/*
 * This file is part of the TeAman project.
 * Copyright 2022 Edward V. Emelianov <edward.emelianoff@gmail.com>.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <netdb.h>
#include <poll.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/un.h>  // unix socket

#include "sersock.h"
#include "teacmd.h"


enum{
    SENDSTAT_OK,
    SENDSTAT_OUTOFRANGE,
    SENDSTAT_NOECHO,
    SENDSTAT_ERR,
    SENDSTAT_SETTER // not an error

};
static const char *sendstatuses[] = {
    [SENDSTAT_OK] = "OK\n",
    [SENDSTAT_OUTOFRANGE] = "Steps out of range\n",
    [SENDSTAT_NOECHO] = "No echo received\n",
    [SENDSTAT_ERR] = "Error in write()\n",
    [SENDSTAT_SETTER] = "OK\n"
};

static char *getserdata(TTY_descr *D, int *len);

/**
 * @brief sendcmd - validate & send command to device
 * @param cmd - command (string with or without "\n" on the end)
 * @param d - serial device
 * @return SENDSTAT_OK if OK or error
 */
static int sendcmd(char *cmd, ssize_t len, TTY_descr *d){
    int v = validate_cmd(cmd, len);
    int ret = SENDSTAT_OK;
    if(v < 0) return SENDSTAT_OUTOFRANGE;
    if(v > 0) ret = SENDSTAT_SETTER; // is setter
    if(len != write(d->comfd, cmd, len)){
        WARN("write()");
        LOGWARN("write()");
        return SENDSTAT_ERR;
    }
    int l;
    usleep(500);
    char *ans = getserdata(d, &l);
    if(ans) DBG("ans: '%s'", ans); else DBG("no ans");
    if(ans && 0 == strcmp(ans, cmd)) return ret;
    return SENDSTAT_NOECHO;
}

// work with single client, return -1 if disconnected or status of `sendcmd`
static int handle_socket(int sock, TTY_descr *d){
    char buff[BUFLEN];
    ssize_t rd = read(sock, buff, BUFLEN-1);;
    DBG("Got %zd bytes", rd);
    if(rd <= 0){ // error or disconnect
        DBG("Nothing to read from fd %d (ret: %zd)", sock, rd);
        return -1;
    }
    // add trailing zero to be on the safe side
    buff[rd] = 0;
    DBG("GOT: %s", buff);
    ssize_t blen = strlen(buff);
    int s = sendcmd(buff, blen, d);
    if(SENDSTAT_OK != s && SENDSTAT_SETTER != s){
        int l = strlen(sendstatuses[s]);
        if(l != send(sock, sendstatuses[s], l, MSG_NOSIGNAL)){
            WARN("send()");
            LOGWARN("send() to fd=%d failed", sock);
        }
    }else{
        if(buff[blen-1] == '\n') buff[blen-1] = 0;
        LOGMSG("CLIENT_%d: %s", sock, buff);
    }
    return s;
}

/**
 * check data from  fd
 * @param fd - file descriptor
 * @return 0 in case of timeout, 1 in case of fd have data, -1 if error
 */
int canberead(int fd){
    fd_set fds;
    struct timeval timeout;
    timeout.tv_sec = 0;
    timeout.tv_usec = 10000; // wait for 10ms max
    FD_ZERO(&fds);
    FD_SET(fd, &fds);
    do{
        int rc = select(fd+1, &fds, NULL, NULL, &timeout);
        if(rc < 0){
            if(errno != EINTR){
                LOGWARN("select()");
                WARN("select()");
                return -1;
            }
            continue;
        }
        break;
    }while(1);
    if(FD_ISSET(fd, &fds)){
        //DBG("FD_ISSET");
        return 1;
    }
    return 0;
}

/**
 * @brief getserdata - read data (ending by '\n') from serial device
 * @param D (i)   - device
 * @param len (o) - amount of butes read (-1 if disconnected)
 * @return pointer to data buffer or NULL if none
 */
static char *getserdata(TTY_descr *D, int *len){
    static char serbuf[BUFLEN], *ptr = serbuf;
    static size_t blen = BUFLEN - 1;
    if(!D || D->comfd < 0) return NULL;
    char *nl = NULL;
    do{
        int s = canberead(D->comfd);
        if(s == 0) break;
        if(s < 0){ // interrupted?
            if(len) *len = 0;
            return NULL;
        }
        ssize_t l = read(D->comfd, ptr, blen);
        if(l < 1){ // disconnected
            DBG("device disconnected");
            if(len) *len = -1;
            return NULL;
        }
        ptr[l] = 0;
        //DBG("GOT %zd bytes: '%s'", l, ptr);
        nl = strchr(ptr, '\n');
        ptr += l;
        blen -= l;
        if(nl){
            //DBG("Got newline");
            break;
        }
    }while(blen);
    // recalculate newline from the beginning (what if old data stays there?)
    nl = strchr(serbuf, '\n');
    if(blen && !nl){
        if(len) *len = 0;
        return NULL;
    }
    // in case of overflow send buffer without trailing '\n'
    int L;
    if(nl) L = nl - serbuf + 1; // get line to '\n'
    else L = strlen(serbuf); // get all buffer
    if(len) *len = L;
    memcpy(D->buf, serbuf, L); // copy all + trailing zero
    D->buflen = L;
    D->buf[L] = 0;
    //DBG("Put to buf %d bytes: '%s'", L, D->buf);
    if(nl){
        L = ptr - nl - 1; // symbols after newline
        if(L > 0){ // there's some data after '\n' -> put it into the beginning
            memmove(serbuf, nl+1, L);
            blen = BUFLEN - 1 - L;
            ptr = serbuf + L;
            *ptr = 0;
            //DBG("now serbuf is '%s'", serbuf);
        }else{
            blen = BUFLEN - 1;
            ptr = serbuf;
            *ptr = 0;
        }
    }else{
        blen = BUFLEN - 1;
        ptr = serbuf;
        *ptr = 0;
    }
    return D->buf;
}

static void run_server(int sock, TTY_descr *d, char *hdrfile){
    if(listen(sock, MAXCLIENTS) == -1){
        WARN("listen");
        LOGWARN("listen");
        return;
    }
    int enable = 1;
    if(ioctl(sock, FIONBIO, (void *)&enable) < 0){ // make socket nonblocking
        LOGERR("Can't make socket nonblocking");
        ERRX("ioctl()");
    }
    int nfd = 1; // only one socket @start
    struct pollfd poll_set[MAXCLIENTS+1];
    bzero(poll_set, sizeof(poll_set));
    // ZERO - listening server socket
    poll_set[0].fd = sock;
    poll_set[0].events = POLLIN;
    int need2poll = 1; // one of motors is moving or in error state - check all
    double tpoll = dtime(); // time of last device polling
    while(1){
        poll(poll_set, nfd, 1); // max timeout - 1ms
        if(poll_set[0].revents & POLLIN){ // check main for accept()
            struct sockaddr_in addr;
            socklen_t len = sizeof(addr);
            int client = accept(sock, (struct sockaddr*)&addr, &len);
            DBG("New connection");
            LOGMSG("Connection, fd=%d", client);
            if(nfd == MAXCLIENTS + 1){
                LOGWARN("Max amount of connections, disconnect fd=%d", client);
                WARNX("Limit of connections reached");
                close(client);
            }else{
                memset(&poll_set[nfd], 0, sizeof(struct pollfd));
                poll_set[nfd].fd = client;
                poll_set[nfd].events = POLLIN;
                ++nfd;
            }
        }
        // scan connections
        for(int fdidx = 1; fdidx < nfd; ++fdidx){
            if((poll_set[fdidx].revents & POLLIN) == 0) continue;
            int fd = poll_set[fdidx].fd;
            int h = handle_socket(fd, d);
            if(h < 0){ // socket closed
                DBG("Client fd=%d disconnected", fd);
                LOGMSG("Client fd=%d disconnected", fd);
                close(fd);
                // move last FD to current position
                poll_set[fdidx] = poll_set[nfd - 1];
                --nfd;
            }else if(h == SENDSTAT_SETTER){
                DBG("NEED TO POLL!");
                need2poll = 1; // should check state
                usleep(110000); // wait for buffers put to USB
            }
        }
        int l = -1;
        char *serdata = NULL;
        while((serdata = getserdata(d, &l))){
            if(l < 0){
                LOGERR("Serial device disconnected");
                ERRX("Serial device disconnected");
            }
            for(int i = 1; i < nfd; ++i){
                if(l != send(poll_set[i].fd, serdata, l, MSG_NOSIGNAL)){
                    LOGWARN("send() to fd=%d failed", poll_set[i].fd);
                    WARN("send()");
                }
                DBG("send 2 client %d", poll_set[i].fd);
            }
            // this call should be AFTER data sending as it changes value of `serdata`
            if(parse_incoming_string(serdata, l, hdrfile)) need2poll = 1; // check later if something is moving
        }
        if(need2poll && dtime() - tpoll > 1.){ // check status once per second
            char buff[BUFLEN];
            for(int i = 0; i < 3; ++i){ // don't need to validate data here
                snprintf(buff, BUFLEN, "%s%d\n", TEACMD_POSITION, i);
                ssize_t blen = strlen(buff);
                if(blen != write(d->comfd, buff, strlen(buff))) WARN("write()");
                DBG("send '%s'", buff);
                serdata = getserdata(d, &l); // clear echo
                if(serdata){
                    DBG("ans: %s", serdata);
                    //parse_incoming_string(serdata, l, hdrfile);
                }
                snprintf(buff, BUFLEN, "%s%d\n", TEACMD_STATUS, i);
                blen = strlen(buff);
                if(blen != write(d->comfd, buff, strlen(buff))) WARN("write()");
                DBG("send %s", buff);
                serdata = getserdata(d, &l); // clear echo
                if(serdata){
                    DBG("ans: %s", serdata);
                    //parse_incoming_string(serdata, l, hdrfile);
                }
            }
            // now clear incoming buffer & process answers (don't spam client)
            /*
            DBG("clear buff, time=0");
            tpoll = dtime();
            while(dtime() - tpoll < 1. && !(serdata = getserdata(d, &l)));
            do{
                need2poll = parse_incoming_string(serdata, l, hdrfile);
                usleep(20000);
            }while((serdata = getserdata(d, &l)));
            DBG("done, time=%g, need2poll=%d", dtime()-tpoll, need2poll);
            */
            need2poll = 0;
            tpoll = dtime();
        }
    }
}

// read console char - for client
static int rc(){
    int rb;
    struct timeval tv;
    int retval;
    fd_set rfds;
    FD_ZERO(&rfds);
    FD_SET(STDIN_FILENO, &rfds);
    tv.tv_sec = 0; tv.tv_usec = 100;
    retval = select(1, &rfds, NULL, NULL, &tv);
    if(!retval) rb = 0;
    else {
        if(FD_ISSET(STDIN_FILENO, &rfds)) rb = getchar();
        else rb = 0;
    }
    return rb;
}

/**
 * @brief mygetline - silently and non-blocking getline
 * @return zero-terminated string with '\n' at end (or without in case of overflow)
 */
static char *mygetline(){
    static char buf[BUFLEN+1];
    static int i = 0;
    while(i < BUFLEN){
        char rd = rc();
        if(!rd) return NULL;
        if(rd == 0x7f && i){ // backspace
            buf[--i] = 0;
            printf("\b \b");
        }else{
            buf[i++] = rd;
            printf("%c", rd);
        }
        fflush(stdout);
        if(rd == '\n') break;
    }
    buf[i] = 0;
    i = 0;
    return buf;
}

static void terminal_client(int sock){
    setup_con(); // convert console mode into non-canon
    int Bufsiz = BUFLEN;
    char *recvBuff = MALLOC(char, Bufsiz);
    while(1){
        char *msg = mygetline();
        if(msg){
            ssize_t L = strlen(msg);
            if(send(sock, msg, L, 0) != L){
                WARN("send");
            }else{
                if(msg[L-1] == '\n') msg[L-1] = 0;
                LOGMSG("TERMINAL: %s", msg);
            }
        }
        if(1 != canberead(sock)) continue;
        int n = read(sock, recvBuff, Bufsiz-1);
        if(n == 0){
            WARNX("Server disconnected");
            signals(0);
        }
        recvBuff[n] = 0;
        printf("%s", recvBuff);
        if(recvBuff[n-1] == '\n') recvBuff[n-1] = 0;
        LOGMSG("SERIAL: %s", recvBuff);
    }
}

/**
 * @brief openserialdev - open connection to serial device
 * @param path (i) - path to device
 * @param speed    - connection speed
 * @return pointer to device structure if all OK
 */
static TTY_descr *openserialdev(char *path, int speed){
    TTY_descr *d = new_tty(path, speed, BUFLEN);
    DBG("Device created");
    if(!d || !(tty_open(d, 1))){
        WARN("Can't open device %s", path);
        LOGWARN("Can't open device %s", path);
        return NULL;
    }
    DBG("device opened");
    return d;
}

int start_socket(int server, glob_pars *P, TTY_descr **dev){
    if(!P || !dev){
        WARNX("Need parameters & device");
        return 1;
    }
    char *hdrfile = NULL;
    int realfile = 0;
    char apath[128], *sockpath = P->path;
    DBG("path: %s", sockpath);
    if(*sockpath == 0){
        DBG("convert name");
        apath[0] = 0;
        strncpy(apath+1, sockpath+1, 126);
    }else if(strncmp("\\0", sockpath, 2) == 0){
        DBG("convert name");
        apath[0] = 0;
        strncpy(apath+1, sockpath+2, 126);
    }else{
        strcpy(apath, sockpath);
        realfile = 1;
    }
    if(server){
        if(!dev) return 1;
        if(!(*dev = openserialdev(P->devpath, P->speed))){
            LOGERR("Can't open serial device %s", P->devpath);
            ERR("Can't open serial device %s", P->devpath);
        }
        if(realfile) unlink(apath); // remove old socket
        if(P->fitshdr){ // open file with header
            FILE *hdrf = fopen(P->fitshdr, "w");
            if(!hdrf){
                WARNX("Can't create file %s", P->fitshdr);
                LOGERR("Can't create file %s", P->fitshdr);
            }else{
                fclose(hdrf);
                hdrfile = strdup(P->fitshdr);
            }
        }
    }
    int sock = -1;
    int reuseaddr = 1;
    struct sockaddr_un saddr = {0};
    saddr.sun_family = AF_UNIX;
    memcpy(saddr.sun_path, apath, 106); // if sun_path[0] == 0 we don't create a file
    if((sock = socket(AF_UNIX, SOCK_SEQPACKET, 0)) < 0){ // or SOCK_STREAM?
        LOGERR("socket()");
        ERR("socket()");
    }
    if(server){
        if(setsockopt(sock, SOL_SOCKET, SO_REUSEADDR, &reuseaddr, sizeof(int)) == -1){
            LOGWARN("setsockopt");
            WARN("setsockopt");
        }
        if(bind(sock, &saddr, sizeof(saddr)) == -1){
            close(sock);
            LOGERR("bind");
            ERR("bind");
        }
    }else{
        if(connect(sock, &saddr, sizeof(saddr)) == -1){
            LOGERR("connect()");
            ERR("connect()");
        }
    }
    int ret = 0;
    if(server) run_server(sock, *dev, hdrfile);
    else if(P->terminal) terminal_client(sock);
    else ret = client_proc(sock, P);
    close(sock);
    return ret;
}