/**
 * BankBot API client — typed fetch wrapper for all backend endpoints.
 * Handles auth headers, token refresh, and error normalization.
 *
 * HF Spaces mode: when NEXT_PUBLIC_API_URL is empty, all /api/* calls
 * go to the same origin — Nginx routes them to FastAPI internally.
 * WebSocket also uses the same origin with ws:// or wss://.
 */

// In HF mode NEXT_PUBLIC_API_URL is "" — use empty string so fetch uses same origin
const API_BASE = process.env.NEXT_PUBLIC_API_URL || "";

// ─── WebSocket URL derivation ─────────────────────────────────────────────────
// HF mode (API_BASE=""): derive from window.location at runtime
// External mode: convert http→ws, https→wss
function getWsBase(): string {
  if (typeof window === "undefined") return "";
  if (!API_BASE) {
    // Same-origin WebSocket — use current page protocol
    const proto = window.location.protocol === "https:" ? "wss:" : "ws:";
    return `${proto}//${window.location.host}`;
  }
  return API_BASE.replace(/^https/, "wss").replace(/^http/, "ws");
}

// ─── Token management (browser-only) ─────────────────────────────────────────
export const tokenStore = {
  getAccess: (): string | null =>
    typeof window !== "undefined" ? localStorage.getItem("bb_access_token") : null,
  getRefresh: (): string | null =>
    typeof window !== "undefined" ? localStorage.getItem("bb_refresh_token") : null,
  setTokens: (access: string, refresh?: string) => {
    if (typeof window === "undefined") return;
    localStorage.setItem("bb_access_token", access);
    if (refresh) localStorage.setItem("bb_refresh_token", refresh);
  },
  clear: () => {
    if (typeof window === "undefined") return;
    localStorage.removeItem("bb_access_token");
    localStorage.removeItem("bb_refresh_token");
    localStorage.removeItem("bb_user");
  },
};

// ─── Core fetch wrapper ───────────────────────────────────────────────────────
async function apiFetch<T>(
  path: string,
  options: RequestInit = {},
  retry = true
): Promise<T> {
  const token = tokenStore.getAccess();
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
    ...(options.headers as Record<string, string>),
  };
  if (token) headers["Authorization"] = `Bearer ${token}`;

  const res = await fetch(`${API_BASE}${path}`, { ...options, headers });

  // Auto-refresh on 401
  if (res.status === 401 && retry) {
    const refreshToken = tokenStore.getRefresh();
    if (refreshToken) {
      try {
        const refreshRes = await fetch(`${API_BASE}/api/auth/refresh`, {
          method: "POST",
          headers: { "Content-Type": "application/json" },
          body: JSON.stringify({ refresh_token: refreshToken }),
        });
        if (refreshRes.ok) {
          const data = await refreshRes.json();
          tokenStore.setTokens(data.access_token);
          return apiFetch<T>(path, options, false);
        }
      } catch {
        // refresh failed — clear tokens
      }
    }
    tokenStore.clear();
    throw new ApiError(401, "Session expired. Please log in again.");
  }

  if (!res.ok) {
    let detail = `HTTP ${res.status}`;
    try {
      const err = await res.json();
      detail = err.detail || detail;
    } catch { /* ignore */ }
    throw new ApiError(res.status, detail);
  }

  return res.json() as Promise<T>;
}

export class ApiError extends Error {
  constructor(public status: number, message: string) {
    super(message);
    this.name = "ApiError";
  }
}

// ─── Auth ─────────────────────────────────────────────────────────────────────
export interface LoginResponse {
  access_token: string;
  refresh_token: string;
  token_type: string;
  user_id: string;
  name: string;
  email: string;
}

export const authApi = {
  login: (email: string, password: string) => {
    const form = new URLSearchParams({ username: email, password });
    return apiFetch<LoginResponse>("/api/auth/login", {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: form.toString(),
    });
  },
  register: (email: string, password: string, name: string) =>
    apiFetch<LoginResponse>("/api/auth/register", {
      method: "POST",
      body: JSON.stringify({ email, password, name }),
    }),
  me: () =>
    apiFetch<{
      user_id: string;
      email: string;
      name: string;
      financial_personality: string;
      notifications_enabled?: boolean;
      ai_coaching_enabled?: boolean;
      fraud_alerts_enabled?: boolean;
    }>("/api/auth/me"),
  updateSettings: (data: {
    name?: string;
    financial_personality?: string;
    notifications_enabled?: boolean;
    ai_coaching_enabled?: boolean;
    fraud_alerts_enabled?: boolean;
  }) =>
    apiFetch<{
      user_id: string;
      email: string;
      name: string;
      financial_personality: string;
      notifications_enabled?: boolean;
      ai_coaching_enabled?: boolean;
      fraud_alerts_enabled?: boolean;
    }>("/api/auth/settings", { method: "PATCH", body: JSON.stringify(data) }),
  logout: () => {
    tokenStore.clear();
    return Promise.resolve();
  },
};

export interface FinancialGoal {
  id: string;
  title: string;
  target_amount: number;
  current_amount: number;
  progress_percent: number;
  target_date: string | null;
  days_left: number | null;
  monthly_contribution?: number;
  months_remaining?: number;
  on_track: boolean;
}

export const goalsApi = {
  list: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      goals: FinancialGoal[];
      summary: { count: number; total_target: number; total_saved: number; overall_progress: number };
    }>(`/api/goals${qs}`);
  },
  contribute: (goalId: string, amount: number, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ id: string; current_amount: number; progress_percent: number; completed: boolean }>(
      `/api/goals/${goalId}/contribute${qs}`,
      { method: "POST", body: JSON.stringify({ amount }) }
    );
  },
};

export const loansApi = {
  eligibility: (data: {
    salary: number;
    credit_score: number;
    existing_loans: number;
    employment_years: number;
    age: number;
    loan_amount: number;
  }, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      approval_probability: number;
      approval_status: string;
      risk_level: string;
      loan_score: number;
      emi: number;
      monthly_emi: number;
      recommendations: string[];
      issues: string[];
      comparison: Array<{ rate: string; tenure: string; emi: number; total_amount: number; interest: number }>;
    }>(`/api/loans/eligibility${qs}`, { method: "POST", body: JSON.stringify(data) });
  },
};

// ─── Dashboard ────────────────────────────────────────────────────────────────
export interface DashboardOverview {
  total_balance: number;
  accounts: Array<{ id: string; type: string; balance: number; currency: string }>;
  monthly_income: number;
  monthly_expenses: number;
  savings_rate: number;
  spending_by_category: Array<{ name: string; value: number }>;
  recent_transactions: Array<{
    id: string; merchant: string; category: string;
    amount: number; type: string; timestamp: string;
  }>;
  cash_flow: Array<{ month: string; income: number; expenses: number; savings: number }>;
  health_score: number;
  fraud_alert_count: number;
  ai_briefing: { summary?: string; briefing?: string; insights?: string[] };
}

export const dashboardApi = {
  overview: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<DashboardOverview>(`/api/dashboard/overview${qs}`);
  },
};

// ─── AI ───────────────────────────────────────────────────────────────────────
export interface HealthScore {
  overall_score: number;
  categories: Record<string, { score: number; max: number; label: string }>;
}

export interface ForecastResult {
  monthly_projections?: Array<{ month: number; balance: number; savings: number }>;
  scenarios?: { conservative: number; expected: number; optimistic: number };
}

export const aiApi = {
  healthScore: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<HealthScore>(`/api/ai/coaching/score${qs}`);
  },
  briefing: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ summary: string; insights: string[] }>(`/api/ai/coaching/briefing${qs}`);
  },
  behaviorInsights: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ insights: string[]; metrics: Record<string, number> }>(`/api/ai/behavior/insights${qs}`);
  },
  twinPredict: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<ForecastResult>(`/api/ai/twin/predict${qs}`);
  },
  twinFuture: (months = 12, userId?: string) => {
    const qs = new URLSearchParams({ months: String(months), ...(userId ? { user_id: userId } : {}) });
    return apiFetch<ForecastResult>(`/api/ai/twin/future?${qs}`);
  },
  twinScenarios: (months = 6, userId?: string) => {
    const qs = new URLSearchParams({ months: String(months), ...(userId ? { user_id: userId } : {}) });
    return apiFetch<{ scenarios: Record<string, number[]> }>(`/api/ai/twin/scenarios?${qs}`);
  },
  fraudAnalysis: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ alerts: Array<{ id: string; risk_score: number; details: string }> }>(`/api/ai/fraud/analysis${qs}`);
  },
  subscriptions: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ subscriptions: Array<{ merchant: string; amount: number; recommendation: string }> }>(`/api/ai/subscriptions/optimize${qs}`);
  },
  chat: (message: string, userId?: string, sessionId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ response: string; session_id: string }>(`/api/ai/chat${qs}`, {
      method: "POST",
      body: JSON.stringify({ message, session_id: sessionId }),
    });
  },
  chatSessions: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      sessions: Array<{
        id: string;
        title: string;
        created_at: string | null;
        updated_at: string | null;
        message_count: number;
        preview: string;
      }>;
      count: number;
    }>(`/api/ai/chat/sessions${qs}`);
  },
  createChatSession: (userId?: string, title = "New chat") => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      id: string;
      title: string;
      created_at: string | null;
      updated_at: string | null;
      message_count: number;
      preview: string;
    }>(`/api/ai/chat/sessions${qs}`, {
      method: "POST",
      body: JSON.stringify({ title }),
    });
  },
  deleteChatSession: (sessionId: string, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ ok: boolean }>(`/api/ai/chat/sessions/${sessionId}${qs}`, { method: "DELETE" });
  },
  chatHistory: (sessionId: string, userId?: string, limit = 100) => {
    const params = new URLSearchParams({ session_id: sessionId, limit: String(limit) });
    if (userId) params.set("user_id", userId);
    return apiFetch<{
      session_id: string;
      messages: Array<{ id: string; role: "user" | "assistant"; content: string; created_at: string | null }>;
      count: number;
    }>(`/api/ai/chat/history?${params}`);
  },
  clearChatHistory: (sessionId: string, userId?: string) => {
    const params = new URLSearchParams({ session_id: sessionId });
    if (userId) params.set("user_id", userId);
    return apiFetch<{ ok: boolean; message: string; session_id: string }>(
      `/api/ai/chat/history?${params}`,
      { method: "DELETE" }
    );
  },
  simulatePurchase: (amount: number, merchant: string, category: string, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<Record<string, unknown>>(`/api/ai/simulate/purchase${qs}`, {
      method: "POST",
      body: JSON.stringify({ amount, merchant, category }),
    });
  },

  // ── Coach Mode ──────────────────────────────────────────────────────────────
  weeklyCoaching: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      generated_at: string;
      week_start: string;
      week_end: string;
      health_score: number;
      week_spend: number;
      week_income: number;
      spend_delta_pct: number;
      top_categories: Array<{ name: string; amount: number }>;
      anomalies: string[];
      coaching_report: string;
      improvements: string[];
    }>(`/api/ai/coach/weekly${qs}`);
  },

  // ── Fraud Explanation ───────────────────────────────────────────────────────
  fraudExplain: (fraudLogId: string) =>
    apiFetch<{
      fraud_log_id: string;
      transaction_id: string;
      merchant: string;
      amount: number;
      timestamp: string;
      risk_score: number;
      raw_reasons: string[];
      ai_explanation: string;
      user_avg_amount: number;
      amount_vs_avg: number;
    }>(`/api/ai/fraud/explain/${fraudLogId}`),

  // ── Monthly Narrative ───────────────────────────────────────────────────────
  monthlyNarrative: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{
      month: string;
      generated_at: string;
      summary: {
        total_spend: number;
        total_income: number;
        spend_delta_pct: number;
        savings_balance: number;
        investment_value: number;
        investment_gain_pct: number;
        monthly_subscriptions: number;
      };
      category_changes: Array<{
        category: string;
        this_month: number;
        last_month: number;
        delta_pct: number;
      }>;
      narrative: string;
    }>(`/api/ai/narrative/monthly${qs}`);
  },
};

// ─── Notifications ────────────────────────────────────────────────────────────
export interface NotificationItem {
  id: string;
  title: string;
  message: string;
  type: "alert" | "insight" | "warning" | string;
  read: boolean;
  created_at: string;
}

export const notificationsApi = {
  list: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ notifications: NotificationItem[]; unread_count: number }>(`/api/notifications/${qs}`);
  },
  markRead: (id: string, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ success: boolean }>(`/api/notifications/${id}/read${qs}`, { method: "PATCH" });
  },
  markAllRead: (userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ success: boolean }>(`/api/notifications/read-all${qs}`, { method: "PATCH" });
  },
  dismiss: (id: string, userId?: string) => {
    const qs = userId ? `?user_id=${userId}` : "";
    return apiFetch<{ success: boolean }>(`/api/notifications/${id}${qs}`, { method: "DELETE" });
  },
};

// ─── Transactions ─────────────────────────────────────────────────────────────
export const transactionsApi = {
  list: (params: { page?: number; limit?: number; category?: string; type?: string; userId?: string } = {}) => {
    const qs = new URLSearchParams();
    if (params.page) qs.set("page", String(params.page));
    if (params.limit) qs.set("limit", String(params.limit));
    if (params.category) qs.set("category", params.category);
    if (params.type) qs.set("type", params.type);
    if (params.userId) qs.set("user_id", params.userId);
    return apiFetch<{
      transactions: Array<{ id: string; merchant: string; category: string; amount: number; type: string; timestamp: string }>;
      total: number; page: number; pages: number;
    }>(`/api/transactions/?${qs}`);
  },
};

// ─── Payments ─────────────────────────────────────────────────────────────────
export interface Payment {
  id: string;
  user_id: string;
  amount: number;
  currency: string;
  recipient_name: string;
  recipient_account: string;
  payment_type: string;
  status: "pending" | "completed" | "failed" | "flagged";
  risk_score: number;
  fraud_flag: boolean;
  created_at: string;
  transaction_reference: string | null;
  note: string | null;
  ai_insight: string | null;
}

export interface PaymentHistoryResponse {
  payments: Payment[];
  total: number;
  page: number;
  pages: number;
  stats: {
    total_sent: number;
    total_received: number;
    flagged_count: number;
  };
}

export const paymentsApi = {
  create: (data: {
    amount: number;
    currency?: string;
    recipient_name: string;
    recipient_account: string;
    payment_type?: string;
    note?: string;
  }) =>
    apiFetch<Payment>("/api/payments/create", {
      method: "POST",
      body: JSON.stringify(data),
    }),

  transfer: (data: { amount: number; to_account_type: string; note?: string }) =>
    apiFetch<Payment>("/api/payments/transfer", {
      method: "POST",
      body: JSON.stringify(data),
    }),

  history: (params: {
    page?: number;
    limit?: number;
    payment_type?: string;
    status?: string;
  } = {}) => {
    const qs = new URLSearchParams();
    if (params.page) qs.set("page", String(params.page));
    if (params.limit) qs.set("limit", String(params.limit));
    if (params.payment_type) qs.set("payment_type", params.payment_type);
    if (params.status) qs.set("status", params.status);
    return apiFetch<PaymentHistoryResponse>(`/api/payments/history?${qs}`);
  },

  get: (id: string) => apiFetch<Payment>(`/api/payments/${id}`),

  verify: (payment_id: string, confirm: boolean) =>
    apiFetch<{ message: string; payment: Payment }>("/api/payments/verify", {
      method: "POST",
      body: JSON.stringify({ payment_id, confirm }),
    }),

  cancel: (id: string) =>
    apiFetch<{ message: string }>(`/api/payments/${id}`, { method: "DELETE" }),
};

// ─── WebSocket factory ────────────────────────────────────────────────────────
export function createChatWebSocket(userId?: string): WebSocket {
  const wsBase = getWsBase();
  const qs = userId ? `?user_id=${userId}` : "";
  return new WebSocket(`${wsBase}/api/ai/chat/ws${qs}`);
}

// ─── Status ───────────────────────────────────────────────────────────────────
export const statusApi = {
  check: () => apiFetch<{ ai_backend: string; ai_available: boolean; db_type: string; cache_type: string }>("/api/status"),
};

// ─── Memory ───────────────────────────────────────────────────────────────────
export interface ChatHistoryMessage {
  id: string;
  session_id: string | null;
  role: "user" | "assistant";
  content: string;
  created_at: string;
}
export interface ChatSession {
  id: string;
  title: string;
  created_at: string;
  updated_at: string;
}

export const memoryApi = {
  history: (sessionId?: string) => {
    const qs = sessionId ? `?session_id=${sessionId}` : "";
    return apiFetch<{ messages: ChatHistoryMessage[]; sessions: ChatSession[]; total: number }>(`/api/memory/history${qs}`);
  },
  save: (data: { session_id?: string; role: string; content: string; session_title?: string }) =>
    apiFetch<ChatHistoryMessage>("/api/memory/save", { method: "POST", body: JSON.stringify(data) }),
  clear: (sessionId?: string) => {
    const qs = sessionId ? `?session_id=${sessionId}` : "";
    return apiFetch<{ deleted: number }>(`/api/memory/clear${qs}`, { method: "DELETE" });
  },
  getPreferences: () =>
    apiFetch<{ theme: string; language: string }>("/api/memory/preferences"),
  updatePreferences: (data: { theme?: string; language?: string }) =>
    apiFetch<{ theme: string; language: string }>("/api/memory/preferences", {
      method: "PATCH",
      body: JSON.stringify(data),
    }),
};

// ─── Documents ────────────────────────────────────────────────────────────────
export interface DocumentRecord {
  id: string;
  filename: string;
  file_type: string;
  file_size: number;
  summary: string | null;
  insights: string[];
  extracted_length: number;
  created_at: string;
}
export interface DocumentDetail extends DocumentRecord {
  messages: Array<{ id: string; role: string; content: string; language: string; created_at: string }>;
}

export const documentsApi = {
  upload: (file: File, language = "en") => {
    const form = new FormData();
    form.append("file", file);
    const token = tokenStore.getAccess();
    return fetch(`${API_BASE}/api/documents/upload?language=${language}`, {
      method: "POST",
      headers: token ? { Authorization: `Bearer ${token}` } : {},
      body: form,
    }).then(async (res) => {
      if (!res.ok) {
        const err = await res.json().catch(() => ({}));
        throw new ApiError(res.status, err.detail || `HTTP ${res.status}`);
      }
      return res.json() as Promise<DocumentRecord & { suspicious: string[]; extracted_length: number }>;
    });
  },
  history: () => apiFetch<{ documents: DocumentRecord[] }>("/api/documents/history"),
  get: (id: string) => apiFetch<DocumentDetail>(`/api/documents/${id}`),
  chat: (id: string, question: string, language = "en") =>
    apiFetch<{ question: string; answer: string; document_id: string; language: string }>(
      `/api/documents/chat/${id}`,
      { method: "POST", body: JSON.stringify({ question, language }) }
    ),
  analyze: (id: string, language = "en") =>
    apiFetch<{ id: string; summary: string; insights: string[]; suspicious: string[] }>(
      `/api/documents/analyze/${id}?language=${language}`,
      { method: "POST" }
    ),
  delete: (id: string) =>
    apiFetch<{ message: string }>(`/api/documents/${id}`, { method: "DELETE" }),
};