/**
 * Build the ES module source that runs inside the dynamic Worker.
 *
 * The module exports a `WorkerEntrypoint` subclass with an `evaluate`
 * method that:
 * 1. Captures console output into `__logs`.
 * 2. Accumulates user-visible output from `emit`, `text`, `file`, `image`,
 *    `audio`, `resource`, and `notify`.
 * 3. Creates a recursive `tools` Proxy that dispatches calls via RPC.
 * 4. Executes the normalised user code with a `Promise.race` timeout.
 * 5. Returns `{ result, output?, error?, logs }`.
 *
 * Tool args cross the dispatcher boundary via Workers RPC, not JSON, so
 * `Uint8Array` / `ArrayBuffer` survive intact. `Blob` / `File` aren't on
 * RPC's structured-clone allow-list, so we encode them to a tagged
 * envelope (`__encodeBinary`) and the host rehydrates them. This is
 * required for any tool whose upstream wants `multipart/form-data`
 * (OpenAI Files API, etc.).
 */
export const buildExecutorModule = (body: string, timeoutMs: number): string =>
  [
    'import { WorkerEntrypoint } from "cloudflare:workers";',
    "",
    "export default class CodeExecutor extends WorkerEntrypoint {",
    "  async evaluate(__dispatcher) {",
    "    const __logs = [];",
    "    const __outputs = [];",
    "    let __pendingOutput = Promise.resolve();",
    "    const __recordOutput = (item) => {",
    "      __outputs.push(item);",
    "      if (__dispatcher && typeof __dispatcher.output === 'function') {",
    "        __pendingOutput = __pendingOutput.then(() => __dispatcher.output(item)).catch(() => undefined);",
    "      }",
    "    };",
    "    const yield_control = async () => {",
    "      await __pendingOutput;",
    "      if (__dispatcher && typeof __dispatcher.yieldControl === 'function') await __dispatcher.yieldControl();",
    "    };",
    "    const yieldControl = yield_control;",
    '    console.log = (...a) => { __logs.push(a.map(String).join(" ")); };',
    '    console.warn = (...a) => { __logs.push("[warn] " + a.map(String).join(" ")); };',
    '    console.error = (...a) => { __logs.push("[error] " + a.map(String).join(" ")); };',
    "    const __serializeErrorValue = (value) => {",
    "      if (value instanceof Error) {",
    "        return {",
    "          __type: 'Error',",
    "          name: value.name,",
    "          message: value.message,",
    "        };",
    "      }",
    "      if (value === null || typeof value === 'string' || typeof value === 'number' || typeof value === 'boolean') {",
    "        return value;",
    "      }",
    "      try {",
    "        return JSON.parse(JSON.stringify(value));",
    "      } catch {",
    "        return String(value);",
    "      }",
    "    };",
    "    const __renderMessage = (value) => {",
    "      if (typeof value === 'string') return value;",
    "      if (value && typeof value === 'object' && value.__type === 'Error' && typeof value.message === 'string') {",
    "        return value.message;",
    "      }",
    "      if (value instanceof Error) return value.message;",
    "      if (value && typeof value === 'object' && typeof value.message === 'string') return value.message;",
    "      if (typeof value === 'undefined') return 'Unknown error';",
    "      if (value && typeof value === 'object') {",
    "        try {",
    "          return JSON.stringify(value);",
    "        } catch {",
    "          return String(value);",
    "        }",
    "      }",
    "      return String(value);",
    "    };",
    "    const __formatOutputText = (value) => {",
    "      if (typeof value === 'undefined') return 'undefined';",
    "      if (value === null) return 'null';",
    "      if (typeof value === 'string') return value;",
    "      try {",
    "        return JSON.stringify(value);",
    "      } catch {",
    "        return String(value);",
    "      }",
    "    };",
    "    const __IMAGE_DETAIL_META_KEY = 'codex/imageDetail';",
    "    const __DEFAULT_IMAGE_DETAIL = 'high';",
    "    const __validImageDetails = new Set(['auto', 'low', 'high', 'original']);",
    "    const __normalizeImageDetail = (detail) => {",
    "      if (detail === null || typeof detail === 'undefined') return undefined;",
    "      if (typeof detail !== 'string') throw new TypeError('image detail must be a string when provided');",
    "      const normalized = detail.toLowerCase();",
    "      if (!__validImageDetails.has(normalized)) throw new TypeError('image detail must be one of: auto, low, high, original');",
    "      return normalized;",
    "    };",
    "    const __isToolFile = (value) => value && typeof value === 'object' && value._tag === 'ToolFile' && typeof value.mimeType === 'string' && value.encoding === 'base64' && typeof value.data === 'string' && typeof value.byteLength === 'number';",
    "    const __isMcpTextContentBlock = (value) => value && typeof value === 'object' && value.type === 'text' && typeof value.text === 'string';",
    "    const __isMcpImageContentBlock = (value) => value && typeof value === 'object' && value.type === 'image' && typeof value.data === 'string' && (typeof value.mimeType === 'string' || typeof value.mime_type === 'string' || value.data.toLowerCase().startsWith('data:'));",
    "    const __isMcpAudioContentBlock = (value) => value && typeof value === 'object' && value.type === 'audio' && typeof value.data === 'string' && typeof value.mimeType === 'string';",
    "    const __isMcpResourceContentBlock = (value) => value && typeof value === 'object' && value.type === 'resource' && value.resource && typeof value.resource === 'object' && typeof value.resource.uri === 'string' && (typeof value.resource.text === 'string' || typeof value.resource.blob === 'string');",
    "    const __isMcpResourceLinkContentBlock = (value) => value && typeof value === 'object' && value.type === 'resource_link' && typeof value.uri === 'string' && typeof value.name === 'string';",
    "    const __isMcpContentBlock = (value) => __isMcpTextContentBlock(value) || __isMcpImageContentBlock(value) || __isMcpAudioContentBlock(value) || __isMcpResourceContentBlock(value) || __isMcpResourceLinkContentBlock(value);",
    "    const __parseDataImageUrl = (imageUrl) => {",
    "      if (typeof imageUrl !== 'string' || imageUrl.length === 0) throw new TypeError('image expects a non-empty data URI, an object with image_url and optional detail, or a raw MCP image block');",
    "      const lower = imageUrl.toLowerCase();",
    "      if (lower.startsWith('http://') || lower.startsWith('https://')) throw new TypeError('remote image URLs are not supported in code output; pass a base64 data URI or MCP image block');",
    "      const match = /^data:([^;,]+);base64,(.*)$/i.exec(imageUrl);",
    "      if (!match) throw new TypeError('image expects a base64 data URI or MCP image block');",
    "      return { mimeType: match[1], data: match[2] };",
    "    };",
    "    const __imageDetailFromMeta = (value) => {",
    "      const meta = value && typeof value === 'object' ? value._meta : undefined;",
    "      const detail = meta && typeof meta === 'object' ? meta[__IMAGE_DETAIL_META_KEY] : undefined;",
    "      return typeof detail === 'string' && __validImageDetails.has(detail) ? detail : undefined;",
    "    };",
    "    const __imageWithDetail = (block, detail) => ({ ...block, _meta: { ...(block._meta && typeof block._meta === 'object' ? block._meta : {}), [__IMAGE_DETAIL_META_KEY]: detail ?? __DEFAULT_IMAGE_DETAIL } });",
    "    const __normalizeImageBlock = (value, detailOverride) => {",
    "      const override = __normalizeImageDetail(detailOverride);",
    "      if (typeof value === 'string') return __imageWithDetail({ type: 'image', ...__parseDataImageUrl(value) }, override);",
    "      if (!value || typeof value !== 'object' || Array.isArray(value)) throw new TypeError('image expects a non-empty data URI, an object with image_url and optional detail, or a raw MCP image block');",
    "      if (typeof value.image_url === 'string') {",
    "        return __imageWithDetail({ type: 'image', ...__parseDataImageUrl(value.image_url) }, override ?? __normalizeImageDetail(value.detail));",
    "      }",
    "      if (value.type === 'image' && typeof value.data === 'string') {",
    "        const parsed = value.data.toLowerCase().startsWith('data:') ? __parseDataImageUrl(value.data) : { data: value.data, mimeType: typeof value.mimeType === 'string' ? value.mimeType : typeof value.mime_type === 'string' ? value.mime_type : 'application/octet-stream' };",
    "        return __imageWithDetail({ ...value, type: 'image', data: parsed.data, mimeType: parsed.mimeType }, override ?? __imageDetailFromMeta(value));",
    "      }",
    "      throw new TypeError('image expects a non-empty data URI, an object with image_url and optional detail, or a raw MCP image block');",
    "    };",
    "    const text = (value) => { __recordOutput({ type: 'content', content: { type: 'text', text: __formatOutputText(value) } }); };",
    "    const image = (value, detail) => { __recordOutput({ type: 'content', content: __normalizeImageBlock(value, detail) }); };",
    "    const audio = (value) => { if (!__isMcpAudioContentBlock(value)) throw new TypeError('audio expects an MCP audio content block'); __recordOutput({ type: 'content', content: value }); };",
    "    const file = (value) => { if (!__isToolFile(value)) throw new TypeError('file expects a ToolFile value'); __recordOutput({ type: 'file', file: value }); };",
    "    const resource = (value) => { if (!__isMcpResourceContentBlock(value) && !__isMcpResourceLinkContentBlock(value)) throw new TypeError('resource expects an MCP resource or resource_link content block'); __recordOutput({ type: 'content', content: value }); };",
    "    const notify = (value) => { const notification = value && typeof value === 'object' && typeof value.message === 'string' ? { message: value.message, ...(Object.prototype.hasOwnProperty.call(value, 'data') ? { data: value.data } : {}) } : { message: __formatOutputText(value) }; __recordOutput({ type: 'notification', notification }); };",
    "    const emit = (value) => {",
    "      if (__isToolFile(value)) { file(value); return; }",
    "      if (__isMcpContentBlock(value)) { __recordOutput({ type: 'content', content: value }); return; }",
    "      text(value);",
    "    };",
    "    const __serializeThrownError = (err) => {",
    "      const primary = __serializeErrorValue(err);",
    "      return {",
    "        kind: 'unknown',",
    "        message: __renderMessage(primary),",
    "        primary,",
    "        failures: [],",
    "        defects: [],",
    "        interrupted: false,",
    "      };",
    "    };",
    "",
    // Blob/File aren't on Workers RPC's structured-clone allow-list, so
    // we encode them to a tagged ArrayBuffer envelope before the call and
    // the host rehydrates them — and symmetrically the host encodes
    // Blob/File results which we rehydrate here. ArrayBuffer / typed
    // arrays cross natively.
    "    const __isPlainObject = (v) => {",
    "      const p = Object.getPrototypeOf(v);",
    "      return p === Object.prototype || p === null;",
    "    };",
    "    const __isBinaryEnvelope = (v) =>",
    "      v && typeof v === 'object' && v.__executorBinary === 1 &&",
    "      v.buffer instanceof ArrayBuffer && typeof v.type === 'string';",
    "    const __encodeBinary = async (value, seen = new WeakSet()) => {",
    "      if (value === null || typeof value !== 'object') return value;",
    "      if (value instanceof ArrayBuffer || ArrayBuffer.isView(value)) return value;",
    "      if (seen.has(value)) throw new Error('Tool RPC payload contains a circular reference');",
    "      seen.add(value);",
    "      if (typeof File !== 'undefined' && value instanceof File) {",
    "        const out = {",
    "          __executorBinary: 1,",
    "          kind: 'file',",
    "          type: value.type,",
    "          name: value.name,",
    "          lastModified: value.lastModified,",
    "          buffer: await value.arrayBuffer(),",
    "        };",
    "        seen.delete(value);",
    "        return out;",
    "      }",
    "      if (value instanceof Blob) {",
    "        const out = { __executorBinary: 1, kind: 'blob', type: value.type, buffer: await value.arrayBuffer() };",
    "        seen.delete(value);",
    "        return out;",
    "      }",
    "      if (Array.isArray(value)) {",
    "        const out = await Promise.all(value.map((item) => __encodeBinary(item, seen)));",
    "        seen.delete(value);",
    "        return out;",
    "      }",
    "      if (!__isPlainObject(value)) { seen.delete(value); return value; }",
    "      const out = {};",
    "      for (const [k, v] of Object.entries(value)) out[k] = await __encodeBinary(v, seen);",
    "      seen.delete(value);",
    "      return out;",
    "    };",
    "    const __decodeBinary = (value, seen = new WeakSet()) => {",
    "      if (value === null || typeof value !== 'object') return value;",
    "      if (value instanceof ArrayBuffer || ArrayBuffer.isView(value)) return value;",
    "      if (seen.has(value)) throw new Error('Tool RPC payload contains a circular reference');",
    "      seen.add(value);",
    "      if (__isBinaryEnvelope(value)) {",
    "        seen.delete(value);",
    "        if (value.kind === 'file' && typeof value.name === 'string') {",
    "          return new File([value.buffer], value.name, {",
    "            type: value.type,",
    "            ...(typeof value.lastModified === 'number' ? { lastModified: value.lastModified } : {}),",
    "          });",
    "        }",
    "        return new Blob([value.buffer], { type: value.type });",
    "      }",
    "      if (Array.isArray(value)) { const out = value.map((item) => __decodeBinary(item, seen)); seen.delete(value); return out; }",
    "      if (!__isPlainObject(value)) { seen.delete(value); return value; }",
    "      const out = {};",
    "      for (const [k, v] of Object.entries(value)) out[k] = __decodeBinary(v, seen);",
    "      seen.delete(value);",
    "      return out;",
    "    };",
    "    const __publicToolErrorMessage = (error) => {",
    "      const values = [error && error.primary, ...(Array.isArray(error && error.failures) ? error.failures : [])];",
    "      for (const value of values) {",
    "        if (value && value.__type === 'Error' && value.name === 'ExecutionToolError' && typeof value.message === 'string') return value.message;",
    "      }",
    "      if (error && typeof error.message === 'string' && error.message.startsWith('Internal tool error')) return error.message;",
    "      return null;",
    "    };",
    "    const __builtinToolKeys = { '': ['search', 'describe', 'executor'], 'describe': ['tool'], 'executor': ['sources'], 'executor.sources': ['list'] };",
    "    const __toolKeysForPath = (path) => __builtinToolKeys[path.join('.')] ?? [];",
    "    const __makeToolsProxy = (path = []) => new Proxy(() => undefined, {",
    "      get(_target, prop) {",
    "        if (prop === 'then' || typeof prop === 'symbol') return undefined;",
    "        return __makeToolsProxy([...path, String(prop)]);",
    "      },",
    "      ownKeys() {",
    "        return __toolKeysForPath(path);",
    "      },",
    "      getOwnPropertyDescriptor(_target, prop) {",
    "        return typeof prop === 'string' && __toolKeysForPath(path).includes(prop) ? { enumerable: true, configurable: true } : undefined;",
    "      },",
    "      apply(_target, _thisArg, args) {",
    "        const toolPath = path.join('.');",
    "        if (!toolPath) throw new Error('Tool path missing in invocation');",
    "        return (async () => {",
    "          const encoded = await __encodeBinary(args[0]);",
    "          const data = await __dispatcher.call(toolPath, encoded);",
    "          if (!data.ok) throw new Error(__publicToolErrorMessage(data.error) || 'Internal tool error');",
    "          return __decodeBinary(data.result);",
    "        })();",
    "      },",
    "    });",
    "    const tools = __makeToolsProxy();",
    "",
    "    try {",
    "      const result = await Promise.race([",
    "        (async () => {",
    body,
    "        })(),",
    "        new Promise((_, reject) =>",
    `          setTimeout(() => reject(new Error("Execution timed out after ${timeoutMs}ms")), ${timeoutMs})`,
    "        ),",
    "      ]);",
    "      await __pendingOutput;",
    "      return { result, output: __outputs.length > 0 ? __outputs : undefined, logs: __logs };",
    "    } catch (err) {",
    "      await __pendingOutput;",
    "      return { result: undefined, output: __outputs.length > 0 ? __outputs : undefined, error: __serializeThrownError(err), logs: __logs };",
    "    }",
    "  }",
    "}",
  ].join("\n");