app/scraper/browser_manager.py

"""
============================================
Browser Manager
- Manages Playwright browser lifecycle
- Creates isolated browser contexts (like separate browser profiles)
- Implements concurrency control with asyncio.Semaphore
- Applies stealth settings to avoid detection
============================================
"""

import asyncio
import logging
from typing import Optional, Dict
from playwright.async_api import (
    async_playwright,
    Browser,
    BrowserContext,
    Page,
    Playwright,
    Error as PlaywrightError,
)
from app.config import settings

logger = logging.getLogger(__name__)


class BrowserManager:
    """
    Singleton-style manager for Playwright browser.
    
    Key Design:
    - ONE browser instance (Chromium)
    - MULTIPLE browser contexts (each novel gets its own context)
    - Semaphore limits concurrent contexts to MAX_CONCURRENT_BROWSERS
    - Each context has its own cookies, storage, fingerprint
    """

    def __init__(self):
        self._playwright: Optional[Playwright] = None
        self._browser: Optional[Browser] = None
        
        # Semaphore controls how many novels scrape simultaneously
        self._semaphore = asyncio.Semaphore(settings.MAX_CONCURRENT_BROWSERS)
        
        # Track active contexts: {novel_id: BrowserContext}
        self._active_contexts: Dict[int, BrowserContext] = {}
        
        # Track active pages: {novel_id: Page}
        self._active_pages: Dict[int, Page] = {}
        
        # Lock for thread-safe operations
        self._lock = asyncio.Lock()
        
        # Status flag
        self._is_initialized = False

    async def initialize(self):
        """
        Start Playwright and launch Chromium browser.
        Called once when the FastAPI app starts.
        """
        async with self._lock:
            if self._is_initialized:
                logger.info("Browser already initialized, skipping.")
                return

            try:
                logger.info("🚀 Starting Playwright...")
                self._playwright = await async_playwright().start()

                logger.info("🌐 Launching Chromium browser...")
                self._browser = await self._playwright.chromium.launch(
                    headless=True,  # MUST be headless on Hugging Face
                    args=[
                        # --- Performance & Stability ---
                        "--no-sandbox",
                        "--disable-setuid-sandbox",
                        "--disable-dev-shm-usage",     # Prevents /dev/shm issues in Docker
                        "--disable-gpu",                # No GPU in Docker
                        "--disable-software-rasterizer",
                        
                        # --- Memory Optimization ---
                        "--disable-extensions",
                        "--disable-background-networking",
                        "--disable-background-timer-throttling",
                        "--disable-backgrounding-occluded-windows",
                        "--disable-breakpad",
                        "--disable-component-update",
                        "--disable-default-apps",
                        "--disable-hang-monitor",
                        "--disable-popup-blocking",
                        "--disable-prompt-on-repost",
                        "--disable-renderer-backgrounding",
                        "--disable-sync",
                        "--disable-translate",
                        "--metrics-recording-only",
                        "--no-first-run",
                        "--safebrowsing-disable-auto-update",
                        
                        # --- Anti-Detection ---
                        "--disable-blink-features=AutomationControlled",
                        "--disable-infobars",
                        "--window-size=1920,1080",
                    ],
                )

                self._is_initialized = True
                logger.info("✅ Browser launched successfully!")

            except Exception as e:
                logger.error(f"❌ Failed to launch browser: {e}")
                await self.shutdown()
                raise

    async def create_context_for_novel(self, novel_id: int) -> tuple:
        """
        Create an isolated browser context for a specific novel.
        
        Returns: (BrowserContext, Page)
        
        Each context is like a fresh browser profile:
        - Separate cookies (login stays separate per novel site)
        - Separate localStorage
        - Own viewport and user agent
        """
        if not self._is_initialized or self._browser is None:
            raise RuntimeError("Browser not initialized! Call initialize() first.")

        # --- Stealth User Agents (rotate randomly) ---
        import random
        user_agents = [
            # Chrome on Windows
            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36",
            # Chrome on Mac
            "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36",
            # Firefox on Windows
            "Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:123.0) Gecko/20100101 Firefox/123.0",
            # Edge on Windows
            "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36 Edg/122.0.0.0",
            # Chrome on Linux
            "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/122.0.0.0 Safari/537.36",
        ]

        # --- Viewport sizes (realistic screen sizes) ---
        viewports = [
            {"width": 1920, "height": 1080},
            {"width": 1366, "height": 768},
            {"width": 1536, "height": 864},
            {"width": 1440, "height": 900},
            {"width": 1280, "height": 720},
        ]

        selected_ua = random.choice(user_agents)
        selected_viewport = random.choice(viewports)

        try:
            context = await self._browser.new_context(
                # --- Identity ---
                user_agent=selected_ua,
                viewport=selected_viewport,
                
                # --- Locale & Timezone (appear as US user) ---
                locale="en-US",
                timezone_id="America/New_York",
                
                # --- Permissions ---
                permissions=["geolocation"],
                geolocation={"latitude": 40.7128, "longitude": -74.0060},  # New York
                
                # --- Other Stealth Settings ---
                color_scheme="light",
                java_script_enabled=True,
                has_touch=False,
                is_mobile=False,
                
                # --- Ignore HTTPS errors (some novel sites have bad certs) ---
                ignore_https_errors=True,
            )

            # --- Inject stealth scripts to hide automation ---
            await context.add_init_script("""
                // Override webdriver detection
                Object.defineProperty(navigator, 'webdriver', {
                    get: () => undefined
                });
                
                // Override chrome detection
                window.chrome = {
                    runtime: {},
                    loadTimes: function() {},
                    csi: function() {},
                    app: {}
                };
                
                // Override permissions query
                const originalQuery = window.navigator.permissions.query;
                window.navigator.permissions.query = (parameters) => (
                    parameters.name === 'notifications' ?
                    Promise.resolve({ state: Notification.permission }) :
                    originalQuery(parameters)
                );
                
                // Override plugins length
                Object.defineProperty(navigator, 'plugins', {
                    get: () => [1, 2, 3, 4, 5]
                });
                
                // Override languages
                Object.defineProperty(navigator, 'languages', {
                    get: () => ['en-US', 'en']
                });
                
                // Override platform
                Object.defineProperty(navigator, 'platform', {
                    get: () => 'Win32'
                });
                
                // Remove automation-related properties
                delete navigator.__proto__.webdriver;
            """)

            # --- Create a new page in this context ---
            page = await context.new_page()

            # --- Set default timeouts ---
            page.set_default_timeout(settings.PAGE_TIMEOUT_SECONDS * 1000)
            page.set_default_navigation_timeout(settings.PAGE_TIMEOUT_SECONDS * 1000)

            # --- Store references ---
            self._active_contexts[novel_id] = context
            self._active_pages[novel_id] = page

            logger.info(
                f"✅ Created browser context for Novel {novel_id} "
                f"(UA: {selected_ua[:50]}..., Viewport: {selected_viewport})"
            )

            return context, page

        except Exception as e:
            logger.error(f"❌ Failed to create context for Novel {novel_id}: {e}")
            raise

    def get_page(self, novel_id: int) -> Optional[Page]:
        """Get the active page for a specific novel."""
        return self._active_pages.get(novel_id)

    def get_context(self, novel_id: int) -> Optional[BrowserContext]:
        """Get the active browser context for a specific novel."""
        return self._active_contexts.get(novel_id)

    async def close_context(self, novel_id: int):
        """
        Close the browser context for a specific novel.
        Called when scraping is done or failed.
        """
        try:
            # Close page first
            page = self._active_pages.pop(novel_id, None)
            if page and not page.is_closed():
                await page.close()

            # Then close context
            context = self._active_contexts.pop(novel_id, None)
            if context:
                await context.close()

            logger.info(f"🔒 Closed browser context for Novel {novel_id}")

        except Exception as e:
            logger.warning(f"Error closing context for Novel {novel_id}: {e}")

    @property
    def semaphore(self) -> asyncio.Semaphore:
        """Get the concurrency semaphore."""
        return self._semaphore

    @property
    def active_count(self) -> int:
        """Get number of currently active browser contexts."""
        return len(self._active_contexts)

    @property
    def is_initialized(self) -> bool:
        """Check if browser is initialized."""
        return self._is_initialized

    def get_active_novel_ids(self) -> list:
        """Get list of novel IDs with active browser contexts."""
        return list(self._active_contexts.keys())

    async def take_screenshot(self, novel_id: int, filename: str) -> Optional[str]:
        """
        Take a screenshot of the current page for a novel.
        Used for captcha detection & manual intervention.
        
        Returns: Path to saved screenshot or None
        """
        page = self._active_pages.get(novel_id)
        if page is None or page.is_closed():
            logger.warning(f"Cannot take screenshot: No active page for Novel {novel_id}")
            return None

        try:
            import os
            os.makedirs(settings.SCREENSHOTS_DIR, exist_ok=True)
            
            filepath = os.path.join(settings.SCREENSHOTS_DIR, filename)
            
            await page.screenshot(
                path=filepath,
                full_page=False,  # Only visible viewport
                type="png",
            )
            
            logger.info(f"📸 Screenshot saved: {filepath}")
            return filepath

        except Exception as e:
            logger.error(f"Failed to take screenshot for Novel {novel_id}: {e}")
            return None

    async def click_at_coordinates(self, novel_id: int, x: int, y: int):
        """
        Click at specific coordinates on the page.
        Used for manual captcha solving from the UI.
        """
        page = self._active_pages.get(novel_id)
        if page is None or page.is_closed():
            raise RuntimeError(f"No active page for Novel {novel_id}")

        try:
            await page.mouse.click(x, y)
            logger.info(f"🖱️ Clicked at ({x}, {y}) for Novel {novel_id}")
            
            # Wait a bit after clicking
            await asyncio.sleep(2)
            
        except Exception as e:
            logger.error(f"Failed to click at ({x}, {y}) for Novel {novel_id}: {e}")
            raise

    async def type_text(self, novel_id: int, selector: str, text: str):
        """
        Type text into an input field.
        Used for captcha text input from the UI.
        """
        page = self._active_pages.get(novel_id)
        if page is None or page.is_closed():
            raise RuntimeError(f"No active page for Novel {novel_id}")

        try:
            await page.fill(selector, text)
            logger.info(f"⌨️ Typed text into '{selector}' for Novel {novel_id}")
        except Exception as e:
            logger.error(f"Failed to type text for Novel {novel_id}: {e}")
            raise

    async def shutdown(self):
        """
        Shut down everything cleanly.
        Called when FastAPI app is stopping.
        """
        async with self._lock:
            logger.info("🛑 Shutting down Browser Manager...")

            # Close all active contexts
            for novel_id in list(self._active_contexts.keys()):
                await self.close_context(novel_id)

            # Close browser
            if self._browser:
                try:
                    await self._browser.close()
                except Exception as e:
                    logger.warning(f"Error closing browser: {e}")
                self._browser = None

            # Stop Playwright
            if self._playwright:
                try:
                    await self._playwright.stop()
                except Exception as e:
                    logger.warning(f"Error stopping Playwright: {e}")
                self._playwright = None

            self._is_initialized = False
            logger.info("✅ Browser Manager shut down completely.")


# ============================================
# Global Singleton Instance
# ============================================
browser_manager = BrowserManager()