import * as store from './itemsStore.js'

interface AddTask { type: 'add', id: number }
interface SelectTask { type: 'select', id: number }
interface DeselectTask { type: 'deselect', id: number }
interface ReorderTask { type: 'reorder', id: number, afterId: number | null }

type Task = AddTask | SelectTask | DeselectTask | ReorderTask

class RequestQueue {
  private addQueue: AddTask[] = []
  private reorderQueue: ReorderTask[] = []
  private pendingKeys = new Set<string>()

  constructor() {
    setInterval(() => this.flushAdd(), 10_000)
    setInterval(() => this.flushReorder(), 1_000)
  }

  enqueue(task: Task): boolean {
    if (task.type === 'reorder') {
      this.reorderQueue.push(task)
      return true
    }

    const key = `${task.type}:${(task as AddTask | SelectTask | DeselectTask).id}`
    if (this.pendingKeys.has(key)) return false
    this.pendingKeys.add(key)

    if (task.type === 'add') {
      this.addQueue.push(task)
      if (this.addQueue.length >= 100) this.flushAdd()
    }
    else {
      // select/deselect применяются немедленно, чтобы GET после POST видел актуальный state
      if (task.type === 'select') store.selectItem(task.id)
      else if (task.type === 'deselect') store.deselectItem(task.id)
      this.pendingKeys.delete(key)
    }
    return true
  }

  private flushAdd(): void {
    const batch = this.addQueue.splice(0)
    for (const task of batch) {
      store.addItem(task.id)
      this.pendingKeys.delete(`add:${task.id}`)
    }
  }

  private flushReorder(): void {
    const batch = this.reorderQueue.splice(0)
    for (const task of batch) {
      store.reorderItem(task.id, task.afterId)
    }
  }
}

export const queue = new RequestQueue()