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

const EVIDENCE_FIELDS = Object.freeze({
  externalizedCheckpoint: Object.freeze([
    'externalizedCheckpointPath',
    'externalizedTrigger',
    'checkpointPath',
  ]),
  concreteNextAction: Object.freeze([
    'nextStep',
    'requiredNextAction',
    'concreteNextAction',
  ]),
  buttonPathMode: Object.freeze([
    'handoffMode',
    'handoff.mode',
    'replyClosureMode',
  ]),
  progressionClaim: Object.freeze([
    'progressionClaim',
    'claimedProgression',
    'statusSummary',
  ]),
  executionEvidence: Object.freeze([
    'executionEvidence',
    'toolCallEvidence',
    'dispatchEvidence',
    'fileChangeEvidence',
    'verificationEvidence',
    'checkpointArtifactEvidence',
  ]),
  progressEvidence: Object.freeze([
    'progressEvidence',
    'progressEvidence.sessionKey',
    'progressEvidence.runId',
    'progressEvidence.modified_files',
    'progressEvidence.verificationResult',
    'sessionKey',
    'runId',
    'modified_files',
    'verificationResult',
  ]),
});

const GATE_REQUIREMENTS = Object.freeze({
  externalizedCheckpoint: Object.freeze({
    evidenceKey: 'externalizedCheckpoint',
    acceptedFields: EVIDENCE_FIELDS.externalizedCheckpoint,
    requiredValue: 'non-empty string',
  }),
  concreteNextAction: Object.freeze({
    evidenceKey: 'concreteNextAction',
    acceptedFields: EVIDENCE_FIELDS.concreteNextAction,
    requiredValue: 'non-empty string',
  }),
  buttonPathMode: Object.freeze({
    evidenceKey: 'buttonPathMode',
    acceptedFields: EVIDENCE_FIELDS.buttonPathMode,
    requiredValue: 'button_path',
  }),
  executionEvidence: Object.freeze({
    evidenceKey: 'executionEvidence',
    acceptedFields: EVIDENCE_FIELDS.executionEvidence,
    requiredValue: 'tool call, dispatch, file change, verification output, or checkpoint artifact evidence',
  }),
  progressEvidence: Object.freeze({
    evidenceKey: 'progressEvidence',
    acceptedFields: EVIDENCE_FIELDS.progressEvidence,
    requiredValue: 'sessionKey, runId, modified_files, verification result, or equivalent concrete progress evidence',
  }),
});

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 parseJson(raw) {
  try {
    return JSON.parse(raw);
  } catch {
    fail('INVALID_JSON', 'input must be valid JSON');
  }
}

function isLongTask(input) {
  return input.classification === 'long_task';
}

function hasNonEmptyString(value) {
  return typeof value === 'string' && value.trim().length > 0;
}

function getPathValue(input, path) {
  return path.split('.').reduce((current, key) => {
    if (current === null || current === undefined) return undefined;
    return current[key];
  }, input);
}

function hasAnyNonEmptyString(input, fieldPaths) {
  return fieldPaths.some((fieldPath) => hasNonEmptyString(getPathValue(input, fieldPath)));
}

function hasAcceptedValue(input, fieldPaths, acceptedValue) {
  return fieldPaths.some((fieldPath) => getPathValue(input, fieldPath) === acceptedValue);
}

function describeRequirement(requirement) {
  return {
    evidenceKey: requirement.evidenceKey,
    acceptedFields: [...requirement.acceptedFields],
    requiredValue: requirement.requiredValue,
  };
}

function hasExternalizedCheckpointPath(input) {
  return hasAnyNonEmptyString(input, EVIDENCE_FIELDS.externalizedCheckpoint);
}

function hasConcreteNextAction(input) {
  return hasAnyNonEmptyString(input, EVIDENCE_FIELDS.concreteNextAction);
}

function wantsSilentContinuation(input) {
  if (typeof input.silentContinuation === 'boolean') return input.silentContinuation;
  if (typeof input.silentCandidate === 'boolean') return input.silentCandidate;
  if (typeof input.needsWaiting === 'boolean' && input.needsWaiting) return true;
  if (typeof input.needsSubagent === 'boolean' && input.needsSubagent) return true;
  return false;
}

function claimsExecution(input) {
  if (typeof input.claimedExecution === 'boolean') return input.claimedExecution;
  if (typeof input.executionClaimed === 'boolean') return input.executionClaimed;
  if (typeof input.status === 'string' && input.status === 'active') return true;
  return false;
}

function needsOwnerDecision(input) {
  if (typeof input.needsOwnerDecision === 'boolean') return input.needsOwnerDecision;
  return false;
}

function usesButtonPath(input) {
  return hasAcceptedValue(input, EVIDENCE_FIELDS.buttonPathMode, 'button_path');
}

function hasExecutionEvidence(input) {
  return EVIDENCE_FIELDS.executionEvidence.some((fieldPath) => {
    const value = getPathValue(input, fieldPath);
    if (hasNonEmptyString(value)) return true;
    if (Array.isArray(value)) return value.length > 0;
    if (value && typeof value === 'object') return Object.keys(value).length > 0;
    return false;
  });
}

function hasProgressEvidence(input) {
  return EVIDENCE_FIELDS.progressEvidence.some((fieldPath) => {
    const value = getPathValue(input, fieldPath);
    if (hasNonEmptyString(value)) return true;
    if (Array.isArray(value)) return value.length > 0;
    if (value && typeof value === 'object') return Object.keys(value).length > 0;
    return false;
  });
}

function claimsProgressionWithoutEvidence(input) {
  const progressionClaim = EVIDENCE_FIELDS.progressionClaim
    .map((fieldPath) => getPathValue(input, fieldPath))
    .find((value) => hasNonEmptyString(value));

  if (!hasNonEmptyString(progressionClaim)) return false;

  return !(hasProgressEvidence(input) || hasExecutionEvidence(input));
}

function evaluateGate(input) {
  const gateRequired = isLongTask(input);
  const reasons = [];
  const requiredEvidence = [];
  const allowedResponseModes = [];

  if (!gateRequired) {
    return {
      gateRequired: false,
      gateStatus: 'not_applicable',
      reasons: ['classification is not long_task'],
      requiredEvidence: [],
      allowedResponseModes: ['direct_reply'],
    };
  }

  let failed = false;

  if (wantsSilentContinuation(input) && !hasExternalizedCheckpointPath(input)) {
    failed = true;
    reasons.push('silent long-task cannot continue without externalized checkpoint path');
    requiredEvidence.push(describeRequirement(GATE_REQUIREMENTS.externalizedCheckpoint));
    allowedResponseModes.push('non_silent_follow_up');
  }

  if (claimsExecution(input) && !hasConcreteNextAction(input)) {
    failed = true;
    reasons.push('claimed execution requires evidence of a concrete next action');
    requiredEvidence.push(describeRequirement(GATE_REQUIREMENTS.concreteNextAction));
    allowedResponseModes.push('checkpoint_only');
  }

  if (needsOwnerDecision(input) && !usesButtonPath(input)) {
    failed = true;
    reasons.push('owner decision flow must end in button-path, not plain text');
    requiredEvidence.push(describeRequirement(GATE_REQUIREMENTS.buttonPathMode));
    allowedResponseModes.push('button_path');
  }

  if (claimsProgressionWithoutEvidence(input)) {
    failed = true;
    reasons.push('claimed progression without concrete progress evidence is forbidden');
    requiredEvidence.push(describeRequirement(GATE_REQUIREMENTS.progressEvidence));
    allowedResponseModes.push('evidence_preserving_follow_up');
  }

  if (!failed) {
    reasons.push('required long-task gate evidence is present or no gated condition was triggered');
    allowedResponseModes.push(needsOwnerDecision(input) ? 'button_path' : 'direct_reply');
    if (wantsSilentContinuation(input)) allowedResponseModes.push('silent_continuation');
  }

  return {
    gateRequired: true,
    gateStatus: failed ? 'fail' : 'pass',
    reasons,
    requiredEvidence,
    allowedResponseModes: [...new Set(allowedResponseModes)],
  };
}

function main() {
  const args = parseArgs(process.argv);
  const raw = readInput(args.input);
  const input = parseJson(raw);
  const output = evaluateGate(input);
  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');
}