from functools import lru_cache
from typing import Literal

from pydantic import Field
from pydantic_settings import BaseSettings, SettingsConfigDict

ProviderName = Literal[
    "mistral",
    "github_models",
    "groq",
    "ollama",
    "openrouter",
    "perplexity",
    "gracekelly",
    "zen",
    "grok_cli",
    "claude_cli",
    "local_vllm",
]


class Settings(BaseSettings):
    model_config = SettingsConfigDict(
        env_file=".env",
        env_file_encoding="utf-8",
        env_prefix="NL_SQL_",
        extra="ignore",
        case_sensitive=False,
        populate_by_name=True,
    )

    log_level: str = "INFO"

    default_provider: ProviderName = "mistral"
    frontier_provider: ProviderName = "groq"  # GitHub Models needs fine-grained PAT
    local_provider: ProviderName = "ollama"

    mistral_gen_model: str = "codestral-latest"
    mistral_nl_model: str = "mistral-large-latest"
    mistral_embed_model: str = "mistral-embed"
    mistral_base_url: str = "https://api.mistral.ai/v1"

    github_models_model: str = "openai/gpt-4o-mini"
    github_models_base_url: str = "https://models.github.ai/inference"

    groq_model: str = "llama-3.3-70b-versatile"
    groq_base_url: str = "https://api.groq.com/openai/v1"

    ollama_gen_model: str = "qwen2.5-coder:7b-instruct"
    ollama_base_url: str = "http://localhost:11434/v1"
    ollama_timeout_seconds: float = 180.0

    # OpenRouter — heterogeneous-CSC slot. Default = deepseek-v4-flash:free
    # (DeepSeek family, ≠ Mistral — needed so self-consistency votes don't
    # collapse into one model's blind spots, as happened in config F + CSC
    # merge-revision saturation on homogeneous codestral). Earlier picks
    # rejected during 2026-05-20 probe:
    #   - z-ai/glm-4.5-air:free → reasoning model, 2186 reasoning_tokens
    #     consumed the whole budget, content=empty (smoke5 → 0% EA).
    #   - qwen/qwen3-coder:free → Venice provider 429-loop (free quota).
    # deepseek-v4-flash:free returned valid JSON+SQL on probe (LIMIT/OFFSET
    # correct for 7th-row case). Other live free models cycle; check
    # `D:\TXT\Free API Keys.txt` / smoke before switching.
    # `deepseek/deepseek-v4-flash:free` used to live here and no longer exists —
    # OpenRouter answers 404 and points at the paid slug, so this provider had
    # been quietly dead. qwen3-coder is free, code-specialised and long-context;
    # note the free tier is rate-limited upstream (429) and needs retry patience.
    openrouter_model: str = "qwen/qwen3-coder:free"
    openrouter_base_url: str = "https://openrouter.ai/api/v1"

    # OpenCode Zen — free generator slot (see llm/providers/zen.py). Only the
    # `*-free` catalogue is reachable: the workspace has no payment method, so
    # paid ids answer CreditsError. Free ids as of 2026-07-14, all of which
    # emitted valid SQL on probe: deepseek-v4-flash-free, north-mini-code-free,
    # nemotron-3-ultra-free, mimo-v2.5-free, hy3-free, big-pickle.
    zen_model: str = "deepseek-v4-flash-free"
    zen_base_url: str = "https://opencode.ai/zen/v1"
    zen_timeout_seconds: float = 180.0

    # Grok Build CLI — subscription path (weekly quota, like GraceKelly), no key.
    # `grok models` advertises grok-4.20-0309-reasoning but the backend rejects it;
    # the tier serves grok-composer-2.5-fast. See llm/providers/grok_cli.py.
    grok_cli_path: str = "grok"
    grok_cli_model: str = "grok-composer-2.5-fast"
    grok_cli_timeout_seconds: float = 600.0
    grok_cli_max_turns: int = 4
    """Must be > 1. Grok spends its first turn announcing what it is about to do;
    `--max-turns 1` returns that preamble instead of the SQL (47.0% / 31% invalid
    on the first n=200 run). See llm/providers/grok_cli.py."""
    grok_cli_effort: str | None = None
    """`--reasoning-effort`. None leaves the CLI on its own default."""

    # Claude Code CLI — subscription path (plan limits, no key). `--system-prompt`
    # replaces the harness prompt, so the model answers as a completion, not an
    # agent. See llm/providers/claude_cli.py.
    claude_cli_path: str = "claude"
    claude_cli_model: str = "claude-sonnet-5"
    claude_cli_timeout_seconds: float = 600.0
    claude_cli_max_turns: int = 4
    """Must be > 1: a denied tool call eats a turn and the CLI then answers
    `error_max_turns` instead of the SQL."""
    claude_cli_effort: str | None = None
    """`--effort` (low|medium|high|xhigh|max). None leaves the CLI on its own
    default. The spawned process does NOT inherit the effort of the session that
    launched it, so this is the only way to run a max-effort ablation."""

    # Local vLLM — rented-GPU student-model slot (S2, plan_autotune.md; see
    # llm/providers/local_vllm.py). No fixed host like Ollama's :11434: the
    # box only exists for the duration of a GPU rental, so `base_url` must be
    # set in `.env` each session. `NL_SQL_LOCAL_LLM_API_KEY` defaults to the
    # literal "dummy" — vLLM's OpenAI-compatible server does not check a key
    # unless started with `--api-key`, but the openai SDK requires a
    # non-empty string.
    local_llm_base_url: str = "http://localhost:8000/v1"
    local_llm_model: str = "Qwen/Qwen2.5-Coder-7B-Instruct"
    local_llm_api_key: str = "dummy"
    local_llm_timeout_seconds: float = 180.0

    # Perplexity browser path via local GraceKelly (D:\GraceKelly). Free
    # because it rides the user's Perplexity Pro subscription via Playwright.
    # `claude-sonnet-4-6` here is the Perplexity menu label, not the
    # Anthropic API model id — GraceKelly resolves it to the browser path.
    perplexity_browser_model: str = "claude-sonnet-4-6"
    perplexity_base_url: str = "http://127.0.0.1:8011"

    # GraceKelly orchestrate path — the AgentFlow branch runs NL->SQL on
    # Claude Sonnet 5 via GraceKelly (AgentFlow ADR 0008), not Mistral. The
    # portfolio default_provider stays `mistral`; this slot is selected
    # explicitly via build_provider("gracekelly"). `claude-sonnet-5` resolves
    # through GraceKelly's live catalog to "Claude Sonnet 5.0".
    gracekelly_model: str = "claude-sonnet-5"
    gracekelly_base_url: str = "http://127.0.0.1:8011"
    gracekelly_timeout_seconds: float = 900.0
    """Browser path, so this is a human-scale wait, not an API round-trip.
    Measured on the NL_SQL generation prompt (schema + few-shot + rules, ~6k
    tokens) against Perplexity: 150-436s per call. The former 180s default
    timed out mid-benchmark and surfaced as `pipeline_exception`, which scores
    as a miss and silently understates the model. 900s leaves headroom."""

    mistral_api_key: str = Field(default="", validation_alias="MISTRAL_API_KEY")
    github_token: str = Field(default="", validation_alias="GITHUB_TOKEN")
    groq_api_key: str = Field(default="", validation_alias="GROQ_API_KEY")
    openrouter_api_key: str = Field(default="", validation_alias="OPENROUTER_API_KEY")
    zen_api_key: str = Field(default="", validation_alias="OPENCODE_API_KEY")
    """One or more OpenCode Zen keys, comma-separated. Free tiers meter per key,
    so extra keys are extra headroom: the provider rotates through them on 429."""

    # Optional API auth for the FastAPI surface. When empty, /ask and /databases
    # are open — but the rate limiter still applies (keyed by client IP), so a
    # keyless public deploy is not unthrottled. Read here (not os.environ) so a
    # value in .env is honoured, per the api/main module docstring.
    api_key: str = Field(default="", validation_alias="NL_SQL_API_KEY")

    # Optional Postgres target. When `pg_dsn` is set, the registry registers a
    # Postgres-backed database under `pg_db_id`. Point it at the read-only role
    # (nl_sql_ro) for defence in depth — the engine also forces read-only
    # transactions on top (see db/connection.py). Empty = SQLite-only (default).
    pg_dsn: str = Field(default="", validation_alias="NL_SQL_PG_DSN")
    pg_db_id: str = "pg_codebase_community"
    pg_description: str = "StackExchange-derived BIRD codebase_community, loaded into Postgres 16."

    # diskcache for LLM generate/embed responses (per docs/02_architecture_v2.md §6.5).
    # Two subdirs ("gen", "embed") are created under this root by `nl_sql.llm.cache`.
    llm_cache_dir: str = ".cache/llm"
    llm_cache_size_limit_gb: int = 4


@lru_cache(maxsize=1)
def get_settings() -> Settings:
    return Settings()