import Auth from './src/auth.js'
import GraffitiArray from './src/array.js'

export default class {

  // There needs to be a new object map for each tag
  constructor(
    graffitiURL="https://graffiti.garden",
    objectMapConstructor=()=>({})) {

    this.graffitiURL = graffitiURL
    this.objectMapConstructor = objectMapConstructor
    this.open = false
    this.eventTarget = new EventTarget()
    this.tagMap = {}
    this.GraffitiArray = GraffitiArray(this)

    this.#initialize()
  }

  async #initialize() {
    // Perform authorization
    this.authParams = await Auth.connect(this.graffitiURL)

    // Rewrite the URL
    this.wsURL = new URL(this.graffitiURL)
    this.wsURL.host = "app." + this.wsURL.host
    if (this.wsURL.protocol == 'https:') {
      this.wsURL.protocol = 'wss:'
    } else {
      this.wsURL.protocol = 'ws:'
    }
    if (this.authParams.token) {
      this.wsURL.searchParams.set("token", this.authParams.token)
    }

    // Commence connection
    this.#connect()
  }
  
  // Wait for the connection to be
  // open (state=true) or closed (state=false)
  async connectionState(state) {
    if (this.open != state) {
      await new Promise(resolve => {
        this.eventTarget.addEventListener(
          state? "open": "closed", ()=> resolve())
      })
    }
  }

  #connect() {
    this.ws = new WebSocket(this.wsURL)
    this.ws.onmessage = this.#onMessage.bind(this)
    this.ws.onclose   = this.#onClose.bind(this)
    this.ws.onopen    = this.#onOpen.bind(this)
  }

  // authorization functions
  get myID() { return this.authParams.myID }
  toggleLogIn() {
    this.myID? Auth.logOut() : Auth.logIn(this.graffitiURL)
  }

  async #onClose() {
    console.error("lost connection to graffiti server, attemping reconnect soon...")
    this.open = false
    this.eventTarget.dispatchEvent(new Event("closed"))
    await new Promise(resolve => setTimeout(resolve, 2000))
    this.#connect()
  }

  async #request(msg) {
    if (!this.open) {
      throw "Can't make request! Not connected to graffiti server"
    }

    // Create a random message ID
    const messageID = crypto.randomUUID()

    // Create a listener for the reply
    const dataPromise = new Promise(resolve => {
      this.eventTarget.addEventListener('$'+messageID, (e) => {
        resolve(e.data)
      })
    })

    // Send the request
    msg.messageID = messageID
    this.ws.send(JSON.stringify(msg))

    // Await the reply
    const data = await dataPromise
    delete data.messageID

    if (data.type == 'error') {
      throw data
    } else {
      return data['reply']
    }
  }

  #onMessage(event) {
    const data = JSON.parse(event.data)

    if ('messageID' in data) {
      // It's a reply
      // Forward it back to the sender
      const messageEvent = new Event('$'+data.messageID)
      messageEvent.data = data
      this.eventTarget.dispatchEvent(messageEvent)

    } else if ('update' in data) {
      this.#updateCallback(data['update'])

    } else if ('remove' in data) {
      this.#removeCallback(data['remove'])

    } else if (data.type == 'error') {
      if (data.reason == 'authorization') {
        Auth.logOut()
      }
      throw data
    }
  }

  #updateCallback(object) {
    const uuid = this.#objectUUID(object)

    let originalObject = null
    for (const tag of object._tags) {
      if (!(tag in this.tagMap)) continue
      const objectMap = this.tagMap[tag].objectMap

      if (uuid in objectMap) {
        // Copy the original object if
        // one exists, in case of failure
        originalObject = Object.assign({},objectMap[uuid])

        // Replace the object by copying
        // so references to it don't break
        this.#recursiveCopy(objectMap[uuid], object)
      } else if (!('_id' in object)) {

        // Add properties to the object
        // so it can be updated and removed
        // without the collection
        Object.defineProperty(object, '_id', { value: this.#objectUUID(object) })
        Object.defineProperty(object, '_update', { value: ()=>this.update(object) })
        Object.defineProperty(object, '_remove', { value: ()=>this.remove(object) })

        objectMap[uuid] = object
      }
    }

    // Return the original in case of failure
    return originalObject
  }

  #removeCallback(object) {
    const uuid = this.#objectUUID(object)

    let originalObject = null
    for (const tag of object._tags) {
      if (!(tag in this.tagMap)) continue
      const objectMap = this.tagMap[tag].objectMap

      if (!(uuid in objectMap)) return
      originalObject = Object.assign({},objectMap[uuid])
      delete objectMap[uuid]
    }
  }

  async update(object) {
    if (!this.myID) {
      throw 'you can\'t update objects without logging in!'
    }

    // Add by/to fields
    object._by = this.myID
    if ('_to' in object && !Array.isArray(object._to)) {
      throw new Error("_to must be an array")
    }

    // Pre-generate the object's ID if it does not already exist
    if (!object._key) object._key = crypto.randomUUID()

    // Immediately replace the object
    const originalObject = this.#updateCallback(object)

    // Send it to the server
    try {
      await this.#request({ update: object })
    } catch(e) {
      if (originalObject) {
        // Restore the original object
        this.#updateCallback(originalObject)
      } else {
        // Delete the temp object
        this.#removeCallback(object)
      }
      throw e
    }
  }

  async remove(object) {
    if (!this.myID) {
      throw 'you can\'t remove objects without logging in!'
    }

    if (this.myID != object._by) {
      throw 'you can\'t remove an object that isn\'t yours!'
    }

    // Immediately remove the object
    // but store it in case there is an error
    const originalObject = this.#removeCallback(object)

    try {
      return await this.#request({ remove: object._key })
    } catch(e) {
      // Delete failed, restore the object
      if (originalObject) this.#updateCallback(originalObject)
      throw e
    }
  }

  async myTags() {
    return await this.#request({ ls: null })
  }

  async objectByKey(userID, objectKey) {
    return await this.#request({ get: {
      _by: userID,
      _key: objectKey
    }})
  }

  objectsByTags(...tags) {
    tags = tags.filter(tag=> tag!=null)
    for (const tag of tags) {
      if (!(tag in this.tagMap)) {
        throw `You are not subscribed to '${tag}'`
      }
    }

    // Merge by UUID to combine all the maps
    const combinedMaps = Object.assign({},
      ...tags.map(tag=> this.tagMap[tag].objectMap))

    // Return an array wrapped with graffiti functions
    return new this.GraffitiArray(...Object.values(combinedMaps))
  }

  async subscribe(...tags) {
    tags = tags.filter(tag=> tag!=null)
    // Look at what is already subscribed to
    const subscribingTags = []
    for (const tag of tags) {
      if (tag in this.tagMap) {
        // Increase the count
        this.tagMap[tag].count++
      } else {
        // Create a new slot
        this.tagMap[tag] = {
          objectMap: this.objectMapConstructor(),
          count: 1
        }
        subscribingTags.push(tag)
      }
    }

    // Try subscribing in the background
    // but don't raise an error since
    // the subscriptions will happen once connected
    if (subscribingTags.length)
      try {
        await this.#request({ subscribe: subscribingTags })
      } catch {}
  }

  async unsubscribe(...tags) {
    tags = tags.filter(tag=> tag!=null)
    // Decrease the count of each tag,
    // removing and marking if necessary
    const unsubscribingTags = []
    for (const tag of tags) {
      this.tagMap[tag].count--

      if (!this.tagMap[tag].count) {
        unsubscribingTags.push(tag)
        delete this.tagMap[tag]
      }
    }

    // Unsubscribe from all remaining tags
    if (unsubscribingTags.length)
      try {
        await this.#request({ unsubscribe: unsubscribingTags })
      } catch {}
  }

  async #onOpen() {
    console.log("connected to the graffiti socket")
    this.open = true
    this.eventTarget.dispatchEvent(new Event("open"))

    // Clear data
    for (let tag in this.tagMap) {
      const objectMap = this.tagMap[tag].objectMap
      for (let uuid in objectMap) delete objectMap[uuid]
    }

    // Resubscribe
    const tags = Object.keys(this.tagMap)
    if (tags.length) await this.#request({ subscribe: tags })
  }

  // Utility function to get a universally unique string
  // that represents a particular object
  #objectUUID(object) {
    if (!object._by || !object._key) {
      throw {
        type: 'error',
        content: 'the object you are trying to identify does not have an owner or key',
        object
      }
    }
    return object._by + object._key
  }

  #recursiveCopy(target, source) {
    for (const field in target) {
      if (!(field in source)) {
        delete target[field]
      }
    }

    for (const field in source) {
      if (field in target && typeof target[field] == 'object' && typeof source[field] == 'object') {
        this.#recursiveCopy(target[field], source[field])
      } else {
        target[field] = source[field]
      }
    }
  }
}