export type DirigentConfig = {
  enabled?: boolean;
  discordOnly?: boolean;
  listMode?: "human-list" | "agent-list";
  humanList?: string[];
  agentList?: string[];
  channelPoliciesFile?: string;
  // backward compatibility
  bypassUserIds?: string[];
  endSymbols?: string[];
  /** Scheduling identifier sent by moderator to activate agents (default: ➡️) */
  schedulingIdentifier?: string;
  noReplyProvider: string;
  noReplyModel: string;
  /** Discord bot token for the moderator bot (used for turn handoff messages) */
  moderatorBotToken?: string;
};

export type ChannelPolicy = {
  listMode?: "human-list" | "agent-list";
  humanList?: string[];
  agentList?: string[];
  endSymbols?: string[];
};

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

/**
 * Strip trailing OpenClaw metadata blocks from the prompt to get the actual message content.
 * The prompt format is: [prepend instruction]\n\n[message]\n\nConversation info (untrusted metadata):\n```json\n{...}\n```\n\nSender (untrusted metadata):\n```json\n{...}\n```
 */
function stripTrailingMetadata(input: string): string {
  // Remove all trailing "XXX (untrusted metadata):\n```json\n...\n```" blocks
  let text = input;
  // eslint-disable-next-line no-constant-condition
  while (true) {
    const m = text.match(/\n*[A-Z][^\n]*\(untrusted metadata\):\s*```json\s*[\s\S]*?```\s*$/);
    if (!m) break;
    text = text.slice(0, text.length - m[0].length);
  }
  return text;
}

function getLastChar(input: string): string {
  const t = stripTrailingMetadata(input).trim();
  if (!t.length) return "";
  // Use Array.from to handle multi-byte characters (emoji, surrogate pairs)
  const chars = Array.from(t);
  return chars[chars.length - 1] || "";
}

export function resolvePolicy(config: DirigentConfig, channelId?: string, channelPolicies?: Record<string, ChannelPolicy>) {
  const globalMode = config.listMode || "human-list";
  const globalHuman = config.humanList || config.bypassUserIds || [];
  const globalAgent = config.agentList || [];
  const globalEnd = config.endSymbols || ["🔚"];

  if (!channelId) {
    return { listMode: globalMode, humanList: globalHuman, agentList: globalAgent, endSymbols: globalEnd };
  }

  const cp = channelPolicies || {};
  const scoped = cp[channelId];
  if (!scoped) {
    return { listMode: globalMode, humanList: globalHuman, agentList: globalAgent, endSymbols: globalEnd };
  }

  return {
    listMode: scoped.listMode || globalMode,
    humanList: scoped.humanList || globalHuman,
    agentList: scoped.agentList || globalAgent,
    endSymbols: scoped.endSymbols || globalEnd,
  };
}

export function evaluateDecision(params: {
  config: DirigentConfig;
  channel?: string;
  channelId?: string;
  channelPolicies?: Record<string, ChannelPolicy>;
  senderId?: string;
  content?: string;
}): Decision {
  const { config } = params;

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

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

  // DM bypass: if no conversation info was found in the prompt (no senderId AND no channelId),
  // this is a DM session where untrusted metadata is not injected. Always allow through.
  if (!params.senderId && !params.channelId) {
    return { shouldUseNoReply: false, shouldInjectEndMarkerPrompt: true, reason: "dm_no_metadata_bypass" };
  }

  const policy = resolvePolicy(config, params.channelId, params.channelPolicies);

  const mode = policy.listMode;
  const humanList = policy.humanList;
  const agentList = policy.agentList;

  const senderId = params.senderId || "";
  const inHumanList = !!senderId && humanList.includes(senderId);
  const inAgentList = !!senderId && agentList.includes(senderId);

  const lastChar = getLastChar(params.content || "");
  const hasEnd = !!lastChar && policy.endSymbols.includes(lastChar);

  if (mode === "human-list") {
    if (inHumanList) {
      return { shouldUseNoReply: false, shouldInjectEndMarkerPrompt: true, reason: "human_list_sender" };
    }
    if (hasEnd) {
      return { shouldUseNoReply: false, shouldInjectEndMarkerPrompt: true, reason: `end_symbol:${lastChar}` };
    }
    return { shouldUseNoReply: true, shouldInjectEndMarkerPrompt: false, reason: "rule_match_no_end_symbol" };
  }

  // agent-list mode: listed senders require end symbol; others bypass requirement.
  if (!inAgentList) {
    return { shouldUseNoReply: false, shouldInjectEndMarkerPrompt: true, reason: "non_agent_list_sender" };
  }
  if (hasEnd) {
    return { shouldUseNoReply: false, shouldInjectEndMarkerPrompt: true, reason: `end_symbol:${lastChar}` };
  }
  return { shouldUseNoReply: true, shouldInjectEndMarkerPrompt: false, reason: "agent_list_missing_end_symbol" };
}