"""
NAIA-WEB Partition Loader
TGP file loading for Quick Search functionality

Reference: NAIA2.0/ui/remote/quick_search_tab.py (145-255)
"""

import struct
import lzma
import pickle
from pathlib import Path
from typing import Dict, List, Set, Optional
from collections import Counter

try:
    import numpy as np
    HAS_NUMPY = True
except ImportError:
    HAS_NUMPY = False
    np = None


# Data directory
DATA_DIR = Path(__file__).parent / "quick_search"


class SinglePartitionStore:
    """
    Single partition storage (inverted index based) - Quick Search lightweight version

    Reference: NAIA2.0/ui/remote/quick_search_tab.py SinglePartitionStore class
    """

    MAGIC = b'TGP1'
    VERSION = 1

    def __init__(self):
        self.num_events: int = 0
        self._event_tag_indices = None
        self._event_tag_indptr = None
        self._event_counts = None
        self._tag_to_events: Dict[int, object] = {}
        self._loaded: bool = False

    @classmethod
    def load(cls, input_path: str) -> 'SinglePartitionStore':
        """Load partition file"""
        if not HAS_NUMPY:
            raise RuntimeError("NumPy is required")

        store = cls()

        with open(input_path, 'rb') as f:
            magic = f.read(4)
            if magic != cls.MAGIC:
                raise ValueError(f"Invalid format: {magic}")

            _ = struct.unpack('<H', f.read(2))[0]  # version
            compressed_len = struct.unpack('<I', f.read(4))[0]
            compressed = f.read(compressed_len)

        serialized = lzma.decompress(compressed)
        data = pickle.loads(serialized)

        store.num_events = data['num_events']
        store._event_tag_indices = np.frombuffer(data['event_tag_indices'], dtype=np.uint16).copy()
        store._event_tag_indptr = np.frombuffer(data['event_tag_indptr'], dtype=np.int32).copy()
        store._event_counts = np.frombuffer(data['event_counts'], dtype=np.int32).copy()

        store._tag_to_events = {
            int(k): np.frombuffer(v, dtype=np.int32).copy()
            for k, v in data['tag_to_events'].items()
        }

        store._loaded = True
        return store

    def filter_events(
        self,
        required_tags: Optional[List[str]] = None,
        excluded_tags: Optional[List[str]] = None,
        tag_to_id: Optional[Dict[str, int]] = None
    ):
        """Return event indices matching conditions"""
        if not self._loaded or not HAS_NUMPY:
            return np.array([], dtype=np.int32) if HAS_NUMPY else []

        # Start with all events
        candidates = set(range(self.num_events))

        # Required tags
        if required_tags and tag_to_id:
            for tag in required_tags:
                if tag in tag_to_id:
                    tag_id = tag_to_id[tag]
                    if tag_id in self._tag_to_events:
                        candidates &= set(self._tag_to_events[tag_id])
                    else:
                        return np.array([], dtype=np.int32)
                else:
                    return np.array([], dtype=np.int32)

        # Excluded tags
        if excluded_tags and tag_to_id:
            for tag in excluded_tags:
                if tag in tag_to_id:
                    tag_id = tag_to_id[tag]
                    if tag_id in self._tag_to_events:
                        candidates -= set(self._tag_to_events[tag_id])

        return np.array(sorted(candidates), dtype=np.int32)

    def get_tag_counts(
        self,
        event_indices=None,
        id_to_tag: Optional[Dict[int, str]] = None
    ) -> Counter:
        """Count events per tag"""
        if not HAS_NUMPY or id_to_tag is None:
            return Counter()

        if event_indices is None:
            # Total tag counts
            return Counter({
                id_to_tag[tag_id]: len(events)
                for tag_id, events in self._tag_to_events.items()
                if tag_id in id_to_tag
            })

        event_set = set(event_indices)
        return Counter({
            id_to_tag[tag_id]: len(set(events) & event_set)
            for tag_id, events in self._tag_to_events.items()
            if tag_id in id_to_tag
        })

    def get_event_tags(
        self,
        event_idx: int,
        id_to_tag: Optional[Dict[int, str]] = None
    ) -> Set[str]:
        """Return tags for an event"""
        if not self._loaded or id_to_tag is None:
            return set()

        if event_idx < 0 or event_idx >= self.num_events:
            return set()

        start = self._event_tag_indptr[event_idx]
        end = self._event_tag_indptr[event_idx + 1]
        tag_ids = self._event_tag_indices[start:end]

        return {id_to_tag[int(tid)] for tid in tag_ids if int(tid) in id_to_tag}


class PartitionMetadata:
    """
    Metadata for partition files

    Reference: NAIA2.0/ui/remote/quick_search_tab.py metadata loading
    """

    MAGIC = b'TGPS'

    def __init__(self):
        self.tag_to_id: Dict[str, int] = {}
        self.id_to_tag: Dict[int, str] = {}
        self.tag_freq: Dict[str, int] = {}
        self.partitions: Dict[str, Dict] = {}
        self._loaded: bool = False

    @classmethod
    def load(cls, input_path: str) -> 'PartitionMetadata':
        """Load metadata file"""
        meta = cls()

        with open(input_path, 'rb') as f:
            magic = f.read(4)
            if magic != cls.MAGIC:
                raise ValueError(f"Invalid metadata format: {magic}")

            _ = struct.unpack('<H', f.read(2))[0]  # version
            compressed_len = struct.unpack('<I', f.read(4))[0]
            compressed = f.read(compressed_len)

        serialized = lzma.decompress(compressed)
        data = pickle.loads(serialized)

        meta.tag_to_id = data.get('tag_to_id', {})
        meta.id_to_tag = data.get('id_to_tag', {})
        meta.tag_freq = data.get('tag_freq', {})
        meta.partitions = data.get('partitions', {})
        meta._loaded = True

        return meta

    @property
    def is_loaded(self) -> bool:
        return self._loaded

    def get_partition_names(self) -> List[str]:
        """Return list of available partition names"""
        return list(self.partitions.keys())


class PartitionManager:
    """
    Manages partition loading and caching
    """

    def __init__(self):
        self._metadata: Optional[PartitionMetadata] = None
        self._loaded_partitions: Dict[str, SinglePartitionStore] = {}
        self._data_dir = DATA_DIR

    def is_data_available(self) -> bool:
        """Check if partition data files are available"""
        metadata_path = self._data_dir / "metadata.tgpm"
        return metadata_path.exists()

    def load_metadata(self) -> Optional[PartitionMetadata]:
        """Load partition metadata"""
        if self._metadata is not None:
            return self._metadata

        metadata_path = self._data_dir / "metadata.tgpm"
        if not metadata_path.exists():
            return None

        try:
            self._metadata = PartitionMetadata.load(str(metadata_path))
            return self._metadata
        except Exception as e:
            print(f"Error loading metadata: {e}")
            return None

    def get_metadata(self) -> Optional[PartitionMetadata]:
        """Get loaded metadata (load if needed)"""
        if self._metadata is None:
            self.load_metadata()
        return self._metadata

    def load_partition(self, partition_name: str) -> Optional[SinglePartitionStore]:
        """Load a specific partition"""
        if partition_name in self._loaded_partitions:
            return self._loaded_partitions[partition_name]

        partition_path = self._data_dir / f"{partition_name}.tgp"
        if not partition_path.exists():
            print(f"Partition file not found: {partition_path}")
            return None

        try:
            store = SinglePartitionStore.load(str(partition_path))
            self._loaded_partitions[partition_name] = store
            return store
        except Exception as e:
            print(f"Error loading partition {partition_name}: {e}")
            return None

    def unload_partition(self, partition_name: str):
        """Unload a partition to free memory"""
        if partition_name in self._loaded_partitions:
            del self._loaded_partitions[partition_name]

    def unload_all(self):
        """Unload all partitions"""
        self._loaded_partitions.clear()

    def get_partition_filename(self, rating: str, person: str) -> str:
        """
        Get partition filename from rating and person category

        Args:
            rating: 'g', 's', 'q', or 'e'
            person: person category like '1girl_solo'

        Returns:
            Partition name like 'g_1girl_solo'
        """
        return f"{rating}_{person}"