import { defineConfig, type Plugin } from "vite";
import react from "@vitejs/plugin-react";
// @ts-expect-error The runtime is Node; this project intentionally avoids a browser dependency on Node types.
import fs from "node:fs";
// @ts-expect-error The runtime is Node; this project intentionally avoids a browser dependency on Node types.
import path from "node:path";
// @ts-expect-error The runtime is Node; this project intentionally avoids a browser dependency on Node types.
import { fileURLToPath } from "node:url";

const deploymentContract = JSON.parse(
  fs.readFileSync(path.resolve(path.dirname(fileURLToPath(import.meta.url)), "../../docs/web/deployment-contract.json"), "utf8"),
) as { responseHeaders: { allResponses: Record<string, string> } };
const isolationHeaders = deploymentContract.responseHeaders.allResponses;
const runtimeEnvironment = (globalThis as { process?: { env?: Record<string, string | undefined> } }).process?.env;
const unisolatedSingleThreadTest = runtimeEnvironment?.WEB_TEST_UNISOLATED_SINGLE_THREAD === "1";
const developmentHeaders = unisolatedSingleThreadTest ? {} : isolationHeaders;

function preserveIsolationHeaders(): Plugin {
  const install = (server: { middlewares: { use: (handler: (request: unknown, response: { setHeader: (name: string, value: string) => void }, next: () => void) => void) => void } }) => {
    server.middlewares.use((_request, response, next) => {
      for (const [name, value] of Object.entries(isolationHeaders)) response.setHeader(name, value);
      next();
    });
  };
  return {
    name: "preserve-isolation-headers",
    configureServer: install,
    configurePreviewServer: install,
  };
}

function serveEngineVariantModuleImports(): Plugin {
  const vendorRoot = path.resolve(path.dirname(fileURLToPath(import.meta.url)), "public/vendor/blender");
  const install = (server: { middlewares: { use: (handler: (request: unknown, response: { setHeader: (name: string, value: string | number) => void }, next: () => void) => void) => void } }) => {
    server.middlewares.use((request, response, next) => {
      const url = new URL((request as { url?: string }).url ?? "/", "http://vite.local");
      const match = url.pathname.match(/^\/vendor\/blender\/(single|pthread)\/web_engine\.js$/);
      if (!match || !url.searchParams.has("import")) { next(); return; }
      const filePath = path.join(vendorRoot, match[1], "web_engine.js");
      if (!fs.existsSync(filePath)) { next(); return; }
      const stat = fs.statSync(filePath);
      response.setHeader("Content-Type", "text/javascript; charset=utf-8");
      response.setHeader("Content-Length", stat.size);
      for (const [name, value] of Object.entries(developmentHeaders)) response.setHeader(name, value);
      fs.createReadStream(filePath).pipe(response as never);
    });
  };
  return {
    name: "serve-engine-variant-module-imports",
    configureServer: install,
    configurePreviewServer: install,
  };
}

function localVDBFixture(): Plugin {
  const resourceRoot = runtimeEnvironment?.VDB_RESOURCE_ROOT ?? path.join(runtimeEnvironment?.HOME ?? "", "resource-library/blender-web-vdb");
  const files = new Map([
    ["/__vdb_fixture__/manifest", { path: path.join(resourceRoot, "manifests/generated-smoke.nanovdb.json"), type: "application/json" }],
    ["/__vdb_fixture__/report", { path: path.join(resourceRoot, "reports/generated-smoke-conversion.json"), type: "application/json" }],
    ["/__vdb_fixture__/bundle", { path: path.join(resourceRoot, "nanovdb/generated-smoke.nvdb"), type: "application/x-nanovdb" }],
    ["/assets/volumes/generated-smoke.nanovdb.json", { path: path.join(resourceRoot, "manifests/generated-smoke.nanovdb.json"), type: "application/json" }],
    ["/assets/volumes/generated-smoke.nvdb", { path: path.join(resourceRoot, "nanovdb/generated-smoke.nvdb"), type: "application/x-nanovdb" }],
    ["/volumes/generated-smoke.nanovdb.json", { path: path.join(resourceRoot, "manifests/generated-smoke.nanovdb.json"), type: "application/json" }],
    ["/volumes/generated-smoke.nvdb", { path: path.join(resourceRoot, "nanovdb/generated-smoke.nvdb"), type: "application/x-nanovdb" }],
  ]);
  return {
    name: "local-vdb-fixture",
    configureServer(server) {
      server.middlewares.use((request, response, next) => {
        const nodeRequest = request as unknown as { url?: string; headers: { range?: string } };
        const pathname = nodeRequest.url?.split("?", 1)[0] ?? "";
        const fixture = files.get(pathname);
        if (!fixture || !fs.existsSync(fixture.path)) { next(); return; }
        const stat = fs.statSync(fixture.path);
        response.setHeader("Content-Type", fixture.type);
        response.setHeader("Accept-Ranges", "bytes");
        response.setHeader("Cache-Control", "no-store");
        response.setHeader("ETag", `"vdb-${stat.size}-${Math.trunc(stat.mtimeMs)}"`);
        const match = nodeRequest.headers.range?.match(/^bytes=(\d+)-(\d+)$/);
        if (match) {
          const start = Number(match[1]);
          const end = Number(match[2]);
          if (!Number.isSafeInteger(start) || !Number.isSafeInteger(end) || start < 0 || end < start || end >= stat.size) { response.writeHead(416); response.end(); return; }
          response.statusCode = 206;
          response.setHeader("Content-Range", `bytes ${start}-${end}/${stat.size}`);
          response.setHeader("Content-Length", end - start + 1);
          fs.createReadStream(fixture.path, { start, end }).pipe(response);
          return;
        }
        response.setHeader("Content-Length", stat.size);
        fs.createReadStream(fixture.path).pipe(response);
      });
    },
  };
}

// Materialize requested bytes over HTTP without checking a 64 MiB performance-only fixture into the repository.
const sparseBundleBytes = 64 * 1024 * 1024;
const sparseChunkBytes = 4 * 1024 * 1024;
const sparseStreamBytes = 64 * 1024;
const sparseChunkSha256 = "bb9f8df61474d25e71fa00722318cd387396ca1736605e1248821cc0de3d3af8";
const sparseBundleSha256 = "3b6a07d0d404fab4e23b6d34bc6696a6a312dd92821332385e5af7c01c421351";
const sparseConverterSha256 = "0000000000000000000000000000000000000000000000000000000000000000";

function sparseBundleManifest(): Record<string, unknown> {
  return {
    schemaVersion: 1,
    projectId: "vdb-sparse-64m",
    sourcePath: "//volumes/generated-synthetic-sparse.vdb",
    sourceSha256: sparseBundleSha256,
    conversionRequestSha256: sparseConverterSha256,
    bundlePath: "//volumes/generated-sparse-64m.nvdb",
    bundleByteLength: sparseBundleBytes,
    bundleSha256: sparseBundleSha256,
    converter: {
      target: "DESKTOP",
      blenderVersion: "5.2.0",
      openVDBVersion: "13.0.0",
      nanoVDBVersion: "32.9.0",
      executableSha256: sparseConverterSha256,
    },
    grids: [{
      name: "density",
      valueType: "FLOAT16",
      gridClass: "FOG_VOLUME",
      semantic: "DENSITY",
      activeVoxelCount: 0,
      segmentByteOffset: 0,
      segmentByteLength: sparseBundleBytes,
      byteOffset: 0,
      byteLength: sparseBundleBytes,
      indexBounds: { min: [0, 0, 0], max: [0, 0, 0] },
      worldBounds: { min: [0, 0, 0], max: [0, 0, 0] },
      voxelSize: [1, 1, 1],
      indexToWorld: [1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1],
    }],
    chunks: Array.from({ length: sparseBundleBytes / sparseChunkBytes }, (_, index) => ({
      index,
      byteOffset: index * sparseChunkBytes,
      byteLength: sparseChunkBytes,
      sha256: sparseChunkSha256,
    })),
    material: {
      densityGrid: "density",
      densityScale: 1,
      emissionScale: 0,
      temperatureScale: 1,
      anisotropy: 0,
      interpolation: "NEAREST",
    },
    gpu: {
      representation: "NANOVDB_STORAGE_BUFFER",
      byteAlignment: 32,
      pageByteLength: 256 * 1024,
      maxResidentBytes: 1 * 1024 * 1024,
      shaderSemanticVersion: "volume-wgsl-v1",
    },
  };
}

function serveSparseVDBFixture(): Plugin {
  return {
    name: "serve-sparse-64m-vdb-fixture",
    configureServer(server) {
      server.middlewares.use((request, response, next) => {
        const nodeRequest = request as unknown as { url?: string; headers: { range?: string } };
        const parsed = new URL(nodeRequest.url ?? "/", "http://vite.local");
        if (parsed.pathname !== "/__vdb_sparse_64m__/manifest" && parsed.pathname !== "/__vdb_sparse_64m__/bundle") { next(); return; }
        const output = response as unknown as {
          statusCode: number;
          setHeader: (name: string, value: string | number) => void;
          writeHead: (status: number) => void;
          write: (data: Uint8Array) => boolean;
          end: (data?: string) => void;
          on: (event: string, listener: () => void) => void;
          once: (event: string, listener: () => void) => void;
        };
        if (parsed.pathname.endsWith("/manifest")) {
          const body = JSON.stringify(sparseBundleManifest());
          output.statusCode = 200;
          output.setHeader("Content-Type", "application/json");
          output.setHeader("Cache-Control", "no-store");
          output.setHeader("Content-Length", body.length);
          output.end(body);
          return;
        }
        const match = nodeRequest.headers.range?.match(/^bytes=(\d+)-(\d+)$/);
        const start = match ? Number(match[1]) : 0;
        const end = match ? Number(match[2]) : sparseBundleBytes - 1;
        if (!Number.isSafeInteger(start) || !Number.isSafeInteger(end) || start < 0 || end < start || end >= sparseBundleBytes) {
          output.statusCode = 416;
          output.end();
          return;
        }
        const length = end - start + 1;
        const delayMs = Math.min(25, Math.max(0, Number.parseInt(parsed.searchParams.get("delayMs") ?? "0", 10) || 0));
        output.statusCode = match ? 206 : 200;
        output.setHeader("Content-Type", "application/x-nanovdb");
        output.setHeader("Accept-Ranges", "bytes");
        output.setHeader("Cache-Control", "no-store");
        output.setHeader("ETag", '"vdb-sparse-64m-v1"');
        output.setHeader("Content-Length", length);
        if (match) output.setHeader("Content-Range", `bytes ${start}-${end}/${sparseBundleBytes}`);
        let closed = false;
        let written = 0;
        const zeroes = new Uint8Array(sparseStreamBytes);
        output.on("close", () => { closed = true; });
        const pump = (): void => {
          if (closed) return;
          if (written >= length) { output.end(); return; }
          const nextLength = Math.min(sparseStreamBytes, length - written);
          const accepted = output.write(nextLength === zeroes.byteLength ? zeroes : zeroes.slice(0, nextLength));
          written += nextLength;
          const continuePump = (): void => { if (!closed) setTimeout(pump, delayMs); };
          if (!accepted) output.once("drain", continuePump);
          else continuePump();
        };
        pump();
      });
    },
  };
}

export default defineConfig({
  root: "app",
  plugins: [
    serveEngineVariantModuleImports(),
    ...(unisolatedSingleThreadTest ? [] : [preserveIsolationHeaders()]),
    localVDBFixture(),
    serveSparseVDBFixture(),
    react(),
  ],
  server: {
    port: 5173,
    strictPort: false,
    headers: developmentHeaders,
  },
  preview: {
    headers: developmentHeaders,
  },
  build: {
    outDir: "../dist",
    emptyOutDir: true,
  },
});