/**
 * \file door_sensor.c
 * \brief Implementation of the door sensor driver using MSP430 GPIO interrupts.
 *
 * This module configures a GPIO pin to detect door open/close events and invokes
 * user-provided callbacks on confirmed state changes.
 */

#include <stdint.h>
#include <msp430.h>
#include <driverlib.h>
#include <stdbool.h>
#include "door_sensor.h"
#include "constants.h"

/**\brief GPIO port used for the door sensor. */
#define SENSOR_PORT   GPIO_PORT_P2
/**\brief GPIO pin used for the door sensor. */
#define SENSOR_PIN    GPIO_PIN0
/**\brief Interrupt vector associated with the sensor port. */
#define SENSOR_VECTOR PORT2_VECTOR

/**
 * \brief Callback invoked when the door is detected as opened.
 *
 * User must supply a function matching this type to be notified of an open event.
 */
static DoorOpenedCallback_t doorOpenedCallback = NULL;
/**
 * \brief Callback invoked when the door is detected as closed.
 *
 * User must supply a function matching this type to be notified of a close event.
 */
static DoorClosedCallback_t doorClosedCallback = NULL;

/**
 * \brief Initialize the door sensor driver.
 *
 * Configures the GPIO pin for input with pull-up resistor and enables
 * interrupts on the specified edge. Also stores the user-provided callbacks.
 *
 * \param ocb Function to call when the door opens (rising edge).
 * \param ccb Function to call when the door closes (falling edge).
 */
void door_init(DoorOpenedCallback_t ocb, DoorClosedCallback_t ccb) {
    doorOpenedCallback = ocb;
    doorClosedCallback = ccb;

    /* Configure port as pull up with interrupt */
    GPIO_setAsInputPinWithPullUpResistor(SENSOR_PORT, SENSOR_PIN);
    GPIO_clearInterrupt(SENSOR_PORT, SENSOR_PIN);
    GPIO_selectInterruptEdge(SENSOR_PORT, SENSOR_PIN, GPIO_LOW_TO_HIGH_TRANSITION);
    GPIO_enableInterrupt(SENSOR_PORT, SENSOR_PIN);

    /* Enable global interrupts */
    __enable_interrupt();
}

/**
 * \brief Tracks the last known door state (open = true, closed = false).
 */
volatile bool door_last_open = false;

/**
 * \brief ISR for PORT2 interrupt handling door sensor events.
 *
 * Detects whether the door is opening or closing based on interrupt edge,
 * invokes the corresponding callback, and reconfigures the interrupt edge
 * for the next transition.
 */
#pragma vector=SENSOR_VECTOR
__interrupt void SENSOR_ISR(void)
{
    uint16_t status = GPIO_getInterruptStatus(SENSOR_PORT, SENSOR_PIN);

    if (status) {
        if (door_last_open) {
            /* Door was open, now closed */
            if (doorClosedCallback)
                doorClosedCallback();
            GPIO_selectInterruptEdge(SENSOR_PORT, SENSOR_PIN, GPIO_LOW_TO_HIGH_TRANSITION);
        } else {
            /* Door was closed, now opened */
            if (doorOpenedCallback)
                doorOpenedCallback();
            GPIO_selectInterruptEdge(SENSOR_PORT, SENSOR_PIN, GPIO_HIGH_TO_LOW_TRANSITION);
        }
    }

    /* Clear the interrupt flag and toggle stored state */
    GPIO_clearInterrupt(SENSOR_PORT, SENSOR_PIN);
    door_last_open = !door_last_open;
}