import { spawnSync } from "node:child_process";
import { resolve } from "node:path";

import openapiTS, { astToString, COMMENT_HEADER } from "openapi-typescript";

const requiredPaths = [
  "/api/v1/demo/status",
  "/api/v1/demo/search",
  "/api/v1/retrieval/search",
  "/api/v1/chat/completions",
  "/api/v1/document-uploads",
  "/api/v1/document-uploads/{upload_id}/content",
  "/api/v1/document-uploads/{upload_id}/complete",
  "/api/v1/documents",
  "/api/v1/documents/{document_id}",
  "/api/v1/documents/{document_id}/review-bundle",
  "/api/v1/documents/{document_id}/review-decisions",
  "/api/v1/document-jobs/{job_id}",
];

async function schemaFromUrl(schemaUrl) {
  const response = await fetch(schemaUrl, {
    headers: { Accept: "application/json" },
    signal: AbortSignal.timeout(10_000),
  });
  if (!response.ok) throw new Error(`OpenAPI schema request failed with HTTP ${response.status}`);
  return response.json();
}

function offlineSchema() {
  const backendDirectory = resolve("..", "backend");
  const python = process.env.BACKEND_PYTHON ?? resolve(backendDirectory, ".venv/bin/python");
  const result = spawnSync(python, ["-m", "app.tools.export_openapi"], {
    cwd: backendDirectory,
    encoding: "utf8",
    stdio: ["ignore", "pipe", "pipe"],
  });
  if (result.status !== 0 || result.error || !result.stdout) {
    throw new Error("Offline OpenAPI export failed; run make backend-sync first");
  }
  try {
    return JSON.parse(result.stdout);
  } catch {
    throw new Error("Offline OpenAPI export returned invalid JSON");
  }
}

export async function loadOpenApiSchema() {
  const schema = process.env.OPENAPI_SCHEMA_URL
    ? await schemaFromUrl(process.env.OPENAPI_SCHEMA_URL)
    : offlineSchema();
  if (typeof schema !== "object" || schema === null || !("paths" in schema)) {
    throw new Error("OpenAPI response does not contain a paths object");
  }
  const paths = schema.paths;
  if (typeof paths !== "object" || paths === null) {
    throw new Error("OpenAPI paths value is invalid");
  }
  for (const path of requiredPaths) {
    if (!(path in paths)) throw new Error(`Required API path is missing: ${path}`);
  }
  return schema;
}

export async function renderOpenApiTypes(schema) {
  const ast = await openapiTS(schema, { alphabetize: true, immutable: true });
  return `${COMMENT_HEADER}${astToString(ast)}`;
}