export type WhisperGateConfig = {
  enabled?: boolean;
  discordOnly?: boolean;
  bypassUserIds?: string[];
  endSymbols?: string[];
  noReplyProvider: string;
  noReplyModel: string;
};

export type Decision = {
  shouldUseNoReply: boolean;
  reason: string;
};

function getLastChar(input: string): string {
  const t = input.trim();
  return t.length ? t[t.length - 1] : "";
}

export function evaluateDecision(params: {
  config: WhisperGateConfig;
  channel?: string;
  senderId?: string;
  content?: string;
}): Decision {
  const { config } = params;

  if (config.enabled === false) {
    return { shouldUseNoReply: false, reason: "disabled" };
  }

  const channel = (params.channel || "").toLowerCase();
  if (config.discordOnly !== false && channel !== "discord") {
    return { shouldUseNoReply: false, reason: "non_discord" };
  }

  if (params.senderId && (config.bypassUserIds || []).includes(params.senderId)) {
    return { shouldUseNoReply: false, reason: "bypass_sender" };
  }

  const lastChar = getLastChar(params.content || "");
  if (lastChar && (config.endSymbols || []).includes(lastChar)) {
    return { shouldUseNoReply: false, reason: `end_symbol:${lastChar}` };
  }

  return { shouldUseNoReply: true, reason: "rule_match_no_end_symbol" };
}