#include <stdint.h>
#include <stdbool.h>
#include <avr/io.h>
#include "config.h"
#include "pump.h"
#include "twi.h"

#define BUFFER_SIZE 4

static uint8_t twiBuffer[BUFFER_SIZE] = {0};
static uint8_t bufferIndex = 0;
bool respondFlag = false;

static inline void twiReset(void) {
    // Enable TWI; enable ACK; clear interrupt flag; enable twi external interrupt
    TWCR = (1 << TWEN) | (1 << TWEA) | (1 << TWINT) | (1 << TWIE);
}

void twiInit(void) {
    TWAR = ((eepromRead(TWI_ADDR)) << 1); //address definition found in config.h
    twiReset();
}

static inline void twiSendAck(void) {
    TWCR = (1 << TWEA) | (1 << TWINT);
}

static inline void twiSendNack(void) {
    TWCR = (TWCR & ~(1 << TWEA)) | (1 << TWINT);
}

static void twiSendData(uint8_t data) {
    TWDR = data;
    twiSendAck();
}

void twiRespond(void) {
    if(respondFlag) {
        switch(twiBuffer[0]) {
            case 0x01: // Get moisture
                twiSendData(*pLastMoistureVal);
                break;
            case 0x02: // Get SENSOR_READINGS
                twiSendData(eepromRead(SENSOR_READINGS));
                break;
            case 0x03: // Get MOISTURE_MIN
                twiSendData(eepromRead(MOISTURE_MIN));
                break;
            case 0x04: // Get MOISTURE_MAX
                twiSendData(eepromRead(MOISTURE_MAX));
                break;
            case 0x05: // Set SENSOR_READINGS
                eepromWrite(SENSOR_READINGS, twiBuffer[1]);
                twiSendAck();
                break;
            case 0x06: // Set parameters
                eepromWrite(MOISTURE_MIN, twiBuffer[1]);
                eepromWrite(MOISTURE_MAX, twiBuffer[2]);
                eepromWrite(SENSOR_READINGS, twiBuffer[3]);
                twiSendAck();
                break;
            case 0x07: // Force water plants (one pumping)
                waterPlant();
                twiSendAck();
                break;
            default:
                twiSendNack();
                break;
        }
    }
}

void twiListen(void) {

    /*
        HOW TO SPEAK MASTER'S LANGUAGE:
            Message is saved bit per bit on a buffer array like this:
            [ message, param0, param1, param2 ]

            So when parsing:
            buffer[0] is the message itself
            buffer[1] to buffer[3] are parameters
    */

    switch (TWSR & 0xF8) {
        case 0x60: // SLA+W received
            bufferIndex = 0;
            twiSendAck();
            break;
        case 0x80: // data received
            if(bufferIndex < BUFFER_SIZE) {
                twiBuffer[bufferIndex++] = TWDR;
                twiSendAck();
            } else twiSendNack();
            break;
        case 0xA0: // stop condition
            respondFlag = true;
            twiReset();
            break;
        default:
            twiSendNack();
            break;
    }
}