import React, { useCallback, useEffect, useRef, useState } from "react";
import {
    View, Text, TouchableOpacity,
    ActivityIndicator, LayoutAnimation, useColorScheme,
} from "react-native";
import { Ionicons } from "@expo/vector-icons";
import { Entry, entriesApi } from "@/services/api";
import ExpandableItem from "./ExpandableItem";

export interface CollapsibleCategoryProps {
    id: string;
    label: string;
    icon: keyof typeof Ionicons.glyphMap;
    color: string;
    darkColor: string;
    groupName: string;
    refreshKey?: number;
}

export default function CollapsibleCategory({
    label,
    icon,
    color,
    darkColor,
    groupName,
    refreshKey = 0,
}: CollapsibleCategoryProps) {
    const dark = useColorScheme() === "dark";
    const accentColor = dark ? darkColor : color;

    const [open, setOpen] = useState();
    const [items, setItems] = useState<Entry[]>([]);
    const [page, setPage] = useState(0);
    const [hasMore, setHasMore] = useState(true);
    const [loading, setLoading] = useState(false);
    const [error, setError] = useState("");

    // Stable fetch — won't re-create when loading changes
    const loadingRef = useRef(false);

    const fetchPage = useCallback(async (pageNum: number) => {
        if (loadingRef.current) return;
        loadingRef.current = true;
        setLoading(true);
        setError("");
        try {
            const data = await entriesApi.getEntries({ groupName, page: pageNum });
            setItems((prev) =>
                pageNum === 0 ? data.content : [...prev, ...data.content]
            );
            setHasMore(!data.last);
            setPage(pageNum);
        } catch {
            setError("Couldn't load entries. Tap to retry.");
        } finally {
            loadingRef.current = false;
            setLoading(false);
        }
    }, [groupName]);

    // Fetch page 0 on mount AND whenever refreshKey changes
    useEffect(() => {
        setItems([]);
        setPage(0);
        setHasMore(true);
        setError("");
        fetchPage(0);
    }, [refreshKey]); // refreshKey bump = full reset

    const toggle = () => {
        LayoutAnimation.configureNext({
            duration: 260,
            create: { type: "easeInEaseOut", property: "opacity" },
            update: { type: "spring", springDamping: 0.85 },
        });
        // @ts-ignore bla bla bla
        setOpen((v) => !v);
    };

    return (
        <View className="mb-4">
            {/* ── Header ── */}
            <TouchableOpacity
                onPress={toggle}
                activeOpacity={0.8}
                className={`mx-4 flex-row items-center px-4 py-3.5 rounded-2xl ${dark
                        ? "bg-obsidian-50 border border-border-dark"
                        : "bg-parchment-100 border border-border-light"
                    }`}
            >
                <View
                    className="w-8 h-8 rounded-xl items-center justify-center mr-3"
                    style={{ backgroundColor: accentColor + "25" }}
                >
                    <Ionicons name={icon} size={16} color={accentColor} />
                </View>

                <Text className={`flex-1 text-sm font-sans font-bold tracking-wide ${dark ? "text-ink-dark" : "text-ink-light"}`}>
                    {label}
                </Text>

                {/* Count badge — spinner while loading first page */}
                <View
                    className="px-2 py-0.5 rounded-full mr-3"
                    style={{ backgroundColor: accentColor + "20" }}
                >
                    {loading && items.length === 0 ? (
                        <ActivityIndicator size="small" color={accentColor} style={{ width: 24 }} />
                    ) : (
                        <Text className="text-xs font-sans font-semibold" style={{ color: accentColor }}>
                            {items.length}
                        </Text>
                    )}
                </View>

                <Ionicons
                    name={open ? "chevron-up" : "chevron-down"}
                    size={16}
                    color={dark ? "#706D67" : "#8A8278"}
                />
            </TouchableOpacity>

            {/* Body */}
            {open && (
                <View className="mt-2">
                    {/* Error with retry */}
                    {error !== "" && (
                        <TouchableOpacity
                            onPress={() => fetchPage(page)}
                            className="mx-4 py-4 items-center"
                        >
                            <Text className={`text-sm font-sans ${dark ? "text-muted-dark" : "text-muted-light"}`}>
                                {error}
                            </Text>
                        </TouchableOpacity>
                    )}

                    {items.map((item) => (
                        <ExpandableItem key={item.id} item={item} />
                    ))}

                    {/* Load more */}
                    {hasMore && items.length > 0 && (
                        <TouchableOpacity
                            onPress={() => fetchPage(page + 1)}
                            disabled={loading}
                            className={`mx-4 mt-1 mb-1 py-3 rounded-2xl border items-center ${dark
                                    ? "bg-obsidian-50 border-border-dark"
                                    : "bg-parchment-100 border-border-light"
                                }`}
                            activeOpacity={0.7}
                        >
                            {loading ? (
                                <ActivityIndicator size="small" color={accentColor} />
                            ) : (
                                <View className="flex-row items-center gap-1.5">
                                    <Ionicons name="chevron-down" size={13} color={accentColor} />
                                    <Text className="text-xs font-sans font-semibold" style={{ color: accentColor }}>
                                        Load more
                                    </Text>
                                </View>
                            )}
                        </TouchableOpacity>
                    )}

                    {!hasMore && items.length > 0 && (
                        <Text className={`text-center text-xs font-sans py-3 ${dark ? "text-muted-dark" : "text-muted-light"}`}>
                            All {items.length} entries loaded
                        </Text>
                    )}
                </View>
            )}
        </View>
    );
}