#include <SPI.h>
#include <Wire.h>
#include <Adafruit_GFX.h>
#include <Adafruit_SSD1306.h>
#include "marquee.h"

#define SCREEN_WIDTH 128 // OLED display width, in pixels
#define SCREEN_HEIGHT 32 // OLED display height, in pixels

// Declaration for an SSD1306 display connected to I2C (SDA, SCL pins)
// The pins for I2C are defined by the Wire-library. 
// On an arduino UNO:       A4(SDA), A5(SCL)
// On an arduino MEGA 2560: 20(SDA), 21(SCL)
// On an arduino LEONARDO:   2(SDA),  3(SCL), ...
#define OLED_RESET     -1 // Reset pin # (or -1 if sharing Arduino reset pin)
#define SCREEN_ADDRESS 0x3C ///< See datasheet for Address; 0x3D for 128x64, 0x3C for 128x32
Adafruit_SSD1306 display(SCREEN_WIDTH, SCREEN_HEIGHT, &Wire, OLED_RESET);

#define LOGO_HEIGHT   30
#define LOGO_WIDTH    30

// 'logoN', 30x30px
const unsigned char epd_bitmap_logoN [] PROGMEM = {
	0x00, 0x03, 0x00, 0x00, 0x00, 0x04, 0x80, 0x00, 0x00, 0x08, 0x40, 0x00, 0x00, 0x1c, 0x20, 0x00, 
	0x00, 0x2a, 0x10, 0x00, 0x00, 0x51, 0x08, 0x00, 0x00, 0xb8, 0x44, 0x00, 0x00, 0x32, 0x22, 0x00, 
	0x02, 0x70, 0x89, 0x00, 0x04, 0xa3, 0x34, 0x80, 0x08, 0x7f, 0x7f, 0x40, 0x11, 0x67, 0xf7, 0xa0, 
	0x22, 0x37, 0xb1, 0x70, 0x40, 0x9f, 0xf0, 0x28, 0x84, 0x7c, 0xfa, 0x44, 0x89, 0x7c, 0xf8, 0x84, 
	0x50, 0x3f, 0xe4, 0x08, 0x3a, 0x27, 0xb1, 0x10, 0x17, 0xaf, 0xda, 0x20, 0x0b, 0xfb, 0xf8, 0x40, 
	0x04, 0xb3, 0x14, 0x80, 0x02, 0x44, 0x39, 0x00, 0x01, 0x11, 0x12, 0x00, 0x00, 0x88, 0x74, 0x00, 
	0x00, 0x42, 0x28, 0x00, 0x00, 0x21, 0x50, 0x00, 0x00, 0x10, 0xe0, 0x00, 0x00, 0x08, 0x40, 0x00, 
	0x00, 0x04, 0x80, 0x00, 0x00, 0x03, 0x00, 0x00
};

marquee_t* marquee;

void setup() {
	Serial.begin(9600);
	// SSD1306_SWITCHCAPVCC = generate display voltage from 3.3V internally
	if(!display.begin(SSD1306_SWITCHCAPVCC, SCREEN_ADDRESS)) {
		Serial.println(F("SSD1306 allocation failed"));
		for(;;); // Don't proceed, loop forever
	}
	write_logo();
	delay(1000);
	marquee = malloc(sizeof(marquee_t));
	*marquee = make_marquee("Nat King Cole - Sweet Loraine");
}

void loop() {
	//check for serial messages
	if (Serial.available() > 0) {
		int r = 0;
		char* bytesRead = malloc(sizeof(char) * 128);
		//read until null
		while (1) {
			int sa = Serial.available();
			if (sa > 0) {
				r += Serial.readBytes(bytesRead + r, sa);
				if (bytesRead[r-1] == '\n') {
					bytesRead[r-1] = '\0';
					break;
				}
			}
			delay(50);
		}
		handle_serial_msg(bytesRead);
		free(bytesRead);
	}
	write_marquee(marquee);
	if (marquee->scrolledBy == 0) {
		delay(1000);
	}
	//check if message needs to be scrolled
	if (marquee->doesScroll) {
		scroll_marquee(marquee, 2);
	}
	delay(1);
}

//serial messages start with one byte to identify message type
//messages are null terminated
void handle_serial_msg(char* bytesRead) {
	//control messages
	if (bytesRead[0] == 'c') {
		display.ssd1306_command(bytesRead[1] == '0' ? SSD1306_DISPLAYOFF : SSD1306_DISPLAYON);
	}
	//marquee messages
	else if (bytesRead[0] == 'm') {
		*marquee = make_marquee(bytesRead + 1);
	}
}

void write_marquee(marquee_t* marquee) {
	display.clearDisplay();
	//draw chars
	//default char size is 5x8, so our char size is 20x32.
	//therefore, the maximum number of whole characters to be displayed is 6.
	//iterate over string
	for (int i = 0; i < marquee->textLength; i++) {
		//multiply by 21 for 20 character pixels and 1 space pixel
		int charX = (i * 21) - marquee->scrolledBy;
		if (charX > -20 && charX < 128) {
			display.drawChar(charX, 0, marquee->text[i], SSD1306_WHITE, SSD1306_BLACK, 4);
		}
	}
	display.display();
}

void write_logo() {
  display.clearDisplay();

  display.drawBitmap(
    (display.width()  - LOGO_WIDTH ) / 2,
    (display.height() - LOGO_HEIGHT) / 2,
    epd_bitmap_logoN, LOGO_WIDTH, LOGO_HEIGHT, 1);
  display.display();
  delay(1000);
}