use field_offset::offset_of;
use stm32l4xx_hal::prelude::{_embedded_hal_blocking_i2c_Read, _embedded_hal_blocking_i2c_Write};
use tock_registers::{
    interfaces::{ReadWriteable, Readable},
    register_bitfields, register_structs,
    registers::InMemoryRegister,
};

register_bitfields![
    u8,
    T_SECOND [
        Value OFFSET(0) NUMBITS(7) [],
    ],
    T_MINUTE [
        Value OFFSET(0) NUMBITS(7) [],
    ],
    T_HOUR [
        Value OFFSET(0) NUMBITS(6) [],
        n24 OFFSET(6) NUMBITS(1) [],
    ],
    T_DAY [
        Value OFFSET(0) NUMBITS(3) [],
    ],
    T_DATE [
        Value OFFSET(0) NUMBITS(6) [],
    ],
    T_MONTH [
        Value OFFSET(0) NUMBITS(5) [],
        Century OFFSET(7) NUMBITS(1) [],
    ],
    T_YEAR [
        Value OFFSET(0) NUMBITS(8) [],
    ],
    A_SECOND [
        Value OFFSET(0) NUMBITS(7) [],
        M1 OFFSET(7) NUMBITS(1) [],
    ],
    A_MINUTE [
        Value OFFSET(0) NUMBITS(7) [],
        M2 OFFSET(7) NUMBITS(1) [],
    ],
    A_HOUR [
        Value OFFSET(0) NUMBITS(6) [],
        n24 OFFSET(6) NUMBITS(1) [],
        M3 OFFSET(7) NUMBITS(1) [],
    ],
    A_DAY_DATE [
        Value OFFSET(0) NUMBITS(6) [],
        nDT OFFSET(6) NUMBITS(1) [],
        M4 OFFSET(7) NUMBITS(1) [],
    ],
    CONTROL_1 [
        A1IE 0,
        A2IE 1,
        INTCN 2,
        RS1 3,
        RS2 4,
        CONV 5,
        BBSQW 6,
        nEOSC 7,
    ],
    CONTROL_2 [
        A1F 0,
        A2F 1,
        BSY 2,
        EN32KHZ 3,
        OSF 7,
    ],
    AGING_OFFSET [
        Value OFFSET(0) NUMBITS(7) [],
        Sign OFFSET(7) NUMBITS(1) [],
    ],
    TEMP_MSB [
        Value OFFSET(0) NUMBITS(7) [],
        Sign OFFSET(7) NUMBITS(1) [],
    ],
    TEMP_LSB [
        Value OFFSET(6) NUMBITS(2) [],
    ],
];

register_structs! {
    Ds3231Registers {
        (0x00 => second: InMemoryRegister<u8, T_SECOND::Register>),
        (0x01 => minute: InMemoryRegister<u8, T_MINUTE::Register>),
        (0x02 => hour: InMemoryRegister<u8, T_HOUR::Register>),
        (0x03 => weekday: InMemoryRegister<u8, T_DAY::Register>),
        (0x04 => day: InMemoryRegister<u8, T_DATE::Register>),
        (0x05 => month: InMemoryRegister<u8, T_MONTH::Register>),
        (0x06 => year: InMemoryRegister<u8, T_YEAR::Register>),
        (0x07 => a1_second: InMemoryRegister<u8, A_SECOND::Register>),
        (0x08 => a1_minute: InMemoryRegister<u8, A_MINUTE::Register>),
        (0x09 => a1_hour: InMemoryRegister<u8, A_HOUR::Register>),
        (0x0A => a1_day_date: InMemoryRegister<u8, A_DAY_DATE::Register>),
        (0x0B => a2_minute: InMemoryRegister<u8, A_MINUTE::Register>),
        (0x0C => a2_hour: InMemoryRegister<u8, A_HOUR::Register>),
        (0x0D => a2_day_date: InMemoryRegister<u8, A_DAY_DATE::Register>),
        (0x0E => control_1: InMemoryRegister<u8, CONTROL_1::Register>),
        (0x0F => control_2: InMemoryRegister<u8, CONTROL_2::Register>),
        (0x10 => aging_offset: InMemoryRegister<u8, AGING_OFFSET::Register>),
        (0x11 => temp_msb: InMemoryRegister<u8, TEMP_MSB::Register>),
        (0x12 => temp_lsb: InMemoryRegister<u8, TEMP_LSB::Register>),
        (0x13 => @END),
    }
}

pub enum Weekday {
    Sunday = 0,
    Monday = 1,
    Tuesday = 2,
    Wednesday = 3,
    Thursday = 4,
    Friday = 5,
    Saturday = 6,
}

impl Ds3231Registers {
    fn i2c_read_regs(&mut self, i2c: &mut impl _embedded_hal_blocking_i2c_Read) {}
    fn set_time(second: &u32, minute: &u32, hour: &u32) {}
    fn set_date(weekday: &Weekday, day: &u32, month: &u32, year: &u32, century: &u32) {}
    fn get_time(second: &mut u32, minute: &mut u32, hour: &mut u32) {}
    fn get_date(
        weekday: &mut Weekday,
        day: &mut u32,
        month: &mut u32,
        year: &mut u32,
        century: &mut u32,
    ) {
    }
}

fn init(address: u8, i2c: &mut impl _embedded_hal_blocking_i2c_Write) {

}

#[inline]
fn bcd_to_decimal(value: u8) -> u8 {
    ((value >> 4) * 10) + (value & 0xF)
}

#[inline]
fn decimal_to_bcd(value: u8) -> u8 {
    ((value / 10) << 4) | (value % 10)
}

pub fn in_dst(weekday: Weekday, day: u32, month: u32, hour_24: u32) -> bool {
    let prev_sunday: i32 = day as i32 - weekday as i32;
    match month {
        0..=2 | 12.. => false,
        4..=10 => true,
        3 => match prev_sunday {
            ..8 => false,
            15.. => true,
            d if d == day as i32 => hour_24 >= 2,
            _ => true,
        },
        11 => match prev_sunday {
            ..=0 => true,
            8.. => false,
            d if d == day as i32 => hour_24 < 2,
            _ => false,
        },
    }
}

#[cfg(test)]
mod test {
    use super::*;

    #[test]
    fn dst_test() {
        // 2020 - begins Mar 8th @ 2AM (Sunday), ends Nov 1st @ 2AM (Sunday)
        assert!(in_dst(Weekday::Sunday, 8, 3, 1) == false);
        assert!(in_dst(Weekday::Sunday, 8, 3, 2) == true);
        assert!(in_dst(Weekday::Sunday, 8, 3, 3) == true);
        assert!(in_dst(Weekday::Sunday, 1, 11, 1) == true);
        assert!(in_dst(Weekday::Sunday, 1, 11, 2) == false);
        assert!(in_dst(Weekday::Sunday, 1, 11, 3) == false);

        // 2021 - begins Mar 14th @ 2AM (Sunday), ends Nov 7th @ 2AM (Sunday)
        assert!(in_dst(Weekday::Sunday, 14, 3, 1) == false);
        assert!(in_dst(Weekday::Sunday, 14, 3, 2) == true);
        assert!(in_dst(Weekday::Sunday, 14, 3, 3) == true);
        assert!(in_dst(Weekday::Sunday, 7, 11, 1) == true);
        assert!(in_dst(Weekday::Sunday, 7, 11, 2) == false);
        assert!(in_dst(Weekday::Sunday, 7, 11, 3) == false);

        // 2022 - begins Mar 13th @ 2AM (Sunday), ends Nov 6th @ 2AM (Sunday)
        assert!(in_dst(Weekday::Sunday, 13, 3, 1) == false);
        assert!(in_dst(Weekday::Sunday, 13, 3, 2) == true);
        assert!(in_dst(Weekday::Sunday, 13, 3, 3) == true);
        assert!(in_dst(Weekday::Sunday, 6, 11, 1) == true);
        assert!(in_dst(Weekday::Sunday, 6, 11, 2) == false);
        assert!(in_dst(Weekday::Sunday, 6, 11, 3) == false);

        // 2023 - begins Mar 12th @ 2AM (Sunday), ends Nov 5th @ 2AM (Sunday)
        assert!(in_dst(Weekday::Sunday, 12, 3, 1) == false);
        assert!(in_dst(Weekday::Sunday, 12, 3, 2) == true);
        assert!(in_dst(Weekday::Sunday, 12, 3, 3) == true);
        assert!(in_dst(Weekday::Sunday, 5, 11, 1) == true);
        assert!(in_dst(Weekday::Sunday, 5, 11, 2) == false);
        assert!(in_dst(Weekday::Sunday, 5, 11, 3) == false);

        // Sanity check other dates in 2021
        assert!(in_dst(Weekday::Friday, 1, 1, 0) == false);
        assert!(in_dst(Weekday::Monday, 1, 2, 0) == false);
        assert!(in_dst(Weekday::Monday, 1, 3, 0) == false);
        assert!(in_dst(Weekday::Thursday, 1, 4, 0) == true);
        assert!(in_dst(Weekday::Saturday, 1, 5, 0) == true);
        assert!(in_dst(Weekday::Tuesday, 1, 6, 0) == true);
        assert!(in_dst(Weekday::Thursday, 1, 7, 0) == true);
        assert!(in_dst(Weekday::Sunday, 1, 8, 0) == true);
        assert!(in_dst(Weekday::Wednesday, 1, 9, 0) == true);
        assert!(in_dst(Weekday::Friday, 1, 10, 0) == true);
        assert!(in_dst(Weekday::Monday, 1, 11, 0) == true);
        assert!(in_dst(Weekday::Wednesday, 1, 12, 0) == false);
    }
}