#include "lcd_hd44780.h"
#include <stddef.h>

static int isStructOk(cm_lcd_hd44780_t *inst){

	if(inst == NULL)return 0;
	if(inst->setGetGpio_event == NULL) return 0;
	if(inst->wait_event == NULL) return 0;

	return 1;

}

void lcd_hd44780_writeToDisp(cm_lcd_hd44780_t *inst){
	
	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
}
/*
void lcd_hd44780_clearDisp(lcd_hd44780_t *inst){

	return;
	
}

void lcd_hd44780_printf(lcd_hd44780_t *inst, char *string){
	
	return;
	
}*/

static int WaitUntilReady(cm_lcd_hd44780_t *inst){

	// If display is init, then use Polling Busy Flag!
	if(inst->isInit){
		// RS = 0, RW = 1
		inst->gpio_data.rs_pin = 0;
		inst->gpio_data.rw_pin = 1;

		// Read from the data bus
		inst->setGetGpio_event(&(inst->gpio_data), LCD_HD44780_GET);

		// Loop until Busy Flag (D7) is clear
		while (inst->gpio_data.data_bus & 0x80) {
		    inst->setGetGpio_event(&(inst->gpio_data), LCD_HD44780_GET);
		}

		return 1;

	}else{
		inst->wait_event(1);
		return 1;
	}


}

static int lcd_write_8bit(cm_lcd_hd44780_t *inst, uint8_t dataOrCmd, hd44780_InstData_t mode){

	// Set cmd on databus
	inst->gpio_data.data_bus = dataOrCmd;

	// We want to set display
	inst->gpio_data.rw_pin = LCD_HD44780_SET;

	// We want to write an instruction.
	inst->gpio_data.rs_pin = mode;

	// E pin must be high when data is not ready yet.
	inst->gpio_data.e_pin = 1;
	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);

	// Then Clock data in with  E pin. Data is clocked on Falling edge:
	inst->gpio_data.e_pin = 0;
	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
	// Wait until display is ready:
	WaitUntilReady(inst);

	// Then set E pin high so its ready for next time:
	inst->gpio_data.e_pin = 1;
	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
	return 0;

}

static void lcd_writeCmd_disp(cm_lcd_hd44780_t *inst, hd44780_cmd_t cmd, hd44780_setGet_t getSet){


	if(inst->bit_mode == LCD_HD44780_BITMODE_8BIT){

		lcd_write_8bit(inst, cmd, LCD_HD44780_INSTRUCTION);

	}else{

		// Write MSB first.
		lcd_write_8bit(inst, ((cmd >> 4) & 0x0F) << 4, LCD_HD44780_INSTRUCTION);
		// Write LSB last.
		lcd_write_8bit(inst, (cmd & 0x0F) << 4, LCD_HD44780_INSTRUCTION);
	}

}

void lcd_hd44780_printChar(cm_lcd_hd44780_t *inst, char character) {
	if (inst->bit_mode == LCD_HD44780_BITMODE_8BIT) {
		lcd_write_8bit(inst, character, LCD_HD44780_DATA);
		} else {
		// Write MSB first
		lcd_write_8bit(inst, ((character >> 4) & 0x0F) << 4, LCD_HD44780_DATA);
		// Then LSB
		lcd_write_8bit(inst, (character & 0x0F) << 4, LCD_HD44780_DATA);
	}
}

void lcd_hd44780_printf(cm_lcd_hd44780_t *inst, char *string) {
	while (*string) {
		lcd_hd44780_printChar(inst, *string++);
	}
}

void lcd_hd44780_print_xy(cm_lcd_hd44780_t *inst, uint8_t x, uint8_t y, const char *str) {
	// Base DDRAM addresses for each row (for 2-line display)
	const uint8_t row_offsets[] = {0x00, 0x40, 0x14, 0x54}; // for 4-line displays

	if (y > 3) return;  // Prevent invalid row access

	// Set DDRAM address command: 0x80 | (offset + x)
	lcd_writeCmd_disp(inst, 0x80 | (row_offsets[y] + x), LCD_HD44780_SET);

	// Write characters
	while (*str) {
		lcd_hd44780_printChar(inst, *str++);
	}
}

void lcd_hd44780_cursorHome(cm_lcd_hd44780_t *inst) {
	lcd_writeCmd_disp(inst, LCD_HD44780_RETURN_HOME, LCD_HD44780_SET);
}

void lcd_hd44780_clearDisp(cm_lcd_hd44780_t *inst) {
	
	lcd_writeCmd_disp(inst, LCD_HD44780_CLEAR_DISP, LCD_HD44780_SET);

	// Wait for the command to finish.
	// This is a long operation (? 1.53 ms), so if not polling BF, delay at least 2 ms.
	if (!inst->isInit) {
		inst->wait_event(2);
		} else {
		WaitUntilReady(inst);
	}
}


void lcd_hd44780_initDisp(cm_lcd_hd44780_t *inst){

	// Make sure E pin is high when data isnt ready on BUS!
	inst->gpio_data.e_pin = 1;
	inst->setGetGpio_event(&(inst->gpio_data),LCD_HD44780_SET);
	inst->wait_event(1);

	// Wait for more than 15ms after VCC rise..
	inst->wait_event(15);
	lcd_writeCmd_disp(inst, LCD_HD44780_FUNCTION_SET,LCD_HD44780_SET);
	
	// Init display to 4 bit mode if selected!
	if(inst->bit_mode == LCD_HD44780_BITMODE_4BIT){
		
		lcd_write_8bit(inst, 0x20, LCD_HD44780_INSTRUCTION);
		inst->wait_event(1);  // Small delay
	}


	// Wait for 4.1ms..
	// Delay(4)
	inst->wait_event(4);

	lcd_writeCmd_disp(inst, LCD_HD44780_DISP_ONOFF_CTL,LCD_HD44780_SET);

	// delay 100us
	inst->wait_event(1);

	lcd_writeCmd_disp(inst, LCD_HD44780_ENTRY_MODE,LCD_HD44780_SET);

	// Init has been done, and we can now use Busy Flag polling instead of delay!
	//inst->isInit = 0x1;

}

void lcd_hd44780_regGpioEvt(cm_lcd_hd44780_t *inst, setGet_Gpio_Event_fpt getGpioEvt_fpt){
	
	if(inst == NULL)return;
	if(getGpioEvt_fpt == NULL) return;

	inst->setGetGpio_event = getGpioEvt_fpt;
}

void lcd_hd44780_regWaitEvt(cm_lcd_hd44780_t *inst, wait_ms_Event_fpt waitEvt_fpt){

	if(inst == NULL)return;
	if(waitEvt_fpt == NULL) return;

	inst->wait_event = waitEvt_fpt;
}


void lcd_hd44780_init(cm_lcd_hd44780_t *inst, lcd_hd44780_bitmode bit_mode){
	
	if(!isStructOk(inst)) return;

	inst->bit_mode = bit_mode;
	lcd_hd44780_initDisp(inst);
	
	lcd_hd44780_clearDisp(inst);

	return;
}