import { createHash } from "node:crypto";
import path from "node:path";
import { Document, NodeIO } from "@gltf-transform/core";
import { ALL_EXTENSIONS } from "@gltf-transform/extensions";
import { getBounds, mergeDocuments, unpartition } from "@gltf-transform/functions";
import { Matrix4, Quaternion, Vector3 } from "three";

const SUPPORTED_RESOURCE_EXTENSIONS = new Set([".ros"]);
const DYNAMIC_HINT_PATTERN = /(?:^|[\\/_-])(door|gate|bridge|drawbridge|lift|elevator|switch|lever|chest|treasure|portal)(?:[\\/_.-]|$)/i;
const DYNAMIC_KINDS = new Set([
  "door",
  "gate",
  "bridge",
  "lift",
  "switch",
  "chest",
  "portal",
  "other",
]);

export function normalizeWdbResourcePath(value) {
  return String(value ?? "")
    .replaceAll("/", "\\")
    .replace(/^\\+/, "")
    .toLowerCase();
}

export function resourceCacheKey(value) {
  return createHash("sha256")
    .update(normalizeWdbResourcePath(value))
    .digest("hex")
    .slice(0, 24);
}

function finiteTuple(value, length, name) {
  if (!Array.isArray(value) || value.length !== length
    || value.some((entry) => !Number.isFinite(Number(entry)))) {
    throw new Error(name + " must contain exactly " + length + " finite numbers.");
  }
  return value.map(Number);
}

export function descriptorSourceMatrix(descriptor) {
  const translation = finiteTuple(descriptor.translation, 3, "descriptor.translation");
  const rotation = finiteTuple(descriptor.rotation, 4, "descriptor.rotation");
  const scale = finiteTuple(descriptor.scale, 3, "descriptor.scale");
  const quaternion = new Quaternion(...rotation);
  if (quaternion.lengthSq() < 1e-12) throw new Error("descriptor.rotation cannot be zero.");
  quaternion.normalize();
  return new Matrix4().compose(
    new Vector3(...translation),
    quaternion,
    new Vector3(...scale),
  );
}

export function placementMatrixInPrimaryThree(descriptor, primary, metersPerSourceUnit) {
  const meters = Number(metersPerSourceUnit);
  if (!Number.isFinite(meters) || meters <= 0) {
    throw new Error("metersPerSourceUnit must be a positive finite number.");
  }
  const sourceToThree = new Matrix4().makeScale(meters, meters, -meters);
  const threeToSource = sourceToThree.clone().invert();
  return sourceToThree
    .clone()
    .multiply(descriptorSourceMatrix(primary).invert())
    .multiply(descriptorSourceMatrix(descriptor))
    .multiply(threeToSource);
}

export function transformSourcePointToPrimaryThree(
  sourcePoint,
  descriptor,
  primary,
  metersPerSourceUnit,
) {
  const point = new Vector3(...finiteTuple(sourcePoint, 3, "sourcePoint"));
  point.applyMatrix4(descriptorSourceMatrix(descriptor));
  point.applyMatrix4(descriptorSourceMatrix(primary).invert());
  const meters = Number(metersPerSourceUnit);
  return [point.x * meters, point.y * meters, -point.z * meters];
}

function cloneNodeTree(document, node) {
  const clone = document.createNode(node.getName())
    .setMatrix(node.getMatrix())
    .setExtras({ ...node.getExtras() })
    .setMesh(node.getMesh())
    .setCamera(node.getCamera())
    .setSkin(node.getSkin())
    .setWeights([...node.getWeights()]);
  for (const child of node.listChildren()) clone.addChild(cloneNodeTree(document, child));
  return clone;
}

export async function assembleInstancedGlb(records, outputFile) {
  if (!records.length) throw new Error("Cannot assemble an empty WDB GLB.");
  const io = new NodeIO().registerExtensions(ALL_EXTENSIONS);
  const target = new Document();
  const scene = target.createScene("WDB assembly");
  const recordsByAsset = new Map();
  for (const record of records) {
    const rows = recordsByAsset.get(record.assetFile) ?? [];
    rows.push(record);
    recordsByAsset.set(record.assetFile, rows);
  }
  for (const assetFile of [...recordsByAsset.keys()].sort()) {
    const source = await io.read(assetFile);
    const sourceScene = source.getRoot().getDefaultScene() ?? source.getRoot().listScenes()[0];
    if (!sourceScene) throw new Error("Cached WDB resource has no scene: " + assetFile);
    const mapping = mergeDocuments(target, source);
    const mergedScene = mapping.get(sourceScene);
    if (!mergedScene) throw new Error("Could not merge cached WDB resource: " + assetFile);
    const roots = mergedScene.listChildren();
    if (!roots.length) throw new Error("Cached WDB resource has no scene roots: " + assetFile);
    for (const [index, record] of recordsByAsset.get(assetFile).entries()) {
      const placement = target.createNode(record.placement.id)
        .setMatrix(record.placement.transform.primaryLocalThreeMatrix)
        .setExtras({
          wdbPlacementId: record.placement.id,
          wdbGuid: record.placement.guid,
          sourceResource: record.placement.resource,
          resourceCacheKey: record.placement.resourceCacheKey,
        });
      const nodes = index === 0
        ? roots
        : roots.map((rootNode) => cloneNodeTree(target, rootNode));
      for (const rootNode of nodes) placement.addChild(rootNode);
      scene.addChild(placement);
    }
    mergedScene.dispose();
  }
  await target.transform(unpartition());
  const bounds = getBounds(scene);
  await io.write(outputFile, target);
  return {
    bounds: {
      min: bounds.min.map((value) => Number(value.toFixed(6))),
      max: bounds.max.map((value) => Number(value.toFixed(6))),
    },
  };
}

function matrixArray(matrix) {
  return matrix.toArray().map((value) => Number(value.toFixed(10)));
}

function selectPrimaryDescriptor(report, recipe) {
  const target = normalizeWdbResourcePath(recipe.source.model);
  const matches = (report.descriptors ?? []).filter((descriptor) => (
    normalizeWdbResourcePath(descriptor.resource) === target
  ));
  if (!matches.length) {
    throw new Error("Expected at least one WDB placement for " + recipe.source.model + ".");
  }
  if (matches.length === 1) return matches[0];
  const expected = recipe.source.primaryPlacementTranslation;
  if (!Array.isArray(expected) || expected.length !== 3) {
    throw new Error("Multiple primary-resource placements require source.primaryPlacementTranslation.");
  }
  const match = matches.find((descriptor) => descriptor.translation.every((value, index) => (
    Math.abs(Number(value) - Number(expected[index])) <= 0.0001
  )));
  if (!match) throw new Error("Configured primary WDB placement was not found.");
  return match;
}

function reviewedDynamicRules(recipe) {
  const rules = recipe.source.wdbAssembly?.dynamicPlacements ?? [];
  const ids = new Set();
  return rules.map((rule, index) => {
    if (!rule || typeof rule !== "object") {
      throw new Error("source.wdbAssembly.dynamicPlacements[" + index + "] must be an object.");
    }
    if (!String(rule.id ?? "").trim()) throw new Error("Dynamic placement rule requires a stable id.");
    if (ids.has(rule.id)) throw new Error("Duplicate dynamic placement id " + rule.id + ".");
    ids.add(rule.id);
    if (!DYNAMIC_KINDS.has(rule.kind)) {
      throw new Error("Dynamic placement " + rule.id + " has unsupported kind " + rule.kind + ".");
    }
    if (!rule.guid && !rule.resource) {
      throw new Error("Dynamic placement " + rule.id + " requires guid or resource evidence.");
    }
    if (!Array.isArray(rule.evidence) || !rule.evidence.length) {
      throw new Error("Dynamic placement " + rule.id + " requires reviewed evidence.");
    }
    return {
      ...rule,
      normalizedResource: rule.resource ? normalizeWdbResourcePath(rule.resource) : null,
    };
  });
}

function matchingDynamicRule(descriptor, rules) {
  const resource = normalizeWdbResourcePath(descriptor.resource);
  return rules.find((rule) => (
    (rule.guid && String(rule.guid).toLowerCase() === String(descriptor.guid).toLowerCase())
    || (rule.normalizedResource && rule.normalizedResource === resource)
  ));
}

function placementRecord(descriptor, index, primary, recipe, classification, dynamicRule = null) {
  const resource = normalizeWdbResourcePath(descriptor.resource);
  const id = classification === "dynamic"
    ? dynamicRule.id + ":" + String(descriptor.guid ?? index)
    : "wdb:" + String(descriptor.guid ?? index);
  return {
    id,
    guid: descriptor.guid ?? null,
    resource: String(descriptor.resource).replaceAll("\\", "/"),
    normalizedResource: resource,
    resourceCacheKey: resourceCacheKey(resource),
    classification,
    transform: {
      source: {
        translation: descriptor.translation.map(Number),
        rotation: descriptor.rotation.map(Number),
        scale: descriptor.scale.map(Number),
      },
      primaryLocalThreeMatrix: matrixArray(placementMatrixInPrimaryThree(
        descriptor,
        primary,
        recipe.coordinateSystem.metersPerSourceUnit,
      )),
    },
    sourceBounds: {
      local: descriptor.localBounds ?? null,
      world: descriptor.worldBounds ?? null,
    },
    sourceFlags: {
      zoneFlags: Number(descriptor.zoneFlags ?? 0),
      detailClass: Number(descriptor.detailClass ?? 0),
      zoneType: Number(descriptor.zoneType ?? 0),
    },
    ...(dynamicRule ? {
      dynamic: {
        definitionId: dynamicRule.id,
        kind: dynamicRule.kind,
        initialState: dynamicRule.initialState ?? "default",
        collision: dynamicRule.collision ?? "stateful",
        evidence: dynamicRule.evidence,
      },
    } : {}),
  };
}

export function buildWdbPlacementPlan(report, recipe) {
  if (!report || !Array.isArray(report.descriptors)) {
    throw new Error("WDB report must contain descriptors.");
  }
  const primary = selectPrimaryDescriptor(report, recipe);
  const dynamicRules = reviewedDynamicRules(recipe);
  const matchedDynamicRuleIds = new Set();
  const staticPlacements = [];
  const dynamicPlacements = [];
  const reviewRequiredPlacements = [];
  const unsupportedPlacements = [];
  const resourceMap = new Map();
  for (const [index, descriptor] of report.descriptors.entries()) {
    const resource = normalizeWdbResourcePath(descriptor.resource);
    const extension = path.extname(resource);
    if (!SUPPORTED_RESOURCE_EXTENSIONS.has(extension)) {
      unsupportedPlacements.push({
        id: "wdb:" + String(descriptor.guid ?? index),
        guid: descriptor.guid ?? null,
        resource: descriptor.resource,
        reason: extension
          ? "unsupported WDB placement resource extension " + extension
          : "WDB placement resource has no extension",
      });
      continue;
    }
    let matrix;
    try {
      matrix = placementMatrixInPrimaryThree(
        descriptor,
        primary,
        recipe.coordinateSystem.metersPerSourceUnit,
      );
    } catch (error) {
      unsupportedPlacements.push({
        id: "wdb:" + String(descriptor.guid ?? index),
        guid: descriptor.guid ?? null,
        resource: descriptor.resource,
        reason: "invalid WDB transform: " + error.message,
      });
      continue;
    }
    if (matrix.elements.some((value) => !Number.isFinite(value))) {
      unsupportedPlacements.push({
        id: "wdb:" + String(descriptor.guid ?? index),
        guid: descriptor.guid ?? null,
        resource: descriptor.resource,
        reason: "WDB transform produced a non-finite matrix",
      });
      continue;
    }
    const dynamicRule = matchingDynamicRule(descriptor, dynamicRules);
    if (descriptor === primary && dynamicRule) {
      throw new Error("The primary coordinate-anchor placement cannot be dynamic ("
        + dynamicRule.id + ").");
    }
    const classification = dynamicRule ? "dynamic" : "static";
    const placement = placementRecord(
      descriptor,
      index,
      primary,
      recipe,
      classification,
      dynamicRule,
    );
    if (dynamicRule) {
      matchedDynamicRuleIds.add(dynamicRule.id);
      dynamicPlacements.push(placement);
    } else {
      staticPlacements.push(placement);
      if (DYNAMIC_HINT_PATTERN.test(resource)) {
        reviewRequiredPlacements.push({
          placementId: placement.id,
          guid: placement.guid,
          resource: placement.resource,
          reason: "Resource name resembles a movable or interactive object, but no reviewed dynamic-placement rule proves its behavior.",
        });
      }
    }
    if (!resourceMap.has(resource)) {
      resourceMap.set(resource, {
        resource: placement.resource,
        normalizedResource: resource,
        cacheKey: placement.resourceCacheKey,
        placementCount: 0,
        staticPlacementCount: 0,
        dynamicPlacementCount: 0,
      });
    }
    const resourceRecord = resourceMap.get(resource);
    resourceRecord.placementCount += 1;
    resourceRecord[classification + "PlacementCount"] += 1;
  }
  const unmatchedDynamicRules = dynamicRules
    .filter((rule) => !matchedDynamicRuleIds.has(rule.id))
    .map((rule) => ({
      id: rule.id,
      guid: rule.guid ?? null,
      resource: rule.resource ?? null,
      reason: "Reviewed dynamic-placement selector matched no WDB descriptor.",
    }));
  if (unmatchedDynamicRules.length) {
    throw new Error(unmatchedDynamicRules.map((rule) => rule.reason + " " + rule.id).join("\n"));
  }
  return {
    schemaVersion: 1,
    dungeonId: recipe.slug,
    sourceWdb: report.sourceWdb,
    sourceDescriptorCount: report.descriptors.length,
    primaryPlacement: {
      guid: primary.guid ?? null,
      resource: String(primary.resource).replaceAll("\\", "/"),
      translation: primary.translation.map(Number),
      rotation: primary.rotation.map(Number),
      scale: primary.scale.map(Number),
    },
    coordinateTransform: {
      source: recipe.coordinateSystem.source,
      nativeBridge: recipe.coordinateSystem.nativeBridge,
      metersPerSourceUnit: Number(recipe.coordinateSystem.metersPerSourceUnit),
      formula: "threeMatrix=S*inverse(primaryTRS)*placementTRS*inverse(S), S=scale(meters,meters,-meters)",
    },
    resources: [...resourceMap.values()].sort((left, right) => (
      left.normalizedResource.localeCompare(right.normalizedResource)
    )),
    staticPlacements: staticPlacements.sort((left, right) => left.id.localeCompare(right.id)),
    dynamicPlacements: dynamicPlacements.sort((left, right) => left.id.localeCompare(right.id)),
    reviewRequiredPlacements: reviewRequiredPlacements
      .sort((left, right) => left.placementId.localeCompare(right.placementId)),
    unsupportedPlacements: unsupportedPlacements.sort((left, right) => left.id.localeCompare(right.id)),
    unsupportedResourceTypes: [
      "WDB placement resources other than ROS",
      "particle, light, sound, camera, and script-only components not represented as ROS mesh descriptors",
      "animated or stateful behavior without a reviewed source.wdbAssembly.dynamicPlacements rule",
    ],
  };
}