/*

 * // Copyright (c) Radzivon Bartoshyk 3/2025. 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.

 * //

 * // 3.  Neither the name of the copyright holder nor the names of its

 * // contributors may be used to endorse or promote products derived from

 * // this software without specific prior written permission.

 * //

 * // 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.

 */

use crate::CmsError;

use crate::writer::write_u16_be;

use std::time::{SystemTime, UNIX_EPOCH};

#[repr(C)]

#[derive(Debug, Clone, Copy, Ord, PartialOrd, Eq, PartialEq, Default)]

pub struct ColorDateTime {

    pub year: u16,

    pub month: u16,

    pub day_of_the_month: u16,

    pub hours: u16,

    pub minutes: u16,

    pub seconds: u16,

}

fn is_leap(year: i32) -> bool {

    (year % 4 == 0 && year % 100 != 0) || (year % 400 == 0)

}

fn days_in_month(year: i32, month: i32) -> i32 {

    match month {

        1 => 31,

        2 => {

            if is_leap(year) {

                29

            } else {

                28

            }

        }

        3 => 31,

        4 => 30,

        5 => 31,

        6 => 30,

        7 => 31,

        8 => 31,

        9 => 30,

        10 => 31,

        11 => 30,

        12 => 31,

        _ => unreachable!("Unknown month"),

    }

}

impl ColorDateTime {

    /// Parses slice for date time

    pub fn new_from_slice(slice: &[u8]) -> Result<ColorDateTime, CmsError> {

        if slice.len() != 12 {

            return Err(CmsError::InvalidProfile);

        }

        let year = u16::from_be_bytes([slice[0], slice[1]]);

        let month = u16::from_be_bytes([slice[2], slice[3]]);

        let day_of_the_month = u16::from_be_bytes([slice[4], slice[5]]);

        let hours = u16::from_be_bytes([slice[6], slice[7]]);

        let minutes = u16::from_be_bytes([slice[8], slice[9]]);

        let seconds = u16::from_be_bytes([slice[10], slice[11]]);

        Ok(ColorDateTime {

            year,

            month,

            day_of_the_month,

            hours,

            minutes,

            seconds,

        })

    }

    /// Creates a new `ColorDateTime` from the current system time (UTC)

    pub fn now() -> Self {

        let now = match SystemTime::now().duration_since(UNIX_EPOCH) {

            Ok(v) => v,

            Err(_) => return Self::default(),

        };

        let mut days = (now.as_secs() / 86_400) as i64;

        let secs_of_day = (now.as_secs() % 86_400) as i64;

        let mut year = 1970;

        loop {

            let year_days = if is_leap(year) { 366 } else { 365 };

            if days >= year_days {

                days -= year_days;

                year += 1;

            } else {

                break;

            }

        }

        let mut month = 1;

        loop {

            let mdays = days_in_month(year, month);

            if days >= mdays as i64 {

                days -= mdays as i64;

                month += 1;

            } else {

                break;

            }

        }

        let day = days + 1; // days from zero based to 1 base

        let hour = secs_of_day / 3600;

        let min = (secs_of_day % 3600) / 60;

        let sec = secs_of_day % 60;

        Self {

            year: year as u16,

            month: month as u16,

            day_of_the_month: day as u16,

            hours: hour as u16,

            minutes: min as u16,

            seconds: sec as u16,

        }

    }

    #[inline]

    pub(crate) fn encode(&self, into: &mut Vec<u8>) {

        let year = self.year;

        let month = self.month;

        let day_of_the_month = self.day_of_the_month;

        let hours = self.hours;

        let minutes = self.minutes;

        let seconds = self.seconds;

        write_u16_be(into, year);

        write_u16_be(into, month);

        write_u16_be(into, day_of_the_month);

        write_u16_be(into, hours);

        write_u16_be(into, minutes);

        write_u16_be(into, seconds);

    }

}