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

import * as Host from '../../../core/host/host.js';
import type * as TimelineUtils from '../../../panels/timeline/utils/utils.js';

import {ResponseType} from './AiAgent.js';
import {CallTreeContext, PerformanceAgent} from './PerformanceAgent.js';

export class PerformanceAnnotationsAgent extends PerformanceAgent {
  override readonly clientFeature = Host.AidaClient.ClientFeature.CHROME_PERFORMANCE_ANNOTATIONS_AGENT;

  /**
   * Used in the Performance panel to automatically generate a label for a selected entry.
   */
  async generateAIEntryLabel(callTree: TimelineUtils.AICallTree.AICallTree): Promise<string> {
    const context = new CallTreeContext(callTree);
    const response = await Array.fromAsync(this.run(AI_LABEL_GENERATION_PROMPT, {selected: context}));
    const lastResponse = response.at(-1);
    if (lastResponse && lastResponse.type === ResponseType.ANSWER && lastResponse.complete === true) {
      return lastResponse.text.trim();
    }
    throw new Error('Failed to generate AI entry label');
  }
}

const AI_LABEL_GENERATION_PROMPT = `## Instruction:
Generate a concise label (max 60 chars, single line) describing the *user-visible effect* of the selected call tree's activity, based solely on the provided call tree data.

## Strict Constraints:
- Output must be a single line of text.
- Maximum 60 characters.
- No full stops.
- Focus on user impact, not internal operations.
- Do not include the name of the selected event.
- Do not make assumptions about when the activity happened.
- Base the description only on the information present within the call tree data.
- Prioritize brevity.
- Only include third-party script names if their identification is highly confident.
- Very important: Only output the 60 character label text, your response will be used in full to show to the user as an annotation in the timeline.
`;