front_end/panels/changes/CombinedDiffView.ts

// Copyright 2025 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.

import '../../ui/kit/kit.js';

import * as Common from '../../core/common/common.js';
import * as i18n from '../../core/i18n/i18n.js';
import * as Persistence from '../../models/persistence/persistence.js';
import type * as Workspace from '../../models/workspace/workspace.js';
import * as WorkspaceDiff from '../../models/workspace_diff/workspace_diff.js';
import type * as Diff from '../../third_party/diff/diff.js';
import * as Buttons from '../../ui/components/buttons/buttons.js';
import type * as DiffView from '../../ui/components/diff_view/diff_view.js';
import * as UI from '../../ui/legacy/legacy.js';
import * as Lit from '../../ui/lit/lit.js';
import * as VisualLogging from '../../ui/visual_logging/visual_logging.js';
import * as PanelUtils from '../utils/utils.js';

import combinedDiffViewStyles from './combinedDiffView.css.js';

const COPIED_TO_CLIPBOARD_TEXT_TIMEOUT_MS = 1000;

const {html, Directives: {classMap}} = Lit;

const UIStrings = {
  /**
   * @description The title of the button after it was pressed and the text was copied to clipboard.
   */
  copied: 'Copied to clipboard',
  /**
   * @description The title of the copy file to clipboard button
   * @example {index.css} PH1
   */
  copyFile: 'Copy file {PH1} to clipboard',
} as const;

const str_ = i18n.i18n.registerUIStrings('panels/changes/CombinedDiffView.ts', UIStrings);
const i18nString = i18n.i18n.getLocalizedString.bind(undefined, str_);

interface SingleDiffViewInput {
  // `DiffArray` can be empty for the modified files that
  // do not have any diff. (e.g. the file content transition was A -> B -> A)
  diff: Diff.Diff.DiffArray;
  fileName: string;
  fileUrl: string;
  mimeType: string;
  icon: Lit.TemplateResult;
  copied: boolean;
  selectedFileUrl?: string;
  onCopy: (fileUrl: string) => void;
  onFileNameClick: (fileUrl: string) => void;
}

export interface ViewOutput {
  scrollToSelectedDiff?: () => void;
}

export interface ViewInput {
  singleDiffViewInputs: SingleDiffViewInput[];
}

type View = (input: ViewInput, output: ViewOutput, target: HTMLElement) => void;

function renderSingleDiffView(singleDiffViewInput: SingleDiffViewInput): Lit.TemplateResult {
  const {fileName, fileUrl, mimeType, icon, diff, copied, selectedFileUrl, onCopy, onFileNameClick} =
      singleDiffViewInput;
  const classes = classMap({
    selected: selectedFileUrl === fileUrl,
  });

  // clang-format off
  return html`
    <details open class=${classes}>
      <summary>
        <div class="summary-left">
          <devtools-icon class="drop-down-icon" name="arrow-drop-down"></devtools-icon>
          ${icon}
          <button class="file-name-link" jslog=${VisualLogging.action('jump-to-file')} @click=${() => onFileNameClick(fileUrl)}>${fileName}</button>
        </div>
        <div class="summary-right">
          <devtools-button
            .title=${i18nString(UIStrings.copyFile, { PH1: fileName })}
            .size=${Buttons.Button.Size.SMALL}
            .iconName=${'copy'}
            .jslogContext=${'combined-diff-view.copy'}
            .variant=${Buttons.Button.Variant.ICON}
            @click=${() => onCopy(fileUrl)}
          ></devtools-button>
          ${copied
            ? html`<span class="copied">${i18nString(UIStrings.copied)}</span>`
            : Lit.nothing}
        </div>
      </summary>
      <div class="diff-view-container">
        <devtools-diff-view
          .data=${{diff, mimeType} as DiffView.DiffView.DiffViewData}>
        </devtools-diff-view>
      </div>
    </details>
  `;
  // clang-format on
}

const DEFAULT_VIEW: View = (input, output, target) => {
  // clang-format off
  Lit.render(
      html`
      <div class="combined-diff-view">
        ${input.singleDiffViewInputs.map(singleDiffViewInput => renderSingleDiffView(singleDiffViewInput))}
      </div>
    `,
      target);
  // clang-format on
};

export class CombinedDiffView extends UI.Widget.Widget {
  /**
   * Ignores urls that start with any in the list
   */
  ignoredUrls: string[] = [];
  #selectedFileUrl?: string;

  #workspaceDiff?: WorkspaceDiff.WorkspaceDiff.WorkspaceDiffImpl;
  #modifiedUISourceCodes: Workspace.UISourceCode.UISourceCode[] = [];
  #copiedFiles: Record<string, boolean> = {};
  #view: View;
  #viewOutput: ViewOutput = {};
  constructor(element?: HTMLElement, view: View = DEFAULT_VIEW) {
    super(element);
    this.registerRequiredCSS(combinedDiffViewStyles);
    this.#view = view;
  }

  override wasShown(): void {
    super.wasShown();
    this.#workspaceDiff?.addEventListener(
        WorkspaceDiff.WorkspaceDiff.Events.MODIFIED_STATUS_CHANGED, this.#onDiffModifiedStatusChanged, this);
    void this.#initializeModifiedUISourceCodes();
  }

  override willHide(): void {
    super.willHide();
    this.#workspaceDiff?.removeEventListener(
        WorkspaceDiff.WorkspaceDiff.Events.MODIFIED_STATUS_CHANGED, this.#onDiffModifiedStatusChanged, this);
  }

  set workspaceDiff(workspaceDiff: WorkspaceDiff.WorkspaceDiff.WorkspaceDiffImpl) {
    this.#workspaceDiff = workspaceDiff;
    void this.#initializeModifiedUISourceCodes();
  }

  set selectedFileUrl(fileUrl: string|undefined) {
    this.#selectedFileUrl = fileUrl;
    this.requestUpdate();
    void this.updateComplete.then(() => {
      this.#viewOutput.scrollToSelectedDiff?.();
    });
  }

  async #onCopyFileContent(fileUrl: string): Promise<void> {
    const file = this.#modifiedUISourceCodes.find(uiSource => uiSource.url() === fileUrl);
    if (!file) {
      return;
    }
    const content = file.workingCopyContentData();
    if (!content.isTextContent) {
      return;
    }

    UI.UIUtils.copyTextToClipboard(content.text, i18nString(UIStrings.copied));
    this.#copiedFiles[fileUrl] = true;
    this.requestUpdate();
    setTimeout(() => {
      delete this.#copiedFiles[fileUrl];
      this.requestUpdate();
    }, COPIED_TO_CLIPBOARD_TEXT_TIMEOUT_MS);
  }

  #onFileNameClick(fileUrl: string): void {
    const uiSourceCode = this.#modifiedUISourceCodes.find(uiSourceCode => uiSourceCode.url() === fileUrl);
    void Common.Revealer.reveal(uiSourceCode);
  }

  async #initializeModifiedUISourceCodes(): Promise<void> {
    if (!this.#workspaceDiff) {
      return;
    }

    const currentModifiedUISourceCodes = this.#modifiedUISourceCodes;
    const nextModifiedUISourceCodes = this.#workspaceDiff.modifiedUISourceCodes();

    // Find the now non modified UI source codes and unsubscribe from their diff changes.
    const nowNonModifiedUISourceCodes =
        currentModifiedUISourceCodes.filter(uiSourceCode => !nextModifiedUISourceCodes.includes(uiSourceCode));
    nowNonModifiedUISourceCodes.forEach(
        nonModifiedUISourceCode =>
            this.#workspaceDiff?.unsubscribeFromDiffChange(nonModifiedUISourceCode, this.requestUpdate, this));

    // Find the newly modified UI source codes and subscribe for their diff changes.
    const newlyModifiedUISourceCodes =
        nextModifiedUISourceCodes.filter(uiSourceCode => !currentModifiedUISourceCodes.includes(uiSourceCode));
    newlyModifiedUISourceCodes.forEach(
        modifiedUISourceCode =>
            this.#workspaceDiff?.subscribeToDiffChange(modifiedUISourceCode, this.requestUpdate, this));
    this.#modifiedUISourceCodes = nextModifiedUISourceCodes;

    if (this.isShowing()) {
      this.requestUpdate();
    }
  }

  async #onDiffModifiedStatusChanged(): Promise<void> {
    if (!this.#workspaceDiff) {
      return;
    }

    await this.#initializeModifiedUISourceCodes();
  }

  override async performUpdate(): Promise<void> {
    const uiSourceCodeAndDiffs = (await Promise.all(this.#modifiedUISourceCodes.map(async modifiedUISourceCode => {
                                   for (const ignoredUrl of this.ignoredUrls) {
                                     if (modifiedUISourceCode.url().startsWith(ignoredUrl)) {
                                       return;
                                     }
                                   }

                                   // `requestDiff` caches the response from the previous `requestDiff` calls if the file did not change
                                   // so we can safely call it here without concerns for performance.
                                   const diffResponse = await this.#workspaceDiff?.requestDiff(modifiedUISourceCode);
                                   return {
                                     diff: diffResponse?.diff ?? [],
                                     uiSourceCode: modifiedUISourceCode,
                                   };
                                 }))).filter(uiSourceCodeAndDiff => !!uiSourceCodeAndDiff);

    const singleDiffViewInputs = uiSourceCodeAndDiffs.map(({uiSourceCode, diff}) => {
      let displayText = uiSourceCode.fullDisplayName();
      // If the UISourceCode is backed by a workspace, we show the path as "{workspace-name}/path/relative/to/workspace"
      const fileSystemUiSourceCode = Persistence.Persistence.PersistenceImpl.instance().fileSystem(uiSourceCode);
      if (fileSystemUiSourceCode) {
        displayText = [
          fileSystemUiSourceCode.project().displayName(),
          ...Persistence.FileSystemWorkspaceBinding.FileSystemWorkspaceBinding.relativePath(fileSystemUiSourceCode)
        ].join('/');
      }
      return {
        diff,
        fileName: `${uiSourceCode.isDirty() ? '*' : ''}${displayText}`,
        fileUrl: uiSourceCode.url(),
        mimeType: uiSourceCode.mimeType(),
        icon: PanelUtils.PanelUtils.getIconForSourceFile(uiSourceCode),
        copied: this.#copiedFiles[uiSourceCode.url()],
        selectedFileUrl: this.#selectedFileUrl,
        onCopy: this.#onCopyFileContent.bind(this),
        onFileNameClick: this.#onFileNameClick.bind(this),
      };
    });

    this.#view({singleDiffViewInputs}, this.#viewOutput, this.contentElement);
  }
}