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#include <stdbool.h>
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#include <assert.h>
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#include <string.h>
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#include <stdlib.h>
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#include <stdio.h>
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#include <unistd.h>
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#include <poll.h>
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#include <sys/uio.h>
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#include <util/math.h>
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#include "cnc_ipc.h"
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#define SSE_HEADER "data: \""
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#define SSE_FOOTER "\"\n\n"
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static int cnc_ipc_get_input_fd(void) {
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	char *cnc_in;
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	if (!(cnc_in = getenv(CNCIPC_IN))) {
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		printf("Error: IPC not found");
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		return 0;
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	}
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	return atoi(cnc_in);
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}
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static int memcpy_iov(void *dst, size_t dst_len, struct iovec *iov, int iovlen) {
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	int i_iov;
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	void *bp;
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	int bp_len;
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	bp = dst;
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	bp_len = dst_len;
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	for (i_iov = 0; i_iov < iovlen; ++i_iov) {
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		const int to_write = min(iov[i_iov].iov_len, bp_len);
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		memcpy(bp, iov[i_iov].iov_base, to_write);
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		bp += to_write;
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		bp_len -= to_write;
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	}
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	return bp - dst;
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}
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int main(int argc, char *argv[]) {
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	const int sock = STDOUT_FILENO;
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	const int ipc_in = cnc_ipc_get_input_fd();
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	char buf[128], out_buf[64];
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	struct pollfd fds[2];
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	struct iovec iov[3];
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	bool sock_conn, ipc_has_data;
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	int buf_len;
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	fds[0].fd = ipc_in;
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	fds[0].events = POLLIN | POLLERR;
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	fds[1].fd = sock;
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	fds[1].events = POLLERR;
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	buf_len = snprintf(buf, sizeof(buf),
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		"HTTP/1.1 200 OK\r\n"
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		"Content-Type: text/event-stream\r\n"
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		"Cache-Control: no-cache\r\n"
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		"Connection: keep-alive\r\n"
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		"\r\n");
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	iov[0].iov_base = SSE_HEADER;
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	iov[0].iov_len = strlen(SSE_HEADER);
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	iov[2].iov_base = SSE_FOOTER;
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	iov[2].iov_len = strlen(SSE_FOOTER);
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	ipc_has_data = false;
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	sock_conn = 0 < write(sock, buf, buf_len);
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	while (sock_conn) {
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		if (poll(fds, 2, -1) > 0) {
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			sock_conn = !(fds[1].revents & POLLERR);
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			ipc_has_data = fds[0].revents & POLLIN;
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		}
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		if (sock_conn && ipc_has_data) {
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			int buf_o;
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			while(1) {
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				buf_len = read(ipc_in, buf, sizeof(buf));
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				if (buf_len > 0) {
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					break;
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				}
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				usleep(1000);
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			}
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			buf_o = 0;
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			while (buf_o < buf_len) {
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				char *eom = memchr(buf + buf_o, '\n', buf_len - buf_o);
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				const int body_len = eom ? eom - (buf + buf_o) : buf_len - buf_o;
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				int write_len;
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				iov[1].iov_base = buf + buf_o;
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				iov[1].iov_len = body_len;
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				write_len = memcpy_iov(out_buf, sizeof(out_buf), iov, 3);
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				sock_conn = 0 < write(STDOUT_FILENO, out_buf, write_len);
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				if (!sock_conn) {
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					break;
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				}
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				buf_o += body_len + 1;
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			}
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		}
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	}
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	return 0;
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}
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