import React, { useState, useEffect, useCallback, useRef } from "react";
import { View, ActivityIndicator, Pressable } from "react-native";
import { useSirouRouter } from "@sirou/react-native";
import { useLocalSearchParams, Stack } from "expo-router";
import { AppRoutes } from "@/lib/routes";
import { Text } from "@/components/ui/text";
import { ScreenWrapper } from "@/components/ScreenWrapper";
import { Keypad } from "@/components/Keypad";
import { ArrowLeft } from "@/lib/icons";
import { api } from "@/lib/api";
import { usePinStore } from "@/lib/pin-store";
import { toast } from "@/lib/toast-store";
import { useColorScheme } from "nativewind";

type Step = "otp" | "pin" | "confirm";

export default function ForgotPinVerifyScreen() {
  const nav = useSirouRouter<AppRoutes>();
  const { phone, verificationId } = useLocalSearchParams<{
    phone: string;
    verificationId: string;
  }>();
  const { colorScheme } = useColorScheme();
  const isDark = colorScheme === "dark";
  const setHasPin = usePinStore((s) => s.setHasPin);
  const unlock = usePinStore((s) => s.unlock);
  const mounted = useRef(true);

  useEffect(() => {
    return () => { mounted.current = false; };
  }, []);

  const [step, setStep] = useState<Step>("otp");
  const [otp, setOtp] = useState("");
  const [pin, setPin] = useState("");
  const [confirmPin, setConfirmPin] = useState("");
  const [loading, setLoading] = useState(false);

  const currentValue = step === "otp" ? otp : step === "pin" ? pin : confirmPin;
  const setCurrentValue = step === "otp" ? setOtp : step === "pin" ? setPin : setConfirmPin;
  const arr = currentValue.split("");

  useEffect(() => {
    if (currentValue.length === 6 && !loading) {
      if (step === "otp") {
        handleVerifyOtp();
      } else if (step === "pin") {
        setStep("confirm");
        setConfirmPin("");
      } else {
        handleSetPin();
      }
    }
  }, [currentValue]);

  const handleVerifyOtp = async () => {
    setLoading(true);
    try {
      await api.auth.forgetPinVerify({
        body: { phone: phone as string, code: otp, verificationId },
      });
      if (mounted.current) setLoading(false);
      setStep("pin");
      setPin("");
    } catch (err: any) {
      if (mounted.current) setLoading(false);
      setOtp("");
      toast.error("Invalid Code", err.message || "Verification code is invalid or expired");
    }
  };

  const handleSetPin = async () => {
    if (confirmPin !== pin) {
      toast.error("Mismatch", "PINs do not match");
      setStep("pin");
      setPin("");
      setConfirmPin("");
      return;
    }

    setLoading(true);
    try {
      await api.auth.setPin({ body: { pin } });
      setHasPin(true);
      unlock();
      toast.success("PIN Reset", "Your PIN has been updated");
      nav.go("(tabs)");
    } catch (err: any) {
      if (mounted.current) setLoading(false);
      toast.error("Failed", err.message || "Could not set PIN");
    }
  };

  const handlePress = useCallback((key: string) => {
    setCurrentValue((prev: string) => (prev + key).slice(0, 6));
  }, [step]);

  const handleDelete = useCallback(() => {
    setCurrentValue((prev: string) => prev.slice(0, -1));
  }, [step]);

  const getTitle = () => {
    switch (step) {
      case "otp": return "Verify Code";
      case "pin": return "New PIN";
      case "confirm": return "Confirm PIN";
    }
  };

  const getSubtitle = () => {
    switch (step) {
      case "otp": return "Enter the 6-digit code sent to your phone";
      case "pin": return "Create a new 6-digit PIN";
      case "confirm": return "Enter the new PIN again";
    }
  };

  return (
    <ScreenWrapper className="bg-background" withSafeArea={false}>
      <Stack.Screen options={{ headerShown: false }} />

      <View className="flex-row items-center px-5 pt-12 pb-2">
        <Pressable
          onPress={() => {
            if (step === "pin") { setStep("otp"); setOtp(""); }
            else if (step === "confirm") { setStep("pin"); setPin(""); setConfirmPin(""); }
            else nav.back();
          }}
          className="h-10 w-10 rounded-lg items-center justify-center"
        >
          <ArrowLeft size={22} color={isDark ? "#f1f5f9" : "#251615"} />
        </Pressable>
        <View className="flex-1 items-center pr-10">
          <Text variant="small" className="text-muted-foreground">
            {step === "otp" ? "Step 1 of 3" : step === "pin" ? "Step 2 of 3" : "Step 3 of 3"}
          </Text>
        </View>
      </View>

      <View className="flex-1 items-center px-4">
        <Text variant="h4" className="font-sans-bold text-foreground text-center mb-1 mt-12">
          {getTitle()}
        </Text>
        <Text variant="muted" className="text-center mb-8 leading-5">
          {getSubtitle()}
        </Text>

        <View className="flex-row justify-center gap-3 mb-6">
          {[0, 1, 2, 3, 4, 5].map((i) => (
            <View
              key={i}
              className={`w-[52px] h-[52px] rounded-xl items-center justify-center border ${
                arr[i] ? "border-primary bg-primary/10" : "border-border bg-card"
              }`}
            >
              {step === "otp" ? (
                <Text className={`text-xl font-sans-bold ${arr[i] ? "text-primary" : "text-foreground"}`}>
                  {arr[i] ?? ""}
                </Text>
              ) : (
                <View className={`w-[10px] h-[10px] rounded-full ${arr[i] ? "bg-primary" : "bg-border"}`} />
              )}
            </View>
          ))}
        </View>

        {loading && <ActivityIndicator color="#E46212" size="small" />}
      </View>

      <Keypad onPress={handlePress} onDelete={handleDelete} disabled={loading} />
    </ScreenWrapper>
  );
}