#!/usr/bin/env node
import { createHash } from "node:crypto";
import {
  access,
  mkdir,
  readFile,
  readdir,
  rename,
  rm,
  stat,
  writeFile,
} from "node:fs/promises";
import path from "node:path";
import { fileURLToPath } from "node:url";
import { Logger, NodeIO } from "@gltf-transform/core";
import { ALL_EXTENSIONS } from "@gltf-transform/extensions";
import { getBounds } from "@gltf-transform/functions";
import { MeshoptDecoder, MeshoptEncoder } from "meshoptimizer";
import {
  CREATURE_MESH_CONSOLIDATION_POLICY,
  consolidateCreatureSkinnedMeshes,
} from "./creature-mesh-consolidation.mjs";
import {
  CREATURE_RUNTIME_ANIMATION_POLICY,
  semanticCreatureAnimations,
  trimCreatureRuntimeAnimations,
} from "./runtime-creature-animations.mjs";

const projectRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "../..");
const dungeonRoot = path.join(projectRoot, "public", "assets", "game", "dungeons");
const sharedRoot = path.join(projectRoot, "public", "assets", "game", "creatures", "shared");
const registryFile = path.join(projectRoot, "src", "game", "generated", "fivePlayerDungeonImports.json");
const reportFile = path.join(
  projectRoot,
  "dungeon-pipeline",
  "reports",
  "runtime-creature-animation-optimization.json",
);
const dryRun = process.argv.includes("--dry-run");

const exists = (file) => access(file).then(() => true, () => false);
const readJson = async (file) => JSON.parse(await readFile(file, "utf8"));
const writeJson = async (file, value) => {
  await mkdir(path.dirname(file), { recursive: true });
  await writeFile(file, `${JSON.stringify(value, null, 2)}\n`, "utf8");
};
const sha256 = async (file) => createHash("sha256").update(await readFile(file)).digest("hex");

function missingAnimationSemantics(semantics) {
  return [
    !semantics.stand && "stand",
    !(semantics.walk || semantics.run) && "locomotion",
    !semantics.attack && "attack",
    !semantics.death && "death",
  ].filter(Boolean);
}

function roundedBounds(bounds) {
  return {
    min: bounds.min.map((value) => Number(value.toFixed(6))),
    max: bounds.max.map((value) => Number(value.toFixed(6))),
  };
}

function protectedNodeInventory(document) {
  const root = document.getRoot();
  const nodes = new Set();
  for (const skin of root.listSkins()) {
    if (skin.getSkeleton()) nodes.add(skin.getSkeleton());
    for (const joint of skin.listJoints()) nodes.add(joint);
  }
  for (const animation of root.listAnimations()) {
    for (const channel of animation.listChannels()) {
      if (channel.getTargetNode()) nodes.add(channel.getTargetNode());
    }
  }
  return [...nodes].map((node) => node.getName()).sort();
}

function materialInventory(document) {
  return document.getRoot().listMaterials().map((material) => ({
    name: material.getName(),
    alphaMode: material.getAlphaMode(),
    alphaCutoff: material.getAlphaCutoff(),
    doubleSided: material.getDoubleSided(),
    baseColorFactor: material.getBaseColorFactor(),
    metallicFactor: material.getMetallicFactor(),
    roughnessFactor: material.getRoughnessFactor(),
    baseColorTexture: material.getBaseColorTexture()?.getName() ?? null,
  }));
}

function descriptorReferences(manifests) {
  const references = new Map();
  for (const manifest of manifests) {
    for (const model of Object.values(manifest.creatureModels ?? {})) {
      if (typeof model.url !== "string" || !model.url.startsWith("/assets/game/creatures/shared/")) {
        continue;
      }
      const models = references.get(model.url) ?? [];
      models.push(model);
      references.set(model.url, models);
    }
  }
  return references;
}

await MeshoptDecoder.ready;
await MeshoptEncoder.ready;
const io = new NodeIO()
  .registerExtensions(ALL_EXTENSIONS)
  .registerDependencies({
    "meshopt.decoder": MeshoptDecoder,
    "meshopt.encoder": MeshoptEncoder,
  });

const manifestFiles = [];
for (const entry of await readdir(dungeonRoot, { withFileTypes: true })) {
  if (!entry.isDirectory()) continue;
  const file = path.join(dungeonRoot, entry.name, "dungeon-pack.json");
  if (await exists(file)) manifestFiles.push(file);
}
manifestFiles.sort();
const manifests = await Promise.all(manifestFiles.map(readJson));
const references = descriptorReferences(manifests);
const targets = [...references.keys()].sort().map((url) => ({
  url,
  file: path.join(projectRoot, "public", url.replace(/^\/+/, "")),
  descriptors: references.get(url),
}));
if (!targets.length) throw new Error("No shared creature GLBs are referenced by dungeon manifests.");

console.log(JSON.stringify({
  mode: dryRun ? "dry-run" : "apply",
  policies: {
    animation: CREATURE_RUNTIME_ANIMATION_POLICY,
    mesh: CREATURE_MESH_CONSOLIDATION_POLICY,
  },
  targets: targets.length,
}, null, 2));

const results = [];
for (let index = 0; index < targets.length; index += 1) {
  const target = targets[index];
  const before = await stat(target.file);
  const document = await io.read(target.file);
  document.setLogger(new Logger(Logger.Verbosity.WARN));
  const scene = document.getRoot().getDefaultScene() ?? document.getRoot().listScenes()[0];
  if (!scene) throw new Error(`${target.url}: GLB has no scene.`);
  const bounds = roundedBounds(getBounds(scene));
  const protectedNodes = protectedNodeInventory(document);
  const materials = materialInventory(document);
  const animationOptimization = await trimCreatureRuntimeAnimations(document);
  if (!animationOptimization.runtimeClipCount) {
    throw new Error(`${target.url}: runtime animation policy retained no clips.`);
  }
  const meshOptimization = await consolidateCreatureSkinnedMeshes(document);
  const temporary = path.join(sharedRoot, `.${path.basename(target.file)}.tmp.glb`);
  await rm(temporary, { force: true });
  await io.write(temporary, document);
  const verification = await io.read(temporary);
  const verifiedScene = verification.getRoot().getDefaultScene() ?? verification.getRoot().listScenes()[0];
  if (JSON.stringify(bounds) !== JSON.stringify(roundedBounds(getBounds(verifiedScene)))) {
    await rm(temporary, { force: true });
    throw new Error(`${target.url}: optimization changed bounds.`);
  }
  if (JSON.stringify(protectedNodes) !== JSON.stringify(protectedNodeInventory(verification))) {
    await rm(temporary, { force: true });
    throw new Error(`${target.url}: protected skeleton/animation nodes changed.`);
  }
  if (JSON.stringify(materials) !== JSON.stringify(materialInventory(verification))) {
    await rm(temporary, { force: true });
    throw new Error(`${target.url}: material semantics changed.`);
  }
  const verifiedNames = verification.getRoot().listAnimations().map((animation) => animation.getName());
  if (JSON.stringify(verifiedNames) !== JSON.stringify(animationOptimization.retainedNames)) {
    await rm(temporary, { force: true });
    throw new Error(`${target.url}: written animation inventory changed.`);
  }

  const checksum = await sha256(temporary);
  const output = path.join(sharedRoot, `${checksum}.glb`);
  const outputUrl = `/assets/game/creatures/shared/${checksum}.glb`;
  const outputSize = (await stat(temporary)).size;
  if (!dryRun) {
    if (!await exists(output)) await rename(temporary, output);
    else {
      if (await sha256(output) !== checksum) throw new Error(`${outputUrl}: hash collision.`);
      await rm(temporary, { force: true });
    }
  } else await rm(temporary, { force: true });

  const previousSourceClips = Math.max(
    animationOptimization.sourceClipCount,
    ...target.descriptors.map((descriptor) => Number(descriptor.sourceAnimationClips) || 0),
  );
  const previousSourceDrawCalls = Math.max(
    meshOptimization.before.drawCalls,
    ...target.descriptors.map((descriptor) => Number(descriptor.meshOptimization?.sourceDrawCalls) || 0),
  );
  const semantics = semanticCreatureAnimations(animationOptimization.retainedNames);
  results.push({
    oldUrl: target.url,
    url: outputUrl,
    checksum,
    previousByteLength: before.size,
    byteLength: outputSize,
    sourceClipCount: previousSourceClips,
    runtimeClipCount: animationOptimization.runtimeClipCount,
    removedClipCount: previousSourceClips - animationOptimization.runtimeClipCount,
    sourceDrawCalls: previousSourceDrawCalls,
    runtimeDrawCalls: meshOptimization.after.drawCalls,
    savedDrawCalls: previousSourceDrawCalls - meshOptimization.after.drawCalls,
    meshGroups: meshOptimization.groups,
    mergedMeshNodes: meshOptimization.mergedNodes,
    semantics,
    missingAnimationSemantics: missingAnimationSemantics(semantics),
  });
  if ((index + 1) % 10 === 0 || index + 1 === targets.length) {
    console.log(`Processed ${index + 1}/${targets.length} shared creature GLBs.`);
  }
}

const totals = results.reduce((summary, result) => ({
  sourceClips: summary.sourceClips + result.sourceClipCount,
  runtimeClips: summary.runtimeClips + result.runtimeClipCount,
  sourceDrawCalls: summary.sourceDrawCalls + result.sourceDrawCalls,
  runtimeDrawCalls: summary.runtimeDrawCalls + result.runtimeDrawCalls,
  previousBytes: summary.previousBytes + result.previousByteLength,
  runtimeBytes: summary.runtimeBytes + result.byteLength,
}), {
  sourceClips: 0,
  runtimeClips: 0,
  sourceDrawCalls: 0,
  runtimeDrawCalls: 0,
  previousBytes: 0,
  runtimeBytes: 0,
});
const summary = {
  models: results.length,
  ...totals,
  removedClips: totals.sourceClips - totals.runtimeClips,
  savedDrawCalls: totals.sourceDrawCalls - totals.runtimeDrawCalls,
  savedBytes: totals.previousBytes - totals.runtimeBytes,
};

if (!dryRun) {
  const byOldUrl = new Map(results.map((result) => [result.oldUrl, result]));
  for (const manifest of manifests) {
    for (const model of Object.values(manifest.creatureModels ?? {})) {
      const optimized = byOldUrl.get(model.url);
      if (!optimized) continue;
      model.url = optimized.url;
      model.checksum = optimized.checksum;
      model.byteLength = optimized.byteLength;
      model.animationClips = optimized.runtimeClipCount;
      model.sourceAnimationClips = optimized.sourceClipCount;
      model.animationOptimization = {
        policy: CREATURE_RUNTIME_ANIMATION_POLICY,
        removedClips: optimized.removedClipCount,
      };
      model.meshOptimization = {
        policy: CREATURE_MESH_CONSOLIDATION_POLICY,
        sourceDrawCalls: optimized.sourceDrawCalls,
        runtimeDrawCalls: optimized.runtimeDrawCalls,
        savedDrawCalls: optimized.savedDrawCalls,
      };
      model.animations = optimized.semantics;
      model.missingAnimationSemantics = optimized.missingAnimationSemantics;
    }
  }
  for (let index = 0; index < manifestFiles.length; index += 1) {
    await writeJson(manifestFiles[index], manifests[index]);
  }
  await writeJson(registryFile, {
    schemaVersion: 1,
    generatedAt: "deterministic",
    imports: manifests.slice().sort((left, right) => left.slug.localeCompare(right.slug)),
  });

  const liveUrls = new Set(descriptorReferences(manifests).keys());
  for (const result of results) {
    if (result.oldUrl !== result.url && !liveUrls.has(result.oldUrl)) {
      const oldFile = path.join(projectRoot, "public", result.oldUrl.replace(/^\/+/, ""));
      await rm(oldFile, { force: true });
    }
  }
  const report = await readJson(reportFile);
  report.shared = { totals: summary, models: results };
  report.shippedTotals = {
    models: Number(report.totals?.models ?? 0) + summary.models,
    sourceClips: Number(report.totals?.sourceClips ?? 0) + summary.sourceClips,
    runtimeClips: Number(report.totals?.runtimeClips ?? 0) + summary.runtimeClips,
    sourceDrawCalls: Number(report.totals?.sourceDrawCalls ?? 0) + summary.sourceDrawCalls,
    runtimeDrawCalls: Number(report.totals?.runtimeDrawCalls ?? 0) + summary.runtimeDrawCalls,
    previousBytes: Number(report.totals?.previousBytes ?? 0) + summary.previousBytes,
    runtimeBytes: Number(report.totals?.runtimeBytes ?? 0) + summary.runtimeBytes,
    removedClips: Number(report.totals?.removedClips ?? 0) + summary.removedClips,
    savedDrawCalls: Number(report.totals?.savedDrawCalls ?? 0) + summary.savedDrawCalls,
    savedBytes: Number(report.totals?.savedBytes ?? 0) + summary.savedBytes,
  };
  await writeJson(reportFile, report);
}

console.log(JSON.stringify(summary, null, 2));