import { useState, useEffect, useRef } from 'react';
import type { DragEvent } from 'react';
import { useGetStickies, useClusterStickies } from '../api/api';
import type { Sticky as StickyType, RankedCluster } from '../types/types';
import Sticky from './sticky';
import Button from './button';
import '../styles/stickies.css';

// In practice, silhouette on cosine distance between text embeddings occupies roughly
// [-0.05, 0.10], not strict theoretical [-1, 1]: near-orthogonal vectors put both the within- and
// nearest-cluster distances close to 0.8, and the coefficient divides their gap
// by the larger. These bands are calibrated to that range for voyage-3. see README, Reading the cohesion score
const scoreLabel = (score: number): string => {
    if (score >= 0.07) return 'Strong';
    if (score >= 0.04) return 'Moderate';
    if (score >= 0.01) return 'Weak';
    return 'Poor';
};

const Stickies = () => {
    const { data: stickies, isLoading, error } = useGetStickies();
    const { mutate: cluster, data: clusterResponse, isPending } = useClusterStickies();

    const [rankedClusters, setRankedClusters] = useState<RankedCluster[]>([]);
    const dragIndex = useRef<number | null>(null);
    const [dragOverIndex, setDragOverIndex] = useState<number | null>(null);

    useEffect(() => {
        if (clusterResponse?.clusters) {
            setRankedClusters(
                clusterResponse.clusters.map((c, i) => ({ ...c, rank: i + 1 }))
            );
        }
    }, [clusterResponse]);

    if (isLoading) return <div>Loading...</div>;
    if (error) return <div>Error: {error.message}</div>;

    const score = clusterResponse?.score;

    const handleCluster = () => {
        cluster();
    };

    const buildStickyMap = (): Map<string, StickyType> => {
        const map = new Map<string, StickyType>();
        stickies?.forEach((s) => map.set(s.id, s));
        return map;
    };

    const stickyMap = buildStickyMap();

    const renderStickies = (items: StickyType[]) =>
        items?.map((sticky) => <Sticky key={sticky.id} sticky={sticky} />);

    const handleDragStart = (index: number) => {
        dragIndex.current = index;
    };

    const handleDragOver = (e: DragEvent, index: number) => {
        e.preventDefault();
        setDragOverIndex(index);
    };

    const handleDragLeave = () => {
        setDragOverIndex(null);
    };

    const handleDrop = (targetIndex: number) => {
        const sourceIndex = dragIndex.current;
        if (sourceIndex === null || sourceIndex === targetIndex) {
            dragIndex.current = null;
            setDragOverIndex(null);
            return;
        }

        const reordered = [...rankedClusters];
        const [moved] = reordered.splice(sourceIndex, 1);
        reordered.splice(targetIndex, 0, moved);

        setRankedClusters(reordered.map((c, i) => ({ ...c, rank: i + 1 })));
        dragIndex.current = null;
        setDragOverIndex(null);
    };

    const handleDragEnd = () => {
        dragIndex.current = null;
        setDragOverIndex(null);
    };
    console.log(score?.toFixed(2))
    return (
        <div className="stickies-container">
            <Button onClick={handleCluster} isLoading={isPending} label="Group Stickies By Topic" />
            {rankedClusters.length > 0 ? (
                <div className="clusters-container">
                    {score != null && (
                        <div className="cohesion-score">
                            Cluster cohesion: <strong>{scoreLabel(score)}</strong>
                        </div>
                    )}
                    {rankedClusters.map((group, index) => (
                        <div
                            key={group.label}
                            className={`cluster-group cluster-draggable${dragOverIndex === index ? ' cluster-drag-over' : ''}`}
                            draggable
                            onDragStart={() => handleDragStart(index)}
                            onDragOver={(e) => handleDragOver(e, index)}
                            onDragLeave={handleDragLeave}
                            onDrop={() => handleDrop(index)}
                            onDragEnd={handleDragEnd}
                        >
                            <div className="cluster-header">
                                <span className="cluster-rank" aria-label={`Priority ${group.rank}`}>
                                    {group.rank}
                                </span>
                                {group.rank === 1 && (
                                    <span className="cluster-reorder-hint">Drag and drop to reorganize cluster priority</span>
                                )}
                                <h3 className="cluster-label">{group.label}</h3>
                                <span className="cluster-drag-handle" aria-hidden="true">⠿</span>
                            </div>
                            <div className="stickies-grid">
                                {renderStickies(
                                    group?.noteIds
                                        .map((id) => stickyMap?.get(id))
                                        .filter((s): s is StickyType => !!s)
                                )}
                            </div>
                        </div>
                    ))}
                </div>
            ) : (
                <div className="stickies-grid">
                    {renderStickies(stickies ?? [])}
                </div>
            )}
        </div>
    );
};

export default Stickies;