import * as THREE from 'https://esm.sh/three@0.165.0';
import { OrbitControls } from 'https://esm.sh/three@0.165.0/examples/jsm/controls/OrbitControls.js';

const canvas = document.getElementById('scene');
const progressInput = document.getElementById('progress');
const progressValue = document.getElementById('progress_value');
const urlParams = new URLSearchParams(window.location.search);

const renderer = new THREE.WebGLRenderer({ canvas, antialias: true });
renderer.setPixelRatio(Math.min(window.devicePixelRatio || 1, 2));
renderer.setClearColor(0x202124, 1);

const scene = new THREE.Scene();
const camera = new THREE.PerspectiveCamera(34, 1, 0.1, 30);
if (urlParams.get('view') === 'profile') {
    camera.position.set(0, 0.82, 5.8);
} else if (urlParams.get('view') === 'top') {
    camera.position.set(0, 5.8, 0.001);
} else {
    camera.position.set(0, 3.25, 5.4);
}

const controls = new OrbitControls(camera, canvas);
controls.target.set(0, urlParams.get('view') === 'profile' ? 0.13 : 0.18, 0);
controls.enableDamping = true;
controls.minDistance = 2.2;
controls.maxDistance = 8.0;
controls.update();

const book = new THREE.Group();
scene.add(book);

const guide = new THREE.GridHelper(5.6, 16, 0x4c4c4c, 0x343434);
guide.position.y = -0.12;
scene.add(guide);

const materials = {
    cover: new THREE.MeshBasicMaterial({ color: 0x2c1810, side: THREE.DoubleSide }),
    spine: new THREE.MeshBasicMaterial({ color: 0x9c1f1f, side: THREE.DoubleSide }),
    pagesLeft: new THREE.MeshBasicMaterial({ color: 0xd8c7a4, side: THREE.DoubleSide }),
    pagesRight: new THREE.MeshBasicMaterial({ color: 0xe7d6b4, side: THREE.DoubleSide }),
    topPage: new THREE.MeshBasicMaterial({ color: 0xf1dfba, side: THREE.DoubleSide }),
    edge: new THREE.MeshBasicMaterial({ color: 0xb99a68, side: THREE.DoubleSide }),
    hinge: new THREE.MeshBasicMaterial({ color: 0x2b0808 })
};

const BOOK_PROFILE = {
    tableY: 0,
    coverThickness: 0.03,
    raisedHingeY: 0.056,
    paperContactOffset: 0.0012
};

let readingProgress = readInitialProgress();
progressInput.value = readingProgress.toFixed(3);
progressValue.value = readingProgress.toFixed(2);
rebuildBook();
resize();
animate();

progressInput.addEventListener('input', () => {
    setReadingProgress(progressInput.value);
});

window.addEventListener('resize', resize);

window.BookShapeLab = {
    get progress() {
        return readingProgress;
    },
    setReadingProgress(value) {
        setReadingProgress(value);
        return readingProgress;
    }
};

function readInitialProgress() {
    const parsed = Number.parseFloat(urlParams.get('progress') ?? '0.25');
    return Number.isFinite(parsed) ? THREE.MathUtils.clamp(parsed, 0, 1) : 0.25;
}

function setReadingProgress(value) {
    const next = THREE.MathUtils.clamp(Number.parseFloat(value), 0, 1);
    if (!Number.isFinite(next)) return;
    readingProgress = next;
    progressInput.value = readingProgress.toFixed(3);
    progressValue.value = readingProgress.toFixed(2);
    rebuildBook();
}

function rebuildBook() {
    clearGroup(book);

    const coverDepth = 2.34;
    const coverThickness = BOOK_PROFILE.coverThickness;
    const pageWidth = 1.62;
    const pageDepth = 2.24;
    const gutter = 0.12;
    const sheetTick = 0.0045;
    const fullBlock = 0.41;
    const leftThickness = THREE.MathUtils.lerp(sheetTick, fullBlock, readingProgress);
    const rightThickness = THREE.MathUtils.lerp(fullBlock, sheetTick, readingProgress);
    const foldX = clothFoldX(gutter);
    const spineWidth = fullBlock;

    addCoverAssembly(pageWidth, coverDepth, coverThickness, spineWidth);
    addSplinePageBlock(-1, pageWidth, pageDepth, leftThickness, foldX);
    addSplinePageBlock(1, pageWidth, pageDepth, rightThickness, foldX);
    addPageLayerLines(-1, pageWidth, pageDepth, leftThickness, foldX);
    addPageLayerLines(1, pageWidth, pageDepth, rightThickness, foldX);
    addClothSpine(pageDepth, spineWidth);
}

function clearGroup(group) {
    while (group.children.length) {
        const child = group.children.pop();
        child.geometry?.dispose();
        if (Array.isArray(child.material)) {
            child.material.forEach((material) => material.dispose?.());
        }
    }
}

function addCoverAssembly(pageWidth, depth, thickness, spineWidth) {
    const cover = new THREE.Mesh(createCoverAssemblyGeometry(pageWidth, depth, thickness, spineWidth), materials.cover);
    book.add(cover);
}

function createCoverAssemblyGeometry(pageWidth, depth, thickness, spineWidth) {
    const overhang = 0.055;
    const spineHalf = spineWidth * 0.5;
    const hingeInset = 0.07;
    const outerX = pageWidth + overhang;
    const hingeX = spineHalf + hingeInset;
    const outerTopY = BOOK_PROFILE.tableY + thickness;
    const connectionTopY = BOOK_PROFILE.raisedHingeY;
    const spineTopY = BOOK_PROFILE.tableY + thickness;
    const section = [
        { x: -outerX, y: outerTopY },
        { x: -hingeX, y: connectionTopY },
        { x: -spineHalf, y: spineTopY },
        { x: spineHalf, y: spineTopY },
        { x: hingeX, y: connectionTopY },
        { x: outerX, y: outerTopY }
    ];
    const positions = [];
    const uvs = [];
    const indices = [];
    const frontTop = [];
    const backTop = [];
    const frontBottom = [];
    const backBottom = [];

    const push = (x, y, z, u, v) => {
        const index = positions.length / 3;
        positions.push(x, y, z);
        uvs.push(u, v);
        return index;
    };

    section.forEach((point, index) => {
        const u = index / (section.length - 1);
        frontTop[index] = push(point.x, point.y, depth * 0.5, u, 1);
        backTop[index] = push(point.x, point.y, -depth * 0.5, u, 0);
        frontBottom[index] = push(point.x, point.y - thickness, depth * 0.5, u, 1);
        backBottom[index] = push(point.x, point.y - thickness, -depth * 0.5, u, 0);
    });

    for (let i = 0; i < section.length - 1; i += 1) {
        indices.push(frontTop[i], backTop[i], frontTop[i + 1], frontTop[i + 1], backTop[i], backTop[i + 1]);
        indices.push(frontBottom[i], frontBottom[i + 1], backBottom[i], frontBottom[i + 1], backBottom[i + 1], backBottom[i]);
        indices.push(frontTop[i], frontTop[i + 1], frontBottom[i], frontTop[i + 1], frontBottom[i + 1], frontBottom[i]);
        indices.push(backTop[i], backBottom[i], backTop[i + 1], backTop[i + 1], backBottom[i], backBottom[i + 1]);
    }

    const last = section.length - 1;
    indices.push(frontTop[0], frontBottom[0], backTop[0], backTop[0], frontBottom[0], backBottom[0]);
    indices.push(frontTop[last], backTop[last], frontBottom[last], backTop[last], backBottom[last], frontBottom[last]);

    const geometry = new THREE.BufferGeometry();
    geometry.setIndex(indices);
    geometry.setAttribute('position', new THREE.Float32BufferAttribute(positions, 3));
    geometry.setAttribute('uv', new THREE.Float32BufferAttribute(uvs, 2));
    geometry.computeVertexNormals();
    return geometry;
}

function addSplinePageBlock(side, width, depth, thickness, foldX) {
    const block = new THREE.Mesh(createSplinePageBlockGeometry(side, width, depth, thickness, foldX), side < 0 ? materials.pagesLeft : materials.pagesRight);
    book.add(block);
}

function addPageLayerLines(side, width, depth, thickness, foldX) {
    const material = new THREE.LineBasicMaterial({ color: 0x8f7750, transparent: true, opacity: 0.55 });
    const z = depth * 0.5 + 0.006;
    const lineCount = Math.max(1, Math.round(thickness / 0.018));
    for (let layer = 1; layer < lineCount; layer += 1) {
        const t = layer / lineCount;
        const points = [];
        for (let i = 0; i <= 40; i += 1) {
            const u = 0.04 + 0.96 * (i / 40);
            const top = pageBlockTopY(thickness, u, 0.5);
            const bottom = pageBlockBottomY(thickness, u, 0.5);
            points.push(new THREE.Vector3(pageX(side, foldX, width, u, 0.5), bottom + (top - bottom) * t, z));
        }
        book.add(new THREE.Line(new THREE.BufferGeometry().setFromPoints(points), material));
    }
}

function clothFoldX(gutter) {
    const spineTravel = gutter * 0.52;
    return THREE.MathUtils.lerp(-spineTravel, spineTravel, readingProgress);
}

function addClothSpine(depth, spineWidth) {
    const material = new THREE.LineBasicMaterial({ color: 0xb51f1f });
    const radiusX = spineWidth * 0.42;
    const radiusY = 0.018;
    const baseY = BOOK_PROFILE.tableY + BOOK_PROFILE.coverThickness + 0.002;
    const profile = [];
    for (let i = 0; i <= 32; i += 1) {
        const u = i / 32;
        const theta = Math.PI * (1 - u);
        const x = Math.cos(theta) * radiusX;
        const y = baseY + Math.sin(theta) * radiusY;
        profile.push({ x, y });
    }

    [depth * 0.5 + 0.008, -depth * 0.5 - 0.008].forEach((z) => {
        const points = profile.map((point) => new THREE.Vector3(point.x, point.y, z));
        book.add(new THREE.Line(new THREE.BufferGeometry().setFromPoints(points), material));
    });
}

function pageBlockTopY(thickness, u, v) {
    const hingeWidth = 0.105;
    const hinge = THREE.MathUtils.clamp(u / hingeWidth, 0, 1);
    const t = easeOutCubic(hinge);
    const sewnY = 0.066;
    const stackY = pageBlockBottomY(thickness, u, v) + thickness;
    const flatCrown = 0.006 * Math.sin(Math.PI * v);
    const foreCurl = 0.006 * smoothstep(THREE.MathUtils.clamp((u - 0.88) / 0.12, 0, 1));
    return sewnY * (1 - t) + (stackY + flatCrown + foreCurl) * t;
}

function pageBlockBottomY(thickness, u, v) {
    const supportY = coverSupportTopY(u);
    return supportY + BOOK_PROFILE.paperContactOffset;
}

function coverSupportTopY(u) {
    const hingeSpan = 0.14;
    const t = THREE.MathUtils.clamp((u - hingeSpan) / (1 - hingeSpan), 0, 1);
    return THREE.MathUtils.lerp(BOOK_PROFILE.raisedHingeY, BOOK_PROFILE.coverThickness, t);
}

function smoothstep(value) {
    return value * value * (3 - 2 * value);
}

function easeOutCubic(value) {
    return 1 - Math.pow(1 - value, 3);
}

function pageWidthAtDepth(width, v) {
    return width;
}

function pageX(side, foldX, width, u, v = 0.5) {
    const foreX = side * pageWidthAtDepth(width, v);
    return foldX * (1 - u) + foreX * u;
}

function createSplinePageBlockGeometry(side, width, depth, thickness, foldX) {
    const columns = 36;
    const rows = 36;
    const positions = [];
    const uvs = [];
    const indices = [];
    const top = [];
    const bottom = [];

    const push = (x, y, z, u, v) => {
        const index = positions.length / 3;
        positions.push(x, y, z);
        uvs.push(u, v);
        return index;
    };

    for (let row = 0; row <= rows; row += 1) {
        const v = row / rows;
        top[row] = [];
        bottom[row] = [];
        for (let column = 0; column <= columns; column += 1) {
            const u = column / columns;
            const z = (v - 0.5) * depth;
            top[row][column] = push(pageX(side, foldX, width, u, v), pageBlockTopY(thickness, u, v), z, u, v);
            bottom[row][column] = push(pageX(side, foldX, width, u, v), pageBlockBottomY(thickness, u, v), z, u, v);
        }
    }

    for (let row = 0; row < rows; row += 1) {
        for (let column = 0; column < columns; column += 1) {
            indices.push(top[row][column], top[row + 1][column], top[row][column + 1]);
            indices.push(top[row][column + 1], top[row + 1][column], top[row + 1][column + 1]);
            indices.push(bottom[row][column], bottom[row][column + 1], bottom[row + 1][column]);
            indices.push(bottom[row][column + 1], bottom[row + 1][column + 1], bottom[row + 1][column]);
        }
    }

    for (let row = 0; row < rows; row += 1) {
        indices.push(top[row][0], bottom[row][0], top[row + 1][0], top[row + 1][0], bottom[row][0], bottom[row + 1][0]);
        indices.push(top[row][columns], top[row + 1][columns], bottom[row][columns], top[row + 1][columns], bottom[row + 1][columns], bottom[row][columns]);
    }

    for (let column = 0; column < columns; column += 1) {
        indices.push(top[0][column], top[0][column + 1], bottom[0][column], top[0][column + 1], bottom[0][column + 1], bottom[0][column]);
        indices.push(top[rows][column], bottom[rows][column], top[rows][column + 1], top[rows][column + 1], bottom[rows][column], bottom[rows][column + 1]);
    }

    const geometry = new THREE.BufferGeometry();
    geometry.setIndex(indices);
    geometry.setAttribute('position', new THREE.Float32BufferAttribute(positions, 3));
    geometry.setAttribute('uv', new THREE.Float32BufferAttribute(uvs, 2));
    geometry.computeVertexNormals();
    return geometry;
}

function resize() {
    const width = window.innerWidth;
    const height = window.innerHeight;
    renderer.setSize(width, height, false);
    camera.aspect = width / height;
    camera.updateProjectionMatrix();
}

function animate() {
    requestAnimationFrame(animate);
    if (urlParams.get('animate') === '1') {
        const t = performance.now() * 0.00035;
        setReadingProgress(0.5 + Math.sin(t) * 0.48);
    }
    controls.update();
    renderer.render(scene, camera);
}