// Copyright 2023 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import * as Common from '../../core/common/common.js';
import * as Platform from '../../core/platform/platform.js';
import * as Trace from '../../models/trace/trace.js';
import * as TimelineComponents from '../../panels/timeline/components/components.js';

import * as AnnotationHelpers from './AnnotationHelpers.js';
import {EntriesFilter} from './EntriesFilter.js';

const modificationsManagerByTraceIndex: ModificationsManager[] = [];
let activeManager: ModificationsManager|null;

export type UpdateAction =
    'Remove'|'Add'|'UpdateLabel'|'UpdateTimeRange'|'UpdateLinkToEntry'|'EnterLabelEditState'|'LabelBringForward';

/**
 * Event dispatched after an annotation was added, removed or updated.
 * The event argument is the Overlay that needs to be created,removed
 * or updated by `Overlays.ts` and the action that needs to be applied to it.
 **/
export class AnnotationModifiedEvent extends Event {
  static readonly eventName = 'annotationmodifiedevent';

  constructor(
      public overlay: Trace.Types.Overlays.Overlay, public action: UpdateAction, public muteAriaNotifications = false) {
    super(AnnotationModifiedEvent.eventName);
  }
}

interface ModificationsManagerData {
  parsedTrace: Trace.TraceModel.ParsedTrace;
  traceBounds: Trace.Types.Timing.TraceWindowMicro;
  rawTraceEvents: readonly Trace.Types.Events.Event[];
  syntheticEvents: Trace.Types.Events.SyntheticBased[];
  modifications?: Trace.Types.File.Modifications;
}

export class ModificationsManager extends EventTarget {
  #entriesFilter: EntriesFilter;
  #timelineBreadcrumbs: TimelineComponents.Breadcrumbs.Breadcrumbs;
  #modifications: Trace.Types.File.Modifications|null = null;
  #parsedTrace: Trace.TraceModel.ParsedTrace;
  #eventsSerializer: Trace.EventsSerializer.EventsSerializer;
  #overlayForAnnotation: Map<Trace.Types.File.Annotation, Trace.Types.Overlays.Overlay>;
  readonly #annotationsHiddenSetting: Common.Settings.Setting<boolean>;

  /**
   * Gets the ModificationsManager instance corresponding to a trace
   * given its index used in Model#traces. If no index is passed gets
   * the manager instance for the last trace. If no instance is found,
   * throws.
   */
  static activeManager(): ModificationsManager|null {
    return activeManager;
  }

  static reset(): void {
    modificationsManagerByTraceIndex.length = 0;
    activeManager = null;
  }

  /**
   * Initializes a ModificationsManager instance for a parsed trace or changes the active manager for an existing one.
   * This needs to be called if and a trace has been parsed or switched to.
   */
  static initAndActivateModificationsManager(traceModel: Trace.TraceModel.Model, traceIndex: number):
      ModificationsManager|null {
    // If a manager for a given index has already been created, active it.
    if (modificationsManagerByTraceIndex[traceIndex]) {
      if (activeManager === modificationsManagerByTraceIndex[traceIndex]) {
        return activeManager;
      }

      activeManager = modificationsManagerByTraceIndex[traceIndex];
      ModificationsManager.activeManager()?.applyModificationsIfPresent();
    }

    const parsedTrace = traceModel.parsedTrace(traceIndex);
    if (!parsedTrace) {
      throw new Error('ModificationsManager was initialized without a corresponding trace data');
    }

    const traceBounds = parsedTrace.data.Meta.traceBounds;
    const newModificationsManager = new ModificationsManager({
      parsedTrace,
      traceBounds,
      rawTraceEvents: parsedTrace.traceEvents,
      modifications: parsedTrace.metadata.modifications,
      syntheticEvents: parsedTrace.syntheticEventsManager.getSyntheticTraces(),
    });
    modificationsManagerByTraceIndex[traceIndex] = newModificationsManager;
    activeManager = newModificationsManager;
    ModificationsManager.activeManager()?.applyModificationsIfPresent();
    return this.activeManager();
  }

  private constructor({parsedTrace, traceBounds, modifications}: ModificationsManagerData) {
    super();
    this.#entriesFilter = new EntriesFilter(parsedTrace);
    // Create first breadcrumb from the initial full window
    this.#timelineBreadcrumbs = new TimelineComponents.Breadcrumbs.Breadcrumbs(traceBounds);
    this.#modifications = modifications || null;
    this.#parsedTrace = parsedTrace;
    this.#eventsSerializer = new Trace.EventsSerializer.EventsSerializer();
    // This method is also called in SidebarAnnotationsTab, but calling this multiple times doesn't recreate the setting.
    // Instead, after the second call, the cached setting is returned.
    this.#annotationsHiddenSetting = Common.Settings.Settings.instance().moduleSetting('annotations-hidden');
    // TODO: Assign annotations loaded from the trace file
    this.#overlayForAnnotation = new Map();
  }

  getEntriesFilter(): EntriesFilter {
    return this.#entriesFilter;
  }

  getTimelineBreadcrumbs(): TimelineComponents.Breadcrumbs.Breadcrumbs {
    return this.#timelineBreadcrumbs;
  }

  deleteEmptyRangeAnnotations(): void {
    for (const annotation of this.#overlayForAnnotation.keys()) {
      if (annotation.type === 'TIME_RANGE' && annotation.label.length === 0) {
        this.removeAnnotation(annotation);
      }
    }
  }

  /**
   * Stores the annotation and creates its overlay.
   * @returns the Overlay that gets created and associated with this annotation.
   */
  createAnnotation(newAnnotation: Trace.Types.File.Annotation, opts: {
    loadedFromFile: boolean,
    muteAriaNotifications: boolean,
  }): Trace.Types.Overlays.Overlay {
    // If a label already exists on an entry and a user is trying to create a new one, start editing an existing label instead.
    if (newAnnotation.type === 'ENTRY_LABEL') {
      const overlay = this.#findLabelOverlayForEntry(newAnnotation.entry);
      if (overlay) {
        this.dispatchEvent(new AnnotationModifiedEvent(overlay, 'EnterLabelEditState'));
        return overlay;
      }
    }

    // If the new annotation created was not loaded from the file, set the annotations visibility setting to true. That way we make sure
    // the annotations are on when a new one is created.
    if (!opts.loadedFromFile) {
      // Time range annotation could also be used to check the length of a selection in the timeline. Therefore, only set the annotations
      // hidden to true if annotations label is added. This is done in OverlaysImpl.
      if (newAnnotation.type !== 'TIME_RANGE') {
        this.#annotationsHiddenSetting.set(false);
      }
    }
    const newOverlay = this.#createOverlayFromAnnotation(newAnnotation);
    this.#overlayForAnnotation.set(newAnnotation, newOverlay);
    this.dispatchEvent(new AnnotationModifiedEvent(newOverlay, 'Add', opts.muteAriaNotifications));
    return newOverlay;
  }

  linkAnnotationBetweenEntriesExists(entryFrom: Trace.Types.Events.Event, entryTo: Trace.Types.Events.Event): boolean {
    for (const annotation of this.#overlayForAnnotation.keys()) {
      if (annotation.type === 'ENTRIES_LINK' &&
          ((annotation.entryFrom === entryFrom && annotation.entryTo === entryTo) ||
           (annotation.entryFrom === entryTo && annotation.entryTo === entryFrom))) {
        return true;
      }
    }
    return false;
  }

  #findLabelOverlayForEntry(entry: Trace.Types.Events.Event): Trace.Types.Overlays.Overlay|null {
    for (const [annotation, overlay] of this.#overlayForAnnotation.entries()) {
      if (annotation.type === 'ENTRY_LABEL' && annotation.entry === entry) {
        return overlay;
      }
    }

    return null;
  }

  bringEntryLabelForwardIfExists(entry: Trace.Types.Events.Event): void {
    const overlay = this.#findLabelOverlayForEntry(entry);
    if (overlay?.type === 'ENTRY_LABEL') {
      this.dispatchEvent(new AnnotationModifiedEvent(overlay, 'LabelBringForward'));
    }
  }

  #createOverlayFromAnnotation(annotation: Trace.Types.File.Annotation): Trace.Types.Overlays.EntryLabel
      |Trace.Types.Overlays.TimeRangeLabel|Trace.Types.Overlays.EntriesLink {
    switch (annotation.type) {
      case 'ENTRY_LABEL':
        return {
          type: 'ENTRY_LABEL',
          entry: annotation.entry,
          label: annotation.label,
        };
      case 'TIME_RANGE':
        return {
          type: 'TIME_RANGE',
          label: annotation.label,
          showDuration: true,
          bounds: annotation.bounds,
        };
      case 'ENTRIES_LINK':
        return {
          type: 'ENTRIES_LINK',
          state: annotation.state,
          entryFrom: annotation.entryFrom,
          entryTo: annotation.entryTo,
        };
      default:
        Platform.assertNever(annotation, 'Overlay for provided annotation cannot be created');
    }
  }

  removeAnnotation(removedAnnotation: Trace.Types.File.Annotation): void {
    const overlayToRemove = this.#overlayForAnnotation.get(removedAnnotation);
    if (!overlayToRemove) {
      console.warn('Overlay for deleted Annotation does not exist', removedAnnotation);
      return;
    }
    this.#overlayForAnnotation.delete(removedAnnotation);
    this.dispatchEvent(new AnnotationModifiedEvent(overlayToRemove, 'Remove'));
  }

  removeAnnotationOverlay(removedOverlay: Trace.Types.Overlays.Overlay): void {
    const annotationForRemovedOverlay = this.getAnnotationByOverlay(removedOverlay);
    if (!annotationForRemovedOverlay) {
      console.warn('Annotation for deleted Overlay does not exist', removedOverlay);
      return;
    }
    this.removeAnnotation(annotationForRemovedOverlay);
  }

  updateAnnotation(updatedAnnotation: Trace.Types.File.Annotation): void {
    const overlay = this.#overlayForAnnotation.get(updatedAnnotation);

    if (overlay && AnnotationHelpers.isTimeRangeLabel(overlay) &&
        Trace.Types.File.isTimeRangeAnnotation(updatedAnnotation)) {
      overlay.label = updatedAnnotation.label;
      overlay.bounds = updatedAnnotation.bounds;
      this.dispatchEvent(new AnnotationModifiedEvent(overlay, 'UpdateTimeRange'));

    } else if (
        overlay && AnnotationHelpers.isEntriesLink(overlay) &&
        Trace.Types.File.isEntriesLinkAnnotation(updatedAnnotation)) {
      overlay.state = updatedAnnotation.state;
      overlay.entryFrom = updatedAnnotation.entryFrom;
      overlay.entryTo = updatedAnnotation.entryTo;
      this.dispatchEvent(new AnnotationModifiedEvent(overlay, 'UpdateLinkToEntry'));

    } else {
      console.error('Annotation could not be updated');
    }
  }

  updateAnnotationOverlay(updatedOverlay: Trace.Types.Overlays.Overlay): void {
    const annotationForUpdatedOverlay = this.getAnnotationByOverlay(updatedOverlay);
    if (!annotationForUpdatedOverlay) {
      console.warn('Annotation for updated Overlay does not exist');
      return;
    }

    if ((updatedOverlay.type === 'ENTRY_LABEL' && annotationForUpdatedOverlay.type === 'ENTRY_LABEL') ||
        (updatedOverlay.type === 'TIME_RANGE' && annotationForUpdatedOverlay.type === 'TIME_RANGE')) {
      this.#annotationsHiddenSetting.set(false);
      annotationForUpdatedOverlay.label = updatedOverlay.label;
      this.dispatchEvent(new AnnotationModifiedEvent(updatedOverlay, 'UpdateLabel'));
    }

    if ((updatedOverlay.type === 'ENTRIES_LINK' && annotationForUpdatedOverlay.type === 'ENTRIES_LINK')) {
      this.#annotationsHiddenSetting.set(false);
      annotationForUpdatedOverlay.state = updatedOverlay.state;
    }
  }

  getAnnotationByOverlay(overlay: Trace.Types.Overlays.Overlay): Trace.Types.File.Annotation|null {
    for (const [annotation, currOverlay] of this.#overlayForAnnotation.entries()) {
      if (currOverlay === overlay) {
        return annotation;
      }
    }
    return null;
  }

  getOverlaybyAnnotation(annotation: Trace.Types.File.Annotation): Trace.Types.Overlays.Overlay|null {
    return this.#overlayForAnnotation.get(annotation) || null;
  }

  getAnnotations(): Trace.Types.File.Annotation[] {
    return [...this.#overlayForAnnotation.keys()];
  }

  getOverlays(): Trace.Types.Overlays.Overlay[] {
    return [...this.#overlayForAnnotation.values()];
  }

  applyAnnotationsFromCache(opts: {muteAriaNotifications: boolean}): void {
    this.#modifications = this.toJSON();
    // The cache is filled by applyModificationsIfPresent, so we clear
    // it beforehand to prevent duplicate entries.
    this.#overlayForAnnotation.clear();
    this.#applyStoredAnnotations(this.#modifications.annotations, opts);
  }

  /**
   * Builds all modifications into a serializable object written into
   * the 'modifications' trace file metadata field.
   */
  toJSON(): Trace.Types.File.Modifications {
    const hiddenEntries = this.#entriesFilter.invisibleEntries()
                              .map(entry => this.#eventsSerializer.keyForEvent(entry))
                              .filter(entry => entry !== null);
    const expandableEntries = this.#entriesFilter.expandableEntries()
                                  .map(entry => this.#eventsSerializer.keyForEvent(entry))
                                  .filter(entry => entry !== null);
    this.#modifications = {
      entriesModifications: {
        hiddenEntries,
        expandableEntries,
      },
      initialBreadcrumb: this.#timelineBreadcrumbs.initialBreadcrumb,
      annotations: this.#annotationsJSON(),
    };
    return this.#modifications;
  }

  #annotationsJSON(): Trace.Types.File.SerializedAnnotations {
    const annotations = this.getAnnotations();
    const entryLabelsSerialized: Trace.Types.File.EntryLabelAnnotationSerialized[] = [];
    const labelledTimeRangesSerialized: Trace.Types.File.TimeRangeAnnotationSerialized[] = [];
    const linksBetweenEntriesSerialized: Trace.Types.File.EntriesLinkAnnotationSerialized[] = [];

    for (let i = 0; i < annotations.length; i++) {
      const currAnnotation = annotations[i];
      if (Trace.Types.File.isEntryLabelAnnotation(currAnnotation)) {
        const serializedEvent = this.#eventsSerializer.keyForEvent(currAnnotation.entry);
        if (serializedEvent) {
          entryLabelsSerialized.push({
            entry: serializedEvent,
            label: currAnnotation.label,
          });
        }
      } else if (Trace.Types.File.isTimeRangeAnnotation(currAnnotation)) {
        labelledTimeRangesSerialized.push({
          bounds: currAnnotation.bounds,
          label: currAnnotation.label,
        });
      } else if (Trace.Types.File.isEntriesLinkAnnotation(currAnnotation)) {
        // Only save the links between entries that are fully created and have the entry that it is pointing to set
        if (currAnnotation.entryTo) {
          const serializedFromEvent = this.#eventsSerializer.keyForEvent(currAnnotation.entryFrom);
          const serializedToEvent = this.#eventsSerializer.keyForEvent(currAnnotation.entryTo);
          if (serializedFromEvent && serializedToEvent) {
            linksBetweenEntriesSerialized.push({
              entryFrom: serializedFromEvent,
              entryTo: serializedToEvent,
            });
          }
        }
      }
    }

    return {
      entryLabels: entryLabelsSerialized,
      labelledTimeRanges: labelledTimeRangesSerialized,
      linksBetweenEntries: linksBetweenEntriesSerialized,
    };
  }

  applyModificationsIfPresent(): void {
    if (!this.#modifications || !this.#modifications.annotations) {
      return;
    }

    const hiddenEntries = this.#modifications.entriesModifications.hiddenEntries;
    const expandableEntries = this.#modifications.entriesModifications.expandableEntries;

    this.#timelineBreadcrumbs.setInitialBreadcrumbFromLoadedModifications(this.#modifications.initialBreadcrumb);
    this.#applyEntriesFilterModifications(hiddenEntries, expandableEntries);
    this.#applyStoredAnnotations(this.#modifications.annotations, {
      muteAriaNotifications: false,
    });
  }

  #applyStoredAnnotations(annotations: Trace.Types.File.SerializedAnnotations, opts: {muteAriaNotifications: boolean}):
      void {
    try {
      // Assign annotations to an empty array if they don't exist to not
      // break the traces that were saved before those annotations were implemented
      const entryLabels = annotations.entryLabels ?? [];
      entryLabels.forEach(entryLabel => {
        this.createAnnotation(
            {
              type: 'ENTRY_LABEL',
              entry: this.#eventsSerializer.eventForKey(entryLabel.entry, this.#parsedTrace),
              label: entryLabel.label,
            },
            {
              loadedFromFile: true,
              muteAriaNotifications: opts.muteAriaNotifications,
            });
      });

      const timeRanges = annotations.labelledTimeRanges ?? [];
      timeRanges.forEach(timeRange => {
        this.createAnnotation(
            {
              type: 'TIME_RANGE',
              bounds: timeRange.bounds,
              label: timeRange.label,
            },
            {
              loadedFromFile: true,
              muteAriaNotifications: opts.muteAriaNotifications,
            });
      });

      const linksBetweenEntries = annotations.linksBetweenEntries ?? [];
      linksBetweenEntries.forEach(linkBetweenEntries => {
        this.createAnnotation(
            {
              type: 'ENTRIES_LINK',
              state: Trace.Types.File.EntriesLinkState.CONNECTED,
              entryFrom: this.#eventsSerializer.eventForKey(linkBetweenEntries.entryFrom, this.#parsedTrace),
              entryTo: this.#eventsSerializer.eventForKey(linkBetweenEntries.entryTo, this.#parsedTrace),
            },
            {
              loadedFromFile: true,
              muteAriaNotifications: opts.muteAriaNotifications,
            });
      });
    } catch (err) {
      // This function is wrapped in a try/catch just in case we get any incoming
      // trace files with broken event keys. Shouldn't happen of course, but if
      // it does, we can discard all the data and then continue loading the
      // trace, rather than have the panel entirely break. This also prevents any
      // issue where we accidentally break the event serializer and break people
      // loading traces; let's at least make sure they can load the panel, even
      // if their annotations are gone.
      console.warn('Failed to apply stored annotations', err);
    }
  }

  #applyEntriesFilterModifications(
      hiddenEntriesKeys: Trace.Types.File.SerializableKey[],
      expandableEntriesKeys: Trace.Types.File.SerializableKey[]): void {
    try {
      const hiddenEntries = hiddenEntriesKeys.map(key => this.#eventsSerializer.eventForKey(key, this.#parsedTrace));
      const expandableEntries =
          expandableEntriesKeys.map(key => this.#eventsSerializer.eventForKey(key, this.#parsedTrace));
      this.#entriesFilter.setHiddenAndExpandableEntries(hiddenEntries, expandableEntries);
    } catch (err) {
      console.warn('Failed to apply entriesFilter modifications', err);
      // If there was some invalid data, let's just back out and clear it
      // entirely. This is better than applying a subset of all the hidden
      // entries, which could cause an odd state in the flamechart.
      this.#entriesFilter.setHiddenAndExpandableEntries([], []);
    }
  }
}