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

void draw_lines(OLEDDisplay *screen, struct display_status *status);
void update_lines(struct display_status *status);
void init_msg(char *msg, size_t size);

static char empty_string[] = "";

void display_status_init(OLEDDisplay *screen, struct display_status *status, char *msg)
{
	status->delta = 2;	/* Currently default */
	status->screen = screen;
	init_msg(msg, strlen(msg));
	status->message = msg;
	status->line_cursor = 0;
	status->last_scroll_time = time(NULL);
	update_lines(status);
}

/**
 * Turns all whitespace into literal spaces to save screen real-estate and
 * possible misinterpretation.
 */
void init_msg(char *msg, size_t size)
{
	size_t i;

	for (i = 0; i < size; i++) {
		switch (msg[i]) {
		case '\n':
		case '\t':
		case '\r':
			msg[i] = ' ';
			break;
		case '\0':
			goto end;
		default:
			break;
		}
	}
end:
	return;
}

int display_update_scroll(struct display_status *status)
{
	time_t crr_time = time(NULL);
	/* Only scroll lines once a delta, because --- duh! */
	if (status->last_scroll_time - crr_time > status->delta) {
		status->last_scroll_time += status->delta;
		status->line_cursor++;
		update_lines(status);
		draw_lines(status->screen, status);
	}
	if (!(*status->first_line) && !(*(status->second_line))) {
		return END_OF_MESSAGE;
	} else {
		return 0;
	}
}

void draw_lines(OLEDDisplay *screen, struct display_status *status)
{
	screen->clear();
	screen->drawString(0, 0, status->first_line);
	screen->drawString(0, SCREEN_HEIGHT / 2, status->second_line);
	screen->display();
}

void update_lines(struct display_status *status)
{
	status->first_line = (status->line_cursor * SCREEN_MAX_CHARS < status->message_len)
			? status->message + status->line_cursor * SCREEN_MAX_CHARS
			: empty_string;
	status->second_line = (status->line_cursor * SCREEN_MAX_CHARS < status->message_len)
			? status->message + (status->line_cursor + 1) * SCREEN_MAX_CHARS
			: empty_string;
}