/*
 *  Guacamole - Clientless Remote Desktop
 *  Copyright (C) 2010  Michael Jumper
 *
 *  This program is free software: you can redistribute it and/or modify
 *  it under the terms of the GNU Affero 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 Affero General Public License for more details.
 *
 *  You should have received a copy of the GNU Affero General Public License
 *  along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

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

#include <syslog.h>

#include <dlfcn.h>

#include "guacio.h"
#include "protocol.h"
#include "client.h"


png_byte** guac_alloc_png_buffer(int w, int h, int bpp) {

    png_byte** png_buffer;
    png_byte* row;
    int y;

    /* Allocate rows for PNG */
    png_buffer = (png_byte**) malloc(h * sizeof(png_byte*));
    for (y=0; y<h; y++) {
        row = (png_byte*) malloc(sizeof(png_byte) * bpp * w);
        png_buffer[y] = row;
    }

    return png_buffer;
}

void guac_free_png_buffer(png_byte** png_buffer, int h) {

    int y;

    /* Free PNG data */
    for (y = 0; y<h; y++)
        free(png_buffer[y]);
    free(png_buffer);

}

guac_client* __guac_alloc_client(GUACIO* io) {

    /* Allocate new client (not handoff) */
    guac_client* client = malloc(sizeof(guac_client));
    memset(client, 0, sizeof(guac_client));

    /* Init new client */
    client->io = io;

    return client;
}


guac_client* guac_get_client(int client_fd) {

    guac_client* client;
    GUACIO* io = guac_open(client_fd);

    /* Pluggable client */
    char protocol_lib[256] = "libguac_client_";
    
    union {
        guac_client_init_handler* client_init;
        void* obj;
    } alias;

    char* error;

    /* Client args description */
    const char** client_args;

    /* Client arguments */
    int argc;
    char** argv;

    /* Instruction */
    guac_instruction instruction;

    /* Wait for select instruction */
    for (;;) {

        int result = guac_read_instruction(io, &instruction);
        if (result < 0) {
            syslog(LOG_ERR, "Error reading instruction while waiting for select");
            guac_close(io);
            return NULL;            
        }

        /* Select instruction read */
        if (result > 0) {

            if (strcmp(instruction.opcode, "select") == 0) {

                /* Get protocol from message */
                char* protocol = instruction.argv[0];

                strcat(protocol_lib, protocol);
                strcat(protocol_lib, ".so");

                /* Create new client */
                client = __guac_alloc_client(io);

                /* Load client plugin */
                client->client_plugin_handle = dlopen(protocol_lib, RTLD_LAZY);
                if (!(client->client_plugin_handle)) {
                    syslog(LOG_ERR, "Could not open client plugin for protocol \"%s\": %s\n", protocol, dlerror());
                    guac_send_error(io, "Could not load server-side client plugin.");
                    guac_flush(io);
                    guac_close(io);
                    guac_free_instruction_data(&instruction);
                    return NULL;
                }

                dlerror(); /* Clear errors */

                /* Get init function */
                alias.obj = dlsym(client->client_plugin_handle, "guac_client_init");

                if ((error = dlerror()) != NULL) {
                    syslog(LOG_ERR, "Could not get guac_client_init in plugin: %s\n", error);
                    guac_send_error(io, "Invalid server-side client plugin.");
                    guac_flush(io);
                    guac_close(io);
                    guac_free_instruction_data(&instruction);
                    return NULL;
                }

                /* Get usage strig */
                client_args = (const char**) dlsym(client->client_plugin_handle, "GUAC_CLIENT_ARGS");

                if ((error = dlerror()) != NULL) {
                    syslog(LOG_ERR, "Could not get GUAC_CLIENT_ in plugin: %s\n", error);
                    guac_send_error(io, "Invalid server-side client plugin.");
                    guac_flush(io);
                    guac_close(io);
                    guac_free_instruction_data(&instruction);
                    return NULL;
                }

                /* Send args */
                guac_send_args(io, client_args);
                guac_flush(io);

                guac_free_instruction_data(&instruction);
                break;

            } /* end if select */

            guac_free_instruction_data(&instruction);
        }

    }

    /* Wait for connect instruction */
    for (;;) {

        int result = guac_read_instruction(io, &instruction);
        if (result < 0) {
            syslog(LOG_ERR, "Error reading instruction while waiting for connect");
            guac_close(io);
            return NULL;            
        }

        /* Connect instruction read */
        if (result > 0) {

            if (strcmp(instruction.opcode, "connect") == 0) {

                /* Initialize client arguments */
                argc = instruction.argc;
                argv = instruction.argv;

                if (alias.client_init(client, argc, argv) != 0) {
                    /* NOTE: On error, proxy client will send appropriate error message */
                    guac_free_instruction_data(&instruction);
                    guac_close(io);
                    return NULL;
                }

                guac_free_instruction_data(&instruction);
                return client;

            } /* end if connect */

            guac_free_instruction_data(&instruction);
        }

    }

}


void guac_free_client(guac_client* client) {

    if (client->free_handler) {
        if (client->free_handler(client))
            syslog(LOG_ERR, "Error calling client free handler");
    }

    guac_close(client->io);

    /* Unload client plugin */
    if (dlclose(client->client_plugin_handle)) {
        syslog(LOG_ERR, "Could not close client plugin while unloading client: %s", dlerror());
    }

    free(client);
}


void guac_start_client(guac_client* client) {

    GUACIO* io = client->io;
    guac_instruction instruction;
    int wait_result;

    /* VNC Client Loop */
    for (;;) {

        /* Handle server messages */
        if (client->handle_messages) {

            int retval = client->handle_messages(client);
            if (retval) {
                syslog(LOG_ERR, "Error handling server messages");
                return;
            }

            guac_flush(io);

        }

        wait_result = guac_instructions_waiting(io);
        if (wait_result > 0) {

            int retval;
            retval = guac_read_instruction(io, &instruction); /* 0 if no instructions finished yet, <0 if error or EOF */

            if (retval > 0) {
           
                do {

                    if (strcmp(instruction.opcode, "ready") == 0) {
                        guac_send_ready(io);
                        guac_flush(io);
                    }

                    else if (strcmp(instruction.opcode, "mouse") == 0) {
                        if (client->mouse_handler)
                            if (
                                    client->mouse_handler(
                                        client,
                                        atoi(instruction.argv[0]), /* x */
                                        atoi(instruction.argv[1]), /* y */
                                        atoi(instruction.argv[2])  /* mask */
                                    )
                               ) {

                                syslog(LOG_ERR, "Error handling mouse instruction");
                                guac_free_instruction_data(&instruction);
                                return;

                            }
                    }

                    else if (strcmp(instruction.opcode, "key") == 0) {
                        if (client->key_handler)
                            if (
                                    client->key_handler(
                                        client,
                                        atoi(instruction.argv[0]), /* keysym */
                                        atoi(instruction.argv[1])  /* pressed */
                                    )
                               ) {

                                syslog(LOG_ERR, "Error handling key instruction");
                                guac_free_instruction_data(&instruction);
                                return;

                            }
                    }

                    else if (strcmp(instruction.opcode, "clipboard") == 0) {
                        if (client->clipboard_handler)
                            if (
                                    client->clipboard_handler(
                                        client,
                                        guac_unescape_string_inplace(instruction.argv[0]) /* data */
                                    )
                               ) {

                                syslog(LOG_ERR, "Error handling clipboard instruction");
                                guac_free_instruction_data(&instruction);
                                return;

                            }
                    }

                    else if (strcmp(instruction.opcode, "disconnect") == 0) {
                        syslog(LOG_INFO, "Client requested disconnect");
                        guac_free_instruction_data(&instruction);
                        return;
                    }

                    guac_free_instruction_data(&instruction);

                } while ((retval = guac_read_instruction(io, &instruction)) > 0);

                if (retval < 0) {
                    syslog(LOG_ERR, "Error reading instruction from stream");
                    return;
                }
            }

            if (retval < 0) {
                syslog(LOG_ERR, "Error or end of stream");
                return; /* EOF or error */
            }

            /* Otherwise, retval == 0 implies unfinished instruction */

        }
        else if (wait_result < 0) {
            syslog(LOG_ERR, "Error waiting for next instruction");
            return;
        }

    }

}