"""
SerieScanner - Scans directories for anime series and missing episodes.

This module provides functionality to scan anime directories, identify
missing episodes, and report progress through callback interfaces.
"""

import logging
import os
import re
import traceback
import uuid
from typing import Callable, Iterable, Iterator, Optional

from src.core.entities.series import Serie
from src.core.exceptions.Exceptions import (
    MatchNotFoundError,
    NoKeyFoundException,
)
from src.core.interfaces.callbacks import (
    CallbackManager,
    CompletionContext,
    ErrorContext,
    OperationType,
    ProgressContext,
    ProgressPhase,
)
from src.core.providers.base_provider import Loader

logger = logging.getLogger(__name__)
error_logger = logging.getLogger("error")
no_key_found_logger = logging.getLogger("series.nokey")


class SerieScanner:
    """
    Scans directories for anime series and identifies missing episodes.

    Supports progress callbacks for real-time scanning updates.
    """

    def __init__(
        self,
        basePath: str,
        loader: Loader,
        callback_manager: Optional[CallbackManager] = None
    ) -> None:
        """
        Initialize the SerieScanner.

        Args:
            basePath: Base directory containing anime series
            loader: Loader instance for fetching series information
            callback_manager: Optional callback manager for progress updates
            
        Raises:
            ValueError: If basePath is invalid or doesn't exist
        """
        # Validate basePath to prevent directory traversal attacks
        if not basePath or not basePath.strip():
            raise ValueError("Base path cannot be empty")
        
        # Resolve to absolute path and validate it exists
        abs_path = os.path.abspath(basePath)
        if not os.path.exists(abs_path):
            raise ValueError(f"Base path does not exist: {abs_path}")
        if not os.path.isdir(abs_path):
            raise ValueError(f"Base path is not a directory: {abs_path}")
        
        self.directory: str = abs_path
        self.keyDict: dict[str, Serie] = {}
        self.loader: Loader = loader
        self._callback_manager: CallbackManager = (
            callback_manager or CallbackManager()
        )
        self._current_operation_id: Optional[str] = None

        logger.info("Initialized SerieScanner with base path: %s", abs_path)

    @property
    def callback_manager(self) -> CallbackManager:
        """Get the callback manager instance."""
        return self._callback_manager

    def reinit(self) -> None:
        """Reinitialize the series dictionary (keyed by serie.key)."""
        self.keyDict: dict[str, Serie] = {}

    def get_total_to_scan(self) -> int:
        """Get the total number of folders to scan.
        
        Returns:
            Total count of folders with MP4 files
        """
        result = self.__find_mp4_files()
        return sum(1 for _ in result)

    def scan(
        self,
        callback: Optional[Callable[[str, int], None]] = None
    ) -> None:
        """
        Scan directories for anime series and missing episodes.

        Args:
            callback: Optional legacy callback function (folder, count)

        Raises:
            Exception: If scan fails critically
        """
        # Generate unique operation ID
        self._current_operation_id = str(uuid.uuid4())

        logger.info("Starting scan for missing episodes")

        # Notify scan starting
        self._callback_manager.notify_progress(
            ProgressContext(
                operation_type=OperationType.SCAN,
                operation_id=self._current_operation_id,
                phase=ProgressPhase.STARTING,
                current=0,
                total=0,
                percentage=0.0,
                message="Initializing scan"
            )
        )

        try:
            # Get total items to process
            total_to_scan = self.get_total_to_scan()
            logger.info("Total folders to scan: %d", total_to_scan)

            # The scanner enumerates folders with mp4 files, loads existing
            # metadata, calculates the missing episodes via the provider, and
            # persists the refreshed metadata while emitting progress events.
            result = self.__find_mp4_files()
            counter = 0

            for folder, mp4_files in result:
                try:
                    counter += 1

                    # Calculate progress
                    if total_to_scan > 0:
                        percentage = (counter / total_to_scan) * 100
                    else:
                        percentage = 0.0

                    # Progress is surfaced both through the callback manager
                    # (for the web/UI layer) and, for compatibility, through a
                    # legacy callback that updates CLI progress bars.
                    # Notify progress
                    self._callback_manager.notify_progress(
                        ProgressContext(
                            operation_type=OperationType.SCAN,
                            operation_id=self._current_operation_id,
                            phase=ProgressPhase.IN_PROGRESS,
                            current=counter,
                            total=total_to_scan,
                            percentage=percentage,
                            message=f"Scanning: {folder}",
                            details=f"Found {len(mp4_files)} episodes"
                        )
                    )

                    # Call legacy callback if provided
                    if callback:
                        callback(folder, counter)

                    serie = self.__read_data_from_file(folder)
                    if (
                        serie is not None
                        and serie.key
                        and serie.key.strip()
                    ):
                        # Delegate the provider to compare local files with
                        # remote metadata, yielding missing episodes per
                        # season. Results are saved back to disk so that both
                        # CLI and API consumers see consistent state.
                        missing_episodes, _site = (
                            self.__get_missing_episodes_and_season(
                                serie.key, mp4_files
                            )
                        )
                        serie.episodeDict = missing_episodes
                        serie.folder = folder
                        data_path = os.path.join(
                            self.directory, folder, 'data'
                        )
                        serie.save_to_file(data_path)

                        # Store by key (primary identifier), not folder
                        if serie.key in self.keyDict:
                            logger.error(
                                "Duplicate series found with key '%s' "
                                "(folder: '%s')",
                                serie.key,
                                folder
                            )
                        else:
                            self.keyDict[serie.key] = serie
                            logger.debug(
                                "Stored series with key '%s' (folder: '%s')",
                                serie.key,
                                folder
                            )
                            no_key_found_logger.info(
                                "Saved Serie: '%s'", str(serie)
                            )

                except NoKeyFoundException as nkfe:
                    # Log error and notify via callback
                    error_msg = f"Error processing folder '{folder}': {nkfe}"
                    logger.error(error_msg)

                    self._callback_manager.notify_error(
                        ErrorContext(
                            operation_type=OperationType.SCAN,
                            operation_id=self._current_operation_id,
                            error=nkfe,
                            message=error_msg,
                            recoverable=True,
                            metadata={"folder": folder, "key": None}
                        )
                    )
                except Exception as e:
                    # Log error and notify via callback
                    error_msg = (
                        f"Folder: '{folder}' - "
                        f"Unexpected error: {e}"
                    )
                    error_logger.error(
                        "%s\n%s",
                        error_msg,
                        traceback.format_exc()
                    )

                    self._callback_manager.notify_error(
                        ErrorContext(
                            operation_type=OperationType.SCAN,
                            operation_id=self._current_operation_id,
                            error=e,
                            message=error_msg,
                            recoverable=True,
                            metadata={"folder": folder, "key": None}
                        )
                    )
                    continue

            # Notify scan completion
            self._callback_manager.notify_completion(
                CompletionContext(
                    operation_type=OperationType.SCAN,
                    operation_id=self._current_operation_id,
                    success=True,
                    message=f"Scan completed. Processed {counter} folders.",
                    statistics={
                        "total_folders": counter,
                        "series_found": len(self.keyDict)
                    }
                )
            )

            logger.info(
                "Scan completed. Processed %d folders, found %d series",
                counter,
                len(self.keyDict)
            )

        except Exception as e:
            # Critical error - notify and re-raise
            error_msg = f"Critical scan error: {e}"
            logger.error("%s\n%s", error_msg, traceback.format_exc())

            self._callback_manager.notify_error(
                ErrorContext(
                    operation_type=OperationType.SCAN,
                    operation_id=self._current_operation_id,
                    error=e,
                    message=error_msg,
                    recoverable=False
                )
            )

            self._callback_manager.notify_completion(
                CompletionContext(
                    operation_type=OperationType.SCAN,
                    operation_id=self._current_operation_id,
                    success=False,
                    message=error_msg
                )
            )

            raise

    def __find_mp4_files(self) -> Iterator[tuple[str, list[str]]]:
        """Find all .mp4 files in the directory structure."""
        logger.info("Scanning for .mp4 files")
        for anime_name in os.listdir(self.directory):
            anime_path = os.path.join(self.directory, anime_name)
            if os.path.isdir(anime_path):
                mp4_files: list[str] = []
                has_files = False
                for root, _, files in os.walk(anime_path):
                    for file in files:
                        if file.endswith(".mp4"):
                            mp4_files.append(os.path.join(root, file))
                            has_files = True
                yield anime_name, mp4_files if has_files else []

    def __remove_year(self, input_string: str) -> str:
        """Remove year information from input string."""
        cleaned_string = re.sub(r'\(\d{4}\)', '', input_string).strip()
        logger.debug(
            "Removed year from '%s' -> '%s'",
            input_string,
            cleaned_string
        )
        return cleaned_string

    def __read_data_from_file(self, folder_name: str) -> Optional[Serie]:
        """Read serie data from file or key file.
        
        Args:
            folder_name: Filesystem folder name
                        (used only to locate data files)
            
        Returns:
            Serie object with valid key if found, None otherwise
            
        Note:
            The returned Serie will have its 'key' as the primary identifier.
            The 'folder' field is metadata only.
        """
        folder_path = os.path.join(self.directory, folder_name)
        key = None
        key_file = os.path.join(folder_path, 'key')
        serie_file = os.path.join(folder_path, 'data')

        if os.path.exists(key_file):
            with open(key_file, 'r', encoding='utf-8') as file:
                key = file.read().strip()
                logger.info(
                    "Key found for folder '%s': %s",
                    folder_name,
                    key
                )
                return Serie(key, "", "aniworld.to", folder_name, dict())

        if os.path.exists(serie_file):
            with open(serie_file, "rb") as file:
                logger.info(
                    "load serie_file from '%s': %s",
                    folder_name,
                    serie_file
                )
                return Serie.load_from_file(serie_file)

        return None

    def __get_episode_and_season(self, filename: str) -> tuple[int, int]:
        """Extract season and episode numbers from filename.
        
        Args:
            filename: Filename to parse
            
        Returns:
            Tuple of (season, episode) as integers
            
        Raises:
            MatchNotFoundError: If pattern not found
        """
        pattern = r'S(\d+)E(\d+)'
        match = re.search(pattern, filename)
        if match:
            season = match.group(1)
            episode = match.group(2)
            logger.debug(
                "Extracted season %s, episode %s from '%s'",
                season,
                episode,
                filename
            )
            return int(season), int(episode)
        else:
            logger.error(
                "Failed to find season/episode pattern in '%s'",
                filename
            )
            raise MatchNotFoundError(
                "Season and episode pattern not found in the filename."
            )

    def __get_episodes_and_seasons(
        self,
        mp4_files: Iterable[str]
    ) -> dict[int, list[int]]:
        """Get episodes grouped by season from mp4 files.
        
        Args:
            mp4_files: List of MP4 filenames
            
        Returns:
            Dictionary mapping season to list of episode numbers
        """
        episodes_dict: dict[int, list[int]] = {}

        for file in mp4_files:
            season, episode = self.__get_episode_and_season(file)

            if season in episodes_dict:
                episodes_dict[season].append(episode)
            else:
                episodes_dict[season] = [episode]
        return episodes_dict

    def __get_missing_episodes_and_season(
        self,
        key: str,
        mp4_files: Iterable[str]
    ) -> tuple[dict[int, list[int]], str]:
        """Get missing episodes for a serie.
        
        Args:
            key: Series key
            mp4_files: List of MP4 filenames
            
        Returns:
            Tuple of (episodes_dict, site_name)
        """
        # key season , value count of episodes
        expected_dict = self.loader.get_season_episode_count(key)
        filedict = self.__get_episodes_and_seasons(mp4_files)
        episodes_dict: dict[int, list[int]] = {}
        for season, expected_count in expected_dict.items():
            existing_episodes = filedict.get(season, [])
            missing_episodes = [
                ep for ep in range(1, expected_count + 1)
                if ep not in existing_episodes
                and self.loader.is_language(season, ep, key)
            ]

            if missing_episodes:
                episodes_dict[season] = missing_episodes

        return episodes_dict, "aniworld.to"