/*
 * Copyright (c) 2018-2020, Andreas Kling <kling@serenityos.org>
 * 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 <AK/String.h>
#include <AK/JsonArray.h>
#include <AK/JsonObject.h>
#include <AK/Vector.h>
#include <LibCore/ArgsParser.h>
#include <LibCore/File.h>
#include <cstring>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

static bool flag_human_readable = false;

struct FileSystem {
    String fs;
    size_t total_block_count { 0 };
    size_t free_block_count { 0 };
    size_t total_inode_count { 0 };
    size_t free_inode_count { 0 };
    size_t block_size { 0 };
    String mount_point;
};

// FIXME: Remove this hackery once printf() supports floats.
// FIXME: Also, we should probably round the sizes in df -h output.
static String number_string_with_one_decimal(float number, const char* suffix)
{
    float decimals = number - (int)number;
    return String::format("%d.%d%s", (int)number, (int)(decimals * 10), suffix);
}

static String human_readable_size(size_t size)
{
    if (size < 1 * KB)
        return String::number(size);
    if (size < 1 * MB)
        return number_string_with_one_decimal((float)size / (float)KB, "K");
    if (size < 1 * GB)
        return number_string_with_one_decimal((float)size / (float)MB, "M");
    return number_string_with_one_decimal((float)size / (float)GB, "G");
}

int main(int argc, char** argv)
{
    Core::ArgsParser args_parser;
    args_parser.add_option(flag_human_readable, "Print human-readable sizes", "human-readable", 'h');
    args_parser.parse(argc, argv);

    auto file = Core::File::construct("/proc/df");
    if (!file->open(Core::IODevice::ReadOnly)) {
        fprintf(stderr, "Failed to open /proc/df: %s\n", file->error_string());
        return 1;
    }

    if (flag_human_readable) {
        printf("Filesystem      Size        Used    Available   Mount point\n");
    } else {
        printf("Filesystem    Blocks        Used    Available   Mount point\n");
    }

    auto file_contents = file->read_all();
    auto json = JsonValue::from_string(file_contents).as_array();
    json.for_each([](auto& value) {
        auto fs_object = value.as_object();
        auto fs = fs_object.get("class_name").to_string();
        auto total_block_count = fs_object.get("total_block_count").to_u32();
        auto free_block_count = fs_object.get("free_block_count").to_u32();
        auto total_inode_count = fs_object.get("total_inode_count").to_u32();
        auto free_inode_count = fs_object.get("free_inode_count").to_u32();
        auto block_size = fs_object.get("block_size").to_u32();
        auto mount_point = fs_object.get("mount_point").to_string();

        (void)total_inode_count;
        (void)free_inode_count;

        printf("%-10s", fs.characters());

        if (flag_human_readable) {
            printf("%10s  ", human_readable_size(total_block_count * block_size).characters());
            printf("%10s   ", human_readable_size((total_block_count - free_block_count) * block_size).characters());
            printf("%10s   ", human_readable_size(free_block_count * block_size).characters());
        } else {
            printf("%10u  ", total_block_count);
            printf("%10u   ", total_block_count - free_block_count);
            printf("%10u   ", free_block_count);
        }

        printf("%s", mount_point.characters());
        printf("\n");
    });

    return 0;
}