"""
Configuration for Knowledge Base MCP Server.

Uses pydantic-settings for environment variable loading.
"""

import os

from pydantic import Field
from pydantic_settings import BaseSettings


class Settings(BaseSettings):
    """Application settings loaded from environment."""

    # Server settings
    host: str = Field(default="0.0.0.0", description="Server host")
    port: int = Field(default=8002, description="Server port")
    debug: bool = Field(default=False, description="Debug mode")

    # Database settings
    database_url: str = Field(
        default="postgresql://postgres:postgres@localhost:5432/syndarix",
        description="PostgreSQL connection URL with pgvector extension",
    )
    database_pool_size: int = Field(default=10, description="Connection pool size")
    database_pool_max_overflow: int = Field(
        default=20, description="Max overflow connections"
    )

    # Redis settings
    redis_url: str = Field(
        default="redis://localhost:6379/0",
        description="Redis connection URL",
    )

    # LLM Gateway settings (for embeddings)
    llm_gateway_url: str = Field(
        default="http://localhost:8001",
        description="LLM Gateway MCP server URL",
    )

    # Embedding settings
    embedding_model: str = Field(
        default="text-embedding-3-large",
        description="Default embedding model",
    )
    embedding_dimension: int = Field(
        default=1536,
        description="Embedding vector dimension",
    )
    embedding_batch_size: int = Field(
        default=100,
        description="Max texts per embedding batch",
    )
    embedding_cache_ttl: int = Field(
        default=86400,
        description="Embedding cache TTL in seconds (24 hours)",
    )

    # Chunking settings
    code_chunk_size: int = Field(
        default=500,
        description="Target tokens per code chunk",
    )
    code_chunk_overlap: int = Field(
        default=50,
        description="Token overlap between code chunks",
    )
    markdown_chunk_size: int = Field(
        default=800,
        description="Target tokens per markdown chunk",
    )
    markdown_chunk_overlap: int = Field(
        default=100,
        description="Token overlap between markdown chunks",
    )
    text_chunk_size: int = Field(
        default=400,
        description="Target tokens per text chunk",
    )
    text_chunk_overlap: int = Field(
        default=50,
        description="Token overlap between text chunks",
    )

    # Search settings
    search_default_limit: int = Field(
        default=10,
        description="Default number of search results",
    )
    search_max_limit: int = Field(
        default=100,
        description="Maximum number of search results",
    )
    semantic_threshold: float = Field(
        default=0.7,
        description="Minimum similarity score for semantic search",
    )
    hybrid_semantic_weight: float = Field(
        default=0.7,
        description="Weight for semantic results in hybrid search",
    )
    hybrid_keyword_weight: float = Field(
        default=0.3,
        description="Weight for keyword results in hybrid search",
    )

    # Storage settings
    embedding_ttl_days: int = Field(
        default=30,
        description="TTL for embedding records in days (0 = no expiry)",
    )

    # Content size limits (DoS prevention)
    max_document_size: int = Field(
        default=10 * 1024 * 1024,  # 10 MB
        description="Maximum size of a single document in bytes",
    )
    max_batch_size: int = Field(
        default=100,
        description="Maximum number of documents in a batch operation",
    )
    max_batch_total_size: int = Field(
        default=50 * 1024 * 1024,  # 50 MB
        description="Maximum total size of all documents in a batch",
    )

    model_config = {"env_prefix": "KB_", "env_file": ".env", "extra": "ignore"}


# Global settings instance (lazy initialization)
_settings: Settings | None = None


def get_settings() -> Settings:
    """Get the global settings instance."""
    global _settings
    if _settings is None:
        _settings = Settings()
    return _settings


def reset_settings() -> None:
    """Reset the global settings (for testing)."""
    global _settings
    _settings = None


def is_test_mode() -> bool:
    """Check if running in test mode."""
    return os.getenv("IS_TEST", "").lower() in ("true", "1", "yes")