'use strict'

class BlackDocument {
  public root: Element
  public methods!: Object
  public sandbox!: HTMLIFrameElement
  constructor (template: string, root: Element = document.body, csp: string = `default-src 'self';`, type?: string) {
    this.root = root
    this.create(template, csp, type)
    // @ts-ignore
    return this.run.bind(this)
  }

  hashSource () {
    return (new Array(8 + Math.round(Math.random() * 8))).join(',').split(',').map(() => {
      return String.fromCharCode(97 + Math.round(Math.random() * 25))
    }).join('')
  }

  injectRequestParentAction (csp: string) {
    let hash = this.hashSource()
    window.addEventListener('message', (data) => {
      let result = data.data || {}
      let method = result.method
      let params = result.params
      let postToSandbox = (data: object) => {
        if (this.sandbox.contentWindow) {
          this.sandbox.contentWindow.postMessage({
            data,
            key: method + ':' + JSON.stringify(params)
          }, '*')
        }
      }

      if (result.hash === hash) {
        let func = this.methods[method]
        let promise: object | Promise<object>
        if (typeof func === 'function') {
          promise = func(params)
        } else {
          promise = func
        }

        if (promise instanceof Promise) {
          promise.then(postToSandbox)
        } else {
          postToSandbox(promise)
        }
      }
    }, false)
    return `
      <meta http-equiv="Content-Security-Policy" content="${csp}">
      <script>
        window.requestParentAction = function (method, params) {
          parent.postMessage({ method: method, params: params, hash: '${hash}' }, '${location.origin}')
          return new Promise(function (reslove, reject) {
            function callback (data) {
              if (data && data.data && data.data.data) {
                if (method + ':' + JSON.stringify(params) === data.data.key) {
                  window.removeEventListener('message', callback)
                  reslove(data.data.data)
                }
              } else {
                reject()
              }
            }
            window.addEventListener('message', callback)
          })
        }
      </script>
    `
  }

  create (template: string, csp: string, type = 'fullscreen') {
    let iframe = document.createElement('iframe')
    iframe.csp = csp
    iframe.src = URL.createObjectURL(new Blob([`${this.injectRequestParentAction(csp)} ;\n ${template}`], { type: 'text/html' }))
    iframe.setAttribute('sandbox', 'allow-scripts')
    if (type === 'fullscreen') iframe.setAttribute('style', `position: fixed; top: 0; right: 0; bottom: 0; left: 0; width: 100%; height: 100%`)
    this.sandbox = iframe
  }

  run (methods: object) {
    this.methods = methods
    this.root.appendChild(this.sandbox)
  }
}

export { BlackDocument }