/**
 * tests/DSLRuntimeCache.test.js — provider-result caching with time expiry.
 *
 * Registered providers retrieve missing facts from a data store; caching the
 * retrieval avoids hammering the store on repeated checks. TTL resolution:
 * DSL-declared `BEHAVES { ttl <duration> }` on a fact > per-fact setFactTTL >
 * policy default (30s). Per-check factProviders are cache-transparent (one-off
 * observations: no cache read, no cache write). Registering a provider or
 * mutating the graph invalidates the cache.
 */
import { describe, it } from 'node:test';
import assert from 'node:assert/strict';
import { Arbiter } from '@arbiter/core';
import { DSLRuntime } from '../src/runtime/DSLRuntime.js';

const BASE_DSL = `
  definition Employee { id: string }
  definition Doc { id: string }
  fact *owns(user: Employee, doc: Doc)
  evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
`;

function makeRuntime(options = {}) {
  let t = 0;
  const clock = () => t;
  const rt = new DSLRuntime(new Arbiter(), { clock, ...options }).compile(BASE_DSL, 'rt-cache');
  rt._test_advance = (ms) => { t += ms; };
  return rt;
}

describe('DSLRuntime provider-result caching', () => {
  it('reuses a registered provider result within the TTL', async () => {
    const rt = makeRuntime();
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('owns', async () => { calls++; return 0.9; });
    await rt.check('u:1', 'can_read', 'doc:9');
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 1, 'provider should be invoked once within TTL');
  });

  it('re-invokes the provider after the TTL expires', async () => {
    const rt = makeRuntime();
    rt.setFactTTL('owns', 100);
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    let value = 0.9;
    rt.registerFact('owns', async () => { calls++; return value; });
    const first = await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(first.possibility, 0.9);
    rt._test_advance(50);
    await rt.check('u:1', 'can_read', 'doc:9'); // within TTL -> cached
    assert.equal(calls, 1);
    rt._test_advance(60); // past TTL (110 total)
    value = 0.4;
    const after = await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 2);
    assert.equal(after.possibility, 0.4);
  });

  it('per-check factProviders override the cache (fresh observation)', async () => {
    const rt = makeRuntime();
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    rt.registerFact('owns', async () => 0.9);
    await rt.check('u:1', 'can_read', 'doc:9');
    // Per-check override is cache-transparent: it must NOT be masked by the
    // cached 0.9, and it must NOT overwrite the cached value.
    const over = await rt.check('u:1', 'can_read', 'doc:9', {
      factProviders: { owns: async () => 0.2 }
    });
    assert.equal(over.possibility, 0.2);
    const next = await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(next.possibility, 0.9, 'registered provider cache untouched by per-check override');
  });

  it('registerFact invalidates the cached result for that relation', async () => {
    const rt = makeRuntime();
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    rt.registerFact('owns', async () => 0.9);
    await rt.check('u:1', 'can_read', 'doc:9');
    rt.registerFact('owns', async () => 0.3); // re-register -> cache invalidated
    const res = await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(res.possibility, 0.3);
  });

  it('invalidates cached results on graph mutations', async () => {
    const rt = makeRuntime();
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('owns', async () => { calls++; return 0.9; });
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 1);
    rt.addRelation('u:1', 'owns', 'doc:9', { possibility: 1.0 }); // mutation clears cache
    const res = await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 2, 'graph mutation should invalidate the provider cache');
  });

  it('invalidateProviderCache() clears all or per relation', async () => {
    const dsl = `
      definition Employee { id: string }
      definition Doc { id: string }
      fact *owns(user: Employee, doc: Doc)
      fact *banned(user: Employee)
      evidence can_read(user: Employee, doc: Doc) { owns(user, doc) }
      evidence can_open(user: Employee, doc: Doc) { WHEN can_read(user, doc) UNLESS banned(user) }
    `;
    const rt = new DSLRuntime(new Arbiter()).compile(dsl, 'rt-cache2');
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let ownsCalls = 0, bannedCalls = 0;
    rt.registerFact('owns', async () => { ownsCalls++; return 0.9; });
    rt.registerFact('banned', async () => { bannedCalls++; return 0; });
    await rt.check('u:1', 'can_open', 'doc:9');
    assert.equal(ownsCalls, 1);
    assert.equal(bannedCalls, 1);
    // Invalidate a non-dependency relation: can_open's cache (owns+banned) survives.
    rt.invalidateProviderCache('does_not_exist');
    await rt.check('u:1', 'can_open', 'doc:9');
    assert.equal(ownsCalls, 1);
    assert.equal(bannedCalls, 1);
    // Invalidate owns only: banned survives, owns re-fetched.
    rt.invalidateProviderCache('owns');
    await rt.check('u:1', 'can_open', 'doc:9');
    assert.equal(ownsCalls, 2, 'owns cache cleared by per-relation invalidation');
    assert.equal(bannedCalls, 1, 'banned cache survives per-relation invalidation');
    // Clear all.
    rt.invalidateProviderCache();
    await rt.check('u:1', 'can_open', 'doc:9');
    assert.equal(bannedCalls, 2, 'full invalidation clears every relation');
  });

  it('policy default TTL applies when no per-fact TTL is set', async () => {
    const rt = makeRuntime({ policy: { providerCacheTTL: 50 } });
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('owns', async () => { calls++; return 0.9; });
    await rt.check('u:1', 'can_read', 'doc:9');
    rt._test_advance(40);
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 1, 'within 50ms policy TTL -> cached');
    rt._test_advance(20);
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 2, 'past 50ms policy TTL -> re-invoked');
  });

  it('uses the DSL-declared fact TTL (BEHAVES { ttl X })', async () => {
    const dsl = `
      definition Employee { id: string }
      definition Doc { id: string }
      fact *balance(user: Employee, amount: number) BEHAVES { ttl 1h }
      evidence can_spend(user: Employee, doc: Doc) { balance(user, 1) }
    `;
    let t = 0;
    const rt = new DSLRuntime(new Arbiter(), { clock: () => t }).compile(dsl, 'rt-dsl-ttl');
    // The DSL declares a 1h TTL for the balance fact.
    assert.equal(rt.relations.get('balance').ttlMs, 3600_000);
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('balance', async () => { calls++; return { possibility: 1.0, value: 50 }; });
    await rt.check('u:1', 'can_spend', 'doc:9');
    assert.equal(calls, 1);
    t += 60 * 60 * 1000 - 1; // just under 1h
    await rt.check('u:1', 'can_spend', 'doc:9');
    assert.equal(calls, 1, 'cached within DSL-declared 1h TTL');
    t += 2;
    await rt.check('u:1', 'can_spend', 'doc:9');
    assert.equal(calls, 2, 're-invoked past the DSL-declared 1h TTL');
  });

  it('cacheProviderResults:false bypasses the cache per check', async () => {
    const rt = makeRuntime();
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('owns', async () => { calls++; return 0.9; });
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 1);
    // Bypass forces a fresh retrieval without clearing the cache.
    await rt.check('u:1', 'can_read', 'doc:9', { cacheProviderResults: false });
    assert.equal(calls, 2);
    // Cache still intact for the next default check.
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 2);
  });

  it('policy.cacheProviderResults:false disables caching globally', async () => {
    const rt = makeRuntime({ policy: { cacheProviderResults: false } });
    rt.addNode('u:1', 'Employee', {});
    rt.addNode('doc:9', 'Doc', {});
    let calls = 0;
    rt.registerFact('owns', async () => { calls++; return 0.9; });
    await rt.check('u:1', 'can_read', 'doc:9');
    await rt.check('u:1', 'can_read', 'doc:9');
    assert.equal(calls, 2, 'no caching when disabled globally');
  });
});