import { useState, useEffect } from 'react';
import { supabase } from '@/lib/supabaseClient';
import type { EntityType, VersionDiff } from '@/types/versioning';
import { handleError } from '@/lib/errorHandler';

/**
 * Hook to compare two versions of an entity and get the diff
 * Uses the relational version tables for type-safe comparison
 */
export function useVersionComparison(
  entityType: EntityType,
  fromVersionId: string | null,
  toVersionId: string | null
) {
  const [diff, setDiff] = useState<VersionDiff | null>(null);
  const [loading, setLoading] = useState(false);
  const [error, setError] = useState<string | null>(null);

  useEffect(() => {
    if (!fromVersionId || !toVersionId || !entityType) {
      setDiff(null);
      return;
    }

    async function fetchDiff() {
      setLoading(true);
      setError(null);

      try {
        // Use the database function to get diff
        const { data, error: rpcError } = await supabase.rpc('get_version_diff', {
          p_entity_type: entityType,
          p_from_version_id: fromVersionId || '',
          p_to_version_id: toVersionId || ''
        });

        if (rpcError) throw rpcError;

        setDiff(data as VersionDiff);
      } catch (err) {
        handleError(err, { 
          action: 'Compare Versions',
          metadata: { entityType, fromVersionId, toVersionId }
        });
        setError(err instanceof Error ? err.message : 'Failed to compare versions');
        setDiff(null);
      } finally {
        setLoading(false);
      }
    }

    fetchDiff();
  }, [entityType, fromVersionId, toVersionId]);

  return { diff, loading, error };
}