ConsoleFormatter.ts

/**
 * @license
 * Copyright 2026 Google LLC
 * SPDX-License-Identifier: Apache-2.0
 */

import {
  createStackTraceForConsoleMessage,
  type TargetUniverse,
} from '../DevtoolsUtils.js';
import type * as DevTools from '../third_party/index.js';
import type {ConsoleMessage} from '../third_party/index.js';

export interface ConsoleFormatterOptions {
  fetchDetailedData?: boolean;
  id?: number;
  devTools?: TargetUniverse;
  resolvedStackTraceForTesting?: DevTools.DevTools.StackTrace.StackTrace.StackTrace;
}

export class ConsoleFormatter {
  #msg: ConsoleMessage | Error;
  #resolvedArgs: unknown[] = [];
  #resolvedStackTrace?: DevTools.DevTools.StackTrace.StackTrace.StackTrace;
  #id?: number;

  private constructor(
    msg: ConsoleMessage | Error,
    options?: ConsoleFormatterOptions,
  ) {
    this.#msg = msg;
    this.#id = options?.id;
    this.#resolvedStackTrace = options?.resolvedStackTraceForTesting;
  }

  static async from(
    msg: ConsoleMessage | Error,
    options?: ConsoleFormatterOptions,
  ): Promise<ConsoleFormatter> {
    const formatter = new ConsoleFormatter(msg, options);
    if (options?.fetchDetailedData) {
      await formatter.#loadDetailedData(options?.devTools);
    }
    return formatter;
  }

  async #loadDetailedData(devTools?: TargetUniverse): Promise<void> {
    if (this.#msg instanceof Error) {
      return;
    }

    this.#resolvedArgs = await Promise.all(
      this.#msg.args().map(async (arg, i) => {
        try {
          return await arg.jsonValue();
        } catch {
          return `<error: Argument ${i} is no longer available>`;
        }
      }),
    );

    if (devTools) {
      try {
        this.#resolvedStackTrace = await createStackTraceForConsoleMessage(
          devTools,
          this.#msg,
        );
      } catch {
        // ignore
      }
    }
  }

  // The short format for a console message.
  toString(): string {
    const type = this.#getType();
    const text = this.#getText();
    const argsCount =
      this.#msg instanceof Error
        ? 0
        : this.#resolvedArgs.length || this.#msg.args().length;
    const idPart = this.#id !== undefined ? `msgid=${this.#id} ` : '';
    return `${idPart}[${type}] ${text} (${argsCount} args)`;
  }

  // The verbose format for a console message, including all details.
  toStringDetailed(): string {
    const result = [
      this.#id !== undefined ? `ID: ${this.#id}` : '',
      `Message: ${this.#getType()}> ${this.#getText()}`,
      this.#formatArgs(),
      this.#formatStackTrace(this.#resolvedStackTrace),
    ].filter(line => !!line);
    return result.join('\n');
  }

  #getType(): string {
    if (this.#msg instanceof Error) {
      return 'error';
    }
    return this.#msg.type();
  }

  #getText(): string {
    if (this.#msg instanceof Error) {
      return this.#msg.message;
    }
    return this.#msg.text();
  }

  #getArgs(): unknown[] {
    if (this.#msg instanceof Error) {
      return [];
    }
    if (this.#resolvedArgs.length > 0) {
      const args = [...this.#resolvedArgs];
      // If there is no text, the first argument serves as text (see formatMessage).
      if (!this.#msg.text()) {
        args.shift();
      }
      return args;
    }
    return [];
  }

  #formatArg(arg: unknown) {
    return typeof arg === 'object' ? JSON.stringify(arg) : String(arg);
  }

  #formatArgs(): string {
    const args = this.#getArgs();

    if (!args.length) {
      return '';
    }

    const result = ['### Arguments'];

    for (const [key, arg] of args.entries()) {
      result.push(`Arg #${key}: ${this.#formatArg(arg)}`);
    }

    return result.join('\n');
  }

  #formatStackTrace(
    stackTrace: DevTools.DevTools.StackTrace.StackTrace.StackTrace | undefined,
  ): string {
    if (!stackTrace) {
      return '';
    }

    return [
      '### Stack trace',
      this.#formatFragment(stackTrace.syncFragment),
      ...stackTrace.asyncFragments.map(this.#formatAsyncFragment.bind(this)),
    ].join('\n');
  }

  #formatFragment(
    fragment: DevTools.DevTools.StackTrace.StackTrace.Fragment,
  ): string {
    return fragment.frames.map(this.#formatFrame.bind(this)).join('\n');
  }

  #formatAsyncFragment(
    fragment: DevTools.DevTools.StackTrace.StackTrace.AsyncFragment,
  ): string {
    const separatorLineLength = 40;
    const prefix = `--- ${fragment.description || 'async'} `;
    const separator = prefix + '-'.repeat(separatorLineLength - prefix.length);
    return separator + '\n' + this.#formatFragment(fragment);
  }

  #formatFrame(frame: DevTools.DevTools.StackTrace.StackTrace.Frame): string {
    let result = `at ${frame.name ?? '<anonymous>'}`;
    if (frame.uiSourceCode) {
      result += ` (${frame.uiSourceCode.displayName()}:${frame.line}:${frame.column})`;
    } else if (frame.url) {
      result += ` (${frame.url}:${frame.line}:${frame.column})`;
    }
    return result;
  }
  toJSON(): object {
    return {
      type: this.#getType(),
      text: this.#getText(),
      argsCount:
        this.#msg instanceof Error
          ? 0
          : this.#resolvedArgs.length || this.#msg.args().length,
      id: this.#id,
    };
  }

  toJSONDetailed(): object {
    return {
      id: this.#id,
      type: this.#getType(),
      text: this.#getText(),
      args: this.#getArgs().map(arg =>
        typeof arg === 'object' ? arg : String(arg),
      ),
      stackTrace: this.#resolvedStackTrace,
    };
  }
}