# geoelevation/map_viewer/map_manager.py
"""
Manages the retrieval, caching, and stitching of map tiles from a selected map service.

This module interacts with a map service provider (implementing BaseMapService),
handles local disk caching of tiles to support offline use and reduce network
requests, and assembles individual tiles into a complete map image.
"""

# Standard library imports
import logging
import os
import time
import threading
from pathlib import Path # For robust path manipulation
from typing import Tuple, Optional, List, Dict # Ensure these are available
import io # To handle byte stream from requests as an image
import shutil # For cache clearing operations

# Third-party imports
try:
    import requests # For downloading map tiles
    REQUESTS_AVAILABLE = True
except ImportError:
    requests = None # type: ignore
    REQUESTS_AVAILABLE = False
    logging.error("MapTileManager: 'requests' library not found. Online tile fetching will fail.")

try:
    from PIL import Image, ImageDraw
    ImageType = Image.Image # type: ignore
    PIL_AVAILABLE_MANAGER = True
except ImportError:
    Image = None # type: ignore
    ImageDraw = None # type: ignore
    ImageType = None # type: ignore
    PIL_AVAILABLE_MANAGER = False
    logging.error("MapTileManager: 'Pillow' library not found. Image operations will fail.")

try:
    # MODIFIED: Import mercantile here.
    # WHY: map_manager uses mercantile directly in _get_bounds_for_tile_range.
    # HOW: Added import.
    import mercantile
except ImportError:
    mercantile = None # type: ignore
    # No module-specific flag needed here, just check `if mercantile is None:` where used.
    logging.warning("MapTileManager: 'mercantile' library not found. Tile bounds calculation will fail.")


# Local application/package imports
from .map_services import BaseMapService

try:
    from ..utils.logger import get_logger
    logger = get_logger(__name__)
except ImportError:
    logger = logging.getLogger(__name__)
    logger.warning("MapTileManager: Could not import application logger. Using standard logging.")


# Default values for the manager if not provided or configured
DEFAULT_MAP_TILE_CACHE_ROOT_DIR = "map_tile_cache"
DEFAULT_ENABLE_ONLINE_FETCHING = True
DEFAULT_NETWORK_TIMEOUT_SECONDS = 10
DEFAULT_DOWNLOAD_RETRY_DELAY_SECONDS = 2
DEFAULT_MAX_DOWNLOAD_RETRIES = 2
DEFAULT_PLACEHOLDER_COLOR_RGB = (220, 220, 220)


class MapTileManager:
    """
    Manages fetching, caching, and assembling map tiles for a given map service.
    Requires 'requests' and 'Pillow' libraries to be installed. 'mercantile'
    is required for calculating geographic bounds of tile ranges.
    """

    def __init__(
        self,
        map_service: BaseMapService,
        cache_root_directory: Optional[str] = None,
        enable_online_tile_fetching: Optional[bool] = None,
        tile_pixel_size: Optional[int] = None
    ) -> None:
        """
        Initializes the MapTileManager.

        Args:
            map_service_instance: An instance of a map service provider
                                  (e.g., OpenStreetMapService).
            cache_root_directory: The root directory for caching tiles from all services.
                                  If None, uses DEFAULT_MAP_TILE_CACHE_ROOT_DIR.
                                  A subdirectory for the specific service will be created.
            enable_online_tile_fetching: Whether to download tiles if not found in cache.
                                         If None, uses DEFAULT_ENABLE_ONLINE_FETCHING.
            tile_pixel_size: The pixel dimension (width/height) of map tiles for this manager.
                             If None, the size is taken from the map_service instance.
        Raises:
            TypeError: If map_service_instance is not a valid BaseMapService instance.
            ImportError: If 'requests' or 'Pillow' libraries are not installed.
            ValueError: If a tile_pixel_size is provided but invalid.
        """
        logger.info("Initializing MapTileManager...")

        if not REQUESTS_AVAILABLE:
            raise ImportError("'requests' library is required by MapTileManager but not found.")

        if not (PIL_AVAILABLE_MANAGER and ImageDraw is not None):
             raise ImportError("'Pillow' library (or its drawing module ImageDraw) is required by MapTileManager but not fully available.")

        # MODIFIED: Add a check for mercantile availability here, as it's used later.
        # WHY: Inform the user early if a required dependency is missing.
        # HOW: Added if mercantile is None check.
        if mercantile is None:
            logger.error("'mercantile' library is required for tile bounds calculation but is not found or is None.")
            # Decide if this is a fatal error for the manager init.
            # The manager can still fetch/stitch if mercantile is missing, but cannot provide bounds.
            # Let's log an error but not raise, allowing partial functionality.


        if not isinstance(map_service, BaseMapService):
            logger.critical("Invalid map_service_instance provided. Must be an instance of BaseMapService.")
            raise TypeError("map_service_instance must be an instance of BaseMapService.")

        self.map_service: BaseMapService = map_service
        self.service_identifier_name: str = self.map_service.name

        if tile_pixel_size is not None:
            if not isinstance(tile_pixel_size, int) or tile_pixel_size <= 0:
                 logger.error(f"Invalid provided tile_pixel_size: {tile_pixel_size}. Must be a positive integer.")
                 raise ValueError(f"Invalid provided tile_pixel_size: {tile_pixel_size}. Must be a positive integer.")
            self.tile_size: int = tile_pixel_size
            logger.info(f"Map tile size explicitly set to {self.tile_size}px.")
        else:
            self.tile_size: int = self.map_service.tile_size
            logger.info(f"Map tile size inherited from service '{self.map_service.name}': {self.tile_size}px.")

        effective_cache_root_dir = cache_root_directory if cache_root_directory is not None \
                                   else DEFAULT_MAP_TILE_CACHE_ROOT_DIR
        self.service_specific_cache_dir: Path = Path(effective_cache_root_dir) / self.service_identifier_name
        logger.info(f"Service-specific cache directory set to: {self.service_specific_cache_dir}")

        self.is_online_fetching_enabled: bool = enable_online_tile_fetching \
            if enable_online_tile_fetching is not None else DEFAULT_ENABLE_ONLINE_FETCHING
        logger.info(f"Online tile fetching enabled: {self.is_online_fetching_enabled}")

        self.http_user_agent: str = "GeoElevationMapViewer/0.1 (Python Requests)"
        self.http_request_headers: Dict[str, str] = {"User-Agent": self.http_user_agent}
        self.http_request_timeout_seconds: int = DEFAULT_NETWORK_TIMEOUT_SECONDS
        self.download_max_retries: int = DEFAULT_MAX_DOWNLOAD_RETRIES
        self.download_retry_delay_seconds: int = DEFAULT_DOWNLOAD_RETRY_DELAY_SECONDS

        self._ensure_service_cache_directory_exists()
        self._cache_access_lock = threading.Lock()

        logger.info(
            f"MapTileManager initialized for service '{self.service_identifier_name}'. Online: {self.is_online_fetching_enabled}"
        )

    def _ensure_service_cache_directory_exists(self) -> None:
        """Creates the service-specific cache directory if it doesn't exist."""
        try:
            self.service_specific_cache_dir.mkdir(parents=True, exist_ok=True)
            logger.debug(f"Cache directory verified/created: {self.service_specific_cache_dir}")
        except OSError as e_mkdir:
            logger.error(
                f"Failed to create cache directory '{self.service_specific_cache_dir}': {e_mkdir}"
            )
        except Exception as e_unexpected_mkdir:
            logger.exception(
                f"Unexpected error ensuring cache directory exists: {e_unexpected_mkdir}"
            )

    def _get_tile_cache_file_path(self, z: int, x: int, y: int) -> Path:
        """
        Constructs the full local file path for a specific map tile.
        The structure is: <service_cache_dir>/<zoom>/<x_tile>/<y_tile>.png
        """
        return self.service_specific_cache_dir / str(z) / str(x) / f"{y}.png"

    def _load_tile_from_cache(
        self, tile_cache_path: Path, tile_coordinates_log_str: str
    ) -> Optional[ImageType]:
        """Attempts to load a tile image from a cache file (thread-safe read)."""
        logger.debug(f"Checking cache for tile {tile_coordinates_log_str} at {tile_cache_path}")
        if not PIL_AVAILABLE_MANAGER:
             logger.error("Pillow not available, cannot load tile from cache.")
             return None

        try:
            with self._cache_access_lock:
                if tile_cache_path.is_file():
                    logger.info(f"Cache hit for tile {tile_coordinates_log_str}. Loading from disk.")
                    if Image:
                        pil_image = Image.open(tile_cache_path)
                        pil_image.load()

                        if pil_image.mode != "RGB":
                            logger.debug(
                                f"Converting cached image {tile_coordinates_log_str} from mode {pil_image.mode} to RGB."
                            )
                            pil_image = pil_image.convert("RGB")
                        return pil_image
                    else:
                        logger.error("Pillow's Image class is None, cannot open image from cache.")
                        return None

                else:
                    logger.debug(f"Cache miss for tile {tile_coordinates_log_str}.")
                    return None
        except IOError as e_io_cache:
            logger.error(
                f"IOError reading cached tile {tile_cache_path}: {e_io_cache}. Treating as cache miss."
            )
            return None
        except Exception as e_cache_unexpected:
            logger.exception(
                f"Unexpected error accessing cache file {tile_cache_path}: {e_cache_unexpected}"
            )
            return None

    def _download_and_save_tile_to_cache(
        self,
        zoom_level: int,
        tile_x: int,
        tile_y: int,
        tile_cache_path: Path,
        tile_coordinates_log_str: str
    ) -> Optional[ImageType]:
        """Attempts to download a tile, process it, and save it to the cache."""
        if not PIL_AVAILABLE_MANAGER:
            logger.error("Pillow not available, cannot download, process, or save tile.")
            return None

        if not self.is_online_fetching_enabled:
            logger.debug(f"Online fetching disabled. Cannot download tile {tile_coordinates_log_str}.")
            return None

        tile_download_url = self.map_service.get_tile_url(zoom_level, tile_x, tile_y)
        if not tile_download_url:
            logger.error(f"Failed to get URL for tile {tile_coordinates_log_str} from service.")
            return None

        logger.info(f"Downloading tile {tile_coordinates_log_str} from: {tile_download_url}")
        downloaded_pil_image: Optional[ImageType] = None

        for attempt_num in range(self.download_max_retries + 1):
            try:
                if requests:
                    response = requests.get(
                        tile_download_url,
                        headers=self.http_request_headers,
                        timeout=self.http_request_timeout_seconds,
                        stream=True
                    )
                    response.raise_for_status()

                else:
                    logger.error("Requests library is None, cannot perform HTTP GET.")
                    break


                image_binary_data = response.content
                if not image_binary_data:
                    logger.warning(f"Downloaded empty content for tile {tile_coordinates_log_str}.")
                    break

                try:
                    if Image:
                        pil_image = Image.open(io.BytesIO(image_binary_data))
                        pil_image.load()
                        if pil_image.mode != "RGB":
                            pil_image = pil_image.convert("RGB")

                        logger.debug(f"Tile {tile_coordinates_log_str} downloaded (Attempt {attempt_num + 1}).")
                        if tile_cache_path:
                             self._save_image_to_cache_file(tile_cache_path, pil_image)
                        else:
                            logger.error(f"Invalid tile_cache_path for tile {tile_coordinates_log_str}. Cannot save.")

                        downloaded_pil_image = pil_image
                        break

                    else:
                        logger.error("Pillow's Image class is None, cannot process downloaded image data.")
                        break


                except (IOError, Image.UnidentifiedImageError) as e_img_proc:
                    logger.error(
                        f"Failed to process image data for {tile_coordinates_log_str}: {e_img_proc}"
                    )
                    break
                except Exception as e_proc_unexpected:
                    logger.exception(
                        f"Unexpected error processing downloaded image {tile_coordinates_log_str}: {e_proc_unexpected}"
                    )
                    break

            except requests.exceptions.Timeout:
                logger.warning(
                    f"Timeout downloading tile {tile_coordinates_log_str} (Attempt {attempt_num + 1})."
                )
            except requests.exceptions.RequestException as e_req:
                status = getattr(e_req.response, "status_code", "N/A")
                logger.warning(
                    f"Request error for tile {tile_coordinates_log_str} (Status: {status}, Attempt {attempt_num + 1}): {e_req}"
                )
                if status == 404: break
            except Exception as e_dl_unexpected:
                logger.exception(
                    f"Unexpected error downloading tile {tile_coordinates_log_str} (Attempt {attempt_num + 1}): {e_dl_unexpected}"
                )
                break

            if attempt_num < self.download_max_retries:
                logger.debug(f"Waiting {self.download_retry_delay_seconds}s before retrying for {tile_coordinates_log_str}.")
                time.sleep(self.download_retry_delay_seconds)

        if downloaded_pil_image is None:
            logger.error(f"Failed to download tile {tile_coordinates_log_str} after all retries.")
        return downloaded_pil_image


    def _save_image_to_cache_file(self, tile_cache_path: Path, pil_image: ImageType) -> None:
        """Saves a PIL Image object to a file in the cache (thread-safe write)."""
        if not PIL_AVAILABLE_MANAGER or pil_image is None:
            logger.error("Pillow not available or image is None, cannot save tile to cache.")
            return

        with self._cache_access_lock:
            try:
                tile_cache_path.parent.mkdir(parents=True, exist_ok=True)
                if Image:
                    pil_image.save(tile_cache_path, format='PNG')
                    logger.debug(f"Saved tile to cache: {tile_cache_path}")
                else:
                    logger.error("Pillow's Image class is None, cannot save image.")

            except IOError as e_io_save:
                logger.error(f"IOError saving tile to cache {tile_cache_path}: {e_io_save}")
            except Exception as e_save_unexpected:
                logger.exception(
                    f"Unexpected error saving tile to cache {tile_cache_path}: {e_save_unexpected}"
                )

    def get_tile_image(
        self,
        zoom_level: int,
        tile_x: int,
        tile_y: int,
        force_online_refresh: bool = False
    ) -> Optional[ImageType]:
        """
        Retrieves a map tile image, using local cache first.
        If not cached or refresh is forced, attempts to download (if enabled).
        Returns a placeholder image if the tile cannot be retrieved.

        Args:
            zoom_level: The zoom level of the tile.
            tile_x: The X coordinate of the tile.
            tile_y: The Y coordinate of the tile.
            force_online_refresh: If True, bypasses cache and attempts download.

        Returns:
            A PIL Image object of the tile, or a placeholder image on failure.
            Returns None only if placeholder creation itself fails critically.
        """
        tile_coords_log_str = f"({zoom_level},{tile_x},{tile_y})"
        logger.debug(f"Requesting tile image for {tile_coords_log_str}")

        if not self.map_service.is_zoom_level_valid(zoom_level):
             logger.error(f"Invalid zoom level {zoom_level} for map service '{self.service_identifier_name}'. Cannot get tile.")
             if PIL_AVAILABLE_MANAGER:
                return self._create_placeholder_tile_image(f"Invalid Zoom {zoom_level} Tile {tile_coords_log_str}")
             else:
                logger.error("Pillow not available, cannot create placeholder for invalid zoom tile.")
                return None

        tile_cache_file = self._get_tile_cache_file_path(zoom_level, tile_x, tile_y)
        retrieved_image: Optional[ImageType] = None

        if not force_online_refresh:
            retrieved_image = self._load_tile_from_cache(tile_cache_file, tile_coords_log_str)

        if retrieved_image is None:
            retrieved_image = self._download_and_save_tile_to_cache(
                zoom_level, tile_x, tile_y, tile_cache_file, tile_coords_log_str
            )

        if retrieved_image is None:
            logger.warning(f"Failed to retrieve tile {tile_coords_log_str}. Using placeholder.")
            retrieved_image = self._create_placeholder_tile_image(tile_coords_log_str)
            if retrieved_image is None:
                logger.critical("Failed to create even a placeholder tile. Returning None.")

        return retrieved_image


    def stitch_map_image(
        self,
        zoom_level: int,
        x_tile_range: Tuple[int, int],
        y_tile_range: Tuple[int, int]
    ) -> Optional[ImageType]:
        """
        Retrieves and stitches multiple map tiles to form a larger composite map image.

        Args:
            zoom_level: The zoom level for all tiles.
            x_tile_range: Inclusive start and end X tile coordinates (min_x, max_x).
            y_tile_range: Inclusive start and end Y tile coordinates (min_y, max_y).

        Returns:
            A PIL Image object of the stitched map, or None if a critical error occurs.
            Missing individual tiles are replaced by placeholders.
        """
        logger.info(
            f"Request to stitch map: Zoom {zoom_level}, X-Range {x_tile_range}, Y-Range {y_tile_range}"
        )

        min_tile_x, max_tile_x = x_tile_range
        min_tile_y, max_tile_y = y_tile_range

        if not (min_tile_x <= max_tile_x and min_tile_y <= max_tile_y):
            logger.error(f"Invalid tile ranges for stitching: X={x_tile_range}, Y={y_tile_range}")
            if PIL_AVAILABLE_MANAGER:
                 try:
                      placeholder_img = Image.new("RGB", (self.tile_size * 3, self.tile_size * 3), (255, 150, 150))
                      if ImageDraw:
                          draw = ImageDraw.Draw(placeholder_img)
                          error_text = f"Stitch Failed\nInvalid Tile Ranges:\nX={x_tile_range}, Y={y_tile_range}"
                          try:
                              try:
                                from geoelevation.image_processor import DEFAULT_FONT
                                font_to_use = DEFAULT_FONT
                              except ImportError:
                                font_to_use = None

                              if font_to_use:
                                   if hasattr(draw, 'textbbox'):
                                       try:
                                          text_bbox = draw.textbbox((0,0), error_text, font=font_to_use, spacing=2)
                                          text_width = text_bbox[2] - text_bbox[0]
                                          text_height = text_bbox[3] - text_bbox[1]
                                          text_x = (placeholder_img.width - text_width) // 2
                                          text_y = (placeholder_img.height - text_height) // 2
                                          draw.text((text_x, text_y), error_text, fill="black", font=font_to_use, spacing=2, anchor="lt")
                                       except AttributeError:
                                            logger.warning("Pillow textbbox not available (Pillow < 8.0). Using textsize fallback for error text.")
                                            text_width, text_height = draw.textsize(error_text, font=font_to_use)
                                            text_x = (placeholder_img.width - text_width) // 2
                                            text_y = (placeholder_img.height - text_height) // 2
                                            draw.text((text_x, text_y), error_text, fill="black", font=font_to_use)
                                       except Exception as e_font_draw:
                                            logger.warning(f"Error drawing text with font on placeholder: {e_font_draw}. Falling back to simple draw.")
                                            draw.text((10, 10), error_text, fill="black")

                                   else:
                                     if font_to_use:
                                         text_width, text_height = draw.textsize(error_text, font=font_to_use)
                                         text_x = (placeholder_img.width - text_width) // 2
                                         text_y = (placeholder_img.height - text_height) // 2
                                         draw.text((text_x, text_y), error_text, fill="black", font=font_to_use)
                                     else:
                                         draw.text((10, 10), error_text, fill="black")

                          except Exception as e_draw:
                               logger.warning(f"Error drawing text on placeholder for invalid ranges: {e_draw}. Falling back to simple draw.")
                               if ImageDraw:
                                   draw.text((10, 10), error_text, fill="black")


                      return placeholder_img
                 except Exception as e_placeholder_fail:
                      logger.exception(f"Failed to create placeholder for invalid tile ranges: {e_placeholder_fail}")
                      return None

            else:
                 logger.error("Pillow not available, cannot create placeholder for invalid ranges.")
                 return None


        single_tile_pixel_size = self.tile_size

        if single_tile_pixel_size <= 0:
            logger.error(f"Invalid tile size ({single_tile_pixel_size}) stored in manager. Cannot stitch.")
            if PIL_AVAILABLE_MANAGER:
                try:
                    if ImageDraw is not None:
                         placeholder_img = Image.new("RGB", (256 * 3, 256 * 3), DEFAULT_PLACEHOLDER_COLOR_RGB)
                         draw = ImageDraw.Draw(placeholder_img)
                         error_text = f"Stitch Failed\nInvalid Tile Size:\n{single_tile_pixel_size}"
                         try:
                             try:
                                 from geoelevation.image_processor import DEFAULT_FONT
                                 font_to_use = DEFAULT_FONT
                             except ImportError:
                                  font_to_use = None

                             if font_to_use:
                                  if hasattr(draw, 'textbbox'):
                                       try:
                                            text_bbox = draw.textbbox((0,0), error_text, font=font_to_use, spacing=2)
                                            text_width = text_bbox[2] - text_bbox[0]
                                            text_height = text_bbox[3] - text_bbox[1]
                                            text_pos = ((placeholder_img.width - text_width) // 2, (placeholder_img.height - text_height) // 2)
                                            draw.text(text_pos, error_text, fill="black", font=font_to_use, spacing=2, anchor="lt")
                                       except AttributeError:
                                            text_width, text_height = draw.textsize(error_text, font=font_to_use)
                                            text_pos = ((placeholder_img.width - text_width) // 2, (placeholder_img.height - text_height) // 2)
                                            draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                       except Exception as e_font_draw:
                                            logger.warning(f"Error drawing text with font on placeholder: {e_font_draw}. Falling back to simple draw.")
                                            draw.text((10, 10), error_text, fill="black")

                                  else:
                                       if font_to_use:
                                           text_width, text_height = draw.textsize(error_text, font=font_to_use)
                                           text_pos = ((placeholder_img.width - text_width) // 2, (placeholder_img.height - text_height) // 2)
                                           draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                       else:
                                           draw.text((10, 10), error_text, fill="black")


                             else:
                                  draw.text((10, 10), error_text, fill="black")

                         except Exception as e_draw:
                              logger.warning(f"Error drawing text on placeholder: {e_draw}. Falling back to simple draw.")
                              if ImageDraw:
                                   draw.text((10, 10), error_text, fill="black")

                         return placeholder_img
                    else:
                          logger.error("Pillow's ImageDraw class is None, cannot create placeholder image.")
                          return None

                except Exception as e_placeholder_fail:
                     logger.exception(f"Failed to create large placeholder for stitching error: {e_placeholder_fail}")
                     return None

            else:
                 logger.error("Pillow not available, cannot create placeholder for invalid tile size.")
                 return None


        num_tiles_wide = (max_tile_x - min_tile_x) + 1
        num_tiles_high = (max_tile_y - min_tile_y) + 1


        total_image_width = num_tiles_wide * single_tile_pixel_size
        total_image_height = num_tiles_high * single_tile_pixel_size
        logger.debug(
            f"Stitched image dimensions: {total_image_width}x{total_image_height} "
            f"({num_tiles_wide}x{num_tiles_high} tiles of {single_tile_pixel_size}px)"
        )

        MAX_IMAGE_DIMENSION = 16384

        if total_image_width > MAX_IMAGE_DIMENSION or total_image_height > MAX_IMAGE_DIMENSION:
            logger.error(
                f"Requested stitched image size ({total_image_width}x{total_image_height}) "
                f"exceeds maximum allowed dimension ({MAX_IMAGE_DIMENSION}). Aborting stitch."
            )
            if PIL_AVAILABLE_MANAGER:
                try:
                    if ImageDraw is not None:
                        placeholder_img = Image.new("RGB", (256 * 3, 256 * 3), (255, 100, 100))
                        draw = ImageDraw.Draw(placeholder_img)
                        error_text = f"Stitch Failed\nImage too large:\n{total_image_width}x{total_image_height}px"
                        try:
                             try:
                                 from geoelevation.image_processor import DEFAULT_FONT
                                 font_to_use = DEFAULT_FONT
                             except ImportError:
                                 font_to_use = None

                             if font_to_use:
                                  if hasattr(draw, 'textbbox'):
                                      try:
                                        text_bbox = draw.textbbox((0,0), error_text, font=font_to_use, spacing=2)
                                        text_w = text_bbox[2] - text_bbox[0]
                                        text_h = text_bbox[3] - text_bbox[1]
                                        text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                        draw.text(text_pos, error_text, fill="black", font=font_to_use, spacing=2, anchor="lt")
                                      except AttributeError:
                                        text_w, text_h = draw.textsize(error_text, font=font_to_use)
                                        text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                        draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                      except Exception as e_font_draw:
                                         logger.warning(f"Error drawing text with font on placeholder: {e_font_draw}. Falling back to simple draw.")
                                         draw.text((10, 10), error_text, fill="black")
                                  else:
                                     if font_to_use:
                                         text_w, text_h = draw.textsize(error_text, font=font_to_use)
                                         text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                         draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                     else:
                                         draw.text((10, 10), error_text, fill="black")

                             else:
                                draw.text((10, 10), error_text, fill="black")

                        except Exception as e_draw:
                             logger.warning(f"Error drawing text on placeholder: {e_draw}. Falling back to simple draw.")
                             if ImageDraw:
                                draw.text((10, 10), error_text, fill="black")

                        return placeholder_img
                    else:
                         logger.error("Pillow's ImageDraw class is None, cannot create placeholder image.")
                         return None

                except Exception as e_placeholder_fail:
                     logger.exception(f"Failed to create large placeholder for size error: {e_placeholder_fail}")
                     return None

            else:
                 logger.error("Pillow not available, cannot create placeholder for excessive size request.")
                 return None


        try:
            if PIL_AVAILABLE_MANAGER:
                if Image:
                    stitched_map_image = Image.new("RGB", (total_image_width, total_image_height))
                else:
                     raise ImportError("Pillow's Image class is None.")
            else:
                 raise ImportError("Pillow not available to create new image.")

        except Exception as e_create_blank:
            logger.exception(f"Failed to create blank image for stitching: {e_create_blank}. Dimensions: {total_image_width}x{total_image_height}")
            if PIL_AVAILABLE_MANAGER:
                try:
                    if ImageDraw is not None:
                        placeholder_img = Image.new("RGB", (256 * 3, 256 * 3), (255, 100, 100))
                        draw = ImageDraw.Draw(placeholder_img)
                        error_text = f"Stitch Failed\nCannot create image:\n{e_create_blank}"
                        try:
                             try:
                                 from geoelevation.image_processor import DEFAULT_FONT
                                 font_to_use = DEFAULT_FONT
                             except ImportError:
                                font_to_use = None

                             if font_to_use:
                                  if hasattr(draw, 'textbbox'):
                                      try:
                                        text_bbox = draw.textbbox((0,0), error_text, font=font_to_use, spacing=2)
                                        text_w = text_bbox[2] - text_bbox[0]
                                        text_h = text_bbox[3] - text_bbox[1]
                                        text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                        draw.text(text_pos, error_text, fill="black", font=font_to_use, spacing=2, anchor="lt")
                                      except AttributeError:
                                        text_w, text_h = draw.textsize(error_text, font=font_to_use)
                                        text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                        draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                      except Exception as e_font_draw:
                                         logger.warning(f"Error drawing text with font on placeholder: {e_font_draw}. Falling back to simple draw.")
                                         draw.text((10, 10), error_text, fill="black")
                                  else:
                                       if font_to_use:
                                           text_w, text_h = draw.textsize(error_text, font=font_to_use)
                                           text_pos = ((placeholder_img.width - text_w) // 2, (placeholder_img.height - text_h) // 2)
                                           draw.text(text_pos, error_text, fill="black", font=font_to_use)
                                       else:
                                           draw.text((10, 10), error_text, fill="black")

                             else:
                                draw.text((10, 10), error_text, fill="black")

                        except Exception as e_draw:
                             logger.warning(f"Error drawing text on placeholder: {e_draw}. Falling back to simple draw.")
                             if ImageDraw:
                                draw.text((10, 10), error_text, fill="black")

                        return placeholder_img
                    else:
                         logger.error("Pillow's ImageDraw class is None, cannot create placeholder image.")
                         return None


                except Exception as e_placeholder_fail:
                     logger.exception(f"Failed to create large placeholder for memory error: {e_placeholder_fail}")
                     return None

            else:
                 logger.error("Pillow not available, cannot create placeholder for image creation error.")
                 return None


        for row_index, current_tile_y in enumerate(range(min_tile_y, max_tile_y + 1)):
            for col_index, current_tile_x in enumerate(range(min_tile_x, max_tile_x + 1)):
                tile_image_pil = self.get_tile_image(zoom_level, current_tile_x, current_tile_y)

                if tile_image_pil is None:
                    logger.critical(
                        f"Critical error: get_tile_image returned None for ({zoom_level},{current_tile_x},{current_tile_y}). Aborting stitch."
                    )
                    return None

                paste_position_x = col_index * single_tile_pixel_size
                paste_position_y = row_index * single_tile_pixel_size
                logger.debug(
                    f"Pasting tile ({zoom_level},{current_tile_x},{current_tile_y}) at "
                    f"pixel position ({paste_position_x},{paste_position_y})"
                )
                try:
                    if tile_image_pil and tile_image_pil.size != (self.tile_size, self.tile_size):
                         logger.warning(f"Tile image size {tile_image_pil.size} doesn't match expected {self.tile_size}. Resizing for stitch.")
                         if PIL_AVAILABLE_MANAGER and Image:
                            tile_image_pil = tile_image_pil.resize((self.tile_size, self.tile_size), Image.Resampling.LANCZOS)
                         else:
                            logger.error("Pillow not available, cannot resize tile for stitch.")
                            continue

                    if tile_image_pil:
                         stitched_map_image.paste(tile_image_pil, (paste_position_x, paste_position_y))
                except Exception as e_paste:
                    logger.exception(
                        f"Error pasting tile ({zoom_level},{current_tile_x},{current_tile_y}) "
                        f"at ({paste_position_x},{paste_position_y}): {e_paste}"
                    )

        logger.info(f"Map stitching complete for zoom {zoom_level}, X={x_tile_range}, Y={y_tile_range}.")
        return stitched_map_image


    def _create_placeholder_tile_image(self, identifier: str = "N/A") -> Optional[ImageType]:
        """
        Creates and returns a placeholder tile image (e.g., a grey square).
        Includes optional text identifier on the placeholder.
        """
        if not (PIL_AVAILABLE_MANAGER and ImageDraw is not None):
            logger.warning("Cannot create placeholder tile: Pillow or ImageDraw library not available.")
            return None
        try:
            tile_pixel_size = self.tile_size
            placeholder_color = DEFAULT_PLACEHOLDER_COLOR_RGB

            if Image:
                placeholder_img = Image.new("RGB", (tile_pixel_size, tile_pixel_size), color=placeholder_color)
            else:
                logger.error("Pillow's Image class is None, cannot create placeholder image.")
                return None

            if ImageDraw:
                draw = ImageDraw.Draw(placeholder_img)
            else:
                logger.error("Pillow's ImageDraw class is None, cannot draw on placeholder.")
                return placeholder_img


            overlay_text = f"Tile Fail\n{identifier}"

            try:
                 try:
                      from geoelevation.image_processor import DEFAULT_FONT
                      font_to_use = DEFAULT_FONT
                 except ImportError:
                      font_to_use = None

                 if font_to_use is not None:
                     if hasattr(draw, 'textbbox'):
                          try:
                               text_bbox = draw.textbbox((0,0), overlay_text, font=font_to_use, spacing=2)
                               text_width = text_bbox[2] - text_bbox[0]
                               text_height = text_bbox[3] - text_bbox[1]

                               text_x = (tile_pixel_size - text_width) // 2
                               text_y = (tile_pixel_size - text_height) // 2

                               bg_padding = 1
                               bg_coords = [
                                   text_x - bg_padding,
                                   text_y - bg_padding,
                                   text_x + text_width + bg_padding,
                                   text_y + text_height + bg_padding,
                               ]
                               draw.rectangle(bg_coords, fill="rgba(0, 0, 0, 150)")

                               draw.text((text_x, text_y), overlay_text, fill="white", font=font_to_use, spacing=2, anchor="lt")


                          except AttributeError:
                                logger.warning("Pillow textbbox not available (Pillow < 8.0). Using textsize fallback for placeholder text.")
                                if font_to_use:
                                    text_width, text_height = draw.textsize(overlay_text, font=font_to_use)
                                    if "\n" in overlay_text:
                                         line_count = overlay_text.count("\n") + 1
                                         pass

                                    text_x = (tile_pixel_size - text_width) // 2
                                    text_y = (tile_pixel_size - text_height) // 2

                                    bg_padding = 1
                                    bg_coords = [text_x - bg_padding, text_y - bg_padding,
                                                 text_x + text_width + bg_padding, text_y + text_height + bg_padding]
                                    draw.rectangle(bg_coords, fill="rgba(0, 0, 0, 150)")

                                    draw.text((text_x, text_y), overlay_text, fill="white", font=font_to_use)

                                else:
                                     draw.text((10, 10), overlay_text, fill="black")


                          except Exception as e_font_draw:
                                logger.warning(f"Error drawing text with font on placeholder: {e_font_draw}. Falling back to simple draw.")
                                draw.text((10, 10), overlay_text, fill="black")

                     else:
                          if font_to_use:
                              draw.text((10, 10), overlay_text, fill="black", font=font_to_use)
                          else:
                              draw.text((10, 10), overlay_text, fill="black")


                 else:
                      logger.debug("No font available for placeholder text drawing.")
                      draw.text((10, 10), overlay_text, fill="black")


            except Exception as e_draw:
                 logger.warning(f"Error drawing text on placeholder: {e_draw}. Falling back to simple draw.")
                 if ImageDraw:
                     draw.text((10, 10), overlay_text, fill="black")


            return placeholder_img

        except Exception as e_placeholder:
            logger.exception(f"Error creating placeholder tile image: {e_placeholder}")
            return None

    def _get_bounds_for_tile_range(
        self,
        zoom: int,
        tile_ranges: Tuple[Tuple[int, int], Tuple[int, int]]
    ) -> Optional[Tuple[float, float, float, float]]:
        """
        Calculates the precise geographic bounds covered by a given range of tiles.
        Requires 'mercantile' library.
        """
        # MODIFIED: Removed check for MERCANTILE_MODULE_LOCALLY_AVAILABLE.
        # WHY: This constant is defined in map_utils.py, not map_manager.py.
        #      Instead, check if the locally imported `mercantile` is None.
        # HOW: Removed the check for MERCANTILE_MODULE_LOCALLY_AVAILABLE.
        if mercantile is None: # Check if mercantile is None from the local import attempt
            logger.error("mercantile library not found or is None, cannot calculate bounds for tile range.")
            return None

        try:
            min_x, max_x = tile_ranges[0]
            min_y, max_y = tile_ranges[1]

            # Get bounds of the top-left tile and bottom-right tile
            # mercantile.bounds(x, y, z) returns (west, south, east, north)
            # MODIFIED: Check for mercantile before using mercantile.bounds.
            # WHY: Prevent AttributeError. (Redundant with the check at the start of the method, but defensive).
            # HOW: Added `if mercantile:`.
            if mercantile:
                 top_left_tile_bounds = mercantile.bounds(min_x, min_y, zoom)
                 bottom_right_tile_bounds = mercantile.bounds(max_x, max_y, zoom)
            else:
                 # This branch should ideally not be hit due to the check at the method start.
                 logger.error("mercantile library is None during bounds calculation step.")
                 return None


            overall_west_lon = top_left_tile_bounds.west
            overall_south_lat = bottom_right_tile_bounds.south
            overall_east_lon = bottom_right_tile_bounds.east
            overall_north_lat = top_left_tile_bounds.north

            return (overall_west_lon, overall_south_lat, overall_east_lon, overall_north_lat)
        except Exception as e_bounds_calc:
            logger.exception(
                f"Error calculating geographic bounds for tile range {tile_ranges} at zoom {zoom}: {e_bounds_calc}"
            )
            return None


    def clear_entire_service_cache(self) -> None:
        """Deletes all cached tiles for the current map service."""
        logger.info(f"Attempting to clear entire cache for service '{self.service_identifier_name}' at {self.service_specific_cache_dir}")
        if not self.service_specific_cache_dir.exists():
            logger.warning(f"Cache directory '{self.service_specific_cache_dir}' does not exist. Nothing to clear.")
            return

        with self._cache_access_lock:
            try:
                if self.service_specific_cache_dir.is_dir():
                    shutil.rmtree(self.service_specific_cache_dir)
                    logger.info(f"Successfully cleared cache at {self.service_specific_cache_dir}.")
                    self._ensure_service_cache_directory_exists()
                else:
                    logger.warning(f"Cache path '{self.service_specific_cache_dir}' is not a directory.")
            except OSError as e_os_clear:
                logger.error(f"OS Error clearing cache at '{self.service_specific_cache_dir}': {e_os_clear}")
            except Exception as e_clear_unexpected:
                logger.exception(
                    f"Unexpected error clearing cache '{self.service_specific_cache_dir}': {e_clear_unexpected}"
                )