import { execFile } from 'node:child_process';
import { rm, writeFile } from 'node:fs/promises';
import path from 'node:path';
import { promisify } from 'node:util';
import { loadApiContracts } from '@/openapi/contracts';
import { discoverApiOperations, discoverContractFiles } from '@/openapi/discover';
import { buildOpenApiDocument } from '@/openapi/document';
import { inferApiContracts } from '@/openapi/infer';
import type { LoadedApiOperationContract } from '@/openapi/operation';

const projectRoot = process.cwd();
const generatedFileName = 'contract.generated.ts';
const generatedHeader = '// Generated by `pnpm openapi:contracts`. Do not edit directly.';
const execFileAsync = promisify(execFile);

const existingGeneratedFiles = (await discoverContractFiles(projectRoot)).filter(
  file => path.basename(file) === generatedFileName,
);

await Promise.all(existingGeneratedFiles.map(file => rm(file)));

const [explicitContracts, discovered] = await Promise.all([
  loadApiContracts(projectRoot),
  discoverApiOperations(projectRoot),
]);
const inferredContracts = inferApiContracts(discovered, explicitContracts);
const { document } = await buildOpenApiDocument('all', projectRoot);
const documentPaths = document.paths ?? {};
const byRoute = new Map<string, LoadedApiOperationContract[]>();
const generatedFiles: string[] = [];

inferredContracts.forEach(contract => {
  byRoute.set(contract.source, [...(byRoute.get(contract.source) ?? []), contract]);
});

function serialize(value: unknown) {
  return JSON.stringify(value, null, 2);
}

for (const [routeSource, contracts] of byRoute) {
  const routeFile = path.join(projectRoot, ...routeSource.split('/'));
  const outputFile = path.join(path.dirname(routeFile), generatedFileName);
  const operationDefinitions = contracts.map((contract, index) => {
    const generatedOperation = documentPaths[contract.path]?.[contract.method];

    if (!generatedOperation || typeof generatedOperation !== 'object') {
      throw new Error(
        `Generated document is missing ${contract.method.toUpperCase()} ${contract.path}.`,
      );
    }

    const operation = structuredClone(generatedOperation) as Record<string, unknown>;
    delete operation.security;
    delete operation['x-umami-audience'];
    delete operation['x-umami-contract'];
    delete operation['x-umami-source'];

    if (
      typeof operation.description === 'string' &&
      operation.description.startsWith('Generated from')
    ) {
      delete operation.description;
    }

    return `const operation${index + 1} = defineOperation({\n  method: ${serialize(contract.method)},\n  path: ${serialize(contract.path)},\n  audience: ${serialize(contract.audience)},\n  auth: ${serialize(contract.auth)},\n  operation: ${serialize(operation)} as ZodOpenApiOperationObject,\n});`;
  });
  const exports = contracts.map((_, index) => `operation${index + 1}`).join(', ');
  const content = `${generatedHeader}\n\nimport type { ZodOpenApiOperationObject } from 'zod-openapi';\nimport { defineOperation } from '@/openapi/operation';\n\n${operationDefinitions.join('\n\n')}\n\nexport const operations = [${exports}] as const;\n`;

  await writeFile(outputFile, content, 'utf8');
  generatedFiles.push(outputFile);
}

const formatter = path.join(projectRoot, 'node_modules', '@biomejs', 'biome', 'bin', 'biome');
for (let index = 0; index < generatedFiles.length; index += 20) {
  await execFileAsync(process.execPath, [
    formatter,
    'format',
    '--write',
    ...generatedFiles.slice(index, index + 20),
  ]);
}

const generatedCount = [...byRoute.values()].reduce(
  (total, contracts) => total + contracts.length,
  0,
);
console.log(`Generated ${generatedCount} explicit contracts in ${byRoute.size} route modules.`);