import { stripHeartbeatToken } from "../heartbeat.js";
import { HEARTBEAT_TOKEN, isSilentReplyText, SILENT_REPLY_TOKEN } from "../tokens.js";
import type { ReplyPayload } from "../types.js";
import { sanitizeUserFacingText } from "../../agents/pi-embedded-helpers.js";
import {
  resolveResponsePrefixTemplate,
  type ResponsePrefixContext,
} from "./response-prefix-template.js";

export type NormalizeReplyOptions = {
  responsePrefix?: string;
  /** Context for template variable interpolation in responsePrefix */
  responsePrefixContext?: ResponsePrefixContext;
  onHeartbeatStrip?: () => void;
  stripHeartbeat?: boolean;
  silentToken?: string;
};

export function normalizeReplyPayload(
  payload: ReplyPayload,
  opts: NormalizeReplyOptions = {},
): ReplyPayload | null {
  const hasMedia = Boolean(payload.mediaUrl || (payload.mediaUrls?.length ?? 0) > 0);
  const trimmed = payload.text?.trim() ?? "";
  if (!trimmed && !hasMedia) return null;

  const silentToken = opts.silentToken ?? SILENT_REPLY_TOKEN;
  let text = payload.text ?? undefined;
  if (text && isSilentReplyText(text, silentToken)) {
    if (!hasMedia) return null;
    text = "";
  }
  if (text && !trimmed) {
    // Keep empty text when media exists so media-only replies still send.
    text = "";
  }

  const shouldStripHeartbeat = opts.stripHeartbeat ?? true;
  if (shouldStripHeartbeat && text?.includes(HEARTBEAT_TOKEN)) {
    const stripped = stripHeartbeatToken(text, { mode: "message" });
    if (stripped.didStrip) opts.onHeartbeatStrip?.();
    if (stripped.shouldSkip && !hasMedia) return null;
    text = stripped.text;
  }

  if (text) {
    text = sanitizeUserFacingText(text);
  }
  if (!text?.trim() && !hasMedia) return null;

  // Resolve template variables in responsePrefix if context is provided
  const effectivePrefix = opts.responsePrefixContext
    ? resolveResponsePrefixTemplate(opts.responsePrefix, opts.responsePrefixContext)
    : opts.responsePrefix;

  if (
    effectivePrefix &&
    text &&
    text.trim() !== HEARTBEAT_TOKEN &&
    !text.startsWith(effectivePrefix)
  ) {
    text = `${effectivePrefix} ${text}`;
  }

  return { ...payload, text };
}
