/**
 * liveProgressUi.ts — host-side relay of TurnProgress snapshots to VS Code UI
 * (#60, spec coauthoring-live-progress.md §3.4). The ONLY surfaces are the
 * existing withProgress notification (an activity line) and a dedicated
 * OutputChannel streaming the full assistant text — no new network/webview
 * surface (INV-45). vscode-only; all pure logic lives in turnProgress.ts.
 */
import * as vscode from "vscode";
import { formatProgressLine, type TurnProgressSnapshot } from "./turnProgress";

const CHANNEL_NAME = "Cowriting: Claude";

export interface TurnUi {
  /** Pass to runEditTurn's opts.onProgress. */
  onProgress: (snapshot: TurnProgressSnapshot) => void;
  /** Pass to runEditTurn's opts.signal — fired when the user cancels the notification. */
  signal: AbortSignal;
}

export class LiveProgressUi {
  readonly channel: vscode.OutputChannel;

  constructor() {
    this.channel = vscode.window.createOutputChannel(CHANNEL_NAME);
  }

  /**
   * Begin one turn's UI. Writes the per-turn header to the channel and returns
   * the onProgress relay + an AbortSignal linked to the notification's cancel
   * token. The channel APPENDS (it doubles as a debug log of recent turns, spec
   * §3.5); it auto-reveals (without stealing focus) on the first streamed text,
   * gated by `cowriting.liveProgress.revealOutput`.
   */
  begin(
    instruction: string,
    progress: vscode.Progress<{ message?: string }>,
    token: vscode.CancellationToken,
  ): TurnUi {
    const controller = new AbortController();
    token.onCancellationRequested(() => controller.abort());
    this.channel.appendLine(`── asking: ${instruction} ──`);

    let revealed = false;
    const reveal = (): void => {
      if (revealed) return;
      revealed = true;
      const cfg = vscode.workspace.getConfiguration("cowriting");
      if (cfg.get<boolean>("liveProgress.revealOutput", true)) this.channel.show(true);
    };

    const onProgress = (s: TurnProgressSnapshot): void => {
      progress.report({ message: formatProgressLine(s) });
      if (s.textDelta) {
        this.channel.append(s.textDelta);
        reveal();
      }
    };

    return { onProgress, signal: controller.signal };
  }

  dispose(): void {
    this.channel.dispose();
  }
}