// 从完整事件名称中提取原始事件名称（移除作用域前缀）
type ExtractOriginalEventName<T extends string, S extends string> = T extends `${S}:${infer Original}` ? Original : never

// 从完整事件映射中提取原始事件映射
type ExtractBaseEventMaps<T extends Record<string, any>, S extends string> = {
  [K in keyof T as ExtractOriginalEventName<K & string, S>]: T[K]
}

type FireFN = (...argu: any[]) => void

// 支持作用域的事件类
class ScopedFireEvent<
  T extends Record<string, FireFN>, // 完整的事件映射类型
  S extends string, // 作用域类型
  B extends Record<string, FireFN> = ExtractBaseEventMaps<T, S>, // 从完整事件映射中提取的基础事件映射
> {
  #scope: S
  #events: Record<string, FireFN[]> = {}

  constructor(scope: S) {
    this.#scope = scope
  }

  // 获取完整的事件名称（添加作用域前缀）
  public getFullEventName(eventName: string): string {
    if (this.#scope === "") return eventName
    return `${this.#scope}:${eventName}`
  }

  print() {
    Object.keys(this.#events).forEach(key => {
      console.log(`${key}: ${this.#events[key]}\n`)
    })
  }

  // 订阅事件，支持自动添加作用域前缀
  on<K extends keyof B>(name: K, fn: B[K]) {
    const fullName = this.getFullEventName(name as string)
    if (!this.#events[fullName]) {
      this.#events[fullName] = []
    }
    this.#events[fullName].push(fn as FireFN)
  }

  // 触发事件，支持自动添加作用域前缀
  emit<K extends keyof B>(name: K, ...argu: Parameters<B[K]>) {
    const fullName = this.getFullEventName(name as string)
    if (this.#events[fullName]) {
      this.#events[fullName].forEach(fn => {
        fn(...argu)
      })
    }
  }

  // 取消订阅事件，支持自动添加作用域前缀
  off<K extends keyof B>(name: K, fn?: B[K]) {
    const fullName = this.getFullEventName(name as string)
    const len = this.#events[fullName]?.length || 0
    if (!len) {
      return
    }
    if (!fn) {
      this.#events[fullName] = []
    } else {
      for (let i = len - 1; i >= 0; i--) {
        const _fn = this.#events[fullName][i]
        if (_fn === fn) {
          this.#events[fullName].splice(i, 1)
        }
      }
    }
  }

  // 一次性订阅事件，支持自动添加作用域前缀
  once<K extends keyof B>(name: K, fn: B[K]) {
    const _fn: FireFN = (...argu: any[]) => {
      fn(...argu)
      this.off(name, _fn as B[K])
    }
    this.on(name, _fn as B[K])
  }
}

// 创建作用域事件发射器的工厂函数 - 仅需一个泛型参数
export function buildEmitter<T extends Record<string | symbol, FireFN>>(scope?: string): ScopedFireEvent<T, typeof scope> {
  return new ScopedFireEvent<T, typeof scope>(scope)
}