import { api, BackendError, clearSessionToken, getSessionToken } from '@/services/backend';

export type AdminStats = {
  totalUsers: number;
  guestUsers: number;
  registeredUsers: number;
  pretestCompletedUsers: number;
  posttestCompletedUsers: number;
  trainingInProgressUsers: number;
  trainingCompletedUsers: number;
  courseCompletedUsers: number;
  totalAssessmentAttempts: number;
  totalChatSessions: number;
  totalChatMessages: number;
  programSessionCount: number;
};

export type AdminUserListItem = {
  id: string;
  email: string | null;
  role: 'user' | 'admin';
  isGuest: boolean;
  profileComplete: boolean;
  name: string | null;
  age: number | null;
  createdAt: string;
  lastActivityAt: string | null;
  currentStep: string | null;
  pretestCompleted: boolean;
  posttestCompleted: boolean;
  trainingCompleted: boolean;
  courseCompleted: boolean;
  completedSessionCount: number;
  programSessionCount: number;
};

export type AdminUserListResult = {
  items: AdminUserListItem[];
  pagination: {
    page: number;
    pageSize: number;
    total: number;
    totalPages: number;
  };
};

export type AdminUsersQuery = {
  q?: string;
  page?: number;
  pageSize?: number;
  sortBy?: 'createdAt' | 'role' | 'externalId' | 'lastActivityAt';
  sortDir?: 'asc' | 'desc';
};

function toQueryString(params: AdminUsersQuery): string {
  const search = new URLSearchParams();
  if (params.q) search.set('q', params.q);
  if (params.page) search.set('page', String(params.page));
  if (params.pageSize) search.set('pageSize', String(params.pageSize));
  if (params.sortBy) search.set('sortBy', params.sortBy);
  if (params.sortDir) search.set('sortDir', params.sortDir);
  const qs = search.toString();
  return qs ? `?${qs}` : '';
}

export function fetchAdminStats(): Promise<AdminStats> {
  return api.get<AdminStats>('/admin/stats');
}

export function fetchAdminUsers(query: AdminUsersQuery = {}): Promise<AdminUserListResult> {
  return api.get<AdminUserListResult>(`/admin/users${toQueryString(query)}`);
}

export type AdminAssignmentSummary = {
  total: number;
  notStarted: number;
  opened: number;
  inProgress: number;
  completed: number;
};

export type AdminUserDetail = {
  id: string;
  email: string | null;
  role: 'user' | 'admin';
  isGuest: boolean;
  profileComplete: boolean;
  name: string | null;
  age: number | null;
  createdAt: string;
  lastActivityAt: string | null;
  currentStep: string | null;
  permissions: {
    canTakePreTest: boolean;
    canOpenTraining: boolean;
    canTakePostTest: boolean;
    isCompleted: boolean;
  } | null;
  pretestCompleted: boolean;
  posttestCompleted: boolean;
  trainingStarted: boolean;
  trainingCompleted: boolean;
  courseCompleted: boolean;
  completedSessionCount: number;
  programSessionCount: number;
  preTestCompletedAt: string | null;
  trainingStartedAt: string | null;
  trainingCompletedAt: string | null;
  postTestCompletedAt: string | null;
  hasPretestAttempt: boolean;
  hasPosttestAttempt: boolean;
  chatSessionCount: number;
  assignments: AdminAssignmentSummary;
};

export function fetchAdminUserDetail(externalId: string): Promise<AdminUserDetail> {
  return api.get<AdminUserDetail>(`/admin/users/${encodeURIComponent(externalId)}`);
}

export type AdminUserOverview = {
  user: { id: string; email: string | null };
  assignments: {
    total: number;
    completed: number;
    inProgress: number;
    notStarted: number;
    reported: number;
    opened: number;
    progressPercent: number | null;
    lastActivityAt: string | null;
  };
  learningProgress: {
    currentStep: string | null;
    trainingStarted: boolean;
    trainingCompleted: boolean;
    courseCompleted: boolean;
    totalLessons: number;
    completedLessons: number;
    progressPercent: number | null;
    lastActivityAt: string | null;
  };
  assessments: {
    completedCount: number;
    expectedCount: number;
    remainingCount: number;
    hasPretest: boolean;
    hasPosttest: boolean;
    pretestCompletedAt: string | null;
    posttestCompletedAt: string | null;
    lastAssessmentAt: string | null;
    overallStatus: 'none' | 'partial' | 'complete';
  };
  recentActivities: Array<{
    type:
      | 'session_completed'
      | 'assignment_activated'
      | 'assignment_completed'
      | 'assessment_submitted'
      | 'chat_started';
    title: string;
    occurredAt: string;
    relatedId: string | null;
  }>;
};

export function fetchAdminUserOverview(externalId: string): Promise<AdminUserOverview> {
  return api.get<AdminUserOverview>(
    `/admin/users/${encodeURIComponent(externalId)}/overview`,
  );
}

export type AdminAssessmentScores = {
  total: number | null;
  efficacy: number | null;
  hope: number | null;
  resilience: number | null;
  optimism: number | null;
};

export type AdminAssessmentAnswer = {
  questionId: string;
  questionNumber: number;
  rawValue: number;
  points: number;
  dimension: string;
  isReverseScored: boolean;
};

export type AdminAssessmentPhaseView = {
  exists: boolean;
  phase: 'pre' | 'post';
  attemptId: string | null;
  status: string | null;
  submittedAt: string | null;
  scoredAt: string | null;
  scores: AdminAssessmentScores | null;
  answerCount: number;
  expectedAnswerCount: number;
  answers: AdminAssessmentAnswer[];
};

export type AdminUserAssessments = {
  user: { id: string; email: string | null };
  pretest: AdminAssessmentPhaseView;
  posttest: AdminAssessmentPhaseView;
};

export function fetchAdminUserAssessments(externalId: string): Promise<AdminUserAssessments> {
  return api.get<AdminUserAssessments>(
    `/admin/users/${encodeURIComponent(externalId)}/assessments`,
  );
}

export type AdminChatSessionListItem = {
  id: string;
  sessionOrder: number;
  title: string;
  status: 'open' | 'ended';
  startedAt: string;
  endedAt: string | null;
  createdAt: string;
  updatedAt: string;
  lastActivityAt: string;
  messageCount: number;
};

export type AdminChatSessionsListResult = {
  user: { id: string; email: string | null };
  items: AdminChatSessionListItem[];
  pagination: {
    page: number;
    pageSize: number;
    total: number;
    totalPages: number;
  };
};

export type AdminChatMessageView = {
  id: string;
  role: 'user' | 'assistant' | 'system';
  content: string;
  createdAt: string;
  sequence: number;
};

export type AdminChatSessionDetail = {
  user: { id: string; email: string | null };
  session: AdminChatSessionListItem;
  messages: AdminChatMessageView[];
};

export type AdminChatSessionsQuery = {
  page?: number;
  pageSize?: number;
  sortBy?: 'startedAt' | 'updatedAt' | 'sessionOrder' | 'createdAt';
  sortDir?: 'asc' | 'desc';
};

function chatSessionsQueryString(params: AdminChatSessionsQuery): string {
  const search = new URLSearchParams();
  if (params.page) search.set('page', String(params.page));
  if (params.pageSize) search.set('pageSize', String(params.pageSize));
  if (params.sortBy) search.set('sortBy', params.sortBy);
  if (params.sortDir) search.set('sortDir', params.sortDir);
  const qs = search.toString();
  return qs ? `?${qs}` : '';
}

export function fetchAdminUserChatSessions(
  externalId: string,
  query: AdminChatSessionsQuery = {},
): Promise<AdminChatSessionsListResult> {
  return api.get<AdminChatSessionsListResult>(
    `/admin/users/${encodeURIComponent(externalId)}/chat-sessions${chatSessionsQueryString(query)}`,
  );
}

export function fetchAdminUserChatSessionDetail(
  externalId: string,
  sessionId: string,
): Promise<AdminChatSessionDetail> {
  return api.get<AdminChatSessionDetail>(
    `/admin/users/${encodeURIComponent(externalId)}/chat-sessions/${encodeURIComponent(sessionId)}`,
  );
}

export type AdminAssignmentListItem = {
  assignmentId: string;
  definitionId: string;
  definitionKey: string;
  definitionTitle: string;
  assignmentType: string;
  programId: null;
  programTitle: null;
  sessionId: string | null;
  sessionOrder: number;
  sessionTitle: string | null;
  status: string;
  assignedAt: string;
  startedAt: string | null;
  completedAt: string | null;
  lastActivityAt: string | null;
  doneDayCount: number;
  expectedDurationDays: number | null;
  progressPercent: number | null;
};

export type AdminAssignmentsSummary = {
  total: number;
  notStarted: number;
  opened: number;
  inProgress: number;
  completed: number;
  pending: number;
  progressPercent: number | null;
};

export type AdminLearningProgress = {
  currentStep: string | null;
  trainingStarted: boolean;
  trainingCompleted: boolean;
  courseCompleted: boolean;
  totalLessons: number;
  completedLessons: number;
  progressPercent: number | null;
};

export type AdminUserAssignmentsResult = {
  user: { id: string; email: string | null };
  learningProgress: AdminLearningProgress;
  summary: AdminAssignmentsSummary;
  items: AdminAssignmentListItem[];
};

export type AdminAssignmentsQuery = {
  sortBy?: 'activatedAt' | 'completedAt' | 'status' | 'sessionOrder';
  sortDir?: 'asc' | 'desc';
  status?: 'NOT_STARTED' | 'ACTIVE' | 'IN_PROGRESS' | 'REPORTED' | 'COMPLETED';
  assignmentType?: 'ONE_TIME' | 'DAILY' | 'ONGOING';
  search?: string;
};

function assignmentsQueryString(params: AdminAssignmentsQuery): string {
  const search = new URLSearchParams();
  if (params.sortBy) search.set('sortBy', params.sortBy);
  if (params.sortDir) search.set('sortDir', params.sortDir);
  if (params.status) search.set('status', params.status);
  if (params.assignmentType) search.set('assignmentType', params.assignmentType);
  if (params.search) search.set('search', params.search);
  const qs = search.toString();
  return qs ? `?${qs}` : '';
}

export function fetchAdminUserAssignments(
  externalId: string,
  query: AdminAssignmentsQuery = {},
): Promise<AdminUserAssignmentsResult> {
  return api.get<AdminUserAssignmentsResult>(
    `/admin/users/${encodeURIComponent(externalId)}/assignments${assignmentsQueryString(query)}`,
  );
}

export type AdminAssignmentDetail = {
  user: { id: string; email: string | null };
  assignment: {
    id: string;
    definitionId: string;
    definitionKey: string;
    definitionTitle: string;
    assignmentType: string;
    status: string;
    assignedAt: string;
    startedAt: string | null;
    completedAt: string | null;
    lastActivityAt: string | null;
    doneDayCount: number;
    expectedDurationDays: number | null;
    progressPercent: number | null;
  };
  session: {
    id: string | null;
    order: number;
    title: string;
  };
  learningProgress: {
    currentStep: string | null;
    totalLessons: number;
    completedLessons: number;
    progressPercent: number | null;
  };
  activity: {
    firstActivityAt: string | null;
    lastActivityAt: string | null;
    completedActivityCount: number;
  } | null;
};

export function fetchAdminUserAssignmentDetail(
  externalId: string,
  assignmentId: string,
): Promise<AdminAssignmentDetail> {
  return api.get<AdminAssignmentDetail>(
    `/admin/users/${encodeURIComponent(externalId)}/assignments/${encodeURIComponent(assignmentId)}`,
  );
}

function parseContentDispositionFilename(header: string | null): string | null {
  if (!header) return null;
  const utf8 = /filename\*=UTF-8''([^;]+)/i.exec(header);
  if (utf8?.[1]) {
    try {
      return decodeURIComponent(utf8[1].trim().replace(/^"|"$/g, ''));
    } catch {
      // fall through
    }
  }
  const plain = /filename="?([^";]+)"?/i.exec(header);
  if (!plain?.[1]) return null;
  const name = plain[1].trim();
  if (!name || /[\\/\n\r"]/.test(name)) return null;
  return name;
}

function triggerBrowserDownload(blob: Blob, filename: string): void {
  const url = URL.createObjectURL(blob);
  const anchor = document.createElement('a');
  anchor.href = url;
  anchor.download = filename;
  anchor.rel = 'noopener';
  document.body.appendChild(anchor);
  anchor.click();
  anchor.remove();
  URL.revokeObjectURL(url);
}

/**
 * Binary XLSX download — bypasses JSON api.get helper.
 */
export async function downloadAdminUserAssignmentsExport(
  externalId: string,
  query: AdminAssignmentsQuery = {},
): Promise<void> {
  const path = `/admin/users/${encodeURIComponent(externalId)}/assignments/export${assignmentsQueryString(query)}`;
  const baseUrl = (import.meta.env.VITE_BACKEND_URL || '/api/backend').replace(/\/$/, '');
  const token = getSessionToken();
  const headers = new Headers();
  if (token) {
    headers.set('Authorization', `Bearer ${token}`);
  }

  let response: Response;
  try {
    response = await fetch(`${baseUrl}${path}`, { method: 'GET', headers });
  } catch {
    throw new BackendError(
      0,
      'NETWORK_ERROR',
      'سرور در دسترس نیست. لطفاً چند لحظه بعد دوباره تلاش کنید.',
    );
  }

  if (!response.ok) {
    let code = 'UNKNOWN';
    let message = `Request failed with status ${response.status}`;
    try {
      const body = (await response.json()) as {
        error?: { code?: string; message?: string };
      };
      code = body.error?.code ?? code;
      message = body.error?.message ?? message;
    } catch {
      // non-JSON error body
    }
    if (response.status === 401) {
      clearSessionToken();
      if (typeof window !== 'undefined') {
        window.dispatchEvent(new CustomEvent('novya:unauthorized'));
      }
    }
    throw new BackendError(response.status, code, message);
  }

  const blob = await response.blob();
  const fromHeader = parseContentDispositionFilename(
    response.headers.get('Content-Disposition'),
  );
  const safeFallback = `noya-assignments-${externalId.replace(/[^a-zA-Z0-9_-]/g, '-').slice(0, 64) || 'user'}.xlsx`;
  triggerBrowserDownload(blob, fromHeader ?? safeFallback);
}