web_scraper.py

"""
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║ ThemisDB - Hybrid Database System                                   ║
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  File:            web_scraper.py                                     ║
  Version:         0.0.47                                             ║
  Last Modified:   2026-04-15 18:43:50                                ║
  Author:          unknown                                            ║
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  Quality Metrics:                                                    ║
    • Maturity Level:  🟢 PRODUCTION-READY                             ║
    • Quality Score:   94.0/100                                       ║
    • Total Lines:     365                                            ║
    • Open Issues:     TODOs: 0, Stubs: 0                             ║
╠═════════════════════════════════════════════════════════════════════╣
  Status: ✅ Production Ready                                          ║
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"""

"""
Web Scraper Module.

This module provides web scraping functionality for collecting code examples
from various sources like GitHub, Stack Overflow, and documentation sites.
"""

import requests
from bs4 import BeautifulSoup
from typing import List, Optional, Dict, Any
import time
import re
from datetime import datetime
import uuid
import os
from abc import ABC, abstractmethod

from models import (
    CodeSnippet, ScrapingJob, ScrapingJobConfig,
    ScrapingJobResults, JobStatus, SourceType
)


class BaseScraper(ABC):
    """Base class for all scrapers."""
    
    def __init__(self):
        self.session = requests.Session()
        self.session.headers.update({
            'User-Agent': 'ThemisDB Code Scraper/1.0 (Educational Project)'
        })
    
    @abstractmethod
    def scrape(self, url: str, config: ScrapingJobConfig) -> List[CodeSnippet]:
        """Scrape code from URL."""
        pass
    
    def fetch_with_retry(self, url: str, max_retries: int = 3) -> requests.Response:
        """Fetch URL with retry logic."""
        for attempt in range(max_retries):
            try:
                response = self.session.get(url, timeout=10)
                response.raise_for_status()
                return response
            except requests.RequestException as e:
                if attempt == max_retries - 1:
                    raise
                time.sleep(2 ** attempt)  # Exponential backoff
    
    def detect_language(self, code: str, hint: Optional[str] = None) -> str:
        """Detect programming language from code."""
        if hint:
            return hint.lower()
        
        # Simple heuristic-based detection
        if 'def ' in code and 'import ' in code:
            return 'python'
        elif 'function ' in code or 'const ' in code or 'let ' in code:
            return 'javascript'
        elif 'public class ' in code or 'private ' in code:
            return 'java'
        elif '#include' in code or 'std::' in code:
            return 'cpp'
        elif 'fn ' in code and 'impl ' in code:
            return 'rust'
        elif 'func ' in code and 'package ' in code:
            return 'go'
        
        return 'unknown'
    
    def extract_code_blocks(self, html: str) -> List[Dict[str, str]]:
        """Extract code blocks from HTML."""
        soup = BeautifulSoup(html, 'html.parser')
        code_blocks = []
        
        # Common patterns for code blocks
        for tag in soup.find_all(['pre', 'code']):
            code = tag.get_text()
            if len(code.strip()) < 20:  # Skip very short blocks
                continue
            
            # Try to detect language from class attribute
            language = None
            classes = tag.get('class', [])
            for cls in classes:
                if cls.startswith('language-'):
                    language = cls.replace('language-', '')
                    break
                elif cls.startswith('lang-'):
                    language = cls.replace('lang-', '')
                    break
            
            code_blocks.append({
                'code': code,
                'language': language or self.detect_language(code)
            })
        
        return code_blocks
    
    def create_snippet(
        self,
        code: str,
        language: str,
        title: str,
        source_url: str,
        source_type: SourceType,
        **kwargs
    ) -> CodeSnippet:
        """Create a CodeSnippet object."""
        return CodeSnippet(
            id=str(uuid.uuid4()),
            title=title,
            code=code,
            language=language,
            description=kwargs.get('description', ''),
            framework=kwargs.get('framework'),
            tags=kwargs.get('tags', []),
            metadata={
                'source_url': source_url,
                'source_type': source_type.value,
                'scraped_at': datetime.now().isoformat(),
                **kwargs.get('metadata', {})
            },
            created_at=datetime.now()
        )


class GitHubScraper(BaseScraper):
    """Scraper for GitHub repositories."""
    
    def __init__(self, token: Optional[str] = None):
        super().__init__()
        self.token = token or os.getenv('GITHUB_TOKEN')
        if self.token:
            self.session.headers.update({
                'Authorization': f'token {self.token}'
            })
    
    def scrape(self, url: str, config: ScrapingJobConfig) -> List[CodeSnippet]:
        """
        Scrape a GitHub repository.
        
        Note: This is a simplified implementation. In production, use PyGithub library.
        """
        snippets = []
        
        # Extract owner and repo from URL
        match = re.match(r'https://github.com/([^/]+)/([^/]+)', url)
        if not match:
            return snippets
        
        owner, repo = match.groups()
        
        # Get repository contents (simplified - would use GitHub API in production)
        # This is a mock implementation for demonstration
        print(f"Scraping GitHub repository: {owner}/{repo}")
        print("Note: This is a mock implementation. Use PyGithub for actual scraping.")
        
        # Mock: Create a sample snippet
        sample_snippet = self.create_snippet(
            code="# Sample code from GitHub\ndef hello_world():\n    print('Hello from GitHub!')",
            language="python",
            title=f"Sample from {repo}",
            source_url=url,
            source_type=SourceType.GITHUB,
            description=f"Sample code from {owner}/{repo}",
            metadata={
                'owner': owner,
                'repo': repo
            }
        )
        snippets.append(sample_snippet)
        
        return snippets
    
    def get_rate_limit(self) -> Dict[str, Any]:
        """Get current GitHub API rate limit."""
        if not self.token:
            return {
                'limit': 60,
                'remaining': 60,
                'reset_time': None
            }
        
        try:
            response = self.session.get('https://api.github.com/rate_limit')
            data = response.json()
            core = data['resources']['core']
            return {
                'limit': core['limit'],
                'remaining': core['remaining'],
                'reset_time': datetime.fromtimestamp(core['reset']),
                'seconds_until_reset': core['reset'] - time.time()
            }
        except Exception:
            return {'limit': 0, 'remaining': 0, 'reset_time': None}


class StackOverflowScraper(BaseScraper):
    """Scraper for Stack Overflow questions and answers."""
    
    def __init__(self, key: Optional[str] = None):
        super().__init__()
        self.key = key or os.getenv('STACKOVERFLOW_KEY')
        self.base_url = 'https://api.stackexchange.com/2.3'
    
    def scrape(self, url: str, config: ScrapingJobConfig) -> List[CodeSnippet]:
        """Scrape Stack Overflow questions."""
        # Mock implementation
        print("Scraping Stack Overflow...")
        print("Note: This is a mock implementation. Use Stack Exchange API for actual scraping.")
        
        snippets = []
        
        # Mock: Create a sample snippet
        sample_snippet = self.create_snippet(
            code="# Sample from Stack Overflow\nasync def fetch_data(url):\n    async with aiohttp.ClientSession() as session:\n        async with session.get(url) as response:\n            return await response.json()",
            language="python",
            title="Async HTTP Request Example",
            source_url=url,
            source_type=SourceType.STACKOVERFLOW,
            description="Example of async HTTP request from Stack Overflow",
            metadata={
                'score': 42,
                'views': 1234
            }
        )
        snippets.append(sample_snippet)
        
        return snippets
    
    def scrape_questions(
        self,
        tags: List[str],
        min_score: int = 0,
        max_questions: int = 50
    ) -> List[CodeSnippet]:
        """Scrape questions by tags."""
        print(f"Scraping Stack Overflow questions with tags: {tags}")
        print("Note: This is a mock implementation.")
        return []


class DocsCrawler(BaseScraper):
    """Crawler for documentation websites."""
    
    def scrape(self, url: str, config: ScrapingJobConfig) -> List[CodeSnippet]:
        """Crawl documentation site for code examples."""
        snippets = []
        
        print(f"Crawling documentation: {url}")
        
        try:
            response = self.fetch_with_retry(url)
            code_blocks = self.extract_code_blocks(response.text)
            
            for i, block in enumerate(code_blocks):
                snippet = self.create_snippet(
                    code=block['code'],
                    language=block['language'],
                    title=f"Code Example {i+1} from Documentation",
                    source_url=url,
                    source_type=SourceType.OFFICIAL_DOCS,
                    description=f"Code example extracted from {url}"
                )
                snippets.append(snippet)
        
        except Exception as e:
            print(f"Error crawling {url}: {e}")
        
        return snippets


class ScraperManager:
    """Manager for coordinating scraping jobs."""
    
    def __init__(self, themis_client):
        self.themis_client = themis_client
        self.scrapers = {
            'github': GitHubScraper(),
            'stackoverflow': StackOverflowScraper(),
            'docs': DocsCrawler()
        }
    
    def create_job(
        self,
        job_type: str,
        source_url: str,
        config: Optional[ScrapingJobConfig] = None
    ) -> ScrapingJob:
        """Create and start a scraping job."""
        if config is None:
            config = ScrapingJobConfig()
        
        job = ScrapingJob(
            id=str(uuid.uuid4()),
            job_type=job_type,
            source_url=source_url,
            config=config,
            started_at=datetime.now()
        )
        
        # Store job in database
        self.themis_client.create_scraping_job(job)
        
        return job
    
    def execute_job(self, job: ScrapingJob) -> ScrapingJob:
        """Execute a scraping job."""
        job.status = JobStatus.RUNNING
        job.started_at = datetime.now()
        
        try:
            # Get appropriate scraper
            scraper_type = job.job_type.split('_')[0]  # github_repo -> github
            scraper = self.scrapers.get(scraper_type)
            
            if not scraper:
                raise ValueError(f"Unknown scraper type: {scraper_type}")
            
            # Scrape content
            snippets = scraper.scrape(job.source_url, job.config)
            
            # Store snippets
            for snippet in snippets:
                self.themis_client.create_snippet(snippet)
            
            # Update job results
            job.results.snippets_created = len(snippets)
            job.status = JobStatus.COMPLETED
            job.completed_at = datetime.now()
            job.progress = 1.0
        
        except Exception as e:
            job.status = JobStatus.FAILED
            job.error_log.append(str(e))
            job.results.errors += 1
        
        return job
    
    def get_job_status(self, job_id: str) -> Optional[Dict[str, Any]]:
        """Get status of a scraping job."""
        return self.themis_client.get_scraping_job(job_id)