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/*
 * Copyright (c) 2010-2021 Haifeng Li. All rights reserved.
 *
 * Smile is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * Smile is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with Smile.  If not, see .
 */

package smile.plot.swing;

import java.awt.Color;

/**
 * Color palette generator.
 *
 * @author Haifeng Li
 */
public interface Palette {
    Color WHITE = Color.WHITE;
    Color BLACK = Color.BLACK;
    Color LIGHT_GRAY = Color.LIGHT_GRAY;
    Color DARK_GRAY = Color.DARK_GRAY;
    Color SLATE_GRAY = new Color(0X708090);
    Color LIGHT_SLATE_GRAY = new Color(0X6D7B8D);
    Color DARK_SLATE_GRAY = new Color(0X2F4F4F);
    Color RED = Color.RED;
    Color DARK_RED = new Color(0X8B0000);
    Color VIOLET_RED = new Color(0XF6358A);
    Color GREEN = Color.GREEN;
    Color DARK_GREEN = new Color(0X006400);
    Color LIGHT_GREEN = new Color(0X90EE90);
    Color PASTEL_GREEN = new Color(0X00FF00);
    Color FOREST_GREEN = new Color(0X808000);
    Color GRASS_GREEN = new Color(0X408080);
    Color BLUE = Color.BLUE;
    Color NAVY_BLUE = new Color(0X000080);
    Color SLATE_BLUE = new Color(0X6A5ACD);
    Color ROYAL_BLUE = new Color(0X2B60DE);
    Color CADET_BLUE = new Color(0X4C787E);
    Color MIDNIGHT_BLUE = new Color(0X151B54);
    Color SKY_BLUE = new Color(0X6698FF);
    Color STEEL_BLUE = new Color(0X4863A0);
    Color DARK_BLUE = new Color(0X00008B);
    Color MAGENTA = Color.MAGENTA;
    Color DARK_MAGENTA = new Color(0X8B008B);
    Color CYAN = Color.CYAN;
    Color DARK_CYAN = new Color(0X008B8B);
    Color PURPLE = new Color(0XA020F0);
    Color LIGHT_PURPLE = new Color(0XFF0080);
    Color DARK_PURPLE = new Color(0X800080);
    Color ORANGE = Color.ORANGE;
    Color PINK = Color.PINK;
    Color YELLOW = Color.YELLOW;
    Color GOLD = new Color(0XFFD700);
    Color BROWN = new Color(0XA52A2A);
    Color SALMON = new Color(0XFA8072);
    Color TURQUOISE = new Color(0X00FFFF);
    Color BURGUNDY = new Color(0X800000);
    Color PLUM = new Color(0XB93B8F);

    Color[] COLORS = {
        RED,
        BLUE,
        GREEN,
        MAGENTA,
        CYAN,
        PURPLE,
        ORANGE,
        PINK,
        YELLOW,
        GOLD,
        BROWN,
        SALMON,
        TURQUOISE,
        BURGUNDY,
        PLUM,
        DARK_RED,
        VIOLET_RED,
        DARK_GREEN,
        LIGHT_GREEN,
        PASTEL_GREEN,
        FOREST_GREEN,
        GRASS_GREEN,
        NAVY_BLUE,
        SLATE_BLUE,
        ROYAL_BLUE,
        CADET_BLUE,
        MIDNIGHT_BLUE,
        SKY_BLUE,
        STEEL_BLUE,
        DARK_BLUE,
        DARK_MAGENTA,
        DARK_CYAN,
        LIGHT_PURPLE,
        DARK_PURPLE,
        LIGHT_GRAY,
        DARK_GRAY,
        SLATE_GRAY,
        LIGHT_SLATE_GRAY,
        DARK_SLATE_GRAY,
        BLACK,
    };

    /**
     * Generate terrain color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] terrain(int n) {
        return terrain(n, 1.0f);
    }

    /**
     * Generate terrain color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] terrain(int n, float alpha) {
        int k = n / 2;
        float[] H = {4 / 12f, 2 / 12f, 0 / 12f};
        float[] S = {1f, 1f, 0f};
        float[] V = {0.65f, 0.9f, 0.95f};

        Color[] palette = new Color[n];

        float h = H[0];
        float hw = (H[1] - H[0]) / (k - 1);

        float s = S[0];
        float sw = (S[1] - S[0]) / (k - 1);

        float v = V[0];
        float vw = (V[1] - V[0]) / (k - 1);

        for (int i = 0; i <
                k; i++) {
            palette[i] = hsv(h, s, v, alpha);
            h +=
                    hw;
            s +=
                    sw;
            v +=
                    vw;
        }

        h = H[1];
        hw = (H[2] - H[1]) / (n - k);

        s = S[1];
        sw = (S[2] - S[1]) / (n - k);

        v = V[1];
        vw = (V[2] - V[1]) / (n - k);

        for (int i = k; i < n; i++) {
            h += hw;
            s += sw;
            v += vw;
            palette[i] = hsv(h, s, v, alpha);
        }

        return palette;
    }

    /**
     * Generate topo color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] topo(int n) {
        return topo(n, 1.0f);
    }

    /**
     * Generate topo color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] topo(int n, float alpha) {
        int j = n / 3;
        int k = n / 3;
        int i = n - j - k;

        Color[] palette = new Color[n];

        float h = 43 / 60.0f;
        float hw = (31 / 60.0f - h) / (i - 1);
        int l = 0;
        for (; l < i; l++) {
            palette[l] = hsv(h, 1.0f, 1.0f, alpha);
            h += hw;
        }

        h = 23 / 60.0f;
        hw = (11 / 60.0f - h) / (j - 1);
        for (; l < i + j; l++) {
            palette[l] = hsv(h, 1.0f, 1.0f, alpha);
            h += hw;
        }

        h = 10 / 60.0f;
        hw = (6 / 60.0f - h) / (k - 1);
        float s = 1.0f;
        float sw = (0.3f - s) / (k - 1);
        for (; l < n; l++) {
            palette[l] = hsv(h, s, 1.0f, alpha);
            h += hw;
            s += sw;
        }

        return palette;
    }

    /**
     * Generate jet color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] jet(int n) {
        return jet(n, 1.0f);
    }

    /**
     * Generate jet color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] jet(int n, float alpha) {
        int m = (int) Math.ceil(n / 4);

        float[] u = new float[3 * m];
        for (int i = 0; i < u.length; i++) {
            if (i == 0) {
                u[i] = 0.0f;
            } else if (i <= m) {
                u[i] = i / (float) m;
            } else if (i <= 2 * m - 1) {
                u[i] = 1.0f;
            } else {
                u[i] = (3 * m - i) / (float) m;
            }

        }

        int m2 = m / 2 + m % 2;
        int mod = n % 4;
        int[] r = new int[n];
        int[] g = new int[n];
        int[] b = new int[n];
        for (int i = 0; i < u.length - 1; i++) {
            if (m2 - mod + i < n) {
                g[m2 - mod + i] = i + 1;
            }
            if (m2 - mod + i + m < n) {
                r[m2 - mod + i + m] = i + 1;
            }
            if (i > 0 && m2 - mod + i < u.length) {
                b[i] = m2 - mod + i;
            }
        }

        Color[] palette = new Color[n];
        for (int i = 0; i < n; i++) {
            palette[i] = new Color(u[r[i]], u[g[i]], u[b[i]], alpha);
        }

        return palette;
    }

    /**
     * Generate red-green color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] redgreen(int n) {
        return redgreen(n, 1.0f);
    }

    /**
     * Generate red-green color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] redgreen(int n, float alpha) {
        Color[] palette = new Color[n];
        for (int i = 0; i < n; i++) {
            palette[i] = new Color((float) Math.sqrt((i + 1.0f) / n), (float) Math.sqrt(1 - (i + 1.0f) / n), 0.0f, alpha);
        }

        return palette;
    }

    /**
     * Generate red-blue color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] redblue(int n) {
        return redblue(n, 1.0f);
    }

    /**
     * Generate red-blue color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] redblue(int n, float alpha) {
        Color[] palette = new Color[n];
        for (int i = 0; i < n; i++) {
            palette[i] = new Color((float) Math.sqrt((i + 1.0f) / n), 0.0f, (float) Math.sqrt(1 - (i + 1.0f) / n), alpha);
        }

        return palette;
    }

    /**
     * Generate heat color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] heat(int n) {
        return heat(n, 1.0f);
    }

    /**
     * Generate heat color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] heat(int n, float alpha) {
        int j = n / 4;
        int k = n - j;
        float h = 1.0f / 6;

        Color[] c = rainbow(k, 0, h, alpha);

        Color[] palette = new Color[n];
        System.arraycopy(c, 0, palette, 0, k);

        float s = 1 - 1.0f / (2 * j);
        float end = 1.0f / (2 * j);
        float w = (end - s) / (j - 1);

        for (int i = k; i < n; i++) {
            palette[i] = hsv(h, s, 1.0f, alpha);
            s += w;
        }

        return palette;
    }

    /**
     * Generate rainbow color palette.
     * @param n the number of colors in the palette.
     */
    static Color[] rainbow(int n) {
        return rainbow(n, 1.0f);
    }

    /**
     * Generate rainbow color palette.
     * @param n the number of colors in the palette.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] rainbow(int n, float alpha) {
        return rainbow(n, 0.0f, (float) (n - 1) / n, alpha);
    }

    /**
     * Generate rainbow color palette.
     * @param n the number of colors in the palette.
     * @param start the start of h in the HSV color model.
     * @param end the start of h in the HSV color model.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] rainbow(int n, float start, float end, float alpha) {
        return rainbow(n, start, end, 1.0f, 1.0f, alpha);
    }

    /**
     * Generate rainbow color palette.
     * @param n the number of colors in the palette.
     * @param start the start of h in the HSV color model.
     * @param end the start of h in the HSV color model.
     * @param s the s in the HSV color model.
     * @param v the v in the HSV color model.
     * @param alpha the parameter in [0,1] for transparency.
     */
    static Color[] rainbow(int n, float start, float end, float s, float v, float alpha) {
        Color[] palette = new Color[n];
        float h = start;
        float w = (end - start) / (n - 1);
        for (int i = 0; i < n; i++) {
            palette[i] = hsv(h, s, v, alpha);
            h += w;
        }

        return palette;
    }

    /**
     * Generate a color based on HSV model.
     */
    static Color hsv(float h, float s, float v, float alpha) {
        float r = 0;
        float g = 0;
        float b = 0;

        if (s == 0) {
            // this color in on the black white center line <=> h = UNDEFINED
            // Achromatic color, there is no hue
            r = v;
            g = v;
            b = v;
        } else {
            if (h == 1.0f) {
                h = 0.0f;
            }

            // h is now in [0,6)
            h *= 6;

            int i = (int) Math.floor(h);
            float f = h - i; //f is fractional part of h
            float p = v * (1 - s);
            float q = v * (1 - (s * f));
            float t = v * (1 - (s * (1 - f)));

            switch (i) {
                case 0:
                    r = v;
                    g = t;
                    b = p;
                    break;

                case 1:
                    r = q;
                    g = v;
                    b = p;
                    break;

                case 2:
                    r = p;
                    g = v;
                    b = t;
                    break;

                case 3:
                    r = p;
                    g = q;
                    b = v;
                    break;

                case 4:
                    r = t;
                    g = p;
                    b = v;
                    break;

                case 5:
                    r = v;
                    g = p;
                    b = q;
                    break;

            }
        }

        return new Color(r, g, b, alpha);
    }
}