/**
 * Turn-based speaking manager for group channels.
 *
 * Rules:
 * - Humans (humanList) and the moderator bot are never in the turn order
 * - Turn order is auto-populated from channel/server members minus humans/moderator
 * - currentSpeaker can be null (dormant state)
 * - When ALL agents in a cycle have NO_REPLY'd, state goes dormant (null)
 * - Dormant → any new message reactivates:
 *   - If sender is NOT in turn order → current = first in list
 *   - If sender IS in turn order → current = next after sender
 * - When turn order is first created via discovery, all agents are forced no-reply
 *   until moderator activates the first speaker
 * - When turn order is pre-populated (e.g. channel-private-create), the first
 *   speaker is immediately activated via moderator handoff
 */

export type ChannelTurnState = {
  /** Ordered accountIds for this channel (auto-populated, shuffled) */
  turnOrder: string[];
  /** Current speaker accountId, or null if dormant */
  currentSpeaker: string | null;
  /** Set of accountIds that have NO_REPLY'd this cycle */
  noRepliedThisCycle: Set<string>;
  /** Timestamp of last state change */
  lastChangedAt: number;
  /**
   * Whether this turn state was pre-populated (e.g. from channel-private-create params).
   * Pre-populated states have a complete member list and can be activated immediately.
   * Discovery-based states may be incomplete and need stabilization.
   */
  prePopulated: boolean;
};

const channelTurns = new Map<string, ChannelTurnState>();

/** Turn timeout: if the current speaker hasn't responded, auto-advance */
const TURN_TIMEOUT_MS = 60_000;

// --- helpers ---

function shuffleArray<T>(arr: T[]): T[] {
  const a = [...arr];
  for (let i = a.length - 1; i > 0; i--) {
    const j = Math.floor(Math.random() * (i + 1));
    [a[i], a[j]] = [a[j], a[i]];
  }
  return a;
}

// --- public API ---

/**
 * Check if a channel already has turn state initialized.
 */
export function hasTurnState(channelId: string): boolean {
  return channelTurns.has(channelId);
}

/**
 * Initialize or update the turn order for a channel.
 * Called with the list of bot accountIds (already filtered, humans excluded).
 * Starts in dormant state — activation happens via onNewMessage or activateFirstSpeaker.
 *
 * @returns true if a NEW turn state was created (callers should trigger moderator activation)
 */
export function initTurnOrder(channelId: string, botAccountIds: string[]): boolean {
  const existing = channelTurns.get(channelId);
  if (existing) {
    // Check if membership changed
    const oldSet = new Set(existing.turnOrder);
    const newSet = new Set(botAccountIds);
    const same = oldSet.size === newSet.size && [...oldSet].every(id => newSet.has(id));
    if (same) return false; // no change

    // Membership changed — update turn order, preserve current state where possible
    const newOrder = shuffleArray(botAccountIds);
    existing.turnOrder = newOrder;
    // If current speaker was removed, go dormant
    if (existing.currentSpeaker && !newSet.has(existing.currentSpeaker)) {
      existing.currentSpeaker = newOrder.length > 0 ? newOrder[0] : null;
    }
    // Clean up noRepliedThisCycle
    for (const id of existing.noRepliedThisCycle) {
      if (!newSet.has(id)) existing.noRepliedThisCycle.delete(id);
    }
    existing.lastChangedAt = Date.now();
    return false;
  }

  channelTurns.set(channelId, {
    turnOrder: shuffleArray(botAccountIds),
    currentSpeaker: null, // start dormant
    noRepliedThisCycle: new Set(),
    lastChangedAt: Date.now(),
    prePopulated: false,
  });
  return true;
}

/**
 * Initialize turn order from a known complete member list (e.g. channel-private-create).
 * Immediately activates the first speaker.
 *
 * @returns the first speaker accountId, or null if no bots
 */
export function initTurnOrderPrePopulated(channelId: string, botAccountIds: string[]): string | null {
  if (botAccountIds.length === 0) return null;

  const order = shuffleArray(botAccountIds);
  channelTurns.set(channelId, {
    turnOrder: order,
    currentSpeaker: order[0],
    noRepliedThisCycle: new Set(),
    lastChangedAt: Date.now(),
    prePopulated: true,
  });
  return order[0];
}

/**
 * Update turn order when members are added or removed (e.g. channel-private-update).
 * Preserves current speaker if still present, otherwise activates first in new order.
 *
 * @returns { turnOrder, currentSpeaker, needsHandoff } — needsHandoff is true if
 *          currentSpeaker changed and moderator should send a handoff message
 */
export function updateTurnMembers(
  channelId: string,
  addAccountIds: string[],
  removeAccountIds: string[],
): { turnOrder: string[]; currentSpeaker: string | null; needsHandoff: boolean } {
  const state = channelTurns.get(channelId);
  const removeSet = new Set(removeAccountIds);

  if (!state) {
    // No existing state — create fresh with the added members
    const order = shuffleArray(addAccountIds.filter(id => !removeSet.has(id)));
    if (order.length === 0) return { turnOrder: [], currentSpeaker: null, needsHandoff: false };
    channelTurns.set(channelId, {
      turnOrder: order,
      currentSpeaker: order[0],
      noRepliedThisCycle: new Set(),
      lastChangedAt: Date.now(),
      prePopulated: true,
    });
    return { turnOrder: order, currentSpeaker: order[0], needsHandoff: true };
  }

  const oldSpeaker = state.currentSpeaker;

  // Remove members
  if (removeAccountIds.length > 0) {
    state.turnOrder = state.turnOrder.filter(id => !removeSet.has(id));
    for (const id of removeAccountIds) {
      state.noRepliedThisCycle.delete(id);
    }
  }

  // Add new members (append, don't shuffle existing order to preserve continuity)
  for (const id of addAccountIds) {
    if (!removeSet.has(id) && !state.turnOrder.includes(id)) {
      state.turnOrder.push(id);
    }
  }

  // Handle current speaker removal
  let needsHandoff = false;
  if (oldSpeaker && !state.turnOrder.includes(oldSpeaker)) {
    // Current speaker was removed — activate first available
    state.currentSpeaker = state.turnOrder.length > 0 ? state.turnOrder[0] : null;
    needsHandoff = state.currentSpeaker !== null;
  }

  state.lastChangedAt = Date.now();
  return { turnOrder: state.turnOrder, currentSpeaker: state.currentSpeaker, needsHandoff };
}

/**
 * Activate the first speaker in the turn order.
 * Used after turn order creation to start the cycle.
 *
 * @returns the activated speaker accountId, or null if no bots / already active
 */
export function activateFirstSpeaker(channelId: string): string | null {
  const state = channelTurns.get(channelId);
  if (!state || state.turnOrder.length === 0) return null;
  if (state.currentSpeaker !== null) return null; // already active

  state.currentSpeaker = state.turnOrder[0];
  state.noRepliedThisCycle = new Set();
  state.lastChangedAt = Date.now();
  return state.currentSpeaker;
}

/**
 * Check if the given accountId is allowed to speak.
 */
export function checkTurn(channelId: string, accountId: string): {
  allowed: boolean;
  currentSpeaker: string | null;
  reason: string;
} {
  const state = channelTurns.get(channelId);
  if (!state || state.turnOrder.length === 0) {
    return { allowed: true, currentSpeaker: null, reason: "no_turn_state" };
  }

  // Not in turn order (human or unknown) → always allowed
  if (!state.turnOrder.includes(accountId)) {
    return { allowed: true, currentSpeaker: state.currentSpeaker, reason: "not_in_turn_order" };
  }

  // Dormant → not allowed (will be activated by onNewMessage or moderator)
  if (state.currentSpeaker === null) {
    return { allowed: false, currentSpeaker: null, reason: "dormant" };
  }

  // Check timeout → auto-advance
  if (Date.now() - state.lastChangedAt > TURN_TIMEOUT_MS) {
    advanceTurn(channelId);
    // Re-check after advance
    const updated = channelTurns.get(channelId)!;
    if (updated.currentSpeaker === accountId) {
      return { allowed: true, currentSpeaker: updated.currentSpeaker, reason: "timeout_advanced_to_self" };
    }
    return { allowed: false, currentSpeaker: updated.currentSpeaker, reason: "timeout_advanced_to_other" };
  }

  if (accountId === state.currentSpeaker) {
    return { allowed: true, currentSpeaker: state.currentSpeaker, reason: "is_current_speaker" };
  }

  return { allowed: false, currentSpeaker: state.currentSpeaker, reason: "not_current_speaker" };
}

/**
 * Called when a new message arrives in the channel.
 * Handles reactivation from dormant state.
 * Any member (human or bot) can trigger activation when dormant.
 *
 * @param senderAccountId - the accountId of the message sender (could be human/bot/unknown)
 * @param isHuman - whether the sender is in the humanList
 */
export function onNewMessage(channelId: string, senderAccountId: string | undefined, isHuman: boolean): void {
  const state = channelTurns.get(channelId);
  if (!state || state.turnOrder.length === 0) return;

  if (state.currentSpeaker !== null) {
    // Already active — human messages reset the cycle, bot messages do nothing
    if (isHuman) {
      state.currentSpeaker = state.turnOrder[0];
      state.noRepliedThisCycle = new Set();
      state.lastChangedAt = Date.now();
    }
    return;
  }

  // Dormant state → reactivate (any member can trigger)
  if (senderAccountId && state.turnOrder.includes(senderAccountId)) {
    // Sender is in turn order → next after sender
    const idx = state.turnOrder.indexOf(senderAccountId);
    const nextIdx = (idx + 1) % state.turnOrder.length;
    state.currentSpeaker = state.turnOrder[nextIdx];
  } else {
    // Sender not in turn order (human or unknown) → start from first
    state.currentSpeaker = state.turnOrder[0];
  }
  state.noRepliedThisCycle = new Set();
  state.lastChangedAt = Date.now();
}

/**
 * Called when the current speaker finishes (end symbol detected) or says NO_REPLY.
 * @param wasNoReply - true if the speaker said NO_REPLY (empty/silent)
 * @returns the new currentSpeaker (or null if dormant)
 */
export function onSpeakerDone(channelId: string, accountId: string, wasNoReply: boolean): string | null {
  const state = channelTurns.get(channelId);
  if (!state) return null;
  if (state.currentSpeaker !== accountId) return state.currentSpeaker; // not current speaker, ignore

  if (wasNoReply) {
    state.noRepliedThisCycle.add(accountId);

    // Check if ALL agents have NO_REPLY'd this cycle
    const allNoReplied = state.turnOrder.every(id => state.noRepliedThisCycle.has(id));
    if (allNoReplied) {
      // Go dormant
      state.currentSpeaker = null;
      state.noRepliedThisCycle = new Set();
      state.lastChangedAt = Date.now();
      return null;
    }
  } else {
    // Successful speech resets the cycle counter
    state.noRepliedThisCycle = new Set();
  }

  return advanceTurn(channelId);
}

/**
 * Advance to next speaker in order.
 */
export function advanceTurn(channelId: string): string | null {
  const state = channelTurns.get(channelId);
  if (!state || state.turnOrder.length === 0) return null;

  if (state.currentSpeaker === null) return null;

  const idx = state.turnOrder.indexOf(state.currentSpeaker);
  const nextIdx = (idx + 1) % state.turnOrder.length;

  // Skip agents that already NO_REPLY'd this cycle
  let attempts = 0;
  let candidateIdx = nextIdx;
  while (state.noRepliedThisCycle.has(state.turnOrder[candidateIdx]) && attempts < state.turnOrder.length) {
    candidateIdx = (candidateIdx + 1) % state.turnOrder.length;
    attempts++;
  }

  if (attempts >= state.turnOrder.length) {
    // All have NO_REPLY'd
    state.currentSpeaker = null;
    state.lastChangedAt = Date.now();
    return null;
  }

  state.currentSpeaker = state.turnOrder[candidateIdx];
  state.lastChangedAt = Date.now();
  return state.currentSpeaker;
}

/**
 * Force reset: go dormant.
 */
export function resetTurn(channelId: string): void {
  const state = channelTurns.get(channelId);
  if (state) {
    state.currentSpeaker = null;
    state.noRepliedThisCycle = new Set();
    state.lastChangedAt = Date.now();
  }
}

/**
 * Get debug info.
 */
export function getTurnDebugInfo(channelId: string): Record<string, unknown> {
  const state = channelTurns.get(channelId);
  if (!state) return { channelId, hasTurnState: false };
  return {
    channelId,
    hasTurnState: true,
    turnOrder: state.turnOrder,
    currentSpeaker: state.currentSpeaker,
    noRepliedThisCycle: [...state.noRepliedThisCycle],
    lastChangedAt: state.lastChangedAt,
    dormant: state.currentSpeaker === null,
    prePopulated: state.prePopulated,
  };
}