#include "i2c_lcd.h"
#include <driverlib.h>
#include <msp430.h>

/* Adjust to your module’s I²C address (often 0x27 or 0x3F) */
#define LCD_I2C_ADDR      0x27

/* PCF8574 pin ↔ LCD pin mapping (change if your backpack is different) */
#define P_RS   0x01   /* P0 → RS */
#define P_RW   0x02   /* P1 → RW */
#define P_EN   0x04   /* P2 → E  */
#define P_BL   0x08   /* P3 → Backlight */
#define DATA_MASK 0xF0


/** spin until BUS not busy, or timeoutCycles hits zero */
static bool waitI2CBusyClear(uint32_t timeoutCycles)
{
    /* keep looping while the BUSY bit remains set */
    while ((EUSCI_B_I2C_isBusBusy(EUSCI_B0_BASE) == EUSCI_B_I2C_BUS_BUSY)
           && --timeoutCycles)
        ;
    return (timeoutCycles != 0);
}

static void i2cWriteByte(uint8_t b)
{
    /* make sure bus is free */
    if (!waitI2CBusyClear(50000)) return;  

    /* generate START + send first byte */
    EUSCI_B_I2C_masterSendMultiByteStart(EUSCI_B0_BASE, b);

    /* wait until the byte is actually out and bus goes busy→idle */
    if (!waitI2CBusyClear(50000)) return;

    /* STOP to free the bus again */
    EUSCI_B_I2C_masterSendMultiByteStop(EUSCI_B0_BASE);

    /* optional small delay for the expander to settle */
    __delay_cycles(50);
}

static void pulse(uint8_t data)
{
    i2cWriteByte(data | P_EN);
    __delay_cycles(200);
    i2cWriteByte(data & ~P_EN);
    __delay_cycles(200);
}

/* send upper or lower nibble with control bits */
static void write4(uint8_t nibble, uint8_t control)
{
    uint8_t out = (nibble << 4) & DATA_MASK;
    out |= control | P_BL;
    i2cWriteByte(out);
    pulse(out);
}

static void send(uint8_t value, uint8_t mode)
{
    write4(value >> 4, mode);
    write4(value & 0x0F, mode);
}

/** Commands (mode = 0), data (mode = P_RS) */
static inline void cmd(uint8_t c) { send(c, 0); }
static inline void data(uint8_t d){ send(d, P_RS); }

void lcdInit(void)
{
    /* 1) Init the MSP I²C peripheral on B0 (P1.6=SCL, P1.7=SDA) */
    GPIO_setAsPeripheralModuleFunctionInputPin(
        GPIO_PORT_P1,
        GPIO_PIN6 | GPIO_PIN7,
        GPIO_PRIMARY_MODULE_FUNCTION
    );

    EUSCI_B_I2C_initMasterParam i2cCfg = {
        .selectClockSource = EUSCI_B_I2C_CLOCKSOURCE_SMCLK,
        .i2cClk          = CS_getSMCLK(),
        .dataRate        = EUSCI_B_I2C_SET_DATA_RATE_100KBPS,
        .byteCounterThreshold = 1,
        .autoSTOPGeneration  = EUSCI_B_I2C_NO_AUTO_STOP,
    };
    EUSCI_B_I2C_initMaster(EUSCI_B0_BASE, &i2cCfg);
    EUSCI_B_I2C_setSlaveAddress(EUSCI_B0_BASE, LCD_I2C_ADDR);
    EUSCI_B_I2C_enable(EUSCI_B0_BASE);

    __delay_cycles(50000);
    /* 4-bit init sequence */
    write4(0x03, 0);
    __delay_cycles(50000);
    write4(0x03, 0);
    __delay_cycles(50000);
    write4(0x03, 0);
    __delay_cycles(50000);
    write4(0x02, 0);
    __delay_cycles(50000);

    /* function set: 2-line, 5×8 dots */
    cmd(0x28);
    /* display off */
    cmd(0x08);
    /* clear */
    cmd(0x01);
    __delay_cycles(20000);
    /* entry mode: cursor moves right */
    cmd(0x06);
    /* display on, cursor off, blink off */
    cmd(0x0C);
}

void lcdPrint(const char *str)
{
    while (*str) {
        data((uint8_t)*str++);
    }
}

void lcdPutChar(char c)
{
    data((uint8_t)c);
}

void lcdSetCursor(uint8_t row, uint8_t col)
{
    /* DDRAM addresses: 0x00 + col for row0, 0x40 + col for row1 */
    uint8_t addr = (row == 0 ? 0x00 : 0x40) + col;
    cmd(0x80 | addr);
}