/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing,
 * software distributed under the License is distributed on an
 * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 */

#include "config.h"

#include "conf-file.h"
#include "conf-parse.h"

#include <guacamole/client.h>

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

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

/**
 * Updates the configuration with the given parameter/value pair, flagging
 * errors as necessary.
 */
static int guacd_conf_callback(const char* section, const char* param, const char* value, void* data) {

    guacd_config* config = (guacd_config*) data;

    /* Network server options */
    if (strcmp(section, "server") == 0) {

        /* Bind host */
        if (strcmp(param, "bind_host") == 0) {
            free(config->bind_host);
            config->bind_host = strdup(value);
            return 0;
        }

        /* Bind port */
        else if (strcmp(param, "bind_port") == 0) {
            free(config->bind_port);
            config->bind_port = strdup(value);
            return 0;
        }

    }

    /* Options related to daemon startup */
    else if (strcmp(section, "daemon") == 0) {

        /* PID file */
        if (strcmp(param, "pid_file") == 0) {
            free(config->pidfile);
            config->pidfile = strdup(value);
            return 0;
        }

        /* Max log level */
        else if (strcmp(param, "log_level") == 0) {

            int level = guacd_parse_log_level(value);

            /* Invalid log level */
            if (level < 0) {
                guacd_conf_parse_error = "Invalid log level. Valid levels are: \"trace\", \"debug\", \"info\", \"warning\", and \"error\".";
                return 1;
            }

            /* Valid log level */
            config->max_log_level = level;
            return 0;

        }

    }

    /* SSL-specific options */
    else if (strcmp(section, "ssl") == 0) {
#ifdef ENABLE_SSL
        /* SSL certificate */
        if (strcmp(param, "server_certificate") == 0) {
            free(config->cert_file);
            config->cert_file = strdup(value);
            return 0;
        }

        /* SSL key */
        else if (strcmp(param, "server_key") == 0) {
            free(config->key_file);
            config->key_file = strdup(value);
            return 0;
        }
#else
        guacd_conf_parse_error = "SSL support not compiled in";
        return 1;
#endif

    }

    /* If still unhandled, the parameter/section is invalid */
    guacd_conf_parse_error = "Invalid parameter or section name";
    return 1;

}

int guacd_conf_parse_file(guacd_config* conf, int fd) {

    int chars_read;

    char buffer[8192];
    int length = 0;

    int line = 1;
    char* line_start = buffer;
    int parsed = 0;

    /* Attempt to fill remaining space in buffer */
    while ((chars_read = read(fd, buffer + length, sizeof(buffer) -  length)) > 0) {

        length += chars_read;

        line_start = buffer;

        /* Attempt to parse entire buffer */
        while ((parsed = guacd_parse_conf(guacd_conf_callback, line_start, length, conf)) > 0) {
            line_start += parsed;
            length -= parsed;
            line++;
        }

        /* Shift contents to front */
        memmove(buffer, line_start, length);

    }

    /* Handle parse errors */
    if (parsed < 0) {
        int column = guacd_conf_parse_error_location - line_start + 1;
        fprintf(stderr, "Parse error at line %i, column %i: %s.\n",
                line, column, guacd_conf_parse_error);
        return 1;
    }

    /* Check for error conditions */
    if (chars_read < 0) {
        fprintf(stderr, "Error reading configuration: %s\n", strerror(errno));
        return 1;
    }

    /* Read successfully */
    return 0;

}

guacd_config* guacd_conf_load() {

    guacd_config* conf = malloc(sizeof(guacd_config));
    if (conf == NULL)
        return NULL;

    /* Load defaults */
    conf->bind_host = NULL;
    conf->bind_port = strdup("4822");
    conf->pidfile = NULL;
    conf->foreground = 0;
    conf->max_log_level = GUAC_LOG_INFO;

#ifdef ENABLE_SSL
    conf->cert_file = NULL;
    conf->key_file = NULL;
#endif

    /* Read configuration from file */
    int fd = open(GUACD_CONF_FILE, O_RDONLY);
    if (fd > 0) {

        int retval = guacd_conf_parse_file(conf, fd);
        close(fd);

        if (retval != 0) {
            fprintf(stderr, "Unable to parse \"" GUACD_CONF_FILE "\".\n");
            return NULL;
        }

    }

    /* Notify of errors preventing reading */
    else if (errno != ENOENT) {
        fprintf(stderr, "Unable to open \"" GUACD_CONF_FILE "\": %s\n", strerror(errno));
        return NULL;
    }

    return conf;

}