/* XXX
 * we should inspire from netcat
 * http://www.openbsd.org/cgi-bin/cvsweb/src/usr.bin/nc/
 * see readwrite(), atomicio()
 */

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#include <sys/socket.h>
#include <poll.h>

#include "pg.h"

extern char *__progname;

static int usage();
static void process(void);
static int pfds_create(struct pollfd *);
static int cmd_init(struct conn *, int, struct msg_header *);
static int cmd_exec(struct conn *, int, struct msg_header *);
static int cmd_kill(struct conn *, int, struct msg_header *);
static int cmd_read(struct conn *, int, struct msg_header *);
static int cmd_write(struct conn *, int, struct msg_header *);
static int cmd_data_conn(struct conn *, int, struct msg_header *);
static int cmd_data_route(struct route *, int, struct msg_header *);
static int cmd_ok(struct route *, int, struct msg_header *);
static int cmd_err(struct route *, int, struct msg_header *);

int
main(int argc, char *argv[]) {
    int opt;
    int loglevel = 1, logstdout = 0;
    int deamonize = 0;
    int server = 0;
    char dest = 0;
    char *cmd = NULL;

    while ((opt = getopt(argc, argv, "dhltv")) != -1) {
        switch (opt) {
            case 'd':
                logstdout = 1;
                deamonize = 0;
                break;
            case 'h':
                usage();
                break;
            case 'l':
                server = 1;
                break;
            case 't':
                dest = optarg[0];
                break;
            case 'v':
                loglevel++;
                break;
            default:
                usage();
                break;
        }
    }

    argc -= optind;
    argv += optind;

    if ((server && argc != 0) ||
            (!server && argc != 1) ||
            (server && conf.client_dest))
        usage();
    if (!server) {
        cmd = argv[0];
        if (dest == 0)
            dest = 'B';
        conf.client_dest = dest;
    }
    
    log_init(loglevel, logstdout);
    log_warn("** Starting propagate v%.1f", VERSION);
    log_warn("**   using message version %d", MSG_VERSION);
    log_warn("**   loglevel %d", loglevel);

    conf.server = server;
    LIST_INIT(&routes);
    routes_count = 0;
    LIST_INIT(&listeners);
    listeners_count = 0;

    /* XXX load conf */
    if (server) {
        conf.me = 'B';
        listener_add(LISTENER_UNIX, "/tmp/propagate_sock");
    } else {
        conf.me = 'A';
        route_add('B', ROUTE_PROC, "nc 127.0.0.1 3333", 0, NULL, 0);
    }

    if (server)
        log_info("starting server %c", conf.me);
    else
        log_info("running client %c, dest %c, command %s", conf.me, conf.client_dest, cmd);

    if (deamonize)
        log_info("XXX deamonize not implemented yet");

    if (!server)
        send_cmd(conf.client_dest, MSG_EXEC, 0, (uint8_t *)cmd, strlen(cmd));

    process();

    return 0;
}

static int
usage() {
    printf("Usage: %s [-dhv] [-t destination] command\n", __progname);
    printf("       %s -l [-dhv]\n", __progname);

    exit(1);
}

static void
process(void) {
    struct listener *l;
    struct conn *c;
    struct route *r;
    uint8_t *buf;
    struct msg_header *hdr;
    struct sockaddr_storage cliaddr;
    socklen_t slen = sizeof(cliaddr);
    int len, n, fd, cfd;
    struct pollfd pfds[POLLER_MAX];
    int pfds_count;
    /* keep in sync with pg.h MSG enum */
    int (*cmd_conn[MSG_MAX+1])
            (struct conn *, int, struct msg_header *) = {
        &cmd_init,
        &cmd_init,
        &cmd_kill,
        &cmd_exec,
        &cmd_read,
        &cmd_write,
        &cmd_data_conn,
        NULL,
        NULL
    };
    int (*cmd_route[MSG_MAX+1])
            (struct route *, int, struct msg_header *) = {
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        NULL,
        &cmd_data_route,
        &cmd_ok,
        &cmd_err
    };


    /* OLD TODO
     * fork frontend and open pipe_fe
     * poll()
     *  - pipe_fe input -> write stdout
     *  - stdin -> append send_buf
     * sigalarm() every second
     *  - MSG_READ and write on stdout 
     *  - if size(send_buf) > 0: MSG_WRITE send_buf
     * handle network errors / retransmission in fe
     * MSG_[READ|WRITE] do not expect MSG_OK, but warns on MSG_ERROR
     * MSG_OK only for MSG_INIT and MSG_EXEC
     */

    for (;;) {
        pfds_count = pfds_create(pfds);
        n = poll(pfds, pfds_count, POLL_TIMEOUT);
        log_tmp("end of poll, %d fds on %d", n, pfds_count);
        if (n < 0) {
            log_warn("polling error"); // XXX fatal ?
            continue;
        }

        for (n=0; n<pfds_count; n++) {
            if ((pfds[n].revents & POLLIN) == 0)
                continue;
            fd = pfds[n].fd;
            log_tmp("  fd %d got something", fd);

            if ((l = listener_find(fd))) {
                log_debug("got listener new connection");
                cfd = accept(fd, (struct sockaddr *)&cliaddr, &slen);
                listener_conn_add(l, cfd);
            } else if ((c = listener_conn_find_exec(fd))) {
                log_debug("got exec data");
                if (c->async)
                    listener_conn_exec_bufferize(c, fd);
                else
                    msg_send_from_fd(c->fd, MSG_DATA, c->orig, 0, fd);
            } else if (fd == fileno(stdin)) {
                log_debug("got stdin data");
                r = route_find(conf.client_dest);
                if (r->proc.async)
                    route_bufferize(r, fd);
                else
                    msg_send_from_fd(r->proc.fd[1], MSG_DATA, r->dest, 0, fd);
            } else {
                log_debug("got command");
                len = readbuf(fd, &buf, sizeof(MSG_MAGIC));
                if (len < sizeof(MSG_MAGIC)) {
                    log_info("Magic number too short");
                    continue;
                }
                if (memcmp(buf, MSG_MAGIC, sizeof(MSG_MAGIC))) {
                    log_info("Invalid magic number %4x", buf);
                    continue;
                }
                len = readbuf(fd, &buf, MSG_HEADER_SIZE_ENCODED);
                if (len < MSG_HEADER_SIZE_ENCODED) {
                    log_warn("Message header too short");
                    continue;
                }
                hdr = msg_unpack_header(buf);
                if (!hdr) {
                    log_warn("Invalid message header");
                    continue;
                }

                if (hdr->dest != conf.me) {
                    route_fw(fd, hdr, buf);
                    free(hdr);
                    continue;
                }

                if ((c = listener_conn_find(fd))) {
                    cmd_conn[hdr->type](c, fd, hdr);
                    break;
                } else if ((r = route_find(hdr->orig))) {
                    cmd_route[hdr->type](r, fd, hdr);
                    break;
                } else
                    log_warn("host %c has no reference ! ignoring command...",
                             hdr->orig);
                free(hdr);
            }
        }
    }
}

static int
pfds_create(struct pollfd *pfds) {
    struct route *r;
    struct listener *l;
    struct conn *c;
    int count = 0;

#define ADDFD(myfd) { \
pfds[count].fd = myfd; \
pfds[count].events = POLLIN; \
count++; \
}

    if (!conf.server)
        ADDFD(fileno(stdin))

    LIST_FOREACH(r, &routes, entry) {
        switch (r->type) {
        case ROUTE_PROC:
            ADDFD(r->proc.fd[0])
        }
    }
        
    LIST_FOREACH(l, &listeners, entry) {
        ADDFD(l->sock)
        LIST_FOREACH(c, &l->conns, entry) {
            ADDFD(c->fd)
            if (c->exec.cmd)
                ADDFD(c->exec.fd[0])
        }
    }

    return count;
}

static int
cmd_init(struct conn *c, int fd, struct msg_header *hdr) {
    struct conn *oldc;
    
    log_debug("received INIT from %c :)", hdr->orig);
    if (c->state == CONN_READY) {
        log_warn("received INIT on an already open connection !");
        send_cmd(hdr->orig, MSG_ERR, 0, NULL, 0);
        return -1;
    }

    /* checking if this client already has a connection opened on
     * another fd */
    oldc = listener_conn_find_orig(hdr->orig);
    if (oldc)
        listener_conn_move(oldc, c);

    c->orig = hdr->orig;
    c->state = CONN_READY;

    switch (hdr->type) {
    case MSG_INIT:
        c->async = 0;
        break;
    case MSG_INIT_ASYNC:
        c->async = 1;
        break;
    }

    send_cmd(hdr->orig, MSG_OK, 0, NULL, 0);

    return 0;
}

static int
cmd_exec(struct conn *c, int fd, struct msg_header *hdr) {
    char *cmd = NULL;
    int cmdlen;
    char **argv = NULL;
    int argc;

    cmdlen = readbuf(fd, (uint8_t **)&cmd, hdr->datalen);
    if (cmdlen <= 0 || !cmd)
        goto err;
    argv = explode(cmd, cmdlen, " ", &argc);
    if (!argv)
        goto err;
    if (listener_conn_exec(c, argv[0], argv) < 0)
        goto err;

    send_cmd(hdr->orig, MSG_OK, 0, NULL, 0);

    return 0;

err:
    log_debug("exec failed");
    if (cmd)
        free(cmd);
    if (argv)
        free(argv);
    send_cmd(hdr->orig, MSG_ERR, 0, NULL, 0);

    return -1;
}

static int
cmd_kill(struct conn *c, int fd, struct msg_header *hdr) {
    listener_conn_exec_kill(c);
    send_cmd(hdr->orig, MSG_OK, 0, NULL, 0);

    return 0;
}

static int
cmd_read(struct conn *c, int fd, struct msg_header *hdr) {
    int len;

    if (!c->exec.cmd) {
        log_warn("cmd_read: no exec in progress !");
        goto err;
    }
    if (c->async == 0) {
        log_warn("cmd_read: not in async mode !");
        goto err;
    }

    len = send_cmd(c->orig, MSG_DATA, 0,
                   c->exec.async_writebuf, c->exec.async_writebuf_size);
    if (len < 0)
        goto err;
    c->exec.async_writebuf_size -= len;
    c->exec.async_writebuf = realloc(c->exec.async_writebuf,
                                     c->exec.async_writebuf_size);
    return 0;

err:
    send_cmd(c->orig, MSG_ERR, 0, NULL, 0);
    return -1;
}

static int
cmd_write(struct conn *c, int fd, struct msg_header *hdr) {
    if (!c->exec.cmd) {
        log_warn("cmd_write: no exec in progress !");
        goto err;
    }
    if (c->async == 0) {
        log_warn("cmd_write: not in async mode !");
        goto err;
    }

    if (msg_read_data_to_fd(fd, c->exec.fd[1], hdr->datalen) < 0) {
        goto err;
    }

    return 0;

err:
    send_cmd(c->orig, MSG_ERR, 0, NULL, 0);
    return -1;
}

static int
cmd_data_conn(struct conn *c, int fd, struct msg_header *hdr) {
    log_debug("received DATA from conn %c !", hdr->orig);

    if (msg_read_data_to_fd(fd, c->exec.fd[1], hdr->datalen) < 0) {
        log_warn("cmd_data: recvwrite failed");
        return -1;
    }

    return 0;
}

static int
cmd_data_route(struct route *r, int fd, struct msg_header *hdr) {
    log_debug("received DATA from route %c !", hdr->orig);

    if (msg_read_data_to_fd(fd, fileno(stdout), hdr->datalen) < 0) {
        log_warn("cmd_data: recvwrite failed");
        return -1;
    }

    return 0;
}

static int
cmd_ok(struct route *r, int fd, struct msg_header *hdr) {
    log_info("received OK from %c !", hdr->orig);

    return 0;
}

static int
cmd_err(struct route *r, int fd, struct msg_header *hdr) {
    log_info("received ERROR from %c !", hdr->orig);

    return 0;
}