"""
Core - Configuration Management

Handles application configuration using Pydantic Settings.
"""
from functools import lru_cache
from typing import List

from pydantic import Field, field_validator
from pydantic_settings import BaseSettings, SettingsConfigDict


class Settings(BaseSettings):
    """Application settings"""

    model_config = SettingsConfigDict(env_file=".env", case_sensitive=False)

    # Application
    app_name: str = Field(default="RAG Onboarding Backend")
    app_version: str = Field(default="1.0.0")
    environment: str = Field(default="development")
    debug: bool = Field(default=True)
    log_level: str = Field(default="INFO")

    # Server
    host: str = Field(default="0.0.0.0")
    port: int = Field(default=8000)
    workers: int = Field(default=4)

    # Database
    database_url: str = Field(
        default="postgresql+asyncpg://postgres:postgres@localhost:5432/rag_onboarding"
    )
    database_pool_size: int = Field(default=20)
    database_max_overflow: int = Field(default=0)

    # Redis
    redis_url: str = Field(default="redis://localhost:6379/0")
    redis_cache_ttl: int = Field(default=3600)

    # Qdrant
    qdrant_url: str = Field(default="http://localhost:6333")
    qdrant_api_key: str = Field(default="")
    qdrant_collection_name: str = Field(default="onboarding_documents")
    qdrant_vector_size: int = Field(default=384)

    # RabbitMQ / Celery
    rabbitmq_url: str = Field(default="amqp://guest:guest@localhost:5672/")
    celery_broker_url: str = Field(default="redis://localhost:6379/1")
    celery_result_backend: str = Field(default="redis://localhost:6379/2")

    # Gemini
    gemini_api_key: str = Field(default="")
    gemini_model: str = Field(default="gemini-2.0-flash")
    gemini_temperature: float = Field(default=0.7)
    gemini_max_tokens: int = Field(default=2048)

    # OpenAI (fallback)
    openai_api_key: str = Field(default="")
    openai_model: str = Field(default="gpt-4-turbo-preview")

    # Embeddings
    embedding_model: str = Field(default="sentence-transformers/all-MiniLM-L6-v2")
    embedding_dimension: int = Field(default=384)
    embedding_batch_size: int = Field(default=32)

    # RAG Configuration
    rag_initial_k: int = Field(default=100)
    rag_final_k: int = Field(default=10)
    rag_min_score: float = Field(default=0.7)
    rag_search_type: str = Field(default="hybrid")
    rag_hybrid_alpha: float = Field(default=0.5)
    rag_max_context_tokens: int = Field(default=4000)

    # Reranking
    rerank_model: str = Field(default="cross-encoder/ms-marco-MiniLM-L-12-v2")
    use_reranking: bool = Field(default=True)

    # Caching
    enable_semantic_cache: bool = Field(default=True)
    cache_embedding_ttl: int = Field(default=86400)
    cache_retrieval_ttl: int = Field(default=3600)
    cache_generation_ttl: int = Field(default=1800)

    # Circuit Breaker
    circuit_breaker_failure_threshold: int = Field(default=5)
    circuit_breaker_recovery_timeout: int = Field(default=60)

    # Retry Policy
    retry_max_attempts: int = Field(default=3)
    retry_wait_exponential_multiplier: int = Field(default=1)
    retry_wait_exponential_max: int = Field(default=10)

    # Rate Limiting
    rate_limit_enabled: bool = Field(default=True)
    rate_limit_per_minute: int = Field(default=60)
    rate_limit_per_hour: int = Field(default=1000)

    # Monitoring
    prometheus_port: int = Field(default=9090)
    enable_tracing: bool = Field(default=True)
    jaeger_agent_host: str = Field(default="localhost")
    jaeger_agent_port: int = Field(default=6831)
    trace_sample_rate: float = Field(default=0.1)

    # CORS
    cors_origins: List[str] = Field(
        default=["http://localhost:3000", "http://localhost:8000"]
    )
    cors_allow_credentials: bool = Field(default=True)

    # Security
    secret_key: str = Field(default="your-secret-key-change-in-production")
    algorithm: str = Field(default="HS256")
    access_token_expire_minutes: int = Field(default=30)

    @field_validator('qdrant_url', mode='before')
    @classmethod
    def validate_qdrant_url(cls, v):
        """Allow :memory: as a valid Qdrant URL"""
        if v == ":memory:" or v.startswith("memory://"):
            return v
        return v


@lru_cache
def get_settings() -> Settings:
    """Get cached settings instance"""
    return Settings()