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);
      });
    },
  };
}

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