/*
 * Copyright (c) 2016 Julien Palard.
 * 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 AUTHOR ``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 AUTHOR 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.
 */

#define _POSIX_C_SOURCE 200809L
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <getopt.h>
#include <sys/mman.h>

#include "is_utf8.h"

#define VERSION "1.2"
#define MIN(X, Y) (((X) < (Y)) ? (X) : (Y))


static int show_str(const char *str, unsigned int max_length)
{
    int printed = 0;

    while (max_length-- > 0)
    {
        printed += printf("%c", (*str >= ' ' && *str <= '~') ? (unsigned char)*str: '.');
        str += 1;
    }
    return printed;
}

static int show_hex_str(const char *str, unsigned int max_length)
{
    int printed = 0;

    while (max_length-- > 0)
        printed += printf("%.2X ", (unsigned char)*str++);
    return printed;
}

/*show_context(, 5, 279, 2, chars_before_error: 8, chars_after_error: -274)
**/
static void show_context(char *str, int str_length, int err_pos_in_str, int faulty_bytes)
{
    int chars_before_error = MIN(err_pos_in_str, 8);
    int chars_after_error = MIN(str_length - err_pos_in_str, 8);
    int printed = 0;

    printed = show_hex_str(str + err_pos_in_str - chars_before_error, chars_before_error + chars_after_error); /* Print up to error. */
    printf("%*s | ", 3 * 16 - printed, "");
    show_str(str + err_pos_in_str - chars_before_error, chars_before_error + chars_after_error); /* Print up to error. */
    printf("\n");
    printed = printf("%*s", (3 * chars_before_error), "");
    printed += printf("%.*s", faulty_bytes * 2 + faulty_bytes - 1, "^^^^^^^^^^^^^^^^");
    printf("%*s | ", 3 * 16 - printed, "");
    printf("%*s", (chars_before_error), "");
    printf("%.*s", faulty_bytes, "^^^^");
    printf("\n\n");
}

static void print_utf8_error(
    const char* file_path,
    int error_line, int error_column, int byte_no,
    char *str, int str_length, int err_pos_in_str,
    const char *message, int faulty_bytes,
    int quiet, int verbose,
    int list_only, int invert)
{
    if (quiet)
        return;
    if (message && !invert)
    {
        if (list_only)
            printf("%s\n", file_path);
        else
            printf("%s: line %d, char %d, byte %d: %s\n",
                   file_path, error_line, error_column, byte_no,
                   message);
        if (verbose && !list_only)
        {
            show_context(str, str_length, err_pos_in_str, faulty_bytes);
        }
    }
    if (!message && invert)
    {
        printf("%s\n", file_path);
    }
}

#define handle_error(msg, target)                                   \
    do {retval = EXIT_FAILURE; perror(msg); goto target;} while (0)

static int is_utf8_readline(FILE *stream, const char *file_path,
                            int quiet, int verbose, int list_only, int invert)
{
    char *string = NULL;
    size_t size = 0;
    ssize_t str_length;
    char *message = NULL;
    int lineno = 1;
    int pos = 0;
    int offset = 0;
    int faulty_bytes = 0;

    while ((str_length = getline(&string, &size, stream)) != -1)
    {
        pos = is_utf8((unsigned char*)string, str_length, &message, &faulty_bytes);
        if (message != NULL)
        {
            offset += pos;
            print_utf8_error(file_path, lineno, pos, offset,
                             string, str_length, pos, message, faulty_bytes,
                             quiet, verbose, list_only, invert);
            break;
        }
        offset += str_length;
        lineno += 1;
    }
    if (string != NULL)
        free(string);
    return message == NULL ? EXIT_SUCCESS : EXIT_FAILURE;
}

static void count_lines(const char *string, int length, int up_to, int *line, int *column)
{
    int pos = 0;
    int line_start_at = 0;

    *line = 1;
    while (pos < length && pos < up_to)
    {
        if (string[pos] == '\n')
        {
            line_start_at = pos + 1;
            *line += 1;
        }
        pos += 1;
    }
    *column = 1 + up_to - line_start_at;
}

static int is_utf8_mmap(const char *file_path, int quiet, int verbose,
                        int list_only, int invert)
{
    char *addr;
    struct stat sb;
    int fd;
    int pos = 0;
    char *message;
    int retval = EXIT_SUCCESS;
    int error_column = 1;
    int error_line = 0;
    int faulty_bytes = 0;

    fd = open(file_path, O_RDONLY);
    if (fd == -1)
        handle_error("open", err_open);
    if (fstat(fd, &sb) == -1)           /* To obtain file size */
        handle_error("fstat", err_fstat);
    addr = mmap(NULL, sb.st_size, PROT_READ, MAP_PRIVATE, fd, 0);
    if (addr == MAP_FAILED)
    {
        /* Can't nmap, maybe a pipe or whatever, let's try readline. */
        close(fd);
        return is_utf8_readline(fopen(file_path, "r"), file_path,
                                quiet, verbose, list_only, invert);
    }
    pos = is_utf8((unsigned char*)addr, sb.st_size, &message, &faulty_bytes);
    if (message != NULL)
        count_lines(addr, sb.st_size, pos, &error_line, &error_column);
    print_utf8_error(file_path, error_line, error_column, pos,
                     addr, sb.st_size, pos, message, faulty_bytes,
                     quiet, verbose, list_only, invert);
    if (message != NULL)
        retval = EXIT_FAILURE;
    munmap(addr, sb.st_size);
err_fstat:
    close(fd);
err_open:
    return retval;
}

static void usage(const char *program_name) {
    printf("Usage: %s [OPTION]... [FILE]...\n"
           "Check whether input files are valid UTF-8.\n"
           "\n"
           "  -h, --help       display this help text and exit\n"
           "  -q, --quiet      suppress all normal output\n"
           "  -l, --list       print only names of FILEs containing invalid UTF-8\n"
           "  -i, --invert     list valid UTF-8 files instead of invalid ones\n"
           "  -v, --verbose    print detailed error (multiple lines)\n"
           "\n"
           "This is version %s.\n",
           program_name, VERSION);
}

int main(int ac, char **av)
{
    int quiet = 0;
    int exit_value = EXIT_SUCCESS;
    int i;
    int list_only = 0;
    int invert = 0;
    int verbose = 0;
    int opt;
    struct option options[] = {
        { "help", no_argument, NULL, 'h' },
        { "quiet", no_argument, &quiet, 1 },
        { "list-only", no_argument, &list_only, 1 },
        { "invert", no_argument, &invert, 1 },
        { "verbose", no_argument, &verbose, 1 },
        { 0, 0, 0, 0 }
    };

    while ((opt = getopt_long(ac, av, "hqliv", options, NULL)) != -1) {
        switch (opt) {
            case 0:
                break;

            case 'h':
                usage(av[0]);
                return EXIT_SUCCESS;

            case 'q':
                quiet = 1;
                break;

            case 'l':
                list_only = 1;
                break;

            case 'i':
                invert = 1;
                break;

            case 'v':
                verbose = 1;
                break;

            case '?':
                usage(av[0]);
                return EXIT_FAILURE;

            default:
                usage(av[0]);
                return EXIT_FAILURE;
        }
    }
    if (optind == ac)
    {
        return is_utf8_readline(stdin, "(standard input)", quiet, verbose,
                                list_only, invert);
    }
    else
    {
        for (i = optind; i < ac; ++i)
        {
            if (is_utf8_mmap(av[i], quiet, verbose,
                             list_only, invert) == EXIT_FAILURE)
                exit_value = EXIT_FAILURE;
        }
        return exit_value;
    }
}