import {spawn} from 'node:child_process';
import {mkdirSync, writeFileSync} from 'node:fs';
import path from 'node:path';

const [, , rawMode = 'debug', ...args] = process.argv;
const mode = rawMode.trim();
const printConfigOnly = args.includes('--print-config');

const supportedModes = new Set(['debug', 'rider']);
if (!supportedModes.has(mode)) {
  console.error('[otelcol] mode must be one of: debug, rider');
  process.exit(1);
}

const otlpHttpEndpoint = readEnv('OTELCOL_OTLP_HTTP_ENDPOINT', '127.0.0.1:4318');
const otlpGrpcEndpoint = readEnv('OTELCOL_OTLP_GRPC_ENDPOINT', '127.0.0.1:4317');
const riderEndpoint = readEnv('RIDER_OTLP_GRPC_ENDPOINT', '127.0.0.1:17011');
const debugVerbosity = readEnv('OTELCOL_DEBUG_VERBOSITY', 'detailed');
const otelcolBin = readEnv('OTELCOL_BIN', 'otelcol-contrib');

const configText = buildConfig(mode);
const configDir = path.resolve('.codex-temp', 'otelcol');
const configPath = path.join(configDir, `genarrative-${mode}.yaml`);
mkdirSync(configDir, {recursive: true});
writeFileSync(configPath, configText, 'utf8');

console.log(`[otelcol] wrote ${configPath}`);
console.log(`[otelcol] receiving OTLP HTTP at http://${otlpHttpEndpoint}`);
console.log(`[otelcol] receiving OTLP gRPC at ${otlpGrpcEndpoint}`);
if (mode === 'rider') {
  console.log(`[otelcol] forwarding traces/metrics/logs to Rider OTLP gRPC at ${riderEndpoint}`);
}
console.log(
  '[otelcol] api-server env: GENARRATIVE_OTEL_ENABLED=true OTEL_EXPORTER_OTLP_ENDPOINT=http://127.0.0.1:4318'
);

if (printConfigOnly) {
  console.log(configText);
  process.exit(0);
}

const child = spawn(otelcolBin, ['--config', configPath], {
  cwd: process.cwd(),
  env: process.env,
  stdio: 'inherit',
});

const stopChild = () => {
  if (!child.killed) {
    child.kill();
  }
};

for (const signal of ['SIGINT', 'SIGTERM', 'SIGHUP']) {
  process.on(signal, () => {
    stopChild();
    process.exit(130);
  });
}

process.on('exit', stopChild);

child.on('error', (error) => {
  console.error(`[otelcol] failed to start ${otelcolBin}: ${error.message}`);
  console.error('[otelcol] install otelcol-contrib and make sure it is on PATH, or set OTELCOL_BIN.');
  process.exit(1);
});

child.on('exit', (code, signal) => {
  if (signal) {
    console.error(`[otelcol] exited by signal: ${signal}`);
    process.exit(1);
  }
  process.exit(code ?? 0);
});

function readEnv(key, fallback) {
  const value = process.env[key]?.trim();
  return value ? value : fallback;
}

function buildConfig(selectedMode) {
  const exporters =
    selectedMode === 'rider'
      ? `  otlp/rider:
    endpoint: ${riderEndpoint}
    tls:
      insecure: true
  debug:
    verbosity: ${debugVerbosity}`
      : `  debug:
    verbosity: ${debugVerbosity}`;

  const pipelineExporters = selectedMode === 'rider' ? '[otlp/rider, debug]' : '[debug]';

  return `receivers:
  otlp:
    protocols:
      grpc:
        endpoint: ${otlpGrpcEndpoint}
      http:
        endpoint: ${otlpHttpEndpoint}

exporters:
${exporters}

service:
  pipelines:
    traces:
      receivers: [otlp]
      exporters: ${pipelineExporters}
    metrics:
      receivers: [otlp]
      exporters: ${pipelineExporters}
    logs:
      receivers: [otlp]
      exporters: ${pipelineExporters}
`;
}