use stm32l4xx_hal::{
    prelude::{
        _embedded_hal_blocking_i2c_Read, _embedded_hal_blocking_i2c_Write,
        _embedded_hal_blocking_i2c_WriteRead,
    },
};

use crate::{ds3231, pca9685};

pub const DS3231_ADDR: u8 = 0x68;
pub const TUSB322_ADDR: u8 = 0x47;
pub const PCA9685_ADDR_1: u8 = 0x41;
pub const PCA9685_ADDR_2: u8 = 0x42;
pub const PCA9685_ADDR_3: u8 = 0x43;

pub const PCA9685_ALL_CALL: u8 = 0x70; // Default enabled
pub const PCA9685_SUB_CALL_1: u8 = 0x71; // Default disabled
pub const PCA9685_SUB_CALL_2: u8 = 0x72; // Default disabled
pub const PCA9685_SUB_CALL_3: u8 = 0x73; // Default disabled

const MAP_DOT_ADDR: u8 = PCA9685_ADDR_2;
const MAP_DOT_PIN: u8 = 15;

const MAP_ADDR: usize = 0;
const MAP_PIN: usize = 1;

const DIGIT_FADE_DURATION_US: u32 = 1_000_000;
const REFRESH_RATE_US: u32 = 1000;

const DIGIT_RNG_FADE_DURATION_US: u32 = 200_000;
const DIGIT_RNG_FADE_ITERATIONS: usize = 20;
const DIGIT_RNG_REFRESH_INTERVAL: usize = 60;
const DIGIT_RNG_REFRESH_VARIANCE: usize = 30;

const DOT_MIN_BRIGHTNESS: u32 = 256;
const DOT_MAX_BRIGHTNESS: u32 = 640;
const DOT_FADE_DURATION_US: u32 = 1_000_000;

const DIGIT_MAX_BRIGHTNESS: u32 = 4096;
const DIGIT_MIN_BRIGHTNESS: u32 = 0;

const NUM_TUBES: usize = 4;
const NUM_DIGITS: usize = 10;

struct DigitToPin {
    address: u8,
    pin: usize,
}

struct PwmDriver {
    digit: [DigitToPin; 10],
}

struct PwmOutputMap {
    driver: [PwmDriver; 4],
    dot_address: u8,
    dot_pin: usize,
}

static TUBE_MAPPING: PwmOutputMap = {
    PwmOutputMap {
        driver: [
            PwmDriver {
                digit: [
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 8,
                    }, // Tube 0 Digit 0
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 9,
                    }, // Tube 0 Digit 1
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 10,
                    }, // Tube 0 Digit 2
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 12,
                    }, // Tube 0 Digit 3
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 15,
                    }, // Tube 0 Digit 4
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 14,
                    }, // Tube 0 Digit 5
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 11,
                    }, // Tube 0 Digit 6
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 0,
                    }, // Tube 0 Digit 7
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 1,
                    }, // Tube 0 Digit 8
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 13,
                    }, // Tube 0 Digit 9
                ],
            },
            PwmDriver {
                digit: [
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 5,
                    }, // Tube 1 Digit 0
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 6,
                    }, // Tube 1 Digit 1
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 7,
                    }, // Tube 1 Digit 2
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 2,
                    }, // Tube 1 Digit 3
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 4,
                    }, // Tube 1 Digit 4
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 1,
                    }, // Tube 1 Digit 5
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 4,
                    }, // Tube 1 Digit 6
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 2,
                    }, // Tube 1 Digit 7
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 3,
                    }, // Tube 1 Digit 8
                    DigitToPin {
                        address: PCA9685_ADDR_1,
                        pin: 3,
                    }, // Tube 1 Digit 9
                ],
            },
            PwmDriver {
                digit: [
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 8,
                    }, // Tube 2 Digit 0
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 9,
                    }, // Tube 2 Digit 1
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 10,
                    }, // Tube 2 Digit 2
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 12,
                    }, // Tube 2 Digit 3
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 12,
                    }, // Tube 2 Digit 4
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 13,
                    }, // Tube 2 Digit 5
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 11,
                    }, // Tube 2 Digit 6
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 14,
                    }, // Tube 2 Digit 7
                    DigitToPin {
                        address: PCA9685_ADDR_2,
                        pin: 11,
                    }, // Tube 2 Digit 8
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 13,
                    }, // Tube 2 Digit 9
                ],
            },
            PwmDriver {
                digit: [
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 5,
                    }, // Tube 3 Digit 0
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 6,
                    }, // Tube 3 Digit 1
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 7,
                    }, // Tube 3 Digit 2
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 2,
                    }, // Tube 3 Digit 3
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 14,
                    }, // Tube 3 Digit 4
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 15,
                    }, // Tube 3 Digit 5
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 4,
                    }, // Tube 3 Digit 6
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 1,
                    }, // Tube 3 Digit 7
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 0,
                    }, // Tube 3 Digit 8
                    DigitToPin {
                        address: PCA9685_ADDR_3,
                        pin: 3,
                    }, // Tube 3 Digit 9
                ],
            },
        ],
        dot_address: PCA9685_ADDR_2,
        dot_pin: 15,
    }
};

#[derive(PartialEq)]
enum DigitState {
    Idle,
    Incrementing,
    Decrementing,
}

struct Digit {
    current_state: DigitState,
    value: u32,
    pwm_start: u32,
    pwm_end: u32,
    updated: bool,
}

impl Digit {
    const fn default() -> Self {
        Self {
            current_state: DigitState::Idle,
            value: 0,
            pwm_start: 0,
            pwm_end: 0,
            updated: false,
        }
    }
}

struct Tube {
    digits: [Digit; NUM_DIGITS],
    last_active_digit: Option<usize>,
    refresh_last_digit: Option<usize>,
    refresh_active: bool,
}

impl Tube {
    const fn default() -> Self {
        const DIGIT_INIT: Digit = Digit::default();
        Self {
            digits: [DIGIT_INIT; 10],
            last_active_digit: None,
            refresh_last_digit: None,
            refresh_active: false,
        }
    }
}

struct Clock {
    tubes: [Tube; NUM_TUBES],
    dot: Digit,
    fade_duration: u32,
}

impl Clock {
    const fn default() -> Self {
        const TUBE_INIT: Tube = Tube::default();
        Self {
            tubes: [TUBE_INIT; NUM_TUBES],
            dot: Digit::default(),
            fade_duration: 0,
        }
    }
}

static mut CLOCK: Clock = Clock::default();

pub fn fade_in_out_digit(tube: usize, digit: Option<usize>, fade_duration: u32, refresh_cmd: bool) {
    // assert!(tube < NUM_TUBES);
    // assert!(Some(digit) < NUM_DIGITS);

    unsafe {
        // If the tube is in the middle of a refresh sequence and a call comes
        // in to update the tube digit (for time), override the last value of
        // the refresh sequence with the new digit.
        if CLOCK.tubes[tube].refresh_active && !refresh_cmd {
            CLOCK.tubes[tube].refresh_last_digit = digit;
        }

        // Dont update if actively refreshing tube unless RngUpdate is set
        if (!CLOCK.tubes[tube].refresh_active && !refresh_cmd) || refresh_cmd {
            // Fade out all digits
            for digit in 0..NUM_DIGITS {
                CLOCK.tubes[tube].digits[digit].current_state = DigitState::Decrementing;
            }

            // Fade in the specified digit
            if let Some(digit) = digit {
                CLOCK.tubes[tube].digits[digit].current_state = DigitState::Incrementing;
            }

            CLOCK.tubes[tube].last_active_digit = digit;
            CLOCK.fade_duration = fade_duration;
        }
    }

    // TODO! trigger refresh timer
}

pub fn refresh_frame() {
    let mut pending_refresh: bool = false;
    unsafe {
        let ticks = CLOCK.fade_duration / REFRESH_RATE_US;
        let steps = ((DIGIT_MAX_BRIGHTNESS - DIGIT_MIN_BRIGHTNESS) + ticks - 1) / ticks;
        CLOCK.tubes.iter_mut().for_each(|tube| {
            tube.digits.iter_mut().for_each(|digit| {
                match digit.current_state {
                    DigitState::Incrementing => {
                        digit.value = digit.value.saturating_add(steps);
                        if digit.value >= DIGIT_MAX_BRIGHTNESS {
                            digit.value = DIGIT_MAX_BRIGHTNESS;
                            digit.current_state = DigitState::Idle;
                        }
                        digit.updated = true;
                        pending_refresh = true;
                    }
                    DigitState::Decrementing => {
                        digit.value = digit.value.saturating_sub(steps);
                        if digit.value <= DIGIT_MIN_BRIGHTNESS {
                            digit.value = DIGIT_MIN_BRIGHTNESS;
                            digit.current_state = DigitState::Idle;
                        }
                        digit.updated = true;
                        pending_refresh = true;
                    }
                    DigitState::Idle => (),
                };
            });
        });

        // Handle dot
        let steps = ((DOT_MAX_BRIGHTNESS - DOT_MIN_BRIGHTNESS) + ticks - 1) / ticks;
        match CLOCK.dot.current_state {
            DigitState::Incrementing => {
                CLOCK.dot.value = CLOCK.dot.value.saturating_add(steps);
                if CLOCK.dot.value >= DIGIT_MAX_BRIGHTNESS {
                    CLOCK.dot.value = DIGIT_MAX_BRIGHTNESS;
                    CLOCK.dot.current_state = DigitState::Idle;
                }
                CLOCK.dot.updated = true;
                pending_refresh = true;
            }
            DigitState::Decrementing => {
                CLOCK.dot.value = CLOCK.dot.value.saturating_sub(steps);
                if CLOCK.dot.value >= DIGIT_MIN_BRIGHTNESS {
                    CLOCK.dot.value = DIGIT_MIN_BRIGHTNESS;
                    CLOCK.dot.current_state = DigitState::Idle;
                }
                CLOCK.dot.updated = true;
                pending_refresh = true;
            }
            DigitState::Idle => (),
        }
    }

    if pending_refresh {
        // TODO! trigger refresh timer
    }
}

pub fn rtc_tick<T>(i2c: &mut T)
where
    T: _embedded_hal_blocking_i2c_WriteRead
        + _embedded_hal_blocking_i2c_Read
        + _embedded_hal_blocking_i2c_Write,
{
    static mut STARTUP: bool = true;
    static mut PREV_MINUTE: u32 = 0;
    static mut PREV_HOUR: u32 = 0;

    let (second, minute, hour) = ds3231::get_time(DS3231_ADDR, i2c);
    let (weekday, day, month, _, _) = ds3231::get_date(DS3231_ADDR, i2c);

    let hour = if ds3231::in_dst(weekday, day, month, hour) {
        (hour + 1) % 12
    } else {
        hour % 12
    };
    let hour = if hour == 0 { 12 } else { hour };

    unsafe {
        if STARTUP || PREV_HOUR / 10 != hour / 10 {
            fade_in_out_digit(
                0,
                if hour / 10 != 0 {
                    Some((hour / 10) as usize)
                } else {
                    None
                },
                DIGIT_FADE_DURATION_US,
                false,
            )
        }
        if STARTUP || PREV_HOUR % 10 != hour % 10 {
            fade_in_out_digit(1, Some((hour % 10) as usize), DIGIT_FADE_DURATION_US, false);
        }
        if STARTUP || PREV_MINUTE / 10 != minute / 10 {
            fade_in_out_digit(
                2,
                Some((minute / 10) as usize),
                DIGIT_FADE_DURATION_US,
                false,
            );
        }
        if STARTUP || PREV_MINUTE % 10 != minute % 10 {
            fade_in_out_digit(
                3,
                Some((minute % 10) as usize),
                DIGIT_FADE_DURATION_US,
                false,
            );
        }

        CLOCK.dot.current_state = match second % 2 {
            0 => DigitState::Incrementing,
            1 => DigitState::Decrementing,
            _ => DigitState::Idle,
        };

        PREV_MINUTE = minute;
        PREV_HOUR = hour;

        STARTUP = false;
    }
}

pub fn refresh_tick<T>(i2c: &mut T)
where
    T: _embedded_hal_blocking_i2c_WriteRead
        + _embedded_hal_blocking_i2c_Read
        + _embedded_hal_blocking_i2c_Write,
{
    compute_pwm_offset();

    unsafe {
        for (t, tube) in CLOCK.tubes.iter().enumerate() {
            for (d, digit) in tube.digits.iter().filter(|d| d.updated).enumerate() {
                pca9685::set_digit(
                    TUBE_MAPPING.driver[t].digit[d].address,
                    i2c,
                    TUBE_MAPPING.driver[t].digit[d].pin,
                    digit.pwm_start,
                    digit.pwm_end,
                );
            }
        }
        if CLOCK.dot.updated {
            pca9685::set_digit(
                TUBE_MAPPING.dot_address,
                i2c,
                TUBE_MAPPING.dot_pin,
                CLOCK.dot.pwm_start,
                CLOCK.dot.pwm_end,
            );
        }
    }
}

pub fn rng_tick<T>(i2c: &mut T)
where
    T: _embedded_hal_blocking_i2c_WriteRead
        + _embedded_hal_blocking_i2c_Read
        + _embedded_hal_blocking_i2c_Write,
{
}

// In the event that there are multiple PWM outputs at less than 100% duty cycle,
// stagger the start time of each PWM to reduce the switch on surge current.
fn compute_pwm_offset() {
    let mut active_digits: u32 = 0;
    let mut total_on_time: u32 = 0;
    let mut last_pwm_end: u32 = 0;

    // Determine the number of active outputs as well as the total on-time across all outputs.
    // Ignore outputs that are off (min) or fully on (max) as they have no surge impact.
    unsafe {
        CLOCK.tubes.iter().for_each(|tube| {
            tube.digits.iter().for_each(|digit| {
                if digit.value != DIGIT_MAX_BRIGHTNESS && digit.value != DIGIT_MIN_BRIGHTNESS {
                    active_digits = active_digits + 1;
                    total_on_time = total_on_time + digit.value;
                }
            });
        });
        if CLOCK.dot.value != DIGIT_MAX_BRIGHTNESS && CLOCK.dot.value != DIGIT_MIN_BRIGHTNESS {
            active_digits = active_digits + 1;
            total_on_time = total_on_time + CLOCK.dot.value;
        }

        // If the total on-time across all outputs is less than one PWM period, stagger each
        // output such that the rise of one pulse begins at the end of the previous pulse.
        if total_on_time <= DIGIT_MAX_BRIGHTNESS {
            CLOCK.tubes.iter_mut().for_each(|tube| {
                tube.digits.iter_mut().for_each(|digit| {
                    if digit.value == DIGIT_MIN_BRIGHTNESS {
                        digit.pwm_start = 0;
                        digit.pwm_end = 0;
                    } else if digit.value == DIGIT_MAX_BRIGHTNESS {
                        digit.pwm_start = 0;
                        digit.pwm_end = DIGIT_MAX_BRIGHTNESS;
                    } else {
                        digit.pwm_start = last_pwm_end;
                        digit.pwm_end = last_pwm_end + digit.value;
                        last_pwm_end = digit.pwm_end;
                        digit.updated = true;
                    }
                });
            });

            if CLOCK.dot.value == DIGIT_MIN_BRIGHTNESS {
                CLOCK.dot.pwm_start = 0;
                CLOCK.dot.pwm_end = 0;
            } else if CLOCK.dot.value == DIGIT_MAX_BRIGHTNESS {
                CLOCK.dot.pwm_start = 0;
                CLOCK.dot.pwm_end = DIGIT_MAX_BRIGHTNESS;
            } else {
                CLOCK.dot.pwm_start = last_pwm_end;
                CLOCK.dot.pwm_end = last_pwm_end + CLOCK.dot.value;
                CLOCK.dot.updated = true;
            }
        } else {
            // Compute the amount of overlap between all outputs
            // int overlap = (totalOnTime - PCA9685_Max_Brightness) / (validOutputs - 1);
            let overlap = (total_on_time - DIGIT_MAX_BRIGHTNESS) / (active_digits - 1);

            // Compute the staggered output period for each output
            CLOCK.tubes.iter_mut().for_each(|tube| {
                tube.digits.iter_mut().for_each(|digit| {
                    if digit.value == DIGIT_MIN_BRIGHTNESS {
                        digit.pwm_start = 0;
                        digit.pwm_end = 0;
                    } else if digit.value == DIGIT_MAX_BRIGHTNESS {
                        digit.pwm_start = 0;
                        digit.pwm_end = DIGIT_MAX_BRIGHTNESS;
                    } else {
                        digit.pwm_start = last_pwm_end.saturating_sub(overlap);
                        digit.pwm_end = digit.pwm_start + digit.value;
                        last_pwm_end = digit.pwm_end;
                        digit.updated = true;
                    }
                });
            });

            if CLOCK.dot.value == DIGIT_MIN_BRIGHTNESS {
                CLOCK.dot.pwm_start = 0;
                CLOCK.dot.pwm_end = 0;
            } else if CLOCK.dot.value == DIGIT_MAX_BRIGHTNESS {
                CLOCK.dot.pwm_start = 0;
                CLOCK.dot.pwm_end = DIGIT_MAX_BRIGHTNESS;
            } else {
                CLOCK.dot.pwm_start = last_pwm_end.saturating_sub(overlap);
                CLOCK.dot.pwm_end = CLOCK.dot.pwm_start + CLOCK.dot.value;
                CLOCK.dot.updated = true;
            }
        }
    }
}