/*
 * Vencord, a Discord client mod
 * Copyright (c) 2023 Vendicated and contributors
 * SPDX-License-Identifier: GPL-3.0-or-later
 */

import "./clientTheme.css";

import { definePluginSettings } from "@api/Settings";
import { Devs } from "@utils/constants";
import { getTheme, Theme } from "@utils/discord";
import { Margins } from "@utils/margins";
import { classes } from "@utils/misc";
import definePlugin, { OptionType, StartAt } from "@utils/types";
import { findComponentByCodeLazy } from "@webpack";
import { Button, Forms } from "@webpack/common";

const ColorPicker = findComponentByCodeLazy(".Messages.USER_SETTINGS_PROFILE_COLOR_SELECT_COLOR", ".BACKGROUND_PRIMARY)");

const colorPresets = [
    "#1E1514", "#172019", "#13171B", "#1C1C28", "#402D2D",
    "#3A483D", "#344242", "#313D4B", "#2D2F47", "#322B42",
    "#3C2E42", "#422938"
];

function onPickColor(color: number) {
    const hexColor = color.toString(16).padStart(6, "0");

    settings.store.color = hexColor;
    updateColorVars(hexColor);
}

function ThemeSettings() {
    const lightnessWarning = hexToLightness(settings.store.color) > 45;
    const lightModeWarning = getTheme() === Theme.Light;

    return (
        <div className="client-theme-settings">
            <div className="client-theme-container">
                <div className="client-theme-settings-labels">
                    <Forms.FormTitle tag="h3">Theme Color</Forms.FormTitle>
                    <Forms.FormText>Add a color to your Discord client theme</Forms.FormText>
                </div>
                <ColorPicker
                    color={parseInt(settings.store.color, 16)}
                    onChange={onPickColor}
                    showEyeDropper={false}
                    suggestedColors={colorPresets}
                />
            </div>
            {lightnessWarning || lightModeWarning
                ? <div>
                    <Forms.FormDivider className={classes(Margins.top8, Margins.bottom8)} />
                    <Forms.FormText className="client-theme-warning">Your theme won't look good:</Forms.FormText>
                    {lightnessWarning && <Forms.FormText className="client-theme-warning">Selected color is very light</Forms.FormText>}
                    {lightModeWarning && <Forms.FormText className="client-theme-warning">Light mode isn't supported</Forms.FormText>}
                </div>
                : null
            }
        </div>
    );
}

const settings = definePluginSettings({
    color: {
        description: "Color your Discord client theme will be based around. Light mode isn't supported",
        type: OptionType.COMPONENT,
        default: "313338",
        component: () => <ThemeSettings />
    },
    resetColor: {
        description: "Reset Theme Color",
        type: OptionType.COMPONENT,
        default: "313338",
        component: () => (
            <Button onClick={() => onPickColor(0x313338)}>
                Reset Theme Color
            </Button>
        )
    }
});

export default definePlugin({
    name: "ClientTheme",
    authors: [Devs.F53, Devs.Nuckyz],
    description: "Recreation of the old client theme experiment. Add a color to your Discord client theme",
    settings,

    startAt: StartAt.DOMContentLoaded,
    start() {
        updateColorVars(settings.store.color);
        generateColorOffsets();
    },

    stop() {
        document.getElementById("clientThemeVars")?.remove();
        document.getElementById("clientThemeOffsets")?.remove();
    }
});

const variableRegex = /(--primary-[5-9]\d{2}-hsl):.*?(\S*)%;/g;

async function generateColorOffsets() {

    const styleLinkNodes = document.querySelectorAll('link[rel="stylesheet"]');
    const variableLightness = {} as Record<string, number>;

    // Search all stylesheets for color variables
    for (const styleLinkNode of styleLinkNodes) {
        const cssLink = styleLinkNode.getAttribute("href");
        if (!cssLink) continue;

        const res = await fetch(cssLink);
        const cssString = await res.text();

        // Get lightness values of --primary variables >=500
        let variableMatch = variableRegex.exec(cssString);
        while (variableMatch !== null) {
            const [, variable, lightness] = variableMatch;
            variableLightness[variable] = parseFloat(lightness);
            variableMatch = variableRegex.exec(cssString);
        }
    }

    // Generate offsets
    const lightnessOffsets = Object.entries(variableLightness)
        .map(([key, lightness]) => {
            const lightnessOffset = lightness - variableLightness["--primary-600-hsl"];
            const plusOrMinus = lightnessOffset >= 0 ? "+" : "-";
            return `${key}: var(--theme-h) var(--theme-s) calc(var(--theme-l) ${plusOrMinus} ${Math.abs(lightnessOffset).toFixed(2)}%);`;
        })
        .join("\n");

    const style = document.createElement("style");
    style.setAttribute("id", "clientThemeOffsets");
    style.textContent = `:root:root {
        ${lightnessOffsets}
    }`;
    document.head.appendChild(style);
}

function updateColorVars(color: string) {
    const { hue, saturation, lightness } = hexToHSL(color);

    let style = document.getElementById("clientThemeVars");
    if (!style) {
        style = document.createElement("style");
        style.setAttribute("id", "clientThemeVars");
        document.head.appendChild(style);
    }

    style.textContent = `:root {
        --theme-h: ${hue};
        --theme-s: ${saturation}%;
        --theme-l: ${lightness}%;
    }`;
}

// https://css-tricks.com/converting-color-spaces-in-javascript/
function hexToHSL(hexCode: string) {
    // Hex => RGB normalized to 0-1
    const r = parseInt(hexCode.substring(0, 2), 16) / 255;
    const g = parseInt(hexCode.substring(2, 4), 16) / 255;
    const b = parseInt(hexCode.substring(4, 6), 16) / 255;

    // RGB => HSL
    const cMax = Math.max(r, g, b);
    const cMin = Math.min(r, g, b);
    const delta = cMax - cMin;

    let hue: number, saturation: number, lightness: number;

    lightness = (cMax + cMin) / 2;

    if (delta === 0) {
        // If r=g=b then the only thing that matters is lightness
        hue = 0;
        saturation = 0;
    } else {
        // Magic
        saturation = delta / (1 - Math.abs(2 * lightness - 1));

        if (cMax === r)
            hue = ((g - b) / delta) % 6;
        else if (cMax === g)
            hue = (b - r) / delta + 2;
        else
            hue = (r - g) / delta + 4;
        hue *= 60;
        if (hue < 0)
            hue += 360;
    }

    // Move saturation and lightness from 0-1 to 0-100
    saturation *= 100;
    lightness *= 100;

    return { hue, saturation, lightness };
}

// Minimized math just for lightness, lowers lag when changing colors
function hexToLightness(hexCode: string) {
    // Hex => RGB normalized to 0-1
    const r = parseInt(hexCode.substring(0, 2), 16) / 255;
    const g = parseInt(hexCode.substring(2, 4), 16) / 255;
    const b = parseInt(hexCode.substring(4, 6), 16) / 255;

    const cMax = Math.max(r, g, b);
    const cMin = Math.min(r, g, b);

    const lightness = 100 * ((cMax + cMin) / 2);

    return lightness;
}