import { useState, useEffect } from "react";
import {
    View,
    Text,
    StyleSheet,
    ScrollView,
    TouchableOpacity,
    ActivityIndicator,
    RefreshControl,
    Alert,
} from "react-native";
import { useAuth } from "@clerk/clerk-expo";
import { Ionicons } from "@expo/vector-icons";
import { API_BASE_URL, API_ENDPOINTS } from "../../config/api";

interface Recommendation {
    id: string;
    userId: string;
    type: "short_term" | "medium_term" | "long_term";
    content: string;
    status: "pending" | "completed";
    createdAt: string;
}

export default function GoalsScreen() {
    const { userId, getToken } = useAuth();
    const [recommendations, setRecommendations] = useState<Recommendation[]>([]);
    const [loading, setLoading] = useState(true);
    const [refreshing, setRefreshing] = useState(false);

    const fetchRecommendations = async () => {
        if (!userId) return;
        try {
            const token = await getToken();
            const response = await fetch(
                `${API_BASE_URL}${API_ENDPOINTS.RECOMMENDATIONS}?userId=${userId}`,
                {
                    headers: {
                        Authorization: `Bearer ${token}`,
                    },
                }
            );

            if (response.ok) {
                const data = await response.json();
                setRecommendations(data);
            } else {
                console.error("Failed to fetch recommendations");
            }
        } catch (error) {
            console.error("Error fetching recommendations:", error);
        } finally {
            setLoading(false);
            setRefreshing(false);
        }
    };

    useEffect(() => {
        fetchRecommendations();
    }, [userId]);

    const onRefresh = () => {
        setRefreshing(true);
        fetchRecommendations();
    };

    const toggleStatus = async (id: string, currentStatus: string) => {
        const newStatus = currentStatus === "pending" ? "completed" : "pending";

        // Optimistic update
        setRecommendations(prev =>
            prev.map(r => r.id === id ? { ...r, status: newStatus } : r)
        );

        try {
            const token = await getToken();
            const response = await fetch(`${API_BASE_URL}${API_ENDPOINTS.RECOMMENDATIONS}`, {
                method: "PUT",
                headers: {
                    "Content-Type": "application/json",
                    Authorization: `Bearer ${token}`,
                },
                body: JSON.stringify({
                    id,
                    status: newStatus,
                }),
            });

            if (!response.ok) {
                // Revert on failure
                setRecommendations(prev =>
                    prev.map(r => r.id === id ? { ...r, status: currentStatus as "pending" | "completed" } : r)
                );
                Alert.alert("Error", "Failed to update status");
            }
        } catch (error) {
            console.error(error);
            // Revert on error
            setRecommendations(prev =>
                prev.map(r => r.id === id ? { ...r, status: currentStatus as "pending" | "completed" } : r)
            );
            Alert.alert("Error", "Failed to update status");
        }
    };

    const renderSection = (
        title: string,
        type: "short_term" | "medium_term" | "long_term"
    ) => {
        const items = recommendations.filter((r) => r.type === type);

        return (
            <View style={styles.section}>
                <Text style={styles.sectionTitle}>{title}</Text>
                {items.length === 0 ? (
                    <Text style={styles.emptyText}>No goals set yet.</Text>
                ) : (
                    items.map((rec) => (
                        <TouchableOpacity
                            key={rec.id}
                            style={[
                                styles.card,
                                rec.status === "completed" && styles.cardCompleted,
                            ]}
                            onPress={() => toggleStatus(rec.id, rec.status)}
                        >
                            <View style={styles.checkbox}>
                                {rec.status === "completed" && (
                                    <Ionicons name="checkmark" size={16} color="#fff" />
                                )}
                            </View>
                            <View style={styles.cardContent}>
                                <Text
                                    style={[
                                        styles.cardText,
                                        rec.status === "completed" && styles.cardTextCompleted,
                                    ]}
                                >
                                    {rec.content}
                                </Text>
                                <Text style={styles.dateText}>
                                    {new Date(rec.createdAt).toLocaleDateString()}
                                </Text>
                            </View>
                        </TouchableOpacity>
                    ))
                )}
            </View>
        );
    };

    if (loading && !refreshing) {
        return (
            <View style={styles.center}>
                <ActivityIndicator size="large" color="#2563eb" />
            </View>
        );
    }

    return (
        <ScrollView
            style={styles.container}
            refreshControl={
                <RefreshControl refreshing={refreshing} onRefresh={onRefresh} />
            }
        >
            <View style={styles.header}>
                <Text style={styles.headerTitle}>My Goals</Text>
                <Text style={styles.headerSubtitle}>
                    Track your fitness journey progress
                </Text>
            </View>

            {renderSection("Short Term Goals", "short_term")}
            {renderSection("Medium Term Goals", "medium_term")}
            {renderSection("Long Term Goals", "long_term")}

            <View style={styles.footer} />
        </ScrollView>
    );
}

const styles = StyleSheet.create({
    container: {
        flex: 1,
        backgroundColor: "#f3f4f6",
    },
    center: {
        flex: 1,
        justifyContent: "center",
        alignItems: "center",
    },
    header: {
        padding: 20,
        backgroundColor: "#fff",
        marginBottom: 10,
    },
    headerTitle: {
        fontSize: 28,
        fontWeight: "bold",
        color: "#111827",
    },
    headerSubtitle: {
        fontSize: 16,
        color: "#6b7280",
        marginTop: 4,
    },
    section: {
        padding: 20,
        paddingTop: 10,
    },
    sectionTitle: {
        fontSize: 18,
        fontWeight: "600",
        color: "#374151",
        marginBottom: 12,
    },
    emptyText: {
        fontStyle: "italic",
        color: "#9ca3af",
    },
    card: {
        backgroundColor: "#fff",
        padding: 16,
        borderRadius: 12,
        marginBottom: 12,
        flexDirection: "row",
        alignItems: "flex-start",
        shadowColor: "#000",
        shadowOffset: { width: 0, height: 1 },
        shadowOpacity: 0.05,
        shadowRadius: 2,
        elevation: 2,
    },
    cardCompleted: {
        backgroundColor: "#f0fdf4", // light green
        borderColor: "#bbf7d0",
        borderWidth: 1,
    },
    checkbox: {
        width: 24,
        height: 24,
        borderRadius: 6,
        borderWidth: 2,
        borderColor: "#d1d5db",
        marginRight: 12,
        marginTop: 2,
        justifyContent: "center",
        alignItems: "center",
        backgroundColor: "#fff",
    },
    cardContent: {
        flex: 1,
    },
    cardText: {
        fontSize: 16,
        color: "#1f2937",
        lineHeight: 24,
    },
    cardTextCompleted: {
        textDecorationLine: "line-through",
        color: "#9ca3af",
    },
    dateText: {
        fontSize: 12,
        color: "#9ca3af",
        marginTop: 4,
    },
    footer: {
        height: 40,
    },
});