/**
 * In-Memory Unit of Work
 *
 * Coordinates multiple in-memory repositories.
 * Simulates transaction boundaries for testing.
 *
 * ADR-006: In-memory adapters for testing
 * - commit() persists all changes
 * - rollback() discards all changes
 * - NOT atomic in production sense, but sufficient for tests
 */

import {
  UnitOfWork,
  FieldSessionRepository,
  MissionRepository,
  DecisionCaseRepository,
  ArtifactRegistry,
  EventStore,
} from '../repositories/repository-interfaces';
import { InMemoryFieldSessionRepository } from './in-memory-session-repository';
import { InMemoryMissionRepository } from './in-memory-mission-repository';
import { InMemoryDecisionCaseRepository } from './in-memory-decision-case-repository';
import { InMemoryArtifactRegistry } from './in-memory-artifact-registry';
import { InMemoryEventStore } from './in-memory-event-store';

export class InMemoryUnitOfWork implements UnitOfWork {
  sessions: FieldSessionRepository;
  missions: MissionRepository;
  decisionCases: DecisionCaseRepository;
  artifacts: ArtifactRegistry;
  events: EventStore;

  private snapshots: {
    sessions: Map<string, unknown>;
    missions: Map<string, unknown>;
    cases: Map<string, unknown>;
    artifacts: Map<string, unknown>;
    events: unknown[];
  } | null = null;

  constructor() {
    this.sessions = new InMemoryFieldSessionRepository();
    this.missions = new InMemoryMissionRepository();
    this.decisionCases = new InMemoryDecisionCaseRepository();
    this.artifacts = new InMemoryArtifactRegistry();
    this.events = new InMemoryEventStore();
  }

  async commit(): Promise<void> {
    // In-memory: changes are already applied
    // Real implementation would flush to database
    this.snapshots = null;
  }

  async rollback(): Promise<void> {
    if (!this.snapshots) {
      throw new Error('No transaction in progress');
    }

    // Restore from snapshots
    (this.sessions as InMemoryFieldSessionRepository).clear();
    (this.missions as InMemoryMissionRepository).clear();
    (this.decisionCases as InMemoryDecisionCaseRepository).clear();
    (this.artifacts as InMemoryArtifactRegistry).clear();
    (this.events as InMemoryEventStore).clear();

    // Re-populate from snapshots
    for (const [id, session] of this.snapshots.sessions) {
      (this.sessions as InMemoryFieldSessionRepository).save(session as any);
    }
    for (const [id, mission] of this.snapshots.missions) {
      (this.missions as InMemoryMissionRepository).save(mission as any);
    }
    for (const [id, c] of this.snapshots.cases) {
      (this.decisionCases as InMemoryDecisionCaseRepository).save(c as any);
    }
    for (const [id, artifact] of this.snapshots.artifacts) {
      (this.artifacts as InMemoryArtifactRegistry).register(artifact as any);
    }
    for (const event of this.snapshots.events) {
      (this.events as InMemoryEventStore).append(event as any);
    }

    this.snapshots = null;
  }

  /** Begin transaction: capture snapshot */
  begin(): void {
    this.snapshots = {
      sessions: new Map((this.sessions as InMemoryFieldSessionRepository as any).sessions),
      missions: new Map((this.missions as InMemoryMissionRepository as any).missions),
      cases: new Map((this.decisionCases as InMemoryDecisionCaseRepository as any).cases),
      artifacts: new Map((this.artifacts as InMemoryArtifactRegistry as any).artifacts),
      events: [...(this.events as InMemoryEventStore as any).events],
    };
  }
}