/*
 * Jexer - Java Text User Interface
 *
 * The MIT License (MIT)
 *
 * Copyright (C) 2019 Kevin Lamonte
 *
 * Permission is hereby granted, free of charge, to any person obtaining a
 * copy of this software and associated documentation files (the "Software"),
 * to deal in the Software without restriction, including without limitation
 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
 * and/or sell copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following conditions:
 *
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
 * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
 * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
 * DEALINGS IN THE SOFTWARE.
 *
 * @author Kevin Lamonte [kevin.lamonte@gmail.com]
 * @version 1
 */
package jexer.tterminal;

import java.awt.Color;
import java.awt.Graphics2D;
import java.awt.image.BufferedImage;
import java.util.HashMap;

/**
 * Sixel parses a buffer of sixel image data into a BufferedImage.
 */
public class Sixel {

    // ------------------------------------------------------------------------
    // Constants --------------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * Parser character scan states.
     */
    private enum ScanState {
        GROUND,
        RASTER,
        COLOR,
        REPEAT,
    }

    // ------------------------------------------------------------------------
    // Variables --------------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * If true, enable debug messages.
     */
    private static boolean DEBUG = false;

    /**
     * Number of pixels to increment when we need more horizontal room.
     */
    private static int WIDTH_INCREASE = 400;

    /**
     * Number of pixels to increment when we need more vertical room.
     */
    private static int HEIGHT_INCREASE = 400;

    /**
     * Maximum width in pixels.
     */
    private static int MAX_WIDTH = 1000;

    /**
     * Maximum height in pixels.
     */
    private static int MAX_HEIGHT = 1000;

    /**
     * Current scanning state.
     */
    private ScanState scanState = ScanState.GROUND;

    /**
     * Parameters being collected.
     */
    private int [] params = new int[5];

    /**
     * Current parameter being collected.
     */
    private int paramsI = 0;

    /**
     * The sixel palette colors specified.
     */
    private HashMap<Integer, Color> palette;

    /**
     * The buffer to parse.
     */
    private String buffer;

    /**
     * The image being drawn to.
     */
    private BufferedImage image;

    /**
     * The real width of image.
     */
    private int width = 0;

    /**
     * The real height of image.
     */
    private int height = 0;

    /**
     * The width of image provided in the raster attribute.
     */
    private int rasterWidth = 0;

    /**
     * The height of image provided in the raster attribute.
     */
    private int rasterHeight = 0;

    /**
     * The repeat count.
     */
    private int repeatCount = -1;

    /**
     * The current drawing x position.
     */
    private int x = 0;

    /**
     * The maximum y drawn to.  This will set the final image height.
     */
    private int y = 0;

    /**
     * The current drawing color.
     */
    private Color color = Color.BLACK;

    /**
     * If set, abort processing this image.
     */
    private boolean abort = false;

    // ------------------------------------------------------------------------
    // Constructors -----------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * Public constructor.
     *
     * @param buffer the sixel data to parse
     * @param palette palette to use, or null for a private palette
     */
    public Sixel(final String buffer, final HashMap<Integer, Color> palette) {
        this.buffer = buffer;
        if (palette == null) {
            this.palette = new HashMap<Integer, Color>();
        } else {
            this.palette = palette;
        }
    }

    // ------------------------------------------------------------------------
    // Sixel ------------------------------------------------------------------
    // ------------------------------------------------------------------------

    /**
     * Get the image.
     *
     * @return the sixel data as an image.
     */
    public BufferedImage getImage() {
        if (buffer != null) {
            for (int i = 0; (i < buffer.length()) && (abort == false); i++) {
                consume(buffer.charAt(i));
            }
            buffer = null;
        }
        if (abort == true) {
            return null;
        }

        if ((width > 0) && (height > 0) && (image != null)) {
            /*
            System.err.println(String.format("%d %d %d %d", width, y + 1,
                    rasterWidth, rasterHeight));
            */

            if ((rasterWidth > width) || (rasterHeight > y + 1)) {
                resizeImage(Math.max(width, rasterWidth),
                    Math.max(y + 1, rasterHeight));
            }
            return image.getSubimage(0, 0, width, y + 1);
        }
        return null;
    }

    /**
     * Resize image to a new size.
     *
     * @param newWidth new width of image
     * @param newHeight new height of image
     */
    private void resizeImage(final int newWidth, final int newHeight) {
        BufferedImage newImage = new BufferedImage(newWidth, newHeight,
            BufferedImage.TYPE_INT_ARGB);

        if (image == null) {
            image = newImage;
            return;
        }

        if (DEBUG) {
            System.err.println("resizeImage(); old " + image.getWidth() + "x" +
                image.getHeight() + " new " + newWidth + "x" + newHeight);
        }

        Graphics2D gr = newImage.createGraphics();
        gr.drawImage(image, 0, 0, image.getWidth(), image.getHeight(), null);
        gr.dispose();
        image = newImage;
    }

    /**
     * Clear the parameters and flags.
     */
    private void toGround() {
        paramsI = 0;
        for (int i = 0; i < params.length; i++) {
            params[i] = 0;
        }
        scanState = ScanState.GROUND;
        repeatCount = -1;
    }

    /**
     * Get a color parameter value, with a default.
     *
     * @param position parameter index.  0 is the first parameter.
     * @param defaultValue value to use if colorParams[position] doesn't exist
     * @return parameter value
     */
    private int getParam(final int position, final int defaultValue) {
        if (position > paramsI) {
            return defaultValue;
        }
        return params[position];
    }

    /**
     * Get a color parameter value, clamped to within min/max.
     *
     * @param position parameter index.  0 is the first parameter.
     * @param defaultValue value to use if colorParams[position] doesn't exist
     * @param minValue minimum value inclusive
     * @param maxValue maximum value inclusive
     * @return parameter value
     */
    private int getParam(final int position, final int defaultValue,
        final int minValue, final int maxValue) {

        assert (minValue <= maxValue);
        int value = getParam(position, defaultValue);
        if (value < minValue) {
            value = minValue;
        }
        if (value > maxValue) {
            value = maxValue;
        }
        return value;
    }

    /**
     * Add sixel data to the image.
     *
     * @param ch the character of sixel data
     */
    private void addSixel(final char ch) {
        int n = ((int) ch - 63);

        if (DEBUG && (color == null)) {
            System.err.println("color is null?!");
            System.err.println(buffer);
        }

        int rgb = color.getRGB();
        int rep = (repeatCount == -1 ? 1 : repeatCount);

        if (DEBUG) {
            System.err.println("addSixel() rep " + rep + " char " +
                Integer.toHexString(n) + " color " + color);
        }

        assert (n >= 0);

        if (image == null) {
            // The raster attributes was not provided.
            resizeImage(WIDTH_INCREASE, HEIGHT_INCREASE);
        }

        if (x + rep > image.getWidth()) {
            // Resize the image, give us another max(rep, WIDTH_INCREASE)
            // pixels of horizontal length.
            resizeImage(image.getWidth() + Math.max(rep, WIDTH_INCREASE),
                image.getHeight());
        }

        // If nothing will be drawn, just advance x.
        if (n == 0) {
            x += rep;
            if (x > width) {
                width = x;
            }
            if (width > MAX_WIDTH) {
                abort = true;
            }
            return;
        }

        int dy = 0;
        for (int i = 0; i < rep; i++) {
            if ((n & 0x01) != 0) {
                dy = 0;
                image.setRGB(x, height + dy, rgb);
            }
            if ((n & 0x02) != 0) {
                dy = 1;
                image.setRGB(x, height + dy, rgb);
            }
            if ((n & 0x04) != 0) {
                dy = 2;
                image.setRGB(x, height + dy, rgb);
            }
            if ((n & 0x08) != 0) {
                dy = 3;
                image.setRGB(x, height + dy, rgb);
            }
            if ((n & 0x10) != 0) {
                dy = 4;
                image.setRGB(x, height + dy, rgb);
            }
            if ((n & 0x20) != 0) {
                dy = 5;
                image.setRGB(x, height + dy, rgb);
            }
            if (height + dy > y) {
                y = height + dy;
            }
            x++;
        }
        if (x > width) {
            width = x;
        }
        if (width > MAX_WIDTH) {
            abort = true;
        }
        if (y + 1 > MAX_HEIGHT) {
            abort = true;
        }
    }

    /**
     * Process a color palette change.
     */
    private void setPalette() {
        int idx = getParam(0, 0);

        if (paramsI == 0) {
            Color newColor = palette.get(idx);
            if (newColor != null) {
                color = newColor;
            } else {
                if (DEBUG) {
                    System.err.println("COLOR " + idx + " NOT FOUND");
                }
                color = Color.BLACK;
            }

            if (DEBUG) {
                System.err.println("set color " + idx + " " + color);
            }
            return;
        }

        int type = getParam(1, 0);
        float red   = (float) (getParam(2, 0, 0, 100) / 100.0);
        float green = (float) (getParam(3, 0, 0, 100) / 100.0);
        float blue  = (float) (getParam(4, 0, 0, 100) / 100.0);

        if (type == 2) {
            Color newColor = new Color(red, green, blue);
            palette.put(idx, newColor);
            if (DEBUG) {
                System.err.println("Palette color " + idx + " --> " + newColor);
            }
        } else {
            if (DEBUG) {
                System.err.println("UNKNOWN COLOR TYPE " + type + ": " + type +
                    " " + idx + " R " + red + " G " + green + " B " + blue);
            }
        }
    }

    /**
     * Parse the raster attributes.
     */
    private void parseRaster() {
        int pan = getParam(0, 0);  // Aspect ratio numerator
        int pad = getParam(1, 0);  // Aspect ratio denominator
        int pah = getParam(2, 0);  // Horizontal width
        int pav = getParam(3, 0);  // Vertical height

        if ((pan == pad) && (pah > 0) && (pav > 0)) {
            rasterWidth = pah;
            rasterHeight = pav;
            if ((rasterWidth <= MAX_WIDTH) && (rasterHeight <= MAX_HEIGHT)) {
                resizeImage(rasterWidth, rasterHeight);
            } else {
                abort = true;
            }
        } else {
            abort = true;
        }
    }

    /**
     * Run this input character through the sixel state machine.
     *
     * @param ch character from the remote side
     */
    private void consume(char ch) {

        // DEBUG
        // System.err.printf("Sixel.consume() %c STATE = %s\n", ch, scanState);

        // Between decimal 63 (inclusive) and 127 (exclusive) --> pixels
        if ((ch >= 63) && (ch < 127)) {
            if (scanState == ScanState.COLOR) {
                setPalette();
            }
            if (scanState == ScanState.RASTER) {
                parseRaster();
                toGround();
            }
            addSixel(ch);
            toGround();
            return;
        }

        if (ch == '#') {
            // Next color is here, parse what we had before.
            if (scanState == ScanState.COLOR) {
                setPalette();
                toGround();
            }
            if (scanState == ScanState.RASTER) {
                parseRaster();
                toGround();
            }
            scanState = ScanState.COLOR;
            return;
        }

        if (ch == '!') {
            // Repeat count
            if (scanState == ScanState.COLOR) {
                setPalette();
                toGround();
            }
            if (scanState == ScanState.RASTER) {
                parseRaster();
                toGround();
            }
            scanState = ScanState.REPEAT;
            repeatCount = 0;
            return;
        }

        if (ch == '-') {
            if (scanState == ScanState.COLOR) {
                setPalette();
                toGround();
            }
            if (scanState == ScanState.RASTER) {
                parseRaster();
                toGround();
            }

            height += 6;
            x = 0;

            if (height + 6 > image.getHeight()) {
                // Resize the image, give us another HEIGHT_INCREASE
                // pixels of vertical length.
                resizeImage(image.getWidth(),
                    image.getHeight() + HEIGHT_INCREASE);
            }
            return;
        }

        if (ch == '$') {
            if (scanState == ScanState.COLOR) {
                setPalette();
                toGround();
            }
            if (scanState == ScanState.RASTER) {
                parseRaster();
                toGround();
            }
            x = 0;
            return;
        }

        if (ch == '"') {
            if (scanState == ScanState.COLOR) {
                setPalette();
                toGround();
            }
            scanState = ScanState.RASTER;
            return;
        }

        switch (scanState) {

        case GROUND:
            // Unknown character.
            if (DEBUG) {
                System.err.println("UNKNOWN CHAR: " + ch);
            }
            return;

        case RASTER:
            // 30-39, 3B --> param
            if ((ch >= '0') && (ch <= '9')) {
                params[paramsI] *= 10;
                params[paramsI] += (ch - '0');
            }
            if (ch == ';') {
                if (paramsI < params.length - 1) {
                    paramsI++;
                }
            }
            return;

        case COLOR:
            // 30-39, 3B --> param
            if ((ch >= '0') && (ch <= '9')) {
                params[paramsI] *= 10;
                params[paramsI] += (ch - '0');
            }
            if (ch == ';') {
                if (paramsI < params.length - 1) {
                    paramsI++;
                }
            }
            return;

        case REPEAT:
            if ((ch >= '0') && (ch <= '9')) {
                if (repeatCount == -1) {
                    repeatCount = (ch - '0');
                } else {
                    repeatCount *= 10;
                    repeatCount += (ch - '0');
                }
            }
            return;

        }

    }

}