/**
 * ProjectionClient - Local TUI-side projection consumer
 * TUI copies minimal projection types from contracts to avoid INV-4 violation
 * (TUI must only depend on contracts; dd §13.2 / c4/code-view §2 rule 3).
 *
 * The runtime package provides the authoritative ProjectionClient in
 * `runtime/projection/ProjectionClient.ts`. TUI defines its own local copy
 * with the same surface so that subscriptions work in-process.
 *
 * @module packages/tui/src/ProjectionClient
 */

import type { SessionID, ProjectID, TaskID, AgentID, ISOTimeString } from '@aircoding/contracts'

export interface SessionProjection {
  session_id: SessionID
  project_id: ProjectID
  status: string
  title?: string
  tasks: TaskProjection[]
  agents: AgentProjection[]
}

export interface TaskProjection {
  id: TaskID
  type: string
  status: string
  title: string
  retry_count: number
  attempts: number
  created_at: string
}

export interface AgentProjection {
  id: AgentID
  type: string
  status: string
  task_id?: TaskID
  last_heartbeat?: string
}

export type ProjectionSubscriber = (projection: SessionProjection) => void

export class ProjectionClient {
  private snapshot: SessionProjection | null = null
  private subscribers: Set<ProjectionSubscriber> = new Set()

  /**
   * Receive and cache a projection snapshot.
   */
  receive_snapshot(projection: SessionProjection): void {
    this.snapshot = projection
    for (const sub of this.subscribers) {
      sub(projection)
    }
  }

  /**
   * Subscribe to projection updates.
   */
  subscribe(subscriber: ProjectionSubscriber): () => void {
    this.subscribers.add(subscriber)
    return () => this.subscribers.delete(subscriber)
  }

  /**
   * Get current snapshot.
   */
  get_snapshot(): SessionProjection | null {
    return this.snapshot
  }
}