import { DiffVectorStoreService } from '../services/diff-vector-store.service';

/**
 * RAG Query Helper for Agents
 *
 * Provides convenient methods for agents to query the vector store
 * with targeted questions about the commit diff.
 */
export class RAGHelper {
  constructor(private readonly vectorStore: DiffVectorStoreService) {}

  /**
   * Query the vector store and return formatted results
   * @param query Natural language question about the commit
   * @param topK Number of results to return (default: 3)
   * @returns Formatted context string with relevant code chunks
   */
  async query(query: string, topK: number = 3): Promise<string> {
    const { chunks, summary } = await this.vectorStore.query(query, { topK });

    if (chunks.length === 0) {
      return `No relevant code found for query: "${query}"`;
    }

    // Format results as markdown (optimized - reduced chunk size)
    const formattedChunks = chunks.map((chunk, idx) => {
      const { file, hunkStartLine, addedLines, deletedLines, changeType } = chunk.metadata;
      const relevancePercent = (chunk.score * 100).toFixed(1);

      return [
        `### Result ${idx + 1}: ${file} (${relevancePercent}% relevance)`,
        `- **Location**: Lines starting at ${hunkStartLine}`,
        `- **Changes**: +${addedLines}/-${deletedLines} lines`,
        `- **Type**: ${changeType}`,
        ``,
        '```diff',
        chunk.content.split('\n').slice(0, 5).join('\n'), // Limit to 5 lines per chunk (reduced from 10)
        chunk.content.split('\n').length > 5 ? '... (truncated for brevity)' : '',
        '```',
        '',
      ].join('\n');
    });

    return [`## ${summary}`, ``, ...formattedChunks].join('\n');
  }

  /**
   * Run multiple queries and aggregate results
   * Useful for cross-pillar validation where agents ask multiple questions
   */
  async queryMultiple(queries: Array<{ q: string; topK?: number }>): Promise<
    Array<{
      query: string;
      results: string;
      relevantFiles: Set<string>;
    }>
  > {
    const queryResults = await Promise.all(
      queries.map(async ({ q, topK = 3 }) => {
        const { chunks } = await this.vectorStore.query(q, { topK });
        const relevantFiles = new Set(chunks.map((c) => c.metadata.file as string));
        const formattedResults = await this.query(q, topK);

        return {
          query: q,
          results: formattedResults,
          relevantFiles,
        };
      })
    );

    return queryResults;
  }

  /**
   * Get a summary of the diff for context
   */
  getSummary(): string {
    const stats = this.vectorStore.getStats();
    return [
      `**Diff Summary**:`,
      `- Files changed: ${stats.filesChanged}`,
      `- Additions: +${stats.additions}`,
      `- Deletions: -${stats.deletions}`,
      `- Total chunks indexed: ${stats.documentCount}`,
    ].join('\n');
  }

  /**
   * Check if RAG is available (vector store initialized)
   */
  static isAvailable(context: { vectorStore?: DiffVectorStoreService }): boolean {
    return context.vectorStore !== undefined;
  }
}