import { useState, type ReactNode } from "react";
import {
  Text,
  TextInput,
  TouchableOpacity,
  Alert,
  ActivityIndicator,
  KeyboardAvoidingView,
  Platform,
  ScrollView,
} from "react-native";
import { useAuth } from "../context/AuthContext";
import { isStrongPassword } from "@cloud-reader/shared";
import { authStyles } from "./authStyles";
import { AuthFormError } from "./AuthFormError";
import { requireValidEmail } from "./authValidation";

export default function RegisterScreen({
  navigation,
}: {
  navigation: any;
}): ReactNode {
  const { register } = useAuth();
  const [username, setUsername] = useState("");
  const [email, setEmail] = useState("");
  const [password, setPassword] = useState("");
  const [confirmPassword, setConfirmPassword] = useState("");
  const [error, setError] = useState<string | null>(null);
  const [submitting, setSubmitting] = useState(false);

  const handleRegister = async () => {
    setError(null);

    if (!username.trim()) {
      Alert.alert("Validation Error", "Please enter a username.");
      return;
    }
    if (!requireValidEmail(email)) {
      return;
    }
    if (!isStrongPassword(password)) {
      Alert.alert(
        "Validation Error",
        "Password must be at least 8 characters and include uppercase, lowercase, and a number.",
      );
      return;
    }
    if (password !== confirmPassword) {
      Alert.alert("Validation Error", "Passwords do not match.");
      return;
    }

    setSubmitting(true);
    try {
      await register(email.trim(), username.trim(), password);
    } catch {
      setError("Could not create the account. Try a different email.");
    } finally {
      setSubmitting(false);
    }
  };

  return (
    <KeyboardAvoidingView
      style={authStyles.container}
      behavior={Platform.OS === "ios" ? "padding" : "height"}
    >
      <ScrollView contentContainerStyle={authStyles.innerScroll}>
        <Text style={authStyles.titleCompact}>Create Account</Text>
        <Text style={authStyles.subtitle}>Join Cloud Reader</Text>

        {error ? <AuthFormError message={error} /> : null}

        <TextInput
          style={authStyles.input}
          placeholder="Username"
          placeholderTextColor="#666"
          value={username}
          onChangeText={setUsername}
          autoCapitalize="none"
          autoCorrect={false}
        />

        <TextInput
          style={authStyles.input}
          placeholder="Email"
          placeholderTextColor="#666"
          value={email}
          onChangeText={setEmail}
          keyboardType="email-address"
          autoCapitalize="none"
          autoCorrect={false}
        />

        <TextInput
          style={authStyles.input}
          placeholder="Password"
          placeholderTextColor="#666"
          value={password}
          onChangeText={setPassword}
          secureTextEntry
        />

        <TextInput
          style={authStyles.input}
          placeholder="Confirm Password"
          placeholderTextColor="#666"
          value={confirmPassword}
          onChangeText={setConfirmPassword}
          secureTextEntry
        />

        <TouchableOpacity
          style={[authStyles.button, submitting && authStyles.buttonDisabled]}
          onPress={handleRegister}
          disabled={submitting}
        >
          {submitting ? (
            <ActivityIndicator color="#fff" />
          ) : (
            <Text style={authStyles.buttonText}>Create Account</Text>
          )}
        </TouchableOpacity>

        <TouchableOpacity onPress={() => navigation.goBack()}>
          <Text style={authStyles.linkText}>
            Already have an account?{" "}
            <Text style={authStyles.linkBold}>Sign In</Text>
          </Text>
        </TouchableOpacity>
      </ScrollView>
    </KeyboardAvoidingView>
  );
}