'use strict'

const TextEditor = require('./text-editor')
const PaneContainer = require('./pane-container')

// Essential: Represents the workspace at the center of the entire window.
module.exports = class WorkspaceCenter {
  constructor (params) {
    params.location = 'center'
    this.paneContainer = new PaneContainer(params)
    this.didActivate = params.didActivate
    this.paneContainer.onDidActivatePane(() => this.didActivate(this))
    this.paneContainer.onDidChangeActivePane((pane) => {
      params.didChangeActivePane(this, pane)
    })
    this.paneContainer.onDidChangeActivePaneItem((item) => {
      params.didChangeActivePaneItem(this, item)
    })
    this.paneContainer.onDidDestroyPaneItem((item) => params.didDestroyPaneItem(item))
  }

  destroy () {
    this.paneContainer.destroy()
  }

  serialize () {
    return this.paneContainer.serialize()
  }

  deserialize (state, deserializerManager) {
    this.paneContainer.deserialize(state, deserializerManager)
  }

  activate () {
    this.getActivePane().activate()
  }

  getLocation () {
    return 'center'
  }

  setDraggingItem () {
    // No-op
  }

  /*
  Section: Event Subscription
  */

  // Essential: Invoke the given callback with all current and future text
  // editors in the workspace center.
  //
  // * `callback` {Function} to be called with current and future text editors.
  //   * `editor` An {TextEditor} that is present in {::getTextEditors} at the time
  //     of subscription or that is added at some later time.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  observeTextEditors (callback) {
    for (let textEditor of this.getTextEditors()) { callback(textEditor) }
    return this.onDidAddTextEditor(({textEditor}) => callback(textEditor))
  }

  // Essential: Invoke the given callback with all current and future panes items
  // in the workspace center.
  //
  // * `callback` {Function} to be called with current and future pane items.
  //   * `item` An item that is present in {::getPaneItems} at the time of
  //      subscription or that is added at some later time.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  observePaneItems (callback) { return this.paneContainer.observePaneItems(callback) }

  // Essential: Invoke the given callback when the active pane item changes.
  //
  // Because observers are invoked synchronously, it's important not to perform
  // any expensive operations via this method. Consider
  // {::onDidStopChangingActivePaneItem} to delay operations until after changes
  // stop occurring.
  //
  // * `callback` {Function} to be called when the active pane item changes.
  //   * `item` The active pane item.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidChangeActivePaneItem (callback) {
    return this.paneContainer.onDidChangeActivePaneItem(callback)
  }

  // Essential: Invoke the given callback when the active pane item stops
  // changing.
  //
  // Observers are called asynchronously 100ms after the last active pane item
  // change. Handling changes here rather than in the synchronous
  // {::onDidChangeActivePaneItem} prevents unneeded work if the user is quickly
  // changing or closing tabs and ensures critical UI feedback, like changing the
  // highlighted tab, gets priority over work that can be done asynchronously.
  //
  // * `callback` {Function} to be called when the active pane item stopts
  //   changing.
  //   * `item` The active pane item.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidStopChangingActivePaneItem (callback) {
    return this.paneContainer.onDidStopChangingActivePaneItem(callback)
  }

  // Essential: Invoke the given callback with the current active pane item and
  // with all future active pane items in the workspace center.
  //
  // * `callback` {Function} to be called when the active pane item changes.
  //   * `item` The current active pane item.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  observeActivePaneItem (callback) {
    return this.paneContainer.observeActivePaneItem(callback)
  }

  // Extended: Invoke the given callback when a pane is added to the workspace
  // center.
  //
  // * `callback` {Function} to be called panes are added.
  //   * `event` {Object} with the following keys:
  //     * `pane` The added pane.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidAddPane (callback) {
    return this.paneContainer.onDidAddPane(callback)
  }

  // Extended: Invoke the given callback before a pane is destroyed in the
  // workspace center.
  //
  // * `callback` {Function} to be called before panes are destroyed.
  //   * `event` {Object} with the following keys:
  //     * `pane` The pane to be destroyed.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onWillDestroyPane (callback) {
    return this.paneContainer.onWillDestroyPane(callback)
  }

  // Extended: Invoke the given callback when a pane is destroyed in the
  // workspace center.
  //
  // * `callback` {Function} to be called panes are destroyed.
  //   * `event` {Object} with the following keys:
  //     * `pane` The destroyed pane.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidDestroyPane (callback) {
    return this.paneContainer.onDidDestroyPane(callback)
  }

  // Extended: Invoke the given callback with all current and future panes in the
  // workspace center.
  //
  // * `callback` {Function} to be called with current and future panes.
  //   * `pane` A {Pane} that is present in {::getPanes} at the time of
  //      subscription or that is added at some later time.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  observePanes (callback) {
    return this.paneContainer.observePanes(callback)
  }

  // Extended: Invoke the given callback when the active pane changes.
  //
  // * `callback` {Function} to be called when the active pane changes.
  //   * `pane` A {Pane} that is the current return value of {::getActivePane}.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidChangeActivePane (callback) {
    return this.paneContainer.onDidChangeActivePane(callback)
  }

  // Extended: Invoke the given callback with the current active pane and when
  // the active pane changes.
  //
  // * `callback` {Function} to be called with the current and future active#
  //   panes.
  //   * `pane` A {Pane} that is the current return value of {::getActivePane}.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  observeActivePane (callback) {
    return this.paneContainer.observeActivePane(callback)
  }

  // Extended: Invoke the given callback when a pane item is added to the
  // workspace center.
  //
  // * `callback` {Function} to be called when pane items are added.
  //   * `event` {Object} with the following keys:
  //     * `item` The added pane item.
  //     * `pane` {Pane} containing the added item.
  //     * `index` {Number} indicating the index of the added item in its pane.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidAddPaneItem (callback) {
    return this.paneContainer.onDidAddPaneItem(callback)
  }

  // Extended: Invoke the given callback when a pane item is about to be
  // destroyed, before the user is prompted to save it.
  //
  // * `callback` {Function} to be called before pane items are destroyed.
  //   * `event` {Object} with the following keys:
  //     * `item` The item to be destroyed.
  //     * `pane` {Pane} containing the item to be destroyed.
  //     * `index` {Number} indicating the index of the item to be destroyed in
  //       its pane.
  //
  // Returns a {Disposable} on which `.dispose` can be called to unsubscribe.
  onWillDestroyPaneItem (callback) {
    return this.paneContainer.onWillDestroyPaneItem(callback)
  }

  // Extended: Invoke the given callback when a pane item is destroyed.
  //
  // * `callback` {Function} to be called when pane items are destroyed.
  //   * `event` {Object} with the following keys:
  //     * `item` The destroyed item.
  //     * `pane` {Pane} containing the destroyed item.
  //     * `index` {Number} indicating the index of the destroyed item in its
  //       pane.
  //
  // Returns a {Disposable} on which `.dispose` can be called to unsubscribe.
  onDidDestroyPaneItem (callback) {
    return this.paneContainer.onDidDestroyPaneItem(callback)
  }

  // Extended: Invoke the given callback when a text editor is added to the
  // workspace center.
  //
  // * `callback` {Function} to be called when panes are added.
  //   * `event` {Object} with the following keys:
  //     * `textEditor` {TextEditor} that was added.
  //     * `pane` {Pane} containing the added text editor.
  //     * `index` {Number} indicating the index of the added text editor in its
  //        pane.
  //
  // Returns a {Disposable} on which `.dispose()` can be called to unsubscribe.
  onDidAddTextEditor (callback) {
    return this.onDidAddPaneItem(({item, pane, index}) => {
      if (item instanceof TextEditor) {
        callback({textEditor: item, pane, index})
      }
    })
  }

  /*
  Section: Pane Items
  */

  // Essential: Get all pane items in the workspace center.
  //
  // Returns an {Array} of items.
  getPaneItems () {
    return this.paneContainer.getPaneItems()
  }

  // Essential: Get the active {Pane}'s active item.
  //
  // Returns an pane item {Object}.
  getActivePaneItem () {
    return this.paneContainer.getActivePaneItem()
  }

  // Essential: Get all text editors in the workspace center.
  //
  // Returns an {Array} of {TextEditor}s.
  getTextEditors () {
    return this.getPaneItems().filter(item => item instanceof TextEditor)
  }

  // Essential: Get the active item if it is an {TextEditor}.
  //
  // Returns an {TextEditor} or `undefined` if the current active item is not an
  // {TextEditor}.
  getActiveTextEditor () {
    const activeItem = this.getActivePaneItem()
    if (activeItem instanceof TextEditor) { return activeItem }
  }

  // Save all pane items.
  saveAll () {
    this.paneContainer.saveAll()
  }

  confirmClose (options) {
    return this.paneContainer.confirmClose(options)
  }

  /*
  Section: Panes
  */

  // Extended: Get all panes in the workspace center.
  //
  // Returns an {Array} of {Pane}s.
  getPanes () {
    return this.paneContainer.getPanes()
  }

  // Extended: Get the active {Pane}.
  //
  // Returns a {Pane}.
  getActivePane () {
    return this.paneContainer.getActivePane()
  }

  // Extended: Make the next pane active.
  activateNextPane () {
    return this.paneContainer.activateNextPane()
  }

  // Extended: Make the previous pane active.
  activatePreviousPane () {
    return this.paneContainer.activatePreviousPane()
  }

  paneForURI (uri) {
    return this.paneContainer.paneForURI(uri)
  }

  paneForItem (item) {
    return this.paneContainer.paneForItem(item)
  }

  // Destroy (close) the active pane.
  destroyActivePane () {
    const activePane = this.getActivePane()
    if (activePane != null) {
      activePane.destroy()
    }
  }
}