import { create } from "zustand";
import { supabase } from "../lib/supabase";
import type { Match } from "@/types";
import { useAuthStore } from "./authStore";

const BATCH_SIZE = 20;

interface MatchState {
    matches: Match[];
    newMatchesCount: number;
    totalCount: number | null;
    isLoading: boolean;
    isLoadingMore: boolean;
    page: number;
    hasMore: boolean;
    error: string | null;
    fetchMatches: (refresh?: boolean) => Promise<void>;
    markAsSeen: (matchId: string) => Promise<void>;
    markAllAsSeen: () => Promise<void>;
    addMatch: (match: Match) => void;
    updateMatchUnreadCount: (matchId: string, delta: number) => void;
    clearMatches: () => void;
}

export const useMatchStore = create<MatchState>((set, get) => ({
    matches: [],
    newMatchesCount: 0,
    totalCount: null,
    isLoading: false,
    isLoadingMore: false,
    page: 0,
    hasMore: true,
    error: null,

    fetchMatches: async (refresh = false) => {
        const userId = useAuthStore.getState().user?.id;
        const coupleId = useAuthStore.getState().user?.couple_id;

        // Early return if no couple - user isn't paired yet
        if (!coupleId) {
            set({ matches: [], newMatchesCount: 0, totalCount: 0, isLoading: false });
            return;
        }

        const state = get();
        if (state.isLoading || (state.isLoadingMore && !refresh)) return;

        if (refresh) {
            set({ isLoading: true, error: null, page: 0, hasMore: true });
        } else {
            if (!state.hasMore) return;
            set({ isLoadingMore: true });
        }

        try {
            const currentPage = refresh ? 0 : state.page;
            const from = currentPage * BATCH_SIZE;
            const to = from + BATCH_SIZE - 1;

            // Fetch total count on refresh
            let totalCount = state.totalCount;
            if (refresh) {
                const { count, error: countError } = await supabase
                    .from("matches")
                    .select("*", { count: "exact", head: true })
                    .eq("couple_id", coupleId);

                if (!countError) {
                    totalCount = count ?? 0;
                }
            }

            const { data: matches, error: matchError } = await supabase
                .from("matches")
                .select(`
            *,
            question:questions(*)
          `)
                .eq("couple_id", coupleId)
                .order("created_at", { ascending: false })
                .range(from, to);

            if (matchError) throw matchError;
            if (!matches || matches.length === 0) {
                 if (refresh) {
                    set({ matches: [], newMatchesCount: 0, totalCount: totalCount ?? 0, isLoading: false, hasMore: false });
                } else {
                    set({ isLoadingMore: false, hasMore: false });
                }
                return;
            }

            // Fetch all responses for these questions to determine who answered first
            const questionIds = matches.map(m => m.question_id);
            let responses: any[] = [];
            if (questionIds.length > 0) {
                const { data } = await supabase
                    .from("responses")
                    .select("*")
                    .in("question_id", questionIds);
                responses = data ?? [];
            }

            // Fetch unread message counts per match
            const matchIds = matches.map(m => m.id);
            let unreadCounts: Record<string, number> = {};

            if (userId && matchIds.length > 0) {
                const { data: unreadMessages, error } = await supabase
                    .from("messages")
                    .select("match_id")
                    .in("match_id", matchIds)
                    .neq("user_id", userId)
                    .is("read_at", null);

                if (error) {
                    console.error("Error fetching unread messages:", error);
                }

                // Count unread messages per match
                unreadMessages?.forEach(msg => {
                    unreadCounts[msg.match_id] = (unreadCounts[msg.match_id] || 0) + 1;
                });
            }

            const data = matches.map(match => ({
                ...match,
                responses: responses.filter(r => r.question_id === match.question_id),
                unreadCount: unreadCounts[match.id] || 0
            }));

            // Sort: unread messages first, then by most recent
            // Note: Since we fetch by created_at desc, and then sort by unread in memory,
            // pagination might be slightly inconsistent if unread messages are scattered.
            // However, implementing complex sort in Supabase with computed columns is harder.
            // For now, we accept that the sort is applied within the fetched batch.
            const sortedData = data.sort((a, b) => {
                // First priority: matches with unread messages
                if (a.unreadCount > 0 && b.unreadCount === 0) return -1;
                if (a.unreadCount === 0 && b.unreadCount > 0) return 1;

                // Second priority: most recent first
                return new Date(b.created_at).getTime() - new Date(a.created_at).getTime();
            });

            // Calculate new matches count - this is tricky with pagination
            // Ideally we should have a separate query for count, but we'll just count in current batch
            const newMatchesInBatch = sortedData.filter((m) => m.is_new).length;
            
            set((state) => ({
                matches: refresh ? sortedData : [...state.matches, ...sortedData],
                newMatchesCount: refresh ? newMatchesInBatch : state.newMatchesCount + newMatchesInBatch,
                totalCount: refresh ? totalCount : state.totalCount,
                isLoading: false,
                isLoadingMore: false,
                page: currentPage + 1,
                hasMore: matches.length === BATCH_SIZE
            }));
        } catch (err) {
            console.error("Error fetching matches:", err);
            set({ error: "Failed to load matches", isLoading: false, isLoadingMore: false });
        }
    },

    markAsSeen: async (matchId) => {
        await supabase
            .from("matches")
            .update({ is_new: false })
            .eq("id", matchId);

        const matches = get().matches.map((m) =>
            m.id === matchId ? { ...m, is_new: false } : m
        );
        const newCount = matches.filter((m) => m.is_new).length;
        set({ matches, newMatchesCount: newCount });
    },

    markAllAsSeen: async () => {
        const newMatches = get().matches.filter((m) => m.is_new);
        if (newMatches.length === 0) return;

        const newMatchIds = newMatches.map((m) => m.id);
        await supabase
            .from("matches")
            .update({ is_new: false })
            .in("id", newMatchIds);

        const matches = get().matches.map((m) =>
            m.is_new ? { ...m, is_new: false } : m
        );
        set({ matches, newMatchesCount: 0 });
    },

    addMatch: (match) => {
        set((state) => ({
            matches: [match, ...state.matches],
            newMatchesCount: state.newMatchesCount + 1,
            totalCount: (state.totalCount ?? 0) + 1,
        }));
    },

    updateMatchUnreadCount: (matchId, delta) => {
        set((state) => ({
            matches: state.matches.map((m) =>
                m.id === matchId
                    ? { ...m, unreadCount: Math.max(0, (m.unreadCount || 0) + delta) }
                    : m
            ),
        }));
    },

clearMatches: () => {
        set({ matches: [], newMatchesCount: 0, totalCount: null, isLoading: false, error: null, page: 0, hasMore: true, isLoadingMore: false });
    },
}));