/**
 * Telegram polling domain helpers
 * Owns polling request builders, stop conditions, and the long-poll loop runtime for Telegram updates
 */

import type { ExtensionContext } from "@mariozechner/pi-coding-agent";

import type { TelegramConfig } from "./api.ts";

export interface TelegramUpdateLike {
  update_id: number;
}

export const TELEGRAM_ALLOWED_UPDATES = [
  "message",
  "edited_message",
  "callback_query",
  "message_reaction",
] as const;

export function buildTelegramInitialSyncRequest(): {
  offset: number;
  limit: number;
  timeout: number;
} {
  return {
    offset: -1,
    limit: 1,
    timeout: 0,
  };
}

export function buildTelegramLongPollRequest(lastUpdateId?: number): {
  offset?: number;
  limit: number;
  timeout: number;
  allowed_updates: readonly string[];
} {
  return {
    offset: lastUpdateId !== undefined ? lastUpdateId + 1 : undefined,
    limit: 10,
    timeout: 30,
    allowed_updates: TELEGRAM_ALLOWED_UPDATES,
  };
}

export function getLatestTelegramUpdateId(
  updates: TelegramUpdateLike[],
): number | undefined {
  return updates.at(-1)?.update_id;
}

export function shouldStopTelegramPolling(
  signalAborted: boolean,
  error: unknown,
): boolean {
  // AbortError-from-our-own-timeout is normalized in fetchWithRetry so it
  // can't reach here as a DOMException. Any AbortError that does reach here
  // is therefore a real caller-abort and should stop the loop.
  return (
    signalAborted ||
    (error instanceof DOMException && error.name === "AbortError")
  );
}

export interface TelegramPollLoopDeps<TUpdate extends TelegramUpdateLike> {
  ctx: ExtensionContext;
  signal: AbortSignal;
  config: TelegramConfig;
  deleteWebhook: (signal: AbortSignal) => Promise<void>;
  getUpdates: (
    body: Record<string, unknown>,
    signal: AbortSignal,
  ) => Promise<TUpdate[]>;
  persistConfig: () => Promise<void>;
  handleUpdate: (update: TUpdate, ctx: ExtensionContext) => Promise<void>;
  onErrorStatus: (message: string) => void;
  onStatusReset: () => void;
  sleep: (ms: number) => Promise<void>;
}

export async function runTelegramPollLoop<TUpdate extends TelegramUpdateLike>(
  deps: TelegramPollLoopDeps<TUpdate>,
): Promise<void> {
  if (!deps.config.botToken) return;
  try {
    await deps.deleteWebhook(deps.signal);
  } catch {
    // ignore
  }
  if (deps.config.lastUpdateId === undefined) {
    try {
      const updates = await deps.getUpdates(
        buildTelegramInitialSyncRequest(),
        deps.signal,
      );
      const lastUpdateId = getLatestTelegramUpdateId(updates);
      if (lastUpdateId !== undefined) {
        deps.config.lastUpdateId = lastUpdateId;
        await deps.persistConfig();
      }
    } catch {
      // ignore
    }
  }
  while (!deps.signal.aborted) {
    try {
      const updates = await deps.getUpdates(
        buildTelegramLongPollRequest(deps.config.lastUpdateId),
        deps.signal,
      );
      for (const update of updates) {
        deps.config.lastUpdateId = update.update_id;
        await deps.persistConfig();
        await deps.handleUpdate(update, deps.ctx);
      }
    } catch (error) {
      if (shouldStopTelegramPolling(deps.signal.aborted, error)) return;
      const message = error instanceof Error ? error.message : String(error);
      deps.onErrorStatus(message);
      await deps.sleep(3000);
      deps.onStatusReset();
    }
  }
}