#!/usr/bin/env node
import fs from 'fs';

function fail(code, message) {
  process.stderr.write(`${code}: ${message}\n`);
  process.exit(1);
}

function parseArgs(argv) {
  const args = { input: '', pretty: true };
  for (let i = 2; i < argv.length; i += 1) {
    const arg = argv[i];
    if (arg === '--input') {
      const value = argv[i + 1];
      if (!value || value.startsWith('--')) fail('CLI_ERROR', '--input requires a value');
      args.input = value;
      i += 1;
    } else if (arg === '--compact') {
      args.pretty = false;
    } else {
      fail('CLI_ERROR', `unknown argument: ${arg}`);
    }
  }
  return args;
}

function readInput(path) {
  if (!path || path === '-') return fs.readFileSync(0, 'utf8');
  return fs.readFileSync(path, 'utf8');
}

function normalizeRequest(raw) {
  let data;
  try {
    data = JSON.parse(raw);
  } catch {
    fail('INVALID_JSON', 'input must be valid JSON');
  }

  return {
    requestText: data.requestText || '',
    hasFilesOrSystems: Boolean(data.hasFilesOrSystems),
    needsWaiting: Boolean(data.needsWaiting),
    needsSubagent: Boolean(data.needsSubagent),
    needsOwnerDecision: Boolean(data.needsOwnerDecision),
    canReplyNow: Boolean(data.canReplyNow),
    taskName: data.taskName || 'Untitled long-task',
    currentStep: data.currentStep || 'Classifying request',
    nextStep: data.nextStep || 'Define next actionable step',
    nextReportCondition: data.nextReportCondition || 'After next meaningful milestone',
    waitingOn: data.waitingOn || 'none',
    blocker: data.blocker || 'none',
    checkpointTrigger: data.checkpointTrigger || '',
    externalizedTrigger: data.externalizedTrigger || '',
    triggerKind: data.triggerKind || '',
  };
}

function inferFromRequestText(input) {
  const text = (input.requestText || '').toLowerCase();
  const inferred = { ...input };

  if (!input.canReplyNow && /\b(can( not|'t)? use|check|inspect|investigate|review|verify|fix|debug|analyze|analyse|compare|deploy|run)\b/.test(text)) {
    inferred.hasFilesOrSystems = true;
  }
  if (!input.needsOwnerDecision && /\b(accept|reject|approve|decision|choose|pick|verdict)\b/.test(text)) {
    inferred.needsOwnerDecision = true;
  }
  if (!input.needsWaiting && /\b(wait|later|after|async|background|follow up|follow-up)\b/.test(text)) {
    inferred.needsWaiting = true;
  }
  if (!input.needsSubagent && /\bsubagent\b/.test(text)) {
    inferred.needsSubagent = true;
  }
  if (!input.checkpointTrigger && inferred.needsSubagent) {
    inferred.checkpointTrigger = 'when delegated work returns or the next checkpoint fires';
  }
  if (!input.externalizedTrigger && inferred.needsSubagent) {
    inferred.externalizedTrigger = 'wrapper-derived checkpoint artifact';
  }
  if (!input.triggerKind && inferred.needsSubagent) {
    inferred.triggerKind = 'artifact';
  }

  return inferred;
}

function classify(input) {
  const classification = input.canReplyNow && !input.hasFilesOrSystems && !input.needsWaiting && !input.needsSubagent && !input.needsOwnerDecision
    ? 'general_chat'
    : 'long_task';

  const silentCandidate = classification === 'long_task' && (input.needsWaiting || input.needsSubagent || Boolean(input.checkpointTrigger));
  const needsCheckpoint = classification === 'long_task';

  return {
    classification,
    silentCandidate,
    needsOwnerDecision: input.needsOwnerDecision,
    needsCheckpoint,
    needsSubagent: input.needsSubagent,
  };
}

function bootstrapTaskState(input, classificationResult) {
  if (classificationResult.classification !== 'long_task') return null;
  return {
    task_name: input.taskName,
    status: input.blocker !== 'none' ? 'blocked' : (input.waitingOn !== 'none' ? 'waiting_user' : 'active'),
    current_step: input.currentStep,
    next_step: input.nextStep,
    next_report_condition: input.nextReportCondition,
    waiting_on: input.waitingOn,
    blocker: input.blocker,
    silent: classificationResult.silentCandidate,
  };
}

function toSlug(value) {
  return String(value || '')
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, '-')
    .replace(/^-+|-+$/g, '')
    .slice(0, 48);
}

function buildExternalizedCheckpointPath(input, classificationResult) {
  if (classificationResult.classification !== 'long_task') return '';
  if (!classificationResult.silentCandidate) return '';
  if (!input.externalizedTrigger) return '';

  const taskSeed = [input.currentStep, input.nextStep, input.waitingOn, input.blocker]
    .map((value) => toSlug(value))
    .filter(Boolean)
    .join('-');
  const stableSeed = taskSeed || 'long-task';

  return `checkpoints/${stableSeed}.json`;
}

function buildProgressEvidence(input, classificationResult, externalizedCheckpointPath) {
  if (classificationResult.classification !== 'long_task') return null;
  if (!classificationResult.silentCandidate) return null;
  if (!externalizedCheckpointPath) return null;

  return {
    sessionKey: toSlug([input.currentStep, input.waitingOn, input.nextStep].filter(Boolean).join('-')) || 'long-task-session',
    checkpointPath: externalizedCheckpointPath,
  };
}

function validateSilentLaunch(input, classificationResult) {
  if (!classificationResult.silentCandidate) {
    return {
      ok: true,
      reason: 'not a silent long-task',
      recommendedFallback: 'none',
      requiredNextAction: 'proceed_with_normal_long_task_flow',
    };
  }

  if (!input.checkpointTrigger) {
    return {
      ok: false,
      reason: 'missing first forced checkpoint trigger',
      recommendedFallback: 'non_silent_follow_up',
      requiredNextAction: 'define_first_checkpoint_trigger_before_silent_launch',
    };
  }

  if (!input.externalizedTrigger) {
    return {
      ok: false,
      reason: 'missing externalized checkpoint path',
      recommendedFallback: 'non_silent_follow_up',
      requiredNextAction: 'bind_externalized_checkpoint_path_or_abort_silent_launch',
    };
  }

  return {
    ok: true,
    reason: `${input.triggerKind || 'externalized'} trigger is defined`,
    recommendedFallback: 'none',
    requiredNextAction: 'proceed_with_silent_launch',
  };
}

function planHandoff(classificationResult) {
  if (classificationResult.needsOwnerDecision) return { mode: 'button_path' };
  return { mode: 'direct_reply' };
}

function main() {
  const args = parseArgs(process.argv);
  const raw = readInput(args.input);
  const input = inferFromRequestText(normalizeRequest(raw));
  const classificationResult = classify(input);
  const taskRecord = bootstrapTaskState(input, classificationResult);
  const externalizedCheckpointPath = buildExternalizedCheckpointPath(input, classificationResult);
  const progressEvidence = buildProgressEvidence(input, classificationResult, externalizedCheckpointPath);
  const silentLaunch = validateSilentLaunch(input, classificationResult);
  const handoff = planHandoff(classificationResult);

  const output = {
    classification: classificationResult.classification,
    silentCandidate: classificationResult.silentCandidate,
    needsOwnerDecision: classificationResult.needsOwnerDecision,
    needsCheckpoint: classificationResult.needsCheckpoint,
    needsSubagent: classificationResult.needsSubagent,
    taskRecord,
    progressEvidence,
    externalizedCheckpointPath,
    silentLaunchOk: silentLaunch.ok,
    silentLaunchReason: silentLaunch.reason,
    recommendedFallback: silentLaunch.recommendedFallback,
    requiredNextAction: silentLaunch.requiredNextAction,
    handoff,
  };

  process.stdout.write(JSON.stringify(output, null, args.pretty ? 2 : 0) + '\n');
}

try {
  main();
} catch (error) {
  fail('CLI_ERROR', error && error.message ? error.message : 'unexpected error');
}