#!/usr/bin/env node
import { randomUUID } from 'node:crypto';
import { hostname } from 'node:os';
import {
  type Dict,
  isRecord,
  pickString,
  pickNumber,
  truncate,
  buildEnvelope,
  createTransport,
  readStdin,
} from '../shared/lib';

const INGEST_URL = process.env.AGENTMON_INGEST_URL || 'http://localhost:8080';
const FRAMEWORK = process.env.AGENTMON_FRAMEWORK || 'codex';
const HOST = process.env.AGENTMON_HOST || hostname();

const { enqueue, flush } = createTransport(INGEST_URL);

const activeRuns = new Map<string, string>();

function getSessionKey(input: Dict): string | undefined {
  return pickString(
    input.id,
    input.session,
    input.sessionId,
    input.session_id,
    input.threadId,
    input.thread_id,
    input.chatId,
    input.chat_id,
    input.conversationId,
    input.conversation_id,
  );
}

function getUsage(input: Dict): Dict | undefined {
  const usage = isRecord(input.usage) ? input.usage :
                isRecord(input.llm) ? input.llm :
                isRecord(input.tokens) ? input.tokens :
                isRecord(input.llm_usage) ? input.llm_usage : undefined;
  if (!usage) return undefined;

  const result: Dict = {};
  if (usage.input_tokens !== undefined) result.input_tokens = usage.input_tokens;
  if (usage.prompt_tokens !== undefined) result.input_tokens = usage.prompt_tokens;
  if (usage.input !== undefined) result.input_tokens = usage.input;
  if (usage.output_tokens !== undefined) result.output_tokens = usage.output_tokens;
  if (usage.completion_tokens !== undefined) result.output_tokens = usage.completion_tokens;
  if (usage.output !== undefined) result.output_tokens = usage.output;
  if (usage.total_tokens !== undefined) result.total_tokens = usage.total_tokens;
  if (usage.total !== undefined) result.total_tokens = usage.total;
  if (usage.cost !== undefined) result.total_cost = usage.cost;
  if (usage.total_cost !== undefined) result.total_cost = usage.total_cost;

  return Object.keys(result).length > 0 ? result : undefined;
}

function getModel(input: Dict): string | undefined {
  return pickString(
    input.model,
    isRecord(input.llm) ? input.llm.model : undefined,
    isRecord(input.usage) ? input.usage.model : undefined,
  );
}

function enqueueMetricSnapshot(sessionKey: string | undefined, runId: string | undefined, usage: Dict | undefined, input: Dict) {
  if (!usage) {
    return;
  }

  const metrics: Dict = { usage };
  const model = getModel(input);
  if (model) {
    metrics.model = model;
  }

  enqueue(buildEnvelope(FRAMEWORK, HOST, 'metric.snapshot', sessionKey, {
    runId,
    payload: { metrics },
  }));
}

function startRun(sessionKey: string | undefined, input: Dict): string {
  const runId = randomUUID();
  if (sessionKey) {
    activeRuns.set(sessionKey, runId);
  }

  enqueue(buildEnvelope(FRAMEWORK, HOST, 'run.start', sessionKey, {
    runId,
    attributes: {
      trigger: pickString(input.trigger_type, input.trigger, input.event, input.event_type),
    },
    payload: {
      prompt_preview: truncate(pickString(input.prompt, input.message, input.text), 200),
    },
  }));

  return runId;
}

function endRun(sessionKey: string | undefined, runId: string | undefined, input: Dict, duration?: number) {
  if (!runId) {
    return;
  }

  const usage = getUsage(input);
  enqueue(buildEnvelope(FRAMEWORK, HOST, 'run.end', sessionKey, {
    runId,
    payload: {
      status: 'success',
      duration_ms: duration,
      model: getModel(input),
      ...(usage && { usage }),
    },
  }));
  enqueueMetricSnapshot(sessionKey, runId, usage, input);
}

async function handleSessionStart(input: Dict) {
  const sessionKey = getSessionKey(input) || randomUUID();

  enqueue(buildEnvelope(FRAMEWORK, HOST, 'session.start', sessionKey));
  startRun(sessionKey, input);

  await flush();
}

async function handleSessionEnd(input: Dict) {
  const sessionKey = getSessionKey(input);
  const runId = sessionKey ? activeRuns.get(sessionKey) : undefined;
  const usage = getUsage(input);
  const duration = pickNumber(input.duration_ms, input.elapsed_ms, input.duration);

  endRun(sessionKey, runId, input, duration);

  enqueue(buildEnvelope(FRAMEWORK, HOST, 'session.end', sessionKey, {
    payload: {
      model: getModel(input),
      ...(usage && { usage }),
    },
  }));

  enqueueMetricSnapshot(sessionKey, runId, usage, input);

  activeRuns.delete(sessionKey || '');
  await flush();
}

async function handlePromptSubmit(input: Dict) {
  const sessionKey = getSessionKey(input);
  const runId = sessionKey ? activeRuns.get(sessionKey) : undefined;
  const duration = pickNumber(input.elapsed_ms, input.duration_ms, input.duration);
  const prompt = pickString(input.prompt, input.text, input.message);

  if (runId && prompt) {
    endRun(sessionKey, runId, input, duration);
  }

  startRun(sessionKey, input);
  await flush();
}

async function handleNotification(input: Dict) {
  const sessionKey = getSessionKey(input);
  const notificationType = pickString(input.type, input.notification_type, input.event, input.event_type);
  const usage = getUsage(input);
  const duration = pickNumber(input.duration_ms, input.elapsed_ms);

  if (notificationType === 'agent-turn-complete' || notificationType === 'Done' || notificationType === 'turn.complete') {
    const runId = sessionKey ? activeRuns.get(sessionKey) : undefined;
    endRun(sessionKey, runId, input, duration);

    if (pickString(input.prompt, input.message, input.text)) {
      startRun(sessionKey, input);
    }
  } else if (usage) {
    enqueueMetricSnapshot(sessionKey, sessionKey ? activeRuns.get(sessionKey) : undefined, usage, input);
  }

  await flush();
}

const handler = async () => {
  const args = process.argv.slice(2);
  const hookType = args[0] || 'unknown';

  let input: Dict = {};
  try {
    const stdin = await readStdin();
    if (stdin) {
      input = JSON.parse(stdin);
    }
  } catch {
    input = {};
  }

  try {
    switch (hookType) {
      case 'start':
        await handleSessionStart(input);
        break;
      case 'stop':
        await handleSessionEnd(input);
        break;
      case 'prompt':
      case 'prompt-submit':
        await handlePromptSubmit(input);
        break;
      case 'notification':
        await handleNotification(input);
        break;
      default:
        console.debug(`[agentmon] unknown hook type: ${hookType}`);
    }
  } catch (err) {
    console.debug('[agentmon] handler error:', err);
  }
};

handler();