import javax.swing.*;
import java.awt.*;
import java.util.ArrayList;
import java.util.HashMap;
import java.util.Collections;
import java.util.Comparator;
import java.util.Calendar;
import java.util.Date;

/*
 * @author
 * Kian Agheli
 *
 * References:
 * https://stackoverflow.com/questions/8693342/drawing-a-simple-line-graph-in-java
 * https://www.geeksforgeeks.org/sorting-a-hashmap-according-to-values/
 * https://stackoverflow.com/questions/16252269/how-to-sort-a-list-arraylist
 * https://stackoverflow.com/questions/2839508/java2d-increase-the-line-width
 * https://stackoverflow.com/questions/4285464/java2d-graphics-anti-aliased
 * https://stackoverflow.com/questions/7182996/java-get-month-integer-from-date
 * https://stackoverflow.com/questions/5799140/java-get-month-string-from-integer
 *
 * Date:
 * 2024-05-08
 *
 * Purpose of class:
 * Draw a line graph.
 */

// A LineGraph is-a JPanel
public class LineGraph extends JPanel {
	private ArrayList<FontFamily> fonts; // A line graph has-a set of fonts
	private final int WIDTH = 640; // A line graph has a preferred width
	private final int HEIGHT = 480; // A line graph has a preferred height
	private final int LINES = 0x10; // A line graph has a maximum lines graphed at a time
	private final int LINE_WIDTH = 3; // A line graph has lines with a given pixel width
	private final int TICK_HEIGHT = 10; // A line graph has ticks with a given pixel height
	/* A line graph has an array of abbreviated month names. */
	private final String[] ABBREVIATED_MONTH = {"Jan", "Feb", "Mar", "Apr", "May", "Jun", "Jul",
		"Aug", "Sep", "Oct", "Nov", "Dec"};
	/* A line graph has an array of unique color values to use for each of the lines. */
	private final int[] COLORS = {0xff0000, 0x00ff00, 0x0000ff, 0xffff00, 0xff00ff, 0x00ffff,
		0xff8040, 0xff4080, 0x80ff40, 0x40ff80, 0x4080ff, 0x8040ff, 0xff8080, 0x80ff80, 0x8080ff,
		0xff4040, 0x40ff40, 0x4040ff};

	/**
	 * Constructor.
	 */
	public LineGraph(ArrayList<FontFamily> fonts) {
		this.fonts = fonts; // Set instance's list of fonts to the list passed.
		this.setPreferredSize(new Dimension(WIDTH, HEIGHT)); // Set the preferred size of the panel.
	}

	/**
	 * Set a point at a pair of coordinates.
	 */
	void setCoordinates(int y, int x) {
	}

	/* Automatically called at construction time. */
	@Override
	public void paintComponent(Graphics g) {
		/* Cast to Graphics2D. Permits use of Graphics2D methods. */
		Graphics2D graphics = (Graphics2D) g;
		/* White background. */
		graphics.setBackground(Color.WHITE);
		/* Fill entire space allocated. No margins or padding. */
		graphics.clearRect(0, 0, getWidth(), getHeight());
		/* Enable anti-aliasing. */
		graphics.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);

		/* Set line width. */
		graphics.setStroke(new BasicStroke(LINE_WIDTH));
		/* Draw in black. */
		graphics.setColor(Color.BLACK);
		/* Store font metrics so as to calculate width and height of each tick's text. */
		FontMetrics metrics = graphics.getFontMetrics();
		/* Store enough space on the left for 12 digits. Assuming tabular figures. */
		int xOffset = metrics.stringWidth("012345678901");
		/* Keep enough space at bottom for text with descenders and ticks. */
		int yMax = getHeight() - (metrics.getHeight() << 1) - TICK_HEIGHT;
		/* Keep enough space at right for the right half of the text "MMM". */
		int xMax = getWidth() - (metrics.stringWidth("MMM") >> 1) - TICK_HEIGHT - xOffset;
		/* Draw x axis. */
		graphics.drawLine(TICK_HEIGHT + xOffset, yMax,
			getWidth(), yMax);

		/* Store calendar, so as to get month. */
		Date date = new Date();
		Calendar calendar = Calendar.getInstance();
		calendar.setTime(date); // Set calendar to current date

		/* For each month in the year, draw a tick on the x axis. */
		int x = xMax;
		int xTicks = 12;
		double xSpace = (float) x / xTicks;

		for (int i = 0; i <= xTicks; i++) {
			graphics.drawLine(x + TICK_HEIGHT + xOffset, yMax,
				x + TICK_HEIGHT + xOffset, getHeight() - metrics.getHeight());
			String month = ABBREVIATED_MONTH[calendar.get(Calendar.MONTH)];
			/* Half the width for centering offset. */
			int textOffset = metrics.stringWidth(month) >> 1;
			graphics.drawString(month, x + TICK_HEIGHT + xOffset - textOffset,
				getHeight() - metrics.getHeight() / 5 * 2);
			x = (int) (x - xSpace); // Decrement x offset.
			calendar.roll(Calendar.MONTH, false); // Roll back by one month
		}

		/* Draw y axis. Subtract one third of stroke width to account for width of first tick. */
		graphics.drawLine(TICK_HEIGHT + xOffset - LINE_WIDTH / 3, 0, TICK_HEIGHT + xOffset -
			LINE_WIDTH / 3, yMax);

		sortFonts("30day"); // Sort the list of fonts by their 30day metrics.

		int y = 0 + metrics.getHeight();
		/* Cast to double within parentheses for floating-point
		division, cast back to int to remove fractional part.
		5/4 spacing for legibility. */
		int yTicks = (int) (yMax / ((double) metrics.getHeight() * 5 / 4));
		/* Sorted values by monthly views in descending order. The greatest value is at the top. */
		long maxViews = fonts.get(0).getViews().get("30day");
		float ySpace = (float) yMax / yTicks;
		for (int i = yTicks; i >= 0; i--) {
			String text = String.format("%d", maxViews * i / yTicks);
			/* Difference between maximum string width and actual string width is offset. */
			int textOff = xOffset - metrics.stringWidth(text);
			graphics.drawString(text, textOff, y);
			y += ySpace;
		}

		/* Draw lines. */
		for (int i = 0; i < LINES; i++) {
			FontFamily font = fonts.get(i); // Keep the current font handy.
			HashMap<String,Long> views = font.getViews(); // Keep the views hashmap handy.

			/* Map of coordinates to draw. */
			HashMap<Integer,Long> coordinates = new HashMap<Integer,Long>();

			/* Use the given metrics to guesstimate the values of each month.
			The last month's views are known. */
			coordinates.put(12, views.get("30day"));

			/* Using 90day views, we may subtract 30day to get a closer approximation
			of 60day views. */
			coordinates.put(11, (views.get("90day") - views.get("30day")) / 2);

			/* Account for changes in views by deriving views 3 months ago from 90day
			views / 3. */
			coordinates.put(10, (views.get("90day") / 3));

			
			/* Guesstimate the rest of the months by yearly views / 12. */
			for (int j = 1; j <= 9; j++) {
				coordinates.put(j, (views.get("year") / 12));
			}

			graphics.setColor(new Color(COLORS[i])); // Set the drawing color.

			/* Previous x and y values. Necessary for drawing lines between points. */
			int xPrevious = 0;
			int yPrevious = 0;
			for (int xCoordinate = 1; xCoordinate <= 12; xCoordinate++) {
				/* x is ratio of month value / 12.
				Because y starts at the top, invert with subtraction from maximum pixel value.
				Ratio of given views over maximum views, multiplied by maximum pixel value.
				Circle with radius of LINE_WIDTH * 2. */
				int xCurrent = xOffset + TICK_HEIGHT + xMax * xCoordinate / 12;
				int yCurrent = yMax - (int) ((float) coordinates.get(xCoordinate) /
					maxViews * yMax);
				graphics.fillOval(xCurrent, yCurrent, LINE_WIDTH << 1, LINE_WIDTH << 1);
				
				/* Line to previous point, if set. */
				if (xPrevious == 0) {
					/* If no previous point, use current y value. */
					graphics.drawLine(xOffset + TICK_HEIGHT + xMax * (xCoordinate - 1) / 12,
						yCurrent, xCurrent, yCurrent);
				} else {
					/* Line from previous x and y to current x and y. */
					graphics.drawLine(xPrevious, yPrevious, xCurrent, yCurrent);
				}

				/* Set previous values for next iteration. */
				yPrevious = yCurrent;
				xPrevious = xCurrent;
			}
		}
	}

	/* Sort by views, in descending order. */
	private void sortFonts(String metric) {
		Collections.sort(fonts, new Comparator<FontFamily>() {
			/* If a is lesser, return 1. If b is lesser, return -1.
			Otherwise, they are equal, return 0. */
			public int compare (FontFamily a, FontFamily b) {
				/* If equal, return 0. */
				if (a.getViews().get(metric) == b.getViews().get(metric)) {
					return 0;
				}

				/* If either is null, it is lesser. */
				if (a.getViews().get(metric) == null) {
					return 1;
				}
				if (b.getViews().get(metric) == null) {
					return -1;
				}

				/* Neither are null, compare. */
				if (a.getViews().get(metric) > b.getViews().get(metric)) {
					return -1;
				}

				/* aViews must be lesser. */
				return 1;
			}
		});
	}
}