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"
    environment: str = "local"
    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
    # Optional bearer token for `GET /metrics`. Empty by default so the
    # current Compose scrape and local development keep working: the endpoint
    # is not reachable from the internet today (Caddy proxies only `web`, and
    # ai-service publishes no host port). Set it wherever the service is
    # exposed through an Ingress, which the Helm chart now allows — metrics
    # carry query volumes, provider failure counts and abstain reasons.
    metrics_token: str = ""
    # OpenTelemetry is opt-in so the existing EC2 Compose deployment keeps
    # answering when no collector is present. Docker/Kubernetes observability
    # profiles enable it and point OTLP/HTTP at their local collector Service.
    otel_enabled: bool = False
    otel_service_name: str = "ai-service"
    otel_exporter_otlp_endpoint: str = "http://localhost:4318/v1/traces"
    otel_sample_ratio: float = Field(default=1.0, ge=0.0, le=1.0)
    # Langfuse ingests the SAME spans over OTLP as a second exporter, so it
    # adds an LLM-shaped view (per-trace answers, eval scores) without
    # replacing Tempo or touching any instrumentation. All three must be set
    # for the exporter to be added; keys are secrets and live only in .env /
    # the cluster Secret, never in values.yaml.
    langfuse_base_url: str = ""
    langfuse_public_key: str = ""
    langfuse_secret_key: str = ""
    entities_path: Path = _default_entities_path()
    # F-08: a per-turn budget across RagAgent's sequential Bedrock calls
    # (understand, generate, one entailment check on the live agent path).
    # Defaults sized with headroom above what a normal turn measures live
    # (~8-9s before the bounded-provider change) — see rag/agent.py's
    # MAX_WALL_CLOCK_MS/
    # MAX_LLM_CALLS_PER_TURN for the full rationale.
    max_wall_clock_ms: int = 40_000
    max_llm_calls_per_turn: int = 8


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