from __future__ import annotations

from functools import lru_cache
from pathlib import Path

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict


def _default_entities_path() -> Path:
    """2 parents up from apps/ai-service/config.py in a full repo checkout.

    A container image that flattens apps/ai-service/ into its own root
    (found live 2026-08-10: the deploy image does exactly this) doesn't have
    that depth — ENTITIES_PATH env override is for it; this fallback just
    keeps the class from crashing at import time when it's shallower.
    """
    here = Path(__file__).resolve()
    return (
        here.parents[2] if len(here.parents) > 2 else here.parent
    ) / "ingestion/data/verified/drug_entities.json"


class Settings(BaseSettings):
    model_config = SettingsConfigDict(env_file=".env", extra="ignore")

    app_name: str = "vsf-duoc-thu-ai-service"
    qdrant_url: str = "http://localhost:6333"
    qdrant_collection: str = "duocthu_v1"
    qdrant_api_key: str | None = None
    postgres_dsn: str = Field(
        default="postgresql://duoc_thu:duoc_thu@localhost:5432/duoc_thu",
        repr=False,
    )
    # `cohere-v4` = semantic query embedding in the corpus's own space (requires
    # live Bedrock). `disabled` skips retrieval entirely. The old local-hash /
    # section-only stub embedders were removed in the 2026-08-06 rebuild.
    embedding_provider: str = "cohere-v4"
    embedding_dimensions: int = 1024
    evidence_minimum_score: float = 0.12
    aws_region: str = "us-east-1"
    # Generation is off unless asked for. `stub` runs the whole answer path —
    # prompt, schema parsing, grounding check, fallback — with no cloud call.
    # Live options: `bedrock-converse` (DeepSeek/Qwen/GLM/Nova via the Converse
    # API) or `bedrock-claude` (Anthropic via the Messages path).
    answer_provider: str = "disabled"
    answer_model_id: str = "deepseek.v3.2"
    # Optional cross-encoder rerank on the similarity fallback (needs live
    # Bedrock invoke on the rerank model). Off by default; the section route
    # never uses it.
    rerank_enabled: bool = False
    metrics_enabled: bool = True
    entities_path: Path = _default_entities_path()
    # F-08: a per-turn budget across RagAgent's sequential Bedrock calls
    # (understand, sufficiency, generate, up to 2 entailment retries).
    # Defaults sized with headroom above what a normal turn measures live
    # (~8-9s, 4-5 calls) — see rag/agent.py's MAX_WALL_CLOCK_MS/
    # MAX_LLM_CALLS_PER_TURN for the full rationale.
    max_wall_clock_ms: int = 20_000
    max_llm_calls_per_turn: int = 8


@lru_cache
def get_settings() -> Settings:
    return Settings()