"""
Per-service runtime config helpers.

Config files live on the shared `app_config` Docker volume at /config/.
Each service has its own JSON file.

Atomic write pattern: write to .tmp in same dir, then os.replace() so
services never read a partial file.
"""
import copy
import json
import os
from pathlib import Path

from pydantic import BaseModel

_CONFIG_DIR = Path(os.environ.get("APP_CONFIG_DIR", "/config"))

# ── AI service config schemas ──────────────────────────────────────────────────


class AnthropicConfig(BaseModel):
    api_key: str = ""
    model: str = "claude-haiku-4-5-20251001"


class OllamaConfig(BaseModel):
    base_url: str = "http://host.docker.internal:11434/v1"
    model: str = "llama3.2"
    api_key: str = "ollama"


class LMStudioConfig(BaseModel):
    base_url: str = "http://host.docker.internal:1234/v1"
    model: str = "local-model"
    api_key: str = "lm-studio"


class AIServiceConfig(BaseModel):
    provider: str = "lmstudio"
    timeout_seconds: int = 60
    max_retries: int = 2
    anthropic: AnthropicConfig = AnthropicConfig()
    ollama: OllamaConfig = OllamaConfig()
    lmstudio: LMStudioConfig = LMStudioConfig()


# ── Doc service config schemas ─────────────────────────────────────────────────


class DocumentsConfig(BaseModel):
    max_pdf_bytes: int = 20 * 1024 * 1024


class DocServiceConfig(BaseModel):
    documents: DocumentsConfig = DocumentsConfig()


# ── Masking ────────────────────────────────────────────────────────────────────

def _mask_key(key: str) -> str:
    if not key or len(key) <= 8:
        return "••••"
    return key[:7] + "••••"


def _mask_ai_config(data: dict) -> dict:
    masked = copy.deepcopy(data)
    for provider in ("anthropic", "ollama", "lmstudio"):
        if provider in masked and "api_key" in masked[provider]:
            masked[provider]["api_key"] = _mask_key(masked[provider]["api_key"])
    return masked


# ── Load / Save ────────────────────────────────────────────────────────────────

def _config_path(service: str) -> Path:
    return _CONFIG_DIR / f"{service}_config.json"


def load_service_config(service: str) -> dict:
    path = _config_path(service)
    if not path.exists():
        if service == "ai_service":
            return AIServiceConfig().model_dump()
        if service == "doc_service":
            return DocServiceConfig().model_dump()
        return {}
    with path.open() as f:
        return json.load(f)


def save_service_config(service: str, data: dict) -> None:
    path = _config_path(service)
    path.parent.mkdir(parents=True, exist_ok=True)
    tmp = path.with_suffix(".tmp")
    tmp.write_text(json.dumps(data, indent=2))
    os.replace(tmp, path)


# AI service helpers

def load_ai_service_config() -> AIServiceConfig:
    raw = load_service_config("ai_service")
    return AIServiceConfig.model_validate(raw)


def save_ai_service_config(config: AIServiceConfig) -> None:
    save_service_config("ai_service", config.model_dump())


def load_ai_service_config_masked() -> dict:
    raw = load_service_config("ai_service")
    return _mask_ai_config(raw)


# Doc service helpers

def load_doc_service_config() -> DocServiceConfig:
    raw = load_service_config("doc_service")
    return DocServiceConfig.model_validate(raw)


def save_doc_service_config(config: DocServiceConfig) -> None:
    save_service_config("doc_service", config.model_dump())


def load_doc_service_config_masked() -> dict:
    return load_service_config("doc_service")


def _merge_api_key(new_key: str, existing_key: str) -> str:
    """If new_key is empty or a masked value, keep the existing key."""
    if not new_key or "••••" in new_key:
        return existing_key
    return new_key