'use client';

import {
    createContext,
    useContext,
    useState,
    useEffect,
    useCallback,
    ReactNode,
} from 'react';
import { datasetLoader, FilterOptions, LoadExamplesResult } from './loader';
import type { DatasetExample, CodingProblem } from '@/types';

type Split = 'train' | 'validation' | 'test';

interface DatasetContextValue {
    isLoading: boolean;
    loadedSplits: Set<Split>;
    splitCounts: Record<string, number>;
    loadSplit: (split: Split) => Promise<void>;
    filterExamples: (
        split: Split,
        filters: FilterOptions,
        limit?: number,
        offset?: number
    ) => LoadExamplesResult;
    getCodingProblems: (split: Split) => CodingProblem[];
    getAllExamples: (split: Split) => DatasetExample[];
}

const DatasetContext = createContext<DatasetContextValue | null>(null);

interface DatasetProviderProps {
    children: ReactNode;
    initialSplits?: Split[];
}

export function DatasetProvider({
    children,
    initialSplits = ['train', 'test', 'validation'],
}: DatasetProviderProps) {
    const [isLoading, setIsLoading] = useState(true);
    const [loadedSplits, setLoadedSplits] = useState<Set<Split>>(new Set());
    const [splitCounts, setSplitCounts] = useState<Record<string, number>>({});

    // Load initial splits on mount
    useEffect(() => {
        const loadInitialData = async () => {
            setIsLoading(true);
            try {
                // Load split info first
                const info = await datasetLoader.getSplitInfo();
                setSplitCounts(info);

                // Load initial splits in parallel
                await Promise.all(
                    initialSplits.map(async (split) => {
                        await datasetLoader.preloadSplit(split);
                        setLoadedSplits((prev) => new Set([...prev, split]));
                    })
                );
            } catch (error) {
                console.error('Failed to load dataset:', error);
            } finally {
                setIsLoading(false);
            }
        };

        loadInitialData();
    }, []);

    const loadSplit = useCallback(async (split: Split) => {
        if (datasetLoader.isLoaded(split)) {
            setLoadedSplits((prev) => new Set([...prev, split]));
            return;
        }

        await datasetLoader.preloadSplit(split);
        setLoadedSplits((prev) => new Set([...prev, split]));

        // Update counts after loading
        const examples = datasetLoader.getAllExamples(split);
        setSplitCounts((prev) => ({ ...prev, [split]: examples.length }));
    }, []);

    const filterExamples = useCallback(
        (
            split: Split,
            filters: FilterOptions,
            limit: number = 50,
            offset: number = 0
        ): LoadExamplesResult => {
            if (!datasetLoader.isLoaded(split)) {
                return { examples: [], total: 0 };
            }
            return datasetLoader.filterExamples(split, filters, limit, offset);
        },
        []
    );

    const getCodingProblems = useCallback((split: Split): CodingProblem[] => {
        return datasetLoader.getCodingProblems(split);
    }, []);

    const getAllExamples = useCallback((split: Split): DatasetExample[] => {
        return datasetLoader.getAllExamples(split);
    }, []);

    return (
        <DatasetContext.Provider
            value={{
                isLoading,
                loadedSplits,
                splitCounts,
                loadSplit,
                filterExamples,
                getCodingProblems,
                getAllExamples,
            }}
        >
            {children}
        </DatasetContext.Provider>
    );
}

export function useDataset() {
    const context = useContext(DatasetContext);
    if (!context) {
        throw new Error('useDataset must be used within a DatasetProvider');
    }
    return context;
}