const TRUE_VALUES = new Set(['1', 'true', 'yes', 'on']);

function readFlag(env, key, fallback = false) {
  const raw = env?.[key];
  if (raw == null || raw === '') return fallback;
  return TRUE_VALUES.has(String(raw).trim().toLowerCase());
}

function normalizeUserIds(value) {
  return String(value ?? '')
    .split(/[\s,]+/u)
    .map((item) => item.trim())
    .filter(Boolean);
}

export function evaluateMemoryV2PhaseAReadiness(env = process.env) {
  const issues = [];
  const warnings = [];
  const agentCanaryUserIds = normalizeUserIds(env.MEMORY_AGENT_CANARY_USER_IDS);
  const lifecycleUserIds = normalizeUserIds(env.MEMORY_LIFECYCLE_ROLLOUT_USER_IDS);
  const candidateMode = String(env.MEMORY_CANDIDATE_MODE ?? 'off').trim().toLowerCase();
  const injectionMode = String(env.MEMORY_AGENT_INJECTION_MODE ?? 'off').trim().toLowerCase();
  const lifecycleMode = String(env.MEMORY_LIFECYCLE_ROLLOUT_MODE ?? 'off').trim().toLowerCase();

  if (!readFlag(env, 'MEMORY_ENABLED')) {
    issues.push({ code: 'memory_disabled', message: 'MEMORY_ENABLED must be 1' });
  }
  if (!readFlag(env, 'MEMORY_CANDIDATE_ENABLED')) {
    issues.push({ code: 'candidate_disabled', message: 'MEMORY_CANDIDATE_ENABLED must be 1' });
  }
  if (candidateMode !== 'canary') {
    issues.push({ code: 'candidate_mode', message: `MEMORY_CANDIDATE_MODE must be canary (current: ${candidateMode || 'off'})` });
  }
  if (readFlag(env, 'MEMORY_CANDIDATE_AUTO_ACCEPT_ALL')) {
    issues.push({ code: 'auto_accept_all', message: 'MEMORY_CANDIDATE_AUTO_ACCEPT_ALL must stay 0 in Phase A' });
  }
  if (!readFlag(env, 'MEMORY_CANDIDATE_PERSISTENCE_ENABLED')) {
    issues.push({ code: 'candidate_persistence', message: 'MEMORY_CANDIDATE_PERSISTENCE_ENABLED must be 1' });
  }
  if (!readFlag(env, 'MEMORY_AGENT_RESOLVE_ENABLED')) {
    issues.push({ code: 'agent_resolve_disabled', message: 'MEMORY_AGENT_RESOLVE_ENABLED must be 1' });
  }
  if (injectionMode !== 'canary') {
    issues.push({ code: 'injection_mode', message: `MEMORY_AGENT_INJECTION_MODE must be canary (current: ${injectionMode || 'off'})` });
  }
  if (agentCanaryUserIds.length === 0) {
    issues.push({ code: 'agent_canary_users_missing', message: 'MEMORY_AGENT_CANARY_USER_IDS must list at least one user id' });
  }
  if (!readFlag(env, 'MEMORY_LIFECYCLE_ENABLED')) {
    issues.push({ code: 'lifecycle_disabled', message: 'MEMORY_LIFECYCLE_ENABLED must be 1' });
  }
  if (lifecycleMode !== 'canary') {
    issues.push({ code: 'lifecycle_mode', message: `MEMORY_LIFECYCLE_ROLLOUT_MODE must be canary (current: ${lifecycleMode || 'off'})` });
  }
  if (lifecycleUserIds.length === 0) {
    issues.push({ code: 'lifecycle_users_missing', message: 'MEMORY_LIFECYCLE_ROLLOUT_USER_IDS must list at least one user id' });
  }
  if (agentCanaryUserIds.join(',') !== lifecycleUserIds.join(',')) {
    issues.push({
      code: 'canary_user_mismatch',
      message: 'MEMORY_AGENT_CANARY_USER_IDS and MEMORY_LIFECYCLE_ROLLOUT_USER_IDS must match exactly',
    });
  }
  if (!readFlag(env, 'MEMORY_PROMOTION_ENABLED')) {
    issues.push({ code: 'promotion_disabled', message: 'MEMORY_PROMOTION_ENABLED must be 1' });
  }
  if (readFlag(env, 'MEMORY_LIFECYCLE_FORGETTING_ENABLED')) {
    issues.push({ code: 'forgetting_enabled', message: 'MEMORY_LIFECYCLE_FORGETTING_ENABLED must stay 0 in Phase A' });
  }
  if (readFlag(env, 'MEMORY_LIFECYCLE_DECAY_ENABLED')) {
    issues.push({ code: 'decay_enabled', message: 'MEMORY_LIFECYCLE_DECAY_ENABLED must stay 0 in Phase A' });
  }

  const pgConfigured = Boolean(String(env.MEMORY_PGVECTOR_DATABASE_URL ?? '').trim())
    && Boolean(String(env.MEMORY_PGVECTOR_EMBEDDING_MODULE ?? '').trim());
  if (!pgConfigured) {
    warnings.push({
      code: 'pgvector_not_configured',
      message: 'pgvector URL/embedding module not configured; recall will stay legacy-only until configured',
    });
  }

  return {
    ok: issues.length === 0,
    issues,
    warnings,
    summary: {
      candidateMode,
      injectionMode,
      lifecycleMode,
      agentCanaryUserIds,
      lifecycleUserIds,
      pgConfigured,
    },
  };
}