#include"mongoose.h"

#include<getopt.h>
#include<stdio.h>
#include<string.h>
#include<stdbool.h>

typedef enum {
	LOADING_HEADER,
	STREAMING,
} State;

static const uint8_t *STATE_CHANGE_STRING[] = {
	[LOADING_HEADER] = "\x1F\x43\xB6\x75",
	[STREAMING] = "\x1A\x45\xDF\xA3",
};

static State state = STREAMING;
static int stateChangeIdx;

static char *header;
static size_t headerSize;

static struct mg_connection *streamerConnected = NULL;

static struct {
	char *wslisten;
	char *tcplisten;
	char *tlscert;
	char *tlsca;
} settings;

static void ws_broadcast(struct mg_mgr *mgr, const char *data, size_t len) {
	for(struct mg_connection *cli = mgr->conns; cli; cli = cli->next) {
		if(cli->is_websocket) {
			mg_ws_send(cli, data, len, WEBSOCKET_OP_BINARY);
		}
	}
}

static void fn(struct mg_connection *c, int ev, void *ev_data) {
	if(ev == MG_EV_ACCEPT) {
		if(mg_url_is_ssl(c->is_websocket ? settings.wslisten : settings.tcplisten)) {
			struct mg_tls_opts opts = {.ca = mg_unpacked(settings.tlsca), .cert = mg_unpacked(settings.tlscert), .key = mg_unpacked(settings.tlscert)};
			mg_tls_init(c, &opts);
		}
	} else if(ev == MG_EV_CLOSE) {
		if(c == streamerConnected) {
			streamerConnected = NULL;
		} 
	} else if(ev == MG_EV_HTTP_MSG) {
		struct mg_http_message *hm = (struct mg_http_message *) ev_data;
		mg_ws_upgrade(c, hm, NULL);
	} else if(ev == MG_EV_WS_OPEN) {
		if(state == STREAMING && header) {
			mg_ws_send(c, header, headerSize, WEBSOCKET_OP_BINARY);
		}
	} else if(ev == MG_EV_WS_MSG) {
		// Incoming WS messages are ignored.
	} else if(ev == MG_EV_READ) {
		if(!c->is_websocket) {
			if(streamerConnected && streamerConnected != c) {
				c->is_closing = 1;
			} else {
				streamerConnected = c;
			}
		} else return;
		
		struct mg_iobuf *r = &c->recv;
		
		if(state == LOADING_HEADER) {
			header = realloc(header, headerSize + r->len);
			memcpy(header + headerSize, r->buf, r->len);
			headerSize += r->len;
			
			char *clusterEl = memmem(header, headerSize, "\x1F\x43\xB6\x75", 4);
			if(clusterEl) {
				ws_broadcast(c->mgr, header, clusterEl - header);
				ws_broadcast(c->mgr, clusterEl, header + headerSize - clusterEl);
				
				headerSize = clusterEl - header;
				state = STREAMING;
			}
		} else {
			int i;
			for(i = 0; i < r->len; i++) {
				if(r->buf[i] == STATE_CHANGE_STRING[state][stateChangeIdx]) { 
					stateChangeIdx++;
					
					if(stateChangeIdx == strlen(STATE_CHANGE_STRING[state])) {
						i++;
						stateChangeIdx = 0;
						state = LOADING_HEADER;
						break;
					}
				} else {
					stateChangeIdx = 0;
				}
			}
			
			if(state == LOADING_HEADER) {
				if(i > 4) {
					ws_broadcast(c->mgr, r->buf, i - 4);
				}
				
				header = realloc(header, headerSize = 4 + (r->len - i));
				memcpy(header, STATE_CHANGE_STRING[STREAMING], 4);
				memcpy(header + 4, r->buf + i, r->len - i);
			} else {
				ws_broadcast(c->mgr, r->buf, r->len);
			}
		}
		
		r->len = 0;
	}
}

int main(int argc, char **argv) {
	int help = 0, err = 0;
	
	int c;
	while((c = getopt(argc, argv, "a:c:i:o:h")) != -1) {
		if(c == 'i') {
			settings.tcplisten = optarg;
		} else if(c == 'o') {
			settings.wslisten = optarg;
		} else if(c == 'a') {
			settings.tlsca = optarg;
		} else if(c == 'c') {
			settings.tlscert = optarg;
		} else if(c == 'h') {
			help = 1;
		}
	}
	
	if(help) {
		fprintf(stderr, "Example usage: %s [-c /path/to/cert.pem] [-a /path/to/certauthority.pem] [-h] <-i tcp://[::]:1234> <-o ws://[::]:8000>\n", argv[0]);
		return;
	}
	
	if(!settings.wslisten) {
		fputs("Missing -o parameter. Try -h for help.\n", stderr);
		err = 1;
	}
	
	if(!settings.tcplisten) {
		fputs("Missing -i parameter. Try -h for help\n", stderr);
		err = 1;
	}
	
	if(err) {
		return err;
	}
	
	struct mg_mgr mgr;
	
	mg_mgr_init(&mgr);
	
	mg_listen(&mgr, settings.tcplisten, fn, NULL);
	mg_http_listen(&mgr, settings.wslisten, fn, NULL);
	
	for (;;) mg_mgr_poll(&mgr, 1000);
	
	mg_mgr_free(&mgr);
	
	return 0;
}