// Pure geometry math for GeckoLib/Blockbench geo.json models.
// No Three.js dependency — shared by model_viewer.js (browser) and unit tests (Node).
//
// Transforms follow the GeckoLib convention: each bone contributes
//   local = T(pivot) · R(bone.rotation) · T(−pivot)
// and cubes are authored in model space (origin at feet, Y up).
// `build()` flattens the bone tree into world-space cubes, avoiding the
// nested-pivot double-counting that broke naive group-based renderers.
(function (global, factory) {
    if (typeof module !== 'undefined' && module.exports) {
        module.exports = factory();
    } else {
        global.GeoBuilder = factory();
    }
})(typeof self !== 'undefined' ? self : this, function () {
    'use strict';

    var DEG = Math.PI / 180;

    // ---------- minimal 4x4 matrix helpers (column-major, Three.js order) ----------
    function identity() {
        return [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1];
    }

    function multiply(a, b) {
        var out = new Array(16);
        for (var c = 0; c < 4; c++) {
            for (var r = 0; r < 4; r++) {
                out[c * 4 + r] =
                    a[0 * 4 + r] * b[c * 4 + 0] +
                    a[1 * 4 + r] * b[c * 4 + 1] +
                    a[2 * 4 + r] * b[c * 4 + 2] +
                    a[3 * 4 + r] * b[c * 4 + 3];
            }
        }
        return out;
    }

    function translation(x, y, z) {
        return [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, x, y, z, 1];
    }

    function rotationXYZ(rx, ry, rz) {
        var cx = Math.cos(rx), sx = Math.sin(rx);
        var cy = Math.cos(ry), sy = Math.sin(ry);
        var cz = Math.cos(rz), sz = Math.sin(rz);
        // R = Rz * Ry * Rx (matches Three.js Euler 'XYZ' default order)
        var r = identity();
        r[0] = cy * cz;
        r[1] = cy * sz;
        r[2] = -sy;
        r[4] = sx * sy * cz - cx * sz;
        r[5] = sx * sy * sz + cx * cz;
        r[6] = sx * cy;
        r[8] = cx * sy * cz + sx * sz;
        r[9] = cx * sy * sz - sx * cz;
        r[10] = cx * cy;
        return r;
    }

    function transformPoint(m, p) {
        var x = p[0], y = p[1], z = p[2];
        var w = m[3] * x + m[7] * y + m[11] * z + m[15];
        return [
            (m[0] * x + m[4] * y + m[8] * z + m[12]) / w,
            (m[1] * x + m[5] * y + m[9] * z + m[13]) / w,
            (m[2] * x + m[6] * y + m[10] * z + m[14]) / w,
        ];
    }

    // ---------- box UV ----------
    // Minecraft "box UV" face rects (u, v, w, h) in texture pixels.
    function boxUVRects(uv, size) {
        var u = uv[0], v = uv[1];
        var x = size[0], y = size[1], z = size[2];
        return {
            top: [u + z, v, x, z],
            bottom: [u + z + x, v, x, z],
            north: [u + z, v + z, x, y],
            south: [u + z + x, v + z, x, y],
            east: [u, v + z, z, y],
            west: [u + z + x + z, v + z, z, y],
        };
    }

    // Build one cube as a BufferGeometry-compatible mesh:
    // 24 positions (6 faces x 4 corners), 24 UVs, 36 indices, outward winding.
    function cubeGeometry(size, uv, tw, th) {
        var hx = size[0] / 2, hy = size[1] / 2, hz = size[2] / 2;
        var rects = boxUVRects(uv, size);
        var order = ['east', 'west', 'top', 'bottom', 'south', 'north'];
        var outward = {
            east: [1, 0, 0], west: [-1, 0, 0],
            top: [0, 1, 0], bottom: [0, -1, 0],
            south: [0, 0, 1], north: [0, 0, -1],
        };

        var positions = [];
        var uvs = [];
        var indices = [];
        var v = 0;

        function pushFace(face, corners) {
            var a = corners[0], b = corners[1], c = corners[2];
            var abx = b[0] - a[0], aby = b[1] - a[1], abz = b[2] - a[2];
            var acx = c[0] - a[0], acy = c[1] - a[1], acz = c[2] - a[2];
            var nx = aby * acz - abz * acy;
            var ny = abz * acx - abx * acz;
            var nz = abx * acy - aby * acx;
            var out = outward[face];
            if (nx * out[0] + ny * out[1] + nz * out[2] < 0) {
                var tmp = corners[1];
                corners[1] = corners[2];
                corners[2] = tmp;
            }
            for (var i = 0; i < 4; i++) {
                var cor = corners[i];
                positions.push(cor[0], cor[1], cor[2]);
                uvs.push(cor[3], cor[4]);
            }
            indices.push(v, v + 1, v + 2, v, v + 2, v + 3);
            v += 4;
        }

        for (var i = 0; i < order.length; i++) {
            var face = order[i];
            var rect = rects[face];
            var u0 = rect[0] / tw, u1 = (rect[0] + rect[2]) / tw;
            var vTop = 1 - (rect[1] + rect[3]) / th;
            var vBot = 1 - rect[1] / th;
            var cs;
            if (face === 'east') {
                cs = [
                    [hx, hy, -hz, u1, vTop], [hx, hy, hz, u0, vTop],
                    [hx, -hy, hz, u0, vBot], [hx, -hy, -hz, u1, vBot],
                ];
            } else if (face === 'west') {
                cs = [
                    [-hx, hy, hz, u1, vTop], [-hx, hy, -hz, u0, vTop],
                    [-hx, -hy, -hz, u0, vBot], [-hx, -hy, hz, u1, vBot],
                ];
            } else if (face === 'top') {
                cs = [
                    [-hx, hy, hz, u0, vTop], [hx, hy, hz, u1, vTop],
                    [hx, hy, -hz, u1, vBot], [-hx, hy, -hz, u0, vBot],
                ];
            } else if (face === 'bottom') {
                cs = [
                    [-hx, -hy, -hz, u0, vTop], [hx, -hy, -hz, u1, vTop],
                    [hx, -hy, hz, u1, vBot], [-hx, -hy, hz, u0, vBot],
                ];
            } else if (face === 'south') {
                cs = [
                    [hx, hy, hz, u0, vTop], [-hx, hy, hz, u1, vTop],
                    [-hx, -hy, hz, u1, vBot], [hx, -hy, hz, u0, vBot],
                ];
            } else { // north
                cs = [
                    [-hx, hy, -hz, u0, vTop], [hx, hy, -hz, u1, vTop],
                    [hx, -hy, -hz, u1, vBot], [-hx, -hy, -hz, u0, vBot],
                ];
            }
            pushFace(face, cs);
        }

        return { positions: positions, uvs: uvs, indices: indices };
    }

    // ---------- model build ----------
    // Returns { cubes: [{matrix, size, uv, texture}], texture_width, texture_height }
    function build(geo) {
        var geometry = ((geo['minecraft:geometry'] || [])[0]) || null;
        if (!geometry) return { cubes: [], texture_width: 64, texture_height: 64 };
        var tw = (geometry.description && geometry.description.texture_width) || 64;
        var th = (geometry.description && geometry.description.texture_height) || 64;
        var textures = geo['afw_bone_textures'] || {};
        var defaultTex = null;
        for (var k in textures) { defaultTex = textures[k]; break; }

        var bones = {};
        (geometry.bones || []).forEach(function (b) { bones[b.name] = b; });

        var cubes = [];
        function walk(name, parentMatrix) {
            var bone = bones[name];
            if (!bone) return;
            var pivot = bone.pivot || [0, 0, 0];
            // Bedrock/GeckoLib rotations are opposite the Three.js default
            // direction, so negate the Euler angles (identity models unaffected).
            var rot = (bone.rotation || [0, 0, 0]).map(function (d) { return -d * DEG; });
            var local = multiply(
                translation(pivot[0], pivot[1], pivot[2]),
                multiply(
                    rotationXYZ(rot[0], rot[1], rot[2]),
                    translation(-pivot[0], -pivot[1], -pivot[2])
                )
            );
            var world = multiply(parentMatrix, local);
            var tex = textures[name] || defaultTex;

            (bone.cubes || []).forEach(function (c) {
                var origin = c.origin || [0, 0, 0];
                var size = c.size || [1, 1, 1];
                var cRot = (c.rotation || [0, 0, 0]).map(function (d) { return -d * DEG; });
                var cubeWorld = multiply(
                    world,
                    multiply(
                        translation(origin[0], origin[1], origin[2]),
                        multiply(
                            rotationXYZ(cRot[0], cRot[1], cRot[2]),
                            translation(size[0] / 2, size[1] / 2, size[2] / 2)
                        )
                    )
                );
                cubes.push({
                    matrix: cubeWorld,
                    size: size,
                    uv: c.uv || [0, 0],
                    texture: tex,
                });
            });

            for (var child in bones) {
                if (bones[child].parent === name) walk(child, world);
            }
        }

        for (var root in bones) {
            if (!bones[root].parent) walk(root, identity());
        }

        return { cubes: cubes, texture_width: tw, texture_height: th };
    }

    return {
        build: build,
        cubeGeometry: cubeGeometry,
        boxUVRects: boxUVRects,
        transformPoint: transformPoint,
        identity: identity,
        translation: translation,
        rotationXYZ: rotationXYZ,
        multiply: multiply,
    };
});