/**
 * ╔═══════════════════════════════════════════════════════════════════════════╗
 * ║                    GRAPH INGESTOR - KNOWLEDGE HARVESTER                   ║
 * ║═══════════════════════════════════════════════════════════════════════════║
 * ║  Converts filesystem structure to Neo4j knowledge graph                   ║
 * ║                                                                           ║
 * ║  Structure:                                                               ║
 * ║  (:Repository)-[:CONTAINS]->(:Directory)-[:CONTAINS]->(:File)             ║
 * ║                                                                           ║
 * ║  Delivered by: Gemini (The Architect)                                     ║
 * ║  Implemented by: Claude (The Captain)                                     ║
 * ╚═══════════════════════════════════════════════════════════════════════════╝
 */

import * as fs from 'fs/promises';
import { createReadStream } from 'fs';
import * as path from 'path';
import * as crypto from 'crypto';
import { setImmediate as yieldToLoop } from 'timers/promises';
import { neo4jAdapter } from '../adapters/Neo4jAdapter.js';
import { getEmbeddingService, EmbeddingService } from './embeddings/EmbeddingService.js';
import { hyperLog } from './HyperLog.js';

// ═══════════════════════════════════════════════════════════════════════════
// Types
// ═══════════════════════════════════════════════════════════════════════════

export interface IngestOptions {
  rootPath: string;
  repositoryName?: string;
  includePatterns?: string[];
  excludePatterns?: string[];
  maxDepth?: number;
  parseContent?: boolean;
  generateEmbeddings?: boolean;
  maxEmbedSizeBytes?: number;
  embeddingTextLimit?: number;
  contentPreviewLength?: number;
}

export interface IngestResult {
  success: boolean;
  repositoryId: string;
  stats: {
    directoriesCreated: number;
    filesCreated: number;
    relationshipsCreated: number;
    totalNodes: number;
    duration: number;
  };
  errors: string[];
}

interface FileInfo {
  name: string;
  path: string;
  relativePath: string;
  extension: string;
  language: string;
  size: number;
  lines?: number;
  contentPreview?: string;
  contentHash?: string;
  embedding?: number[];
  embeddingProvider?: string;
}

// ═══════════════════════════════════════════════════════════════════════════
// Language Detection
// ═══════════════════════════════════════════════════════════════════════════

const LANGUAGE_MAP: Record<string, string> = {
  '.ts': 'TypeScript',
  '.tsx': 'TypeScript/React',
  '.js': 'JavaScript',
  '.jsx': 'JavaScript/React',
  '.md': 'Markdown',
  '.json': 'JSON',
  '.yaml': 'YAML',
  '.yml': 'YAML',
  '.css': 'CSS',
  '.scss': 'SCSS',
  '.html': 'HTML',
  '.sql': 'SQL',
  '.py': 'Python',
  '.sh': 'Shell',
  '.bat': 'Batch',
  '.ps1': 'PowerShell',
  '.dockerfile': 'Dockerfile',
  '.env': 'Environment',
  '.gitignore': 'Git',
};

const DEFAULT_EXCLUDE = [
  'node_modules',
  '.git',
  'dist',
  'build',
  '.next',
  'coverage',
  '.cache',
  '__pycache__',
  '.vscode',
  '.idea',
];

// ═══════════════════════════════════════════════════════════════════════════
// Graph Ingestor Class
// ═══════════════════════════════════════════════════════════════════════════

export class GraphIngestor {
  private options: Required<IngestOptions>;
  private stats = {
    directoriesCreated: 0,
    filesCreated: 0,
    relationshipsCreated: 0,
    totalNodes: 0,
    duration: 0,
  };
  private errors: string[] = [];
  private readonly yieldInterval = 100; // Yield to event loop every N entries
  private embeddingService: EmbeddingService | null = null;
  private embeddingProvider: string | null = null;

  constructor(options: IngestOptions) {
    this.options = {
      rootPath: options.rootPath,
      repositoryName: options.repositoryName || path.basename(options.rootPath),
      includePatterns: options.includePatterns || ['*'],
      excludePatterns: options.excludePatterns || DEFAULT_EXCLUDE,
      maxDepth: options.maxDepth || 10,
      parseContent: options.parseContent ?? false,
      generateEmbeddings: options.generateEmbeddings ?? false,
      maxEmbedSizeBytes: options.maxEmbedSizeBytes ?? 120_000,
      embeddingTextLimit: options.embeddingTextLimit ?? 4000,
      contentPreviewLength: options.contentPreviewLength ?? 800,
    };
  }

  // ═══════════════════════════════════════════════════════════════════════
  // Main Ingestion Method
  // ═══════════════════════════════════════════════════════════════════════

  async ingest(): Promise<IngestResult> {
    const startTime = Date.now();

    try {
      console.log(`[GraphIngestor] 🚀 Starting ingestion of: ${this.options.rootPath}`);
      await hyperLog.logEvent('GRAPH_INGEST_START', {
        rootPath: this.options.rootPath,
        repository: this.options.repositoryName,
        embeddings: this.options.generateEmbeddings,
      });

      // Create Repository node
      const repoId = this.generateId('Repository', this.options.repositoryName);
      await this.createRepositoryNode(repoId);

      // Recursively process directory
      await this.processDirectory(this.options.rootPath, repoId, 0);

      this.stats.duration = Date.now() - startTime;
      this.stats.totalNodes = this.stats.directoriesCreated + this.stats.filesCreated + 1;

      console.log(`[GraphIngestor] ✅ Ingestion complete in ${this.stats.duration}ms`);
      console.log(
        `[GraphIngestor] 📊 Stats: ${this.stats.totalNodes} nodes, ${this.stats.relationshipsCreated} relationships`
      );

      await hyperLog.logEvent('GRAPH_INGEST_COMPLETED', {
        repository: this.options.repositoryName,
        stats: this.stats,
        errors: this.errors.length,
      });

      return {
        success: true,
        repositoryId: repoId,
        stats: this.stats,
        errors: this.errors,
      };
    } catch (error: any) {
      this.errors.push(`Fatal error: ${error.message}`);
      await hyperLog.logEvent('GRAPH_INGEST_FATAL', {
        repository: this.options.repositoryName,
        error: error.message,
      });
      return {
        success: false,
        repositoryId: '',
        stats: this.stats,
        errors: this.errors,
      };
    }
  }

  // ═══════════════════════════════════════════════════════════════════════
  // Node Creation
  // ═══════════════════════════════════════════════════════════════════════

  private async createRepositoryNode(repoId: string): Promise<void> {
    await neo4jAdapter.writeQuery(
      `
            MERGE (r:Repository {id: $id})
            SET r.name = $name,
                r.path = $path,
                r.ingestedAt = datetime(),
                r.source = 'graph-ingestor'
            RETURN r
        `,
      {
        id: repoId,
        name: this.options.repositoryName,
        path: this.options.rootPath,
      }
    );

    console.log(`[GraphIngestor] 📦 Created Repository: ${this.options.repositoryName}`);
  }

  private async createDirectoryNode(
    dirPath: string,
    parentId: string,
    depth: number
  ): Promise<string> {
    const dirName = path.basename(dirPath);
    const relativePath = path.relative(this.options.rootPath, dirPath);
    const dirId = this.generateId('Directory', relativePath || dirName);

    await neo4jAdapter.writeQuery(
      `
            MERGE (d:Directory {id: $id})
            SET d.name = $name,
                d.path = $path,
                d.relativePath = $relativePath,
                d.depth = $depth,
                d.ingestedAt = datetime()
            WITH d
            MATCH (p {id: $parentId})
            MERGE (p)-[:CONTAINS]->(d)
            RETURN d
        `,
      {
        id: dirId,
        name: dirName,
        path: dirPath,
        relativePath: relativePath || '.',
        depth: depth,
        parentId: parentId,
      }
    );

    this.stats.directoriesCreated++;
    this.stats.relationshipsCreated++;

    return dirId;
  }

  private async createFileNode(fileInfo: FileInfo, parentId: string): Promise<void> {
    const fileId = this.generateId('File', fileInfo.relativePath);

    await neo4jAdapter.writeQuery(
      `
            MERGE (f:File:${this.sanitizeLabel(fileInfo.language)} {id: $id})
            SET f.name = $name,
                f.path = $path,
                f.relativePath = $relativePath,
                f.extension = $extension,
                f.language = $language,
                f.size = $size,
                f.lines = $lines,
                f.contentPreview = coalesce($contentPreview, f.contentPreview),
                f.contentHash = coalesce($contentHash, f.contentHash),
                f.embedding = CASE WHEN $embedding IS NOT NULL THEN $embedding ELSE f.embedding END,
                f.embeddingProvider = coalesce($embeddingProvider, f.embeddingProvider),
                f.embeddingDimensions = CASE
                    WHEN $embedding IS NOT NULL THEN size($embedding)
                    ELSE coalesce(f.embeddingDimensions, CASE WHEN f.embedding IS NOT NULL THEN size(f.embedding) END)
                END,
                f.hasEmbedding = CASE
                    WHEN $embedding IS NOT NULL THEN true
                    WHEN f.embedding IS NOT NULL THEN true
                    ELSE false
                END,
                f.ingestedAt = datetime()
            WITH f
            MATCH (p {id: $parentId})
            MERGE (p)-[:CONTAINS]->(f)
            RETURN f
        `,
      {
        id: fileId,
        name: fileInfo.name,
        path: fileInfo.path,
        relativePath: fileInfo.relativePath,
        extension: fileInfo.extension,
        language: fileInfo.language,
        size: fileInfo.size,
        lines: fileInfo.lines || 0,
        contentPreview: fileInfo.contentPreview || null,
        contentHash: fileInfo.contentHash || null,
        embedding: fileInfo.embedding || null,
        embeddingProvider: fileInfo.embeddingProvider || null,
        parentId: parentId,
      }
    );

    this.stats.filesCreated++;
    this.stats.relationshipsCreated++;
  }

  // ═══════════════════════════════════════════════════════════════════════
  // Directory Processing
  // ═══════════════════════════════════════════════════════════════════════

  private async processDirectory(dirPath: string, parentId: string, depth: number): Promise<void> {
    const queue: Array<{ dirPath: string; parentId: string; depth: number }> = [
      { dirPath, parentId, depth },
    ];
    let processed = 0;

    while (queue.length) {
      const current = queue.shift();
      if (!current || current.depth > this.options.maxDepth) {
        continue;
      }

      let entries;
      try {
        entries = await fs.readdir(current.dirPath, { withFileTypes: true });
      } catch (error: any) {
        this.errors.push(`Error processing ${current.dirPath}: ${error.message}`);
        continue;
      }

      for (const entry of entries) {
        const fullPath = path.join(current.dirPath, entry.name);

        if (this.shouldExclude(entry.name)) {
          continue;
        }

        processed++;
        if (processed % this.yieldInterval === 0) {
          await yieldToLoop(); // Yield to avoid starving the event loop on large trees
        }

        if (entry.isDirectory()) {
          const dirId = await this.createDirectoryNode(fullPath, current.parentId, current.depth);
          queue.push({ dirPath: fullPath, parentId: dirId, depth: current.depth + 1 });
        } else if (entry.isFile()) {
          const fileInfo = await this.getFileInfo(fullPath);
          if (fileInfo) {
            await this.createFileNode(fileInfo, current.parentId);
          }
        }
      }
    }
  }

  // ═══════════════════════════════════════════════════════════════════════
  // Helpers
  // ═══════════════════════════════════════════════════════════════════════

  private async getFileInfo(filePath: string): Promise<FileInfo | null> {
    try {
      const stats = await fs.stat(filePath);
      const ext = path.extname(filePath).toLowerCase();
      const relativePath = path.relative(this.options.rootPath, filePath);

      const shouldLoadContent =
        (this.options.parseContent || this.options.generateEmbeddings) && this.isTextFile(ext);
      let content: string | null = null;

      let lines: number | undefined;
      if (this.isTextFile(ext)) {
        if (shouldLoadContent && stats.size <= this.options.maxEmbedSizeBytes) {
          content = await fs.readFile(filePath, 'utf-8');
          lines = content.split(/\r?\n/).length;
        } else {
          lines = await this.countLines(filePath, stats.size);
        }
      }

      const contentPreview = content
        ? content.slice(0, this.options.contentPreviewLength)
        : undefined;

      let embedding: number[] | undefined;
      let embeddingProvider: string | undefined;
      if (this.options.generateEmbeddings && content && content.trim()) {
        let embedText = content;
        if (embedText.length > this.options.embeddingTextLimit) {
          embedText = embedText.slice(0, this.options.embeddingTextLimit);
        }
        const embedded = await this.generateEmbedding(embedText, relativePath);
        if (embedded) {
          embedding = embedded;
          embeddingProvider = this.embeddingProvider || undefined;
        }
      } else if (
        this.options.generateEmbeddings &&
        stats.size > this.options.maxEmbedSizeBytes &&
        this.isTextFile(ext)
      ) {
        await hyperLog.logEvent('GRAPH_INGEST_EMBEDDING_SKIPPED', {
          path: relativePath,
          reason: 'file_too_large',
          size: stats.size,
          limit: this.options.maxEmbedSizeBytes,
        });
      }

      return {
        name: path.basename(filePath),
        path: filePath,
        relativePath: relativePath,
        extension: ext,
        language: this.detectLanguage(ext, path.basename(filePath)),
        size: stats.size,
        lines: lines,
        contentPreview,
        contentHash: content ? this.hashContent(content) : undefined,
        embedding,
        embeddingProvider,
      };
    } catch (error) {
      return null;
    }
  }

  private detectLanguage(ext: string, filename: string): string {
    // Special cases for files without extensions
    const lowerName = filename.toLowerCase();
    if (lowerName === 'dockerfile') return 'Dockerfile';
    if (lowerName === 'makefile') return 'Makefile';
    if (lowerName.startsWith('.env')) return 'Environment';
    if (lowerName === '.gitignore') return 'Git';

    return LANGUAGE_MAP[ext] || 'Unknown';
  }

  private isTextFile(ext: string): boolean {
    const textExtensions = [
      '.ts',
      '.tsx',
      '.js',
      '.jsx',
      '.json',
      '.md',
      '.yaml',
      '.yml',
      '.css',
      '.scss',
      '.html',
      '.sql',
      '.py',
      '.sh',
      '.bat',
      '.ps1',
      '.txt',
      '.env',
      '.gitignore',
      '.prettierrc',
      '.eslintrc',
    ];
    return textExtensions.includes(ext);
  }

  private shouldExclude(name: string): boolean {
    return this.options.excludePatterns.some(pattern => {
      if (pattern.includes('*')) {
        const regex = new RegExp(pattern.replace(/\*/g, '.*'));
        return regex.test(name);
      }
      return name === pattern;
    });
  }

  private generateId(type: string, identifier: string): string {
    const content = `${type}:${identifier}`;
    return crypto.createHash('md5').update(content).digest('hex');
  }

  private sanitizeLabel(language: string): string {
    // Convert language to valid Neo4j label
    return language.replace(/[^a-zA-Z0-9]/g, '_').replace(/^_+|_+$/g, '') || 'Unknown';
  }

  private async countLines(filePath: string, size: number): Promise<number | undefined> {
    if (size > 2_000_000) {
      return undefined; // Avoid heavy scans on very large files
    }

    return new Promise(resolve => {
      let count = 0;
      const stream = createReadStream(filePath);

      stream.on('data', (chunk: Buffer) => {
        for (let i = 0; i < chunk.length; i++) {
          if (chunk[i] === 10) count++; // '\n'
        }
      });

      stream.on('end', () => resolve(count || 1));
      stream.on('error', () => resolve(undefined));
    });
  }

  private hashContent(content: string): string {
    return crypto.createHash('md5').update(content).digest('hex');
  }

  private async ensureEmbeddingService(): Promise<void> {
    if (this.embeddingService) return;

    try {
      this.embeddingService = getEmbeddingService();
      await this.embeddingService.initialize();
      this.embeddingProvider = this.embeddingService.getProviderName();
    } catch (error: any) {
      this.errors.push(`Embedding provider unavailable: ${error.message}`);
      await hyperLog.logEvent('GRAPH_INGEST_EMBEDDING_PROVIDER_FAILED', {
        error: error.message,
      });
      throw error;
    }
  }

  private async generateEmbedding(content: string, relativePath: string): Promise<number[] | null> {
    try {
      await this.ensureEmbeddingService();
      const embedding = await this.embeddingService!.generateEmbedding(content);
      return embedding;
    } catch (error: any) {
      this.errors.push(`Embedding failed for ${relativePath}: ${error.message}`);
      await hyperLog.logEvent('GRAPH_INGEST_EMBEDDING_FAILED', {
        path: relativePath,
        error: error.message,
      });
      return null;
    }
  }
}

// ═══════════════════════════════════════════════════════════════════════════
// Export Factory Function
// ═══════════════════════════════════════════════════════════════════════════

export async function ingestRepository(options: IngestOptions): Promise<IngestResult> {
  const ingestor = new GraphIngestor(options);
  return ingestor.ingest();
}