"""
DocMind — Centralized Configuration

All magic numbers, thresholds, model names, and environment-dependent
settings live here so they can be tuned in one place.
"""

import os
from dataclasses import dataclass, field
from typing import List

from dotenv import load_dotenv

load_dotenv()


@dataclass(frozen=True)
class ChunkingConfig:
    """Token-based chunking parameters."""
    max_tokens: int = 400
    overlap_tokens: int = 50
    encoding_name: str = "cl100k_base"


@dataclass(frozen=True)
class RetrievalConfig:
    """Hybrid retrieval tuning knobs."""
    bm25_top_k: int = 20
    dense_top_k: int = 20
    rrf_k: int = 60          # RRF constant (higher = more uniform weighting)
    rrf_top_k: int = 8       # Final chunks sent to the LLM


@dataclass(frozen=True)
class GroundingConfig:
    """NLI grounding gate thresholds."""
    high_threshold: float = 0.65
    medium_threshold: float = 0.45
    nli_model_name: str = "cross-encoder/nli-deberta-v3-base"

    def __post_init__(self):
        model_name = os.getenv("NLI_MODEL_NAME", "cross-encoder/nli-deberta-v3-base")
        object.__setattr__(self, "nli_model_name", model_name)


@dataclass(frozen=True)
class LLMConfig:
    """Groq LLM settings."""
    api_key: str = ""
    model_name: str = "llama-3.3-70b-versatile"
    fallback_model: str = "llama-3.1-8b-instant"
    max_tokens: int = 400
    temperature: float = 0.1
    max_context_tokens: int = 6000   # Budget for document chunks in prompt
    max_response_sentences: int = 4

    def __post_init__(self):
        # frozen=True means we use object.__setattr__
        key = os.getenv("GROQ_API_KEY", "")
        model_name = os.getenv("GROQ_MODEL_NAME", "llama-3.3-70b-versatile")
        fallback_model = os.getenv("GROQ_FALLBACK_MODEL", "llama-3.1-8b-instant")
        object.__setattr__(self, "api_key", key)
        object.__setattr__(self, "model_name", model_name)
        object.__setattr__(self, "fallback_model", fallback_model)


@dataclass(frozen=True)
class EmbeddingConfig:
    """Dense embedding model settings."""
    model_name: str = "BAAI/bge-m3"
    vector_size: int = 1024
    batch_size: int = 32

    def __post_init__(self):
        model_name = os.getenv("EMBEDDING_MODEL_NAME", "BAAI/bge-m3")
        vector_size = int(os.getenv("EMBEDDING_VECTOR_SIZE", "1024"))
        object.__setattr__(self, "model_name", model_name)
        object.__setattr__(self, "vector_size", vector_size)


@dataclass(frozen=True)
class QdrantConfig:
    """Qdrant vector store settings."""
    url: str = ""
    api_key: str = ""
    collection_name: str = "docmind_chunks"
    use_local: bool = True     # Default to local in-memory for easy setup
    local_path: str = ""       # Empty = pure in-memory (no persistence)

    def __post_init__(self):
        url = os.getenv("QDRANT_URL", "")
        api_key = os.getenv("QDRANT_API_KEY", "")
        use_local = not (url and api_key)
        object.__setattr__(self, "url", url)
        object.__setattr__(self, "api_key", api_key)
        object.__setattr__(self, "use_local", use_local)


@dataclass(frozen=True)
class RouterConfig:
    """Intent router sensitive keywords."""
    sensitive_keywords: tuple = (
        "refund", "compensation", "legal", "liability", "sue",
        "medical", "diagnose", "toxic", "dangerous", "illegal",
        "lawsuit", "attorney", "malpractice", "fraud",
    )
    handoff_message: str = (
        "This query involves a sensitive topic I cannot advise on from "
        "documents alone. Please consult a qualified professional."
    )


@dataclass(frozen=True)
class UIConfig:
    """UI display settings."""
    max_documents: int = 3
    max_chat_history: int = 10
    max_upload_mb: int = 20
    document_colors: tuple = ("#3B82F6", "#10B981", "#F59E0B")  # blue, green, orange
    document_color_names: tuple = ("blue", "green", "orange")
    app_name: str = "DocMind"
    app_tagline: str = "Grounded RAG Document Intelligence"


@dataclass(frozen=True)
class AppConfig:
    """Top-level config aggregating all sub-configs."""
    chunking: ChunkingConfig = field(default_factory=ChunkingConfig)
    retrieval: RetrievalConfig = field(default_factory=RetrievalConfig)
    grounding: GroundingConfig = field(default_factory=GroundingConfig)
    llm: LLMConfig = field(default_factory=LLMConfig)
    embedding: EmbeddingConfig = field(default_factory=EmbeddingConfig)
    qdrant: QdrantConfig = field(default_factory=QdrantConfig)
    router: RouterConfig = field(default_factory=RouterConfig)
    ui: UIConfig = field(default_factory=UIConfig)


# ── Singleton instance used across the app ──────────────────────────
CONFIG = AppConfig()