#include "lcdlib.h"

// ===================================================================
// Globals
// ===================================================================

static char previous_lines[LCD_HEIGHT][LCD_WIDTH+1];
static FILE *lcd = NULL;
static int line_idx;

static const char* esc = "\x1B[L";

int
lcd_begin(void) {
	lcd = fopen("/dev/lcd", "w");
	if (lcd == NULL) return EXIT_FAILURE;
	fprintf(lcd, "%sB", esc);
	fflush(lcd);
	lcd_clear();
	return EXIT_SUCCESS;
}

void
lcd_end(void) {
	fclose(lcd);
}

void
lcd_clear(void) {
	line_idx = 0;
	for (int y = 0; y + 1 < LCD_HEIGHT; y++) {
		fprintf(lcd, "%sy%dx0;%sk", esc, y, esc);
		previous_lines[y][0] = 0;
	}
	fflush(lcd);
}

void
lcd_put_line(const enum LCD_WRITE_MODE mode, const char *line) {
	if (mode == L_SCROLL && line_idx == LCD_HEIGHT) {
		// If we're at the bottom, ``shift'' everything up
		for (int y = 1; y < LCD_HEIGHT; y++) {
			// Go to the start of row y, clear the line, and print the
			// previous string there
			fprintf(lcd, "%sy%dx0;%sk%s", esc, y-1, esc, previous_lines[y]);
			// Overwrite the stored previous line with the next
			strncpy(previous_lines[y-1], previous_lines[y], 16);
		}
		line_idx--;
	}
	// Go to the correct line, clear it, and write the input.
	fprintf(lcd, "%sy%dx0;%sk%s", esc, line_idx, esc, line);
	fflush(lcd);
	// Store this line, null-terminate!
	strncpy(previous_lines[line_idx], line, 16);
	previous_lines[line_idx][16] = 0;
	if (mode == L_SCROLL && line_idx < LCD_HEIGHT) line_idx++;
}

void
lcd_printf_line(const enum LCD_WRITE_MODE mode,
								const char *format, ...) {
	char buf[16];

	va_list(args);
	va_start(args, format);
	vsnprintf(buf, 16, format, args);
	va_end(args);

	lcd_put_line(mode, buf);
}