"""
Metadata models for RAG optimization.
Implements structured metadata for knowledge chunks.
Reference: rag-optimization/spec.md Section 3.2
"""

from dataclasses import dataclass, field
from datetime import date, datetime
from enum import Enum
from typing import Any

from pydantic import BaseModel


class RetrievalStrategy(str, Enum):
    """Retrieval strategy options."""
    VECTOR_ONLY = "vector"
    BM25_ONLY = "bm25"
    HYBRID = "hybrid"
    TWO_STAGE = "two_stage"


class ChunkMetadataModel(BaseModel):
    """Pydantic model for API serialization."""
    category: str = ""
    subcategory: str = ""
    target_audience: list[str] = []
    source_doc: str = ""
    source_url: str = ""
    department: str = ""
    valid_from: str | None = None
    valid_until: str | None = None
    priority: int = 5
    keywords: list[str] = []


@dataclass
class ChunkMetadata:
    """
    Metadata for knowledge chunks.
    Reference: rag-optimization/spec.md Section 3.2.2
    """
    category: str = ""
    subcategory: str = ""
    target_audience: list[str] = field(default_factory=list)
    source_doc: str = ""
    source_url: str = ""
    department: str = ""
    valid_from: date | None = None
    valid_until: date | None = None
    priority: int = 5
    keywords: list[str] = field(default_factory=list)

    def to_dict(self) -> dict[str, Any]:
        """Convert to dictionary for storage."""
        return {
            "category": self.category,
            "subcategory": self.subcategory,
            "target_audience": self.target_audience,
            "source_doc": self.source_doc,
            "source_url": self.source_url,
            "department": self.department,
            "valid_from": self.valid_from.isoformat() if self.valid_from else None,
            "valid_until": self.valid_until.isoformat() if self.valid_until else None,
            "priority": self.priority,
            "keywords": self.keywords,
        }

    @classmethod
    def from_dict(cls, data: dict[str, Any]) -> "ChunkMetadata":
        """Create from dictionary."""
        return cls(
            category=data.get("category", ""),
            subcategory=data.get("subcategory", ""),
            target_audience=data.get("target_audience", []),
            source_doc=data.get("source_doc", ""),
            source_url=data.get("source_url", ""),
            department=data.get("department", ""),
            valid_from=date.fromisoformat(data["valid_from"]) if data.get("valid_from") else None,
            valid_until=date.fromisoformat(data["valid_until"]) if data.get("valid_until") else None,
            priority=data.get("priority", 5),
            keywords=data.get("keywords", []),
        )


@dataclass
class MetadataFilter:
    """
    Filter conditions for metadata-based retrieval.
    Reference: rag-optimization/spec.md Section 4.1
    """
    categories: list[str] | None = None
    target_audiences: list[str] | None = None
    departments: list[str] | None = None
    valid_only: bool = True
    min_priority: int | None = None
    keywords: list[str] | None = None

    def to_qdrant_filter(self) -> dict[str, Any] | None:
        """Convert to Qdrant filter format."""
        conditions = []

        if self.categories:
            conditions.append({
                "key": "metadata.category",
                "match": {"any": self.categories}
            })

        if self.departments:
            conditions.append({
                "key": "metadata.department",
                "match": {"any": self.departments}
            })

        if self.target_audiences:
            conditions.append({
                "key": "metadata.target_audience",
                "match": {"any": self.target_audiences}
            })

        if self.valid_only:
            today = date.today().isoformat()
            conditions.append({
                "should": [
                    {"key": "metadata.valid_until", "match": {"value": None}},
                    {"key": "metadata.valid_until", "range": {"gte": today}}
                ]
            })

        if self.min_priority is not None:
            conditions.append({
                "key": "metadata.priority",
                "range": {"lte": self.min_priority}
            })

        if not conditions:
            return None

        if len(conditions) == 1:
            return {"must": conditions}

        return {"must": conditions}


@dataclass
class KnowledgeChunk:
    """
    Knowledge chunk with multi-dimensional embeddings.
    Reference: rag-optimization/spec.md Section 3.2.1
    """
    chunk_id: str
    document_id: str
    content: str
    embedding_full: list[float] = field(default_factory=list)
    embedding_256: list[float] = field(default_factory=list)
    embedding_512: list[float] = field(default_factory=list)
    metadata: ChunkMetadata = field(default_factory=ChunkMetadata)
    created_at: datetime = field(default_factory=datetime.utcnow)
    updated_at: datetime = field(default_factory=datetime.utcnow)

    def to_qdrant_point(self, point_id: int | str) -> dict[str, Any]:
        """Convert to Qdrant point format."""
        return {
            "id": point_id,
            "vector": {
                "full": self.embedding_full,
                "dim_256": self.embedding_256,
                "dim_512": self.embedding_512,
            },
            "payload": {
                "chunk_id": self.chunk_id,
                "document_id": self.document_id,
                "text": self.content,
                "metadata": self.metadata.to_dict(),
                "created_at": self.created_at.isoformat(),
                "updated_at": self.updated_at.isoformat(),
            }
        }


@dataclass
class RetrieveRequest:
    """
    Request for knowledge retrieval.
    Reference: rag-optimization/spec.md Section 4.1
    """
    query: str
    query_with_prefix: str = ""
    top_k: int = 10
    filters: MetadataFilter | None = None
    strategy: RetrievalStrategy = RetrievalStrategy.HYBRID

    def __post_init__(self):
        if not self.query_with_prefix:
            self.query_with_prefix = f"search_query:{self.query}"


@dataclass
class RetrieveResult:
    """
    Result from knowledge retrieval.
    Reference: rag-optimization/spec.md Section 4.1
    """
    chunk_id: str
    content: str
    score: float
    vector_score: float = 0.0
    bm25_score: float = 0.0
    metadata: ChunkMetadata = field(default_factory=ChunkMetadata)
    rank: int = 0