// tools/parallel-session-lock.test.mjs
// Stream H Task 7 — pure parallel-session-lock module tests.
import { describe, it, expect, vi } from 'vitest';
import {
  acquire,
  release,
  refresh,
  computeWorkspaceHash,
  LOCK_DEFAULT_TTL_MS,
} from './parallel-session-lock.mjs';

function mkMockStore(initial = null) {
  let current = initial;
  return {
    readLock: () => current,
    writeLock: (v) => { current = v; },
    deleteLock: () => { current = null; },
    peek: () => current,
  };
}

describe('parallel-session-lock pure module (Stream H Task 7)', () => {
  it('acquire on empty store succeeds and writes holder record', () => {
    const store = mkMockStore(null);
    const r = acquire({
      sessionId: 's1', pid: 100, workspaceHash: 'abc', now: 1000,
      readLock: store.readLock, writeLock: store.writeLock,
    });
    expect(r.acquired).toBe(true);
    expect(r.holder).toMatchObject({ session_id: 's1', pid: 100, acquired_at: 1000 });
    expect(store.peek()).toMatchObject({ schema_version: 1, session_id: 's1', pid: 100, acquired_at: 1000, ttl_ms: LOCK_DEFAULT_TTL_MS });
  });

  it('acquire blocked when a fresh lock from another session exists', () => {
    const existing = { schema_version: 1, session_id: 'other', pid: 999, acquired_at: 500, ttl_ms: LOCK_DEFAULT_TTL_MS };
    const store = mkMockStore(existing);
    const r = acquire({
      sessionId: 's1', pid: 100, workspaceHash: 'abc', now: 1000,
      readLock: store.readLock, writeLock: store.writeLock,
    });
    expect(r.acquired).toBe(false);
    expect(r.holder).toMatchObject({ session_id: 'other', pid: 999 });
    expect(store.peek()).toBe(existing); // unchanged
  });

  it('acquire takes over a stale lock from another session (past TTL)', () => {
    const existing = { schema_version: 1, session_id: 'old', pid: 7, acquired_at: 0, ttl_ms: 100 };
    const store = mkMockStore(existing);
    const r = acquire({
      sessionId: 's1', pid: 100, workspaceHash: 'abc', now: 1000,
      readLock: store.readLock, writeLock: store.writeLock,
    });
    expect(r.acquired).toBe(true);
    expect(r.holder).toMatchObject({ session_id: 's1', pid: 100, acquired_at: 1000 });
  });

  it('refresh same-session updates acquired_at without losing ownership', () => {
    const existing = { schema_version: 1, session_id: 's1', pid: 100, acquired_at: 500, ttl_ms: LOCK_DEFAULT_TTL_MS };
    const store = mkMockStore(existing);
    const r = refresh({
      sessionId: 's1', workspaceHash: 'abc', now: 1000,
      readLock: store.readLock, writeLock: store.writeLock,
    });
    expect(r.refreshed).toBe(true);
    expect(store.peek().acquired_at).toBe(1000);
  });

  it('refresh other-session is a no-op (does not steal lock)', () => {
    const existing = { schema_version: 1, session_id: 'other', pid: 999, acquired_at: 500, ttl_ms: LOCK_DEFAULT_TTL_MS };
    const store = mkMockStore(existing);
    const r = refresh({
      sessionId: 's1', workspaceHash: 'abc', now: 1000,
      readLock: store.readLock, writeLock: store.writeLock,
    });
    expect(r.refreshed).toBe(false);
    expect(store.peek()).toBe(existing);
  });

  it('release same-session deletes the lock', () => {
    const existing = { schema_version: 1, session_id: 's1', pid: 100, acquired_at: 500, ttl_ms: LOCK_DEFAULT_TTL_MS };
    const store = mkMockStore(existing);
    release({ sessionId: 's1', workspaceHash: 'abc', readLock: store.readLock, deleteLock: store.deleteLock });
    expect(store.peek()).toBe(null);
  });

  it('release other-session does NOT delete the lock', () => {
    const existing = { schema_version: 1, session_id: 'other', pid: 999, acquired_at: 500, ttl_ms: LOCK_DEFAULT_TTL_MS };
    const store = mkMockStore(existing);
    release({ sessionId: 's1', workspaceHash: 'abc', readLock: store.readLock, deleteLock: store.deleteLock });
    expect(store.peek()).toBe(existing);
  });
});

describe('computeWorkspaceHash (Stream H Task 7)', () => {
  it('returns 12 hex chars', () => {
    const h = computeWorkspaceHash('/some/path');
    expect(h).toMatch(/^[0-9a-f]{12}$/);
  });
  it('is deterministic per path', () => {
    expect(computeWorkspaceHash('/some/path')).toBe(computeWorkspaceHash('/some/path'));
  });
  it('differs across paths', () => {
    expect(computeWorkspaceHash('/a')).not.toBe(computeWorkspaceHash('/b'));
  });
});