#include <stdlib.h>
#include <string.h>
#include <OLEDDisplay.h>
#include <Wire.h>
#include "screen.h"

static void draw_lines(OLEDDisplay *screen, struct display_status *status);
static void update_lines(struct display_status *status);
static void sanitize_msg(char *msg);

void display_status_init(OLEDDisplay *screen, struct display_status *status, char *msg, size_t size, unsigned long int period)
{
	status->period = period;
	status->screen = screen;
	size = MESSAGE_MAX < size ? MESSAGE_MAX : size;
	memset(status->message, 0, size + 1);
	memcpy(status->message, msg, size);
	status->msg_len = size;
	sanitize_msg(status->message);
	status->cursor = status->message;
	status->remaining = status->msg_len;
	update_lines(status);
	draw_lines(status->screen, status);
	status->last_scroll_time = millis();
}

int display_update_scroll(struct display_status *status)
{
	unsigned long crr_time;
	int ret = END_OF_MESSAGE;

	if (status->remaining) {
		crr_time = millis();
		/* Only scroll lines once a period, because --- duh! */
		if ((crr_time - status->last_scroll_time) > status->period) {
			status->last_scroll_time = crr_time;
			update_lines(status);
			draw_lines(status->screen, status);
		}
		ret = 0;
	}

	return ret;
}

/**
 * Turns all whitespace and special characters into literal spaces to save
 * screen real-estate and possible misinterpretation.
 */
static void sanitize_msg(char *msg)
{
	do {
		switch (*msg) {
		case '\f':
		case '\n':
		case '\r':
		case '\t':
		case '\v':
			*msg = ' ';
			break;
		default:
			if (*msg < 0x20 || *msg > 0x7f) {
				*msg = '?';
			}
			break;
		}
	} while (*(++msg));
end:
	return;
}

static void draw_lines(OLEDDisplay *screen, struct display_status *status)
{
	size_t i;
	screen->clear();

	for (i = 0; i < SCREEN_LINE_COUNT; ++i) {
		screen->drawString(0, i * FONT_HEIGHT, status->lines[i]);
	}

	screen->display();
}

static void update_lines(struct display_status *status)
{
	size_t i;

	if (status->remaining) {

		memset(status->lines, 0, sizeof(status->lines));

		for (i = 0; i < SCREEN_LINE_COUNT; ++i) {
			if (status->remaining > SCREEN_LINE_CHARS) {
				memcpy(status->lines[i], status->cursor, SCREEN_LINE_CHARS);
				status->cursor += SCREEN_LINE_CHARS;
				status->remaining -= SCREEN_LINE_CHARS;
			} else if (status->remaining) {
				memcpy(status->lines[i], status->cursor, status->remaining);
				status->cursor += status->remaining;
				status->remaining = 0;
			}
		}
	}
}