import AsyncStorage from "@react-native-async-storage/async-storage";
import { create } from "zustand";
import { createJSONStorage, persist } from "zustand/middleware";
import { DEMO_USER } from "@/lib/data/seed";

export type AuthProvider =
  | "google"
  | "email"
  | "phone"
  | "telegram"
  | "guest";

export type AuthUser = {
  id: string;
  name: string;
  phone: string;
  email?: string;
  points: number;
  tier: "bronze" | "silver" | "gold";
  isGuest: boolean;
  biometricEnabled: boolean;
  avatarUri?: string | null;
  referralCode?: string;
  activeVoucher?: string | null;
  /** How the user signed in (demo providers included). */
  authProvider?: AuthProvider;
};

export type PointsEntry = {
  id: string;
  at: string;
  label: string;
  delta: number;
  balance: number;
};

type AuthState = {
  user: AuthUser | null;
  hasOnboarded: boolean;
  ledger: PointsEntry[];
  setHasOnboarded: (v: boolean) => void;
  signIn: (
    payload: Partial<AuthUser> & {
      phone: string;
      name: string;
      authProvider?: AuthProvider;
    }
  ) => void;
  signOut: () => void;
  setBiometric: (enabled: boolean) => void;
  setAvatar: (uri: string | null) => void;
  updateProfile: (
    patch: Partial<Pick<AuthUser, "name" | "email" | "phone">>
  ) => void;
  addPoints: (pts: number, label?: string) => void;
  redeemPoints: (pts: number) => boolean;
  setActiveVoucher: (code: string | null) => void;
  ensureDemoUser: () => void;
};

function tierFor(points: number): AuthUser["tier"] {
  if (points >= 1000) return "gold";
  if (points >= 300) return "silver";
  return "bronze";
}

const seedLedger: PointsEntry[] = [
  {
    id: "pts_1",
    at: new Date(Date.now() - 1000 * 60 * 60 * 24 * 20).toISOString(),
    label: "Welcome bonus",
    delta: 50,
    balance: 50,
  },
  {
    id: "pts_2",
    at: new Date(Date.now() - 1000 * 60 * 60 * 24 * 12).toISOString(),
    label: "Order reward",
    delta: 28,
    balance: 78,
  },
  {
    id: "pts_3",
    at: new Date(Date.now() - 1000 * 60 * 60 * 24 * 5).toISOString(),
    label: "Referral bonus",
    delta: 100,
    balance: 178,
  },
  {
    id: "pts_4",
    at: new Date(Date.now() - 1000 * 60 * 60 * 24 * 2).toISOString(),
    label: "Order reward",
    delta: 242,
    balance: 420,
  },
];

export const useAuthStore = create<AuthState>()(
  persist(
    (set, get) => ({
      user: {
        ...DEMO_USER,
        email: DEMO_USER.email,
        referralCode: "GISHEN-KIRU",
        activeVoucher: null,
      },
      hasOnboarded: true,
      ledger: seedLedger,
      setHasOnboarded: (v) => set({ hasOnboarded: v }),
      signIn: ({ phone, name, email, isGuest, avatarUri, authProvider }) =>
        set({
          user: {
            id: `u_${Date.now()}`,
            name,
            phone,
            email,
            points: isGuest ? 0 : 50,
            tier: "bronze",
            isGuest: !!isGuest,
            biometricEnabled: false,
            avatarUri: avatarUri ?? null,
            referralCode: `GISHEN-${name.slice(0, 4).toUpperCase() || "USER"}`,
            activeVoucher: null,
            authProvider:
              authProvider ?? (isGuest ? "guest" : "phone"),
          },
          hasOnboarded: true,
          ledger: isGuest
            ? []
            : [
                {
                  id: `pts_${Date.now()}`,
                  at: new Date().toISOString(),
                  label: "Welcome bonus",
                  delta: 50,
                  balance: 50,
                },
              ],
        }),
      signOut: () => set({ user: null }),
      setBiometric: (enabled) => {
        const user = get().user;
        if (!user) return;
        set({ user: { ...user, biometricEnabled: enabled } });
      },
      setAvatar: (uri) => {
        const user = get().user;
        if (!user) return;
        set({ user: { ...user, avatarUri: uri } });
      },
      updateProfile: (patch) => {
        const user = get().user;
        if (!user) return;
        set({ user: { ...user, ...patch } });
      },
      addPoints: (pts, label = "Order reward") => {
        const user = get().user;
        if (!user || user.isGuest || pts === 0) return;
        const points = user.points + pts;
        const entry: PointsEntry = {
          id: `pts_${Date.now()}`,
          at: new Date().toISOString(),
          label,
          delta: pts,
          balance: points,
        };
        set({
          user: { ...user, points, tier: tierFor(points) },
          ledger: [entry, ...get().ledger],
        });
      },
      redeemPoints: (pts) => {
        const user = get().user;
        if (!user || user.isGuest || user.points < pts) return false;
        const points = user.points - pts;
        const entry: PointsEntry = {
          id: `pts_${Date.now()}`,
          at: new Date().toISOString(),
          label: `Redeemed for voucher`,
          delta: -pts,
          balance: points,
        };
        set({
          user: {
            ...user,
            points,
            tier: tierFor(points),
            activeVoucher: "GISHEN10",
          },
          ledger: [entry, ...get().ledger],
        });
        return true;
      },
      setActiveVoucher: (code) => {
        const user = get().user;
        if (!user) return;
        set({ user: { ...user, activeVoucher: code } });
      },
      ensureDemoUser: () => {
        if (!get().user) {
          set({
            user: {
              ...DEMO_USER,
              referralCode: "GISHEN-KIRU",
              activeVoucher: null,
            },
            hasOnboarded: true,
            ledger: seedLedger,
          });
        }
      },
    }),
    {
      name: "gishen-auth",
      storage: createJSONStorage(() => AsyncStorage),
      version: 4,
      migrate: (persisted: unknown) => {
        const state = (persisted ?? {}) as Partial<AuthState>;
        if (!state.user) {
          return {
            ...state,
            user: {
              ...DEMO_USER,
              referralCode: "GISHEN-KIRU",
              activeVoucher: null,
              authProvider: "phone" as const,
            },
            hasOnboarded: true,
            ledger: seedLedger,
          };
        }
        return {
          ...state,
          user: {
            ...DEMO_USER,
            ...state.user,
            avatarUri: state.user.avatarUri ?? null,
            referralCode: state.user.referralCode ?? "GISHEN-KIRU",
            activeVoucher: state.user.activeVoucher ?? null,
            authProvider:
              state.user.authProvider ??
              (state.user.isGuest ? ("guest" as const) : ("phone" as const)),
          },
          ledger: state.ledger?.length ? state.ledger : seedLedger,
        };
      },
    }
  )
);