/*
 * Copyright (c) 2020-2022, the SerenityOS developers.
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#include <AK/Assertions.h>
#include <AK/NumberFormat.h>
#include <AK/NumericLimits.h>
#include <AK/Time.h>

namespace AK {

// FIXME: Remove this hackery once printf() supports floats.
static String number_string_with_one_decimal(u64 number, u64 unit, StringView suffix, UseThousandsSeparator use_thousands_separator)
{
    constexpr auto max_unit_size = NumericLimits<u64>::max() / 10;
    VERIFY(unit < max_unit_size);

    auto integer_part = number / unit;
    auto decimal_part = (number % unit) * 10 / unit;
    if (use_thousands_separator == UseThousandsSeparator::Yes)
        return MUST(String::formatted("{:'d}.{} {}", integer_part, decimal_part, suffix));

    return MUST(String::formatted("{}.{} {}", integer_part, decimal_part, suffix));
}

String human_readable_quantity(u64 quantity, HumanReadableBasedOn based_on, StringView unit, UseThousandsSeparator use_thousands_separator)
{
    u64 size_of_unit = based_on == HumanReadableBasedOn::Base2 ? 1024 : 1000;
    constexpr auto unit_prefixes = AK::Array { "", "K", "M", "G", "T", "P", "E" };
    auto full_unit_suffix = [&](int index) {
        auto binary_infix = (based_on == HumanReadableBasedOn::Base2 && index != 0) ? "i"sv : ""sv;
        return MUST(String::formatted("{}{}{}",
            unit_prefixes[index], binary_infix, unit));
    };

    auto size_of_current_unit = size_of_unit;

    if (quantity < size_of_unit)
        return MUST(String::formatted("{} {}", quantity, full_unit_suffix(0)));

    for (size_t i = 1; i < unit_prefixes.size() - 1; i++) {
        auto suffix = full_unit_suffix(i);
        if (quantity < size_of_unit * size_of_current_unit) {
            return number_string_with_one_decimal(quantity, size_of_current_unit, suffix, use_thousands_separator);
        }

        size_of_current_unit *= size_of_unit;
    }

    return number_string_with_one_decimal(quantity,
        size_of_current_unit, full_unit_suffix(unit_prefixes.size() - 1), use_thousands_separator);
}

String human_readable_size(u64 size, HumanReadableBasedOn based_on, UseThousandsSeparator use_thousands_separator)
{
    return human_readable_quantity(size, based_on, "B"sv, use_thousands_separator);
}

String human_readable_size_long(u64 size, UseThousandsSeparator use_thousands_separator)
{
    if (size < 1 * KiB) {
        if (use_thousands_separator == UseThousandsSeparator::Yes)
            return MUST(String::formatted("{:'d} bytes", size));

        return MUST(String::formatted("{} bytes", size));
    }

    auto human_readable_size_string = human_readable_size(size, HumanReadableBasedOn::Base2, use_thousands_separator);
    if (use_thousands_separator == UseThousandsSeparator::Yes)
        return MUST(String::formatted("{} ({:'d} bytes)", human_readable_size_string, size));

    return MUST(String::formatted("{} ({} bytes)", human_readable_size_string, size));
}

String human_readable_time(Duration duration)
{
    auto milliseconds = duration.to_milliseconds();

    auto days = milliseconds / 86400000;
    milliseconds = milliseconds % 86400000;

    auto hours = milliseconds / 3600000;
    milliseconds = milliseconds % 3600000;

    auto minutes = milliseconds / 60000;
    milliseconds = milliseconds % 60000;

    auto seconds = static_cast<double>(milliseconds) / 1000.0;

    StringBuilder builder;

    if (days > 0)
        builder.appendff("{} day{} ", days, days == 1 ? "" : "s");

    if (hours > 0)
        builder.appendff("{} hour{} ", hours, hours == 1 ? "" : "s");

    if (minutes > 0)
        builder.appendff("{} minute{} ", minutes, minutes == 1 ? "" : "s");

    builder.appendff("{:.3} second{}", seconds, seconds == 1.0 ? "" : "s");

    return MUST(builder.to_string());
}

String human_readable_short_time(Duration duration)
{
    auto nanoseconds = duration.to_nanoseconds();
    if (nanoseconds < 1'000)
        return MUST(String::formatted("{}ns", nanoseconds));
    if (nanoseconds < 1'000'000)
        return MUST(String::formatted("{:.3}µs", static_cast<double>(nanoseconds) / 1'000.0));
    if (nanoseconds < 1'000'000'000)
        return MUST(String::formatted("{:.3}ms", static_cast<double>(nanoseconds) / 1'000'000.0));
    if (nanoseconds < 60'000'000'000)
        return MUST(String::formatted("{:.3}s", static_cast<double>(nanoseconds) / 1'000'000'000.0));

    auto days = nanoseconds / 86'400'000'000'000;
    nanoseconds = nanoseconds % 86'400'000'000'000;
    auto hours = nanoseconds / 3'600'000'000'000;
    nanoseconds = nanoseconds % 3'600'000'000'000;
    auto minutes = nanoseconds / 60'000'000'000;
    nanoseconds = nanoseconds % 60'000'000'000;
    auto seconds = static_cast<double>(nanoseconds) / 1'000'000'000.0;

    StringBuilder builder;
    if (days > 0)
        builder.appendff("{}d", days);

    if (hours > 0) {
        if (!builder.is_empty())
            builder.append(' ');
        builder.appendff("{}h", hours);
    }

    if (minutes > 0) {
        if (!builder.is_empty())
            builder.append(' ');
        builder.appendff("{}m", minutes);
    }

    if (seconds > 0.0) {
        if (!builder.is_empty())
            builder.append(' ');
        builder.appendff("{:.3}s", seconds);
    }

    return MUST(builder.to_string());
}

String human_readable_digital_time(i64 time_in_seconds)
{
    auto hours = time_in_seconds / 3600;
    time_in_seconds = time_in_seconds % 3600;

    auto minutes = time_in_seconds / 60;
    time_in_seconds = time_in_seconds % 60;

    StringBuilder builder;

    if (hours > 0)
        builder.appendff("{:02}:", hours);
    builder.appendff("{:02}:", minutes);
    builder.appendff("{:02}", time_in_seconds);

    return MUST(builder.to_string());
}

}
