/**
 * @file client.c
 * @author Ivaylo Ivanov 11777707
 * @date 03.11.2018
 *
 * @brief Client program module.
 *
 * The client module takes a URL as input, connects to the corresponding server on the corresponding
 * port(`80` by default) and requests the file specified in the URL.
 * The content of that file is written to `stdout`, to a file or to a directory.
 *
 *   SYNOPSIS
 *   client [-p PORT] [ -o FILE | -d DIR ] URL
 *
 *   EXAMPLE
 *   client http://ivayloivanov.eu/en/
 *
 **/

#define _GNU_SOURCE ///< in order for optarg to be defined
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netdb.h>
#include "shared/http.h"

static struct addrinfo* get_host_info(const char *hostname, char *port);

int main(int argc, char *argv[]) {
    check_opts_number(argc);

    char *port = "80";
    char *ofile = NULL;
    char *dir = NULL;
    char *url = NULL;
    int c;

    /// Process the options
    while((c = getopt(argc, argv, "p:o:d:h")) != -1) {
        switch(c) {
            case 'p':
                port = optarg;
                break;
            case 'o':
                ofile = optarg;
                break;
            case 'd':
                dir = optarg;
                break;
            case 'h':
                printf("Command usage:\n");
                print_usage();
                exit(EXIT_SUCCESS);
                break;
            case '?':
                print_usage();
                exit(EXIT_FAILURE);
            default:
                abort();
        }
    }

    /// Check for the case that both output file and directory are set
    if(ofile != NULL && dir != NULL) {
        printf("Either output file or directory is specified. You cannot use both.\n");
        print_usage();
        exit(EXIT_FAILURE);
    }

    /// Check if the required argument is there
    if(argv[optind] == NULL) {
        fprintf(stderr, "Mandatory argument 'url' missing.\n");
        print_usage();
        exit(EXIT_FAILURE);
    } else {
        url = argv[optind];
    }

    const char *full_url = strstr(url, "http://") + 7; //< the full url starts after http://
    const char *path = strstr(full_url, "/");
    const char *hostname = "google.com"; //< TODO: Change this later

    struct addrinfo* res = get_host_info(hostname, port); //< Check if the address is resolvable

    freeaddrinfo(res); //< Free the addrinfo struct
}

static void print_usage(void) {
    printf("client [-p PORT] [ -o FILE | -d DIR ] URL\n");
}

/**
 * @brief Function to check the number of arguments
 * @details Checks the number of arguments supplied to the command line.
 *          If the arguments are less than the required or more than possible, it exits
 * @param argc - Number of arguments obtained from the command line
 * @return none
 *
 **/
static void check_opts_number(int argc) {
    if(argc <= 1) {
        fprintf(stderr, "At least one argument expected.\n");
        print_usage();
        exit(EXIT_FAILURE);
    } else if(argc > 6) {
        fprintf(stderr, "Too many arguments supplied.\n");
        print_usage();
        exit(EXIT_FAILURE);
    }
}

/**
 * @brief Function to check if the address is resolvable by the client
 * @details Checks if the address is resolvable by the client.
 *          If the address is resolvable, it writes the result to res
 *          If the address is not resolvable, it exits with an error
 * @param
 *          hostname - The address to be resolved
 *          port     - The port to try
 * @return res - The result of getaddrinfo()
 *
 **/
static struct addrinfo* get_host_info(const char *hostname, char *port) {
    struct addrinfo hints; //< Configuration for the client
    hints.ai_family = AF_INET; //< Use IPv4
    hints.ai_socktype = SOCK_STREAM; //< Stream socket
    hints.ai_flags = 0; //< Do not use any flags
    hints.ai_protocol = IPPROTO_TCP; //< Use only TCP

    struct addrinfo* res = NULL;

    int err = getaddrinfo(hostname, port, &hints, &res);

    if(err != 0) {
        (void) fprintf(stderr, "ERROR:  %s\n", gai_strerror(err));
        exit(EXIT_FAILURE); //< Exit if there is an error
    }

    if(res == NULL) {
        (void) fprintf(stderr, "ERROR:  Could not resolve address %s\n", hostname);
        exit(EXIT_FAILURE); //< Exit if the address is not resolved
    }

    return res;
}