get()-start;
				}
			}
	
			if(config.sv_sendheartbeats)
			{
				if (t > lastheartbeat+time_per_heartbeat)
				{
					server_send_heartbeat();
					lastheartbeat = t+time_per_heartbeat;
				}
			}
	
			{
				int64 start = time_get();
				server_pump_network();
				networktime += time_get()-start;
			}
	
			if(reporttime < time_get())
			{
				if(config.debug)
				{
					static NETSTATS prev_stats;
					NETSTATS stats;
					netserver_stats(net, &stats);
					dbg_msg("server", "sim=%.02fms snap=%.02fms net=%.02fms tot=%.02fms load=%.02f%%",
						(simulationtime/reportinterval)/(double)time_freq()*1000,
						(snaptime/reportinterval)/(double)time_freq()*1000,
						(networktime/reportinterval)/(double)time_freq()*1000,
						(totaltime/reportinterval)/(double)time_freq()*1000,
						(totaltime)/reportinterval/(double)time_freq()*100.0f);

					dbg_msg("server", "send=%8d recv=%8d",
						(stats.send_bytes - prev_stats.send_bytes)/reportinterval,
						(stats.recv_bytes - prev_stats.recv_bytes)/reportinterval);
						
					prev_stats = stats;
				}
	
				simulationtime = 0;
				snaptime = 0;
				networktime = 0;
				totaltime = 0;
	
				reporttime += time_freq()*reportinterval;
			}
			totaltime += time_get()-t;
			thread_sleep(1);
		}
	}

	mods_shutdown();
	map_unload();

	return 0;
}


int main(int argc, char **argv)
{
	dbg_msg("server", "starting...");
	engine_init("Teewars", argc, argv);
	server_run();
	return 0;
}