/*
 * Copyright (c) 2018-2020, Andreas Kling <andreas@ladybird.org>
 *
 * SPDX-License-Identifier: BSD-2-Clause
 */

#pragma once

#include <AK/ByteString.h>
#include <AK/StringView.h>
#include <LibIPC/Forward.h>
#include <time.h>

namespace Core {

// Represents a time in local time.
class DateTime {
public:
    time_t timestamp() const { return m_timestamp; }

    unsigned year() const { return m_year; }
    unsigned month() const { return m_month; }
    unsigned day() const { return m_day; }

    unsigned hour() const { return m_hour; }
    unsigned minute() const { return m_minute; }
    unsigned second() const { return m_second; }
    unsigned weekday() const;
    unsigned days_in_month() const;
    unsigned day_of_year() const;
    bool is_leap_year() const;

    void set_time(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
    void set_time_only(int hour, int minute, Optional<int> second = {});
    void set_date(Core::DateTime const& other);

    enum class LocalTime {
        Yes,
        No,
    };

    // %a:      require short day name
    // %A:      require long day name
    // %h/b:    require short month name
    // %B:      require long month name
    // %C:      require short year number (hundreds) (ex: 19 -> 1900)
    // %d:      require day number
    // %D:      require month number/day number/short year number (ex: 12/31/24)
    // %e:      require day number
    // %H:      require hour (24h format)
    // %I:      require hour (12h format)
    // %j:      require defining date with day number ? (not sure)
    // %m:      require set to month entred - 1
    // %M:      require minutes
    // %n:      require newline
    // %t:      require tab
    // %r/p:    require AM | PM
    // %R:      require hours:minutes (ex: 13:57)
    // %S:      require seconds
    // %T:      require hours:minutes:seconds (ex: 13:57:34)
    // %w:      require week day number
    // %y:      require 2 digits year (69 < year < 99: in the 1900 else in 2000)
    // %Y:      require full year
    // %z:      require timezone hours:minutes or single number to represent hour and minutes
    // %x:      require single number to represent hour and minutes
    // %X:      require sub second precision
    // %Z:      require timezone name
    // %+:      ignore until next '%'
    // %%:      require character '%'
    ErrorOr<String> to_string(StringView format = "%Y-%m-%d %H:%M:%S"sv, LocalTime = LocalTime::Yes) const;
    ByteString to_byte_string(StringView format = "%Y-%m-%d %H:%M:%S"sv, LocalTime = LocalTime::Yes) const;

    static DateTime create(int year, int month = 1, int day = 1, int hour = 0, int minute = 0, int second = 0);
    static DateTime now();
    static DateTime from_timestamp(time_t);
    static Optional<DateTime> parse(StringView format, StringView string);

    bool operator<(DateTime const& other) const { return m_timestamp < other.m_timestamp; }
    bool operator>(DateTime const& other) const { return m_timestamp > other.m_timestamp; }
    bool operator<=(DateTime const& other) const { return m_timestamp <= other.m_timestamp; }
    bool operator>=(DateTime const& other) const { return m_timestamp >= other.m_timestamp; }
    bool operator==(DateTime const& other) const { return m_timestamp == other.m_timestamp; }

private:
    time_t m_timestamp { 0 };
    int m_year { 0 };
    int m_month { 0 };
    int m_day { 0 };
    int m_hour { 0 };
    int m_minute { 0 };
    int m_second { 0 };
};

}

namespace AK {

template<>
struct Formatter<Core::DateTime> : StandardFormatter {
    ErrorOr<void> format(FormatBuilder& builder, Core::DateTime const& value)
    {
        // Can't use DateTime::to_string() here: It doesn't propagate allocation failure.
        return builder.builder().try_appendff("{:04d}-{:02d}-{:02d} {:02d}:{:02d}:{:02d}",
            value.year(), value.month(), value.day(),
            value.hour(), value.minute(), value.second());
    }
};

}

namespace IPC {

template<>
ErrorOr<void> encode(Encoder&, Core::DateTime const&);

template<>
ErrorOr<Core::DateTime> decode(Decoder&);

}
