/**
 * AI Coach — Educational Session Context (architecture prep)
 *
 * Resolves the learner's current session and packages it as context
 * for a future AI Coach. Session data is knowledge for the AI, not UI.
 *
 * Does NOT call any AI provider or send messages.
 */

import {
  getSessionByOrder,
  PROGRAM_SESSION_COUNT,
  type ProgramSession,
  type ContentBlock
} from '@/data/program/sessions';
import {
  isProgramCompleted,
  isSessionCompleted,
  isSessionUnlocked,
  isWaitingForNextSession,
  getProgramProgress,
} from '@/services/programService';

/**
 * Structured payload the future AI Coach will receive.
 * Built from course data; not rendered in Chat UI.
 */
export interface AiCoachSessionContext {
  sessionId: string;
  order: number;
  title: string;
  description: string;
  estimatedDurationMinutes: number;
  objectivesHint: string;
  /** Full session blocks — teaching material for the AI, not for direct display */
  blocks: ContentBlock[];
  totalSessions: number;
  isFinalSession: boolean;
  /** ISO timestamp when the next session becomes available (only during cooldown) */
  nextSessionUnlocksAt?: string | null;
}

/**
 * First unlocked incomplete session (sequential).
 * Uses existing unlock/completion helpers — does not skip locked sessions.
 */
export function getCurrentEducationalSession(userId: string): ProgramSession | null {
  if (isProgramCompleted(userId)) return null;

  for (let order = 1; order <= PROGRAM_SESSION_COUNT; order++) {
    if (isSessionCompleted(userId, order)) continue;
    if (!isSessionUnlocked(userId, order)) break;
    return getSessionByOrder(order) ?? null;
  }

  return null;
}

/**
 * Package a ProgramSession for future AI Coach injection.
 * Chat must not render this as a content panel.
 */
export function buildAiCoachSessionContext(
  session: ProgramSession,
  extras?: { nextSessionUnlocksAt?: string | null },
): AiCoachSessionContext {
  return {
    sessionId: session.id,
    order: session.order,
    title: session.title,
    description: session.description,
    estimatedDurationMinutes: session.estimatedDurationMinutes,
    objectivesHint: session.description,
    blocks: session.blocks,
    totalSessions: PROGRAM_SESSION_COUNT,
    isFinalSession: session.order >= PROGRAM_SESSION_COUNT,
    nextSessionUnlocksAt: extras?.nextSessionUnlocksAt ?? null,
  };
}

/**
 * Resolve + package current session context for a user.
 * Returns null when the program is finished or no session is available.
 */
export function resolveAiCoachSessionContext(
  userId: string
): AiCoachSessionContext | null {
  const session = getCurrentEducationalSession(userId);
  if (!session) return null;
  const progress = getProgramProgress(userId);
  return buildAiCoachSessionContext(session, {
    nextSessionUnlocksAt: isWaitingForNextSession(userId) ? progress.nextSessionUnlocksAt : null,
  });
}

export function getWaitingForNextSession(userId: string): {
  sessionOrder: number;
  unlocksAt: string;
  title: string;
} | null {
  const progress = getProgramProgress(userId);
  if (!isWaitingForNextSession(userId) || !progress.nextSessionUnlocksAt || !progress.waitingForSessionOrder) {
    return null;
  }

  const session = getSessionByOrder(progress.waitingForSessionOrder);
  return {
    sessionOrder: progress.waitingForSessionOrder,
    unlocksAt: progress.nextSessionUnlocksAt,
    title: session?.title ?? `جلسه ${progress.waitingForSessionOrder}`,
  };
}