/*
 * This file is part of the MicroPython project, http://micropython.org/
 *
 * The MIT License (MIT)
 *
 * Copyright (c) 2021 Lucian Copeland for Adafruit Industries
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 */

#include "py/runtime.h"
#include "samd/external_interrupts.h"
#include "eic_handler.h"
#include "atmel_start_pins.h"
#include "hal/include/hal_gpio.h"
// #include <stdio.h>

#include "shared-bindings/alarm/pin/PinAlarm.h"
#include "shared-bindings/microcontroller/__init__.h"
#include "shared-bindings/microcontroller/Pin.h"
#include "common-hal/alarm/__init__.h"

// This variable stores whether a PinAlarm woke in light sleep or fake deep sleep
// It CANNOT detect if the program woke from deep sleep.
STATIC volatile bool woke_up;
// TODO: replace pinalarm_on with SAMD_ALARM_FLAG bit flags
STATIC volatile bool pinalarm_on;

// TODO: Create tables here reserving IRQ instances, and for the IRQ
//       callback to store what pin triggered the interrupt
// STATIC bool reserved_alarms[SOME_VAL];
// STATIC uint16_t triggered_pins[SOME_VAL];

void pin_alarm_callback(uint8_t num) { // parameters can be changed
    // TODO: This is responsible for resetting the IRQ (so it doesn't
    //       go off constantly, and recording what pin was responsible for
    //       the trigger. This will only work for light sleep/fake deep
    //       sleep, in conjunction with the find_triggered_alarm function

    if (pinalarm_on) {
        // clear flag and interrupt setting
        RTC->MODE0.INTENCLR.reg = RTC_MODE0_INTENCLR_TAMPER;
        pinalarm_on = false;
        // QUESTION: How to reference the correct EIC?
        // set_eic_handler(self->channel, EIC_HANDLER_NO_INTERRUPT);
        // turn_off_eic_channel(self->channel);
        // reset_pin_number(self->pin);
        woke_up = true;
    }
}

void common_hal_alarm_pin_pinalarm_construct(alarm_pin_pinalarm_obj_t *self, const mcu_pin_obj_t *pin, bool value, bool edge, bool pull) {
    // Tamper Pins: IN0:PB00; IN1:PB02; IN2:PA02; IN3:PC00; IN4:PC01; OUT:PB01
    // TODO: Catch edge or level mode if not supported
    if (!pin->has_extint) {
        mp_raise_RuntimeError(translate("No hardware support on pin"));
    }
    if (eic_get_enable()) {
        if (!eic_channel_free(pin->extint_channel)) {
            mp_raise_RuntimeError(translate("A hardware interrupt channel is already in use"));
        }
    } else {
        turn_on_external_interrupt_controller();
    }

    // TODO: determine if pin has an interrupt channel available
    // TODO: set pin pull settings, input/output, etc
    // QUESTION: can PORT/EVSYS interrupts (lightsleep) coexist with RTC->TAMPER (deepsleep) settings?
    // Actual initialization of the interrupt should be delayed until set_alarm

    self->channel = pin->extint_channel;
    self->pin = pin;
    self->value = value;
    self->pull = pull;

    gpio_set_pin_function(pin->number, GPIO_PIN_FUNCTION_A);
    if (self->pull) {
        if (self->value) {
            // detect rising edge means pull down
            gpio_set_pin_pull_mode(pin->number, GPIO_PULL_DOWN);
        } else {
            // detect falling edge means pull up
            gpio_set_pin_pull_mode(pin->number, GPIO_PULL_UP);
        }
    }
    set_eic_channel_data(self->channel, (void *)self);

    claim_pin(self->pin);
}

const mcu_pin_obj_t *common_hal_alarm_pin_pinalarm_get_pin(alarm_pin_pinalarm_obj_t *self) {
    return self->pin;
}

bool common_hal_alarm_pin_pinalarm_get_value(alarm_pin_pinalarm_obj_t *self) {
    return self->value;
}

bool common_hal_alarm_pin_pinalarm_get_edge(alarm_pin_pinalarm_obj_t *self) {
    return true;
}

bool common_hal_alarm_pin_pinalarm_get_pull(alarm_pin_pinalarm_obj_t *self) {
    return self->pull;
}

bool alarm_pin_pinalarm_woke_this_cycle(void) {
    if (pinalarm_on && RTC->MODE0.INTFLAG.bit.TAMPER) {
        woke_up = true;
    }
    return woke_up;
}

mp_obj_t alarm_pin_pinalarm_find_triggered_alarm(size_t n_alarms, const mp_obj_t *alarms) {
    for (size_t i = 0; i < n_alarms; i++) {
        if (!mp_obj_is_type(alarms[i], &alarm_pin_pinalarm_type)) {
            continue;
        }
        alarm_pin_pinalarm_obj_t *alarm = MP_OBJ_TO_PTR(alarms[i]);
        (void)alarm;


        // TODO: Determine whether any pins have been marked as
        //       triggering the alarm (using the static vars at
        //       start of file) and if so return that alarm.
    }
    // Return nothing if no matching alarms are found.
    return mp_const_none;
}

mp_obj_t alarm_pin_pinalarm_create_wakeup_alarm(void) {
    alarm_pin_pinalarm_obj_t *alarm = m_new_obj(alarm_pin_pinalarm_obj_t);
    alarm->base.type = &alarm_pin_pinalarm_type;
    // TODO: Extract information about what pin woke the device.
    //       Because this interrupt occurs in deep sleep, the callback
    //       cannot be used to store this information. It must be extracted
    //       from the registers, if possible. It may be impossible to
    //       obtain, in which case return a dummy value.
    return alarm;
}

void alarm_pin_pinalarm_reset(void) {
    // TODO: this is responsible for resetting ALL pinalarms. Make
    //       sure to clear any reserved tables, deinit both PORT and TAMPER
    //       settings, etc. If flags are set to indicate this module is in
    //       use, reset them.
    pinalarm_on = false;
    woke_up = false;
    SAMD_ALARM_FLAG &= ~SAMD_ALARM_FLAG_PIN; // clear flag
    // Disable TAMPER interrupt
    RTC->MODE0.INTENCLR.reg = RTC_MODE0_INTENCLR_TAMPER;
    // Disable TAMPER control
    common_hal_mcu_disable_interrupts();
    RTC->MODE0.CTRLA.bit.ENABLE = 0;            // Disable the RTC
    while (RTC->MODE0.SYNCBUSY.bit.ENABLE) {    // Wait for synchronization
        ;
    }
    RTC->MODE0.TAMPCTRL.reg = 0;                // reset everything
    RTC->MODE0.CTRLA.bit.ENABLE = 1;            // Enable the RTC
    while (RTC->MODE0.SYNCBUSY.bit.ENABLE) {    // Wait for synchronization
        ;
    }
    common_hal_mcu_enable_interrupts();
}

void alarm_pin_pinalarm_set_alarms(bool deep_sleep, size_t n_alarms, const mp_obj_t *alarms) {
    // The outer layer of this loop simply checks if there are any pin
    // alarms in the parameter array
    for (size_t i = 0; i < n_alarms; i++) {
        if (mp_obj_is_type(alarms[i], &alarm_pin_pinalarm_type)) {
            alarm_pin_pinalarm_obj_t *alarm = MP_OBJ_TO_PTR(alarms[i]);
            gpio_set_pin_function(alarm->pin->number, GPIO_PIN_FUNCTION_A);
            if (alarm->pull) {
                if (alarm->value) {
                    // detect rising edge means pull down
                    gpio_set_pin_pull_mode(alarm->pin->number, GPIO_PULL_DOWN);
                } else {
                    // detect falling edge means pull up
                    gpio_set_pin_pull_mode(alarm->pin->number, GPIO_PULL_UP);
                }
            }
            if (deep_sleep) {
                // Tamper Pins: IN0:PB00; IN1:PB02; IN2:PA02; IN3:PC00; IN4:PC01; OUT:PB01
                // Only these pins can do TAMPER
                if (
                    #ifdef PIN_PB00
                    alarm->pin != &pin_PB00
                    #else
                    true
                    #endif
                    #ifdef PIN_PB02
                    && alarm->pin != &pin_PB02
                    #endif
                    && alarm->pin != &pin_PA02) {
                    mp_raise_ValueError(translate("Pin cannot wake from Deep Sleep"));
                }
                pinalarm_on = true;
                SAMD_ALARM_FLAG |= SAMD_ALARM_FLAG_PIN;

                // Set tamper interrupt so deep sleep knows that's the intent
                RTC->MODE0.INTENSET.reg = RTC_MODE0_INTENSET_TAMPER;
                common_hal_mcu_disable_interrupts();
                RTC->MODE0.CTRLA.bit.ENABLE = 0;                     // Disable the RTC
                while (RTC->MODE0.SYNCBUSY.bit.ENABLE) {             // Wait for synchronization
                    ;
                }
                // TODO: map requested pin to limited selection of TAMPER pins
                // PA02 is n=2: IN2, LVL2, etc...
                RTC->MODE0.TAMPCTRL.bit.DEBNC2 = 1;  // Edge triggered when INn is stable for 4 CLK_RTC_DEB periods
                RTC->MODE0.TAMPCTRL.bit.TAMLVL2 = alarm->value; // rising or falling edge
                RTC->MODE0.TAMPCTRL.bit.IN2ACT = 1;  // WAKE on IN2 (doesn't save timestamp)
                common_hal_mcu_enable_interrupts();
                RTC->MODE0.INTENSET.reg = RTC_MODE0_INTENSET_TAMPER;
                RTC->MODE0.CTRLA.bit.ENABLE = 1;                      // Enable the RTC
                while (RTC->MODE0.SYNCBUSY.bit.ENABLE) {              // Wait for synchronization
                    ;
                }
                // TODO: Set up deep sleep alarms.
                //       For deep sleep alarms, first check if the
                //       alarm pin value is valid for RTC->TAMPER. Ensure
                //       that the PULL and VALUE values are possible to
                //       implement with TAMPER, and throw value errors if
                //       not.
                //       A VM reset will occur before deep sleep
                //       starts, so either init these settings now and
                //       protect them with a `never_reset` function, or
                //       store them all in static variables and only
                //       actually implement the settings in
                //       `alarm_pin_pinalarm_prepare_for_deep_sleep`
                //       below.
            } // use else-if here if RTC-TAMPER can wake from IDLE
            else {
                // Light sleep so turn on EIC channel
                set_eic_handler(alarm->channel, EIC_HANDLER_ALARM);
                turn_on_eic_channel(alarm->channel, EIC_CONFIG_SENSE0_RISE_Val);
            }

            // TODO: Set up light sleep / fake deep sleep alarms.
            //       PORT/EVSYS should have more valid pin combinations
            //       than the TAMPER system. Check if there is a valid
            //       PORT/EVSYS combination, set it up, and reserve it with
            //       the tables at the start of this file so it can't be
            //       reused. Also set up IRQ callbacks and any other
            //       busywork.

            // TODO: Might want to reserve or otherwise interact with
            //       peripherals/sam_d5x/external_interrupts.c or events.c here

            // TODO: Even if an alarm is being set for deep sleep, it
            //       still needs to be able to wake from fake deep sleep,
            //       which is actually just like a light sleep. If the
            //       RTC Tamper IRQs are capable of waking from IDLE mode,
            //       this isn't a big deal, and there can be a strict
            //       if-else statement here. Otherwise, it will need to
            //       either set PORT and TAMPER IRQs simultaniously, or if that
            //       isn't possible, make a new function that can shunt fake deep
            //       sleep setup to common_hal_alarm_pretending_deep_sleep
        }
    }
}

void alarm_pin_pinalarm_prepare_for_deep_sleep(void) {
    // TODO: This function is called after the VM reset, right before
    //       the program actually enters deep sleep. If the VM reset
    //       (see port_reset) resets any pins/EVSYS settings/RTC values
    //       needed by the pinalarms, this function is responsible for setting them
    //       back up again.
}