const FrankieSDK = (() => {
  const _handlers = {}
  const _llmResolvers = {}

  // _handle dispatches an inbound postMessage event to the registered hook.
  function _handle(type, payload) {
    const hook = _handlers[type]
    if (typeof hook === 'function') hook(payload)
  }

  // Boot: listen for messages from the Frankie parent frame.
  window.addEventListener('message', (event) => {
    const { type, payload, id } = event.data || {}
    if (typeof type !== 'string' || !type.startsWith('FRANKIE_')) return

    const hook = type.slice(8).toLowerCase() // FRANKIE_INIT → 'init'

    // LLM responses are resolved as promises rather than dispatched as hooks.
    if (hook === 'llm_response') {
      const resolve = _llmResolvers[id]
      if (typeof resolve === 'function') {
        resolve(payload?.content ?? '')
        delete _llmResolvers[id]
      }
      return
    }

    _handle(hook, payload)
  })

  return {
    // on registers a lifecycle hook. Returns the SDK for chaining.
    on(event, handler) {
      _handlers[event] = handler
      return this
    },

    // emit sends a typed event to the Frankie parent frame.
    emit(event, payload = {}) {
      window.parent.postMessage(
        { type: `FRANKIE_${event.toUpperCase()}`, payload },
        '*'
      )
    },

    // llm sends a chat-completion request to Frankie's LLM and returns a Promise
    // that resolves with the model's reply as a string.
    llm(messages) {
      return new Promise((resolve) => {
        const id = `llm_${Date.now()}_${Math.random().toString(36).slice(2)}`
        _llmResolvers[id] = resolve
        window.parent.postMessage(
          { type: 'FRANKIE_LLM_REQUEST', id, payload: { messages } },
          '*'
        )
      })
    }
  }
})()

export default FrankieSDK