/*
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
 *
 * Copyright 2021 Olaf Wintermann. All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *   1. Redistributions of source code must retain the above copyright
 *      notice, this list of conditions and the following disclaimer.
 *
 *   2. Redistributions in binary form must reproduce the above copyright
 *      notice, this list of conditions and the following disclaimer in the
 *      documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include "srvctrl.h"

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <signal.h>
#include <errno.h>
#include <time.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <sys/un.h>
#include <sys/fcntl.h>
#include <pthread.h>
#include <poll.h>

#include <ucx/utils.h>
#include <libidav/utils.h>

#define TIMEOUT_IDLE -1
#define TIMEOUT_CLIENT 1000
#define CLIENT_UPDATE_INTERVALL 1

static char *socket_path;

static int srvctrl;


int create_control_socket(void) {
    const char *copydir = mzcp_get_copydir();
    
    // create unix domain socket
    char *random_str = util_random_str();
    sstr_t socketp = ucx_sprintf("%s/%.*s", copydir, 8, random_str);
    free(random_str);
    socket_path = socketp.ptr;
    
    struct sockaddr_un addr;
    if(socketp.length > sizeof(addr.sun_path)-1) {
        fprintf(stderr,
                "path '%s' too long for unix domain socket",
                socketp.ptr);
        return 1;
    }
    
    memset(&addr, 0, sizeof(addr));
    addr.sun_family = AF_UNIX;
    memcpy(addr.sun_path, socketp.ptr, socketp.length);
    
    srvctrl = socket(AF_UNIX, SOCK_STREAM, 0);
    if(srvctrl == -1) {
        fprintf(stderr,
                "Cannot create server control socket: %s",
                strerror(errno));
        return 1;
    }
    if(bind(srvctrl, (struct sockaddr*)&addr, sizeof(addr))) {
        fprintf(stderr,
                "srvctrl socket bind failed: %s",
                strerror(errno));
        return 1;
    }
    
    listen(srvctrl, 4);
    
    return 0;
}

const char* mzcp_get_socketpath(void) {
    return socket_path;
}

int mzcp_srvctrl(CPSettings *settings) {
    
    size_t allocfds = 8;
    size_t numfds = 1;
    
    struct pollfd *fds = calloc(allocfds, sizeof(struct pollfd));
    CtrlClient **clients = calloc(allocfds, sizeof(void*));
    
    int timeout = TIMEOUT_IDLE;
    
    fds[0].fd = srvctrl;
    fds[0].events = POLLIN;
    
    int abort = 0;
    
    time_t tbegin = time(NULL);
    
    while(poll(fds, numfds, 1000) >= 0) {
        time_t tend = time(NULL);
        time_t diff = tend - tbegin;
        tbegin = tend;
        
        if((fds[0].revents & POLLIN) == POLLIN) {
            printf("accept\n");
            int fd = accept(srvctrl, NULL, 0);
            if(fd < 0) {
                break;
            }
            
            //int flags = fcntl(fd, F_GETFL, 0);
            //flags = flags & ~O_NONBLOCK;
            //fcntl(fd, F_SETFL, flags);
            
            CtrlClient *client = malloc(sizeof(CtrlClient));
            memset(client, 0, sizeof(CtrlClient));
            client->fd = fd;
            
            printf("add client: %d\n", client->fd);
            
            fds[numfds].fd = client->fd;
            fds[numfds].events = POLLIN;
            fds[numfds].revents = 0;
            clients[numfds] = client;
            numfds++;
        }
        
        // check clients
        int remove = 0;
        for(int i=1;i<numfds;i++) {
            if((fds[i].revents & POLLIN) == POLLIN) {
                CtrlClient *client = clients[i];
                ssize_t r = read(fds[i].fd, client->buf + client->pos, CLIENT_MSG_BUFSIZE - client->pos);
                if(r <= 0) {
                    printf("remove client: %d\n", fds[i].fd);
                    fds[i].events = 0;
                    remove = 1;
                } else {
                    client->pos += r;
                    
                    int msgret = handle_messages(client);
                    if(msgret == 1) {
                        fds[i].events = 0;
                        remove = 1;
                    } else if(msgret == -1) {
                        abort = 1;
                    }
                }
            }
        }
        
        if(remove) {
            int j = 1;
            for(int i=1;i<numfds;i++) {
                if(fds[i].events != 0) {
                    fds[j] = fds[i];
                    clients[j] = clients[j];
                    j++;
                } else {
                    client_free(clients[i]);
                    close(fds[i].fd);
                }
            }
            numfds = j;
        }
        
        if(diff >= CLIENT_UPDATE_INTERVALL) {
            for(int i=1;i<numfds;i++) {
                client_send_status(clients[i]);
            }
        }
        
        if(abort) break;
        
        timeout = numfds > 1 ? TIMEOUT_CLIENT : TIMEOUT_IDLE;
    }
    
    unlink(socket_path);
    
    return 0;
}


void client_free(CtrlClient *client) {
    free(client);
}

int handle_messages(CtrlClient *client) {
    if(client->pos == CLIENT_MSG_BUFSIZE) {
        return 1;
    }
    
    int msgstart = 0;
    for(int i=0;i<client->pos;i++) {
        if(client->buf[i] == '\n') {
            sstr_t msg;
            msg.ptr = &client->buf[msgstart];
            msg.length = i - msgstart;
            msgstart = i+1;
            
            int msgret = handle_client_msg(client, msg);
            if(msgret) return msgret;
        }
    }
    
    if(msgstart < client->pos) {
        // incomplete message
        memmove(client->buf, client->buf + msgstart, client->pos - msgstart);
        client->pos -= msgstart;
    } else {
        client->pos = 0;
    }
    
    return 0;
}

int handle_client_msg(CtrlClient *client, sstr_t msg) {
    printf("msg: %.*s\n", (int)msg.length, msg.ptr);
    
    if(!sstrcmp(msg, S("abort"))) {
        return -1;
    }
    
    return 0;
}

void client_send_status(CtrlClient *client) {
    char *msg = "s 0\n";
    write(client->fd, msg, strlen(msg));
}