"""
LLM Configuration Management API.
[AC-ASA-14, AC-ASA-15, AC-ASA-16, AC-ASA-17, AC-ASA-18] LLM provider management endpoints.
"""

import logging
from typing import Any

from fastapi import APIRouter, Depends, Header, HTTPException

from app.services.llm.factory import (
    LLMProviderFactory,
    LLMUsageType,
    LLM_USAGE_DISPLAY_NAMES,
    LLM_USAGE_DESCRIPTIONS,
    get_llm_config_manager,
)

logger = logging.getLogger(__name__)

router = APIRouter(prefix="/admin/llm", tags=["LLM Management"])


def get_tenant_id(x_tenant_id: str = Header(..., alias="X-Tenant-Id")) -> str:
    """Extract tenant ID from header."""
    if not x_tenant_id:
        raise HTTPException(status_code=400, detail="X-Tenant-Id header is required")
    return x_tenant_id


@router.get("/providers")
async def list_providers(
    tenant_id: str = Depends(get_tenant_id),
) -> dict[str, Any]:
    """
    List all available LLM providers.
    [AC-ASA-15] Returns provider list with configuration schemas.
    """
    logger.info(f"[AC-ASA-15] Listing LLM providers for tenant={tenant_id}")

    providers = LLMProviderFactory.get_providers()
    return {
        "providers": [
            {
                "name": p.name,
                "display_name": p.display_name,
                "description": p.description,
                "config_schema": p.config_schema,
            }
            for p in providers
        ],
    }


@router.get("/usage-types")
async def list_usage_types(
    tenant_id: str = Depends(get_tenant_id),
) -> dict[str, Any]:
    """
    List all available LLM usage types.
    """
    logger.info(f"Listing LLM usage types for tenant={tenant_id}")

    return {
        "usage_types": [
            {
                "name": ut.value,
                "display_name": LLM_USAGE_DISPLAY_NAMES[ut],
                "description": LLM_USAGE_DESCRIPTIONS[ut],
            }
            for ut in LLMUsageType
        ],
    }


@router.get("/config")
async def get_config(
    tenant_id: str = Depends(get_tenant_id),
    usage_type: str | None = None,
) -> dict[str, Any]:
    """
    Get current LLM configuration.
    [AC-ASA-14] Returns current provider and config.
    If usage_type is specified, returns config for that usage type.
    Otherwise, returns all configs.
    """
    logger.info(f"[AC-ASA-14] Getting LLM config for tenant={tenant_id}, usage_type={usage_type}")

    manager = get_llm_config_manager()

    if usage_type:
        try:
            ut = LLMUsageType(usage_type)
            config = manager.get_current_config(ut)
            masked_config = _mask_secrets(config.get("config", {}))
            return {
                "usage_type": config["usage_type"],
                "provider": config["provider"],
                "config": masked_config,
            }
        except ValueError:
            raise HTTPException(status_code=400, detail=f"Invalid usage_type: {usage_type}")

    all_configs = manager.get_current_config()
    result = {}
    for ut_key, config in all_configs.items():
        result[ut_key] = {
            "provider": config["provider"],
            "config": _mask_secrets(config.get("config", {})),
        }
    return result


@router.put("/config")
async def update_config(
    body: dict[str, Any],
    tenant_id: str = Depends(get_tenant_id),
) -> dict[str, Any]:
    """
    Update LLM configuration.
    [AC-ASA-16] Updates provider and config with validation.

    Request body format:
    - For specific usage type:
        {
            "usage_type": "chat" | "kb_processing",
            "provider": "openai",
            "config": {...}
        }
    - For all usage types (backward compatible):
        {
            "provider": "openai",
            "config": {...}
        }
    """
    provider = body.get("provider")
    config = body.get("config", {})
    usage_type_str = body.get("usage_type")

    logger.info(f"[AC-ASA-16] Updating LLM config for tenant={tenant_id}, provider={provider}, usage_type={usage_type_str}")

    if not provider:
        return {
            "success": False,
            "message": "Provider is required",
        }

    try:
        manager = get_llm_config_manager()

        if usage_type_str:
            try:
                usage_type = LLMUsageType(usage_type_str)
                await manager.update_usage_config(usage_type, provider, config)
                return {
                    "success": True,
                    "message": f"LLM configuration updated for {usage_type_str} to {provider}",
                }
            except ValueError:
                raise HTTPException(status_code=400, detail=f"Invalid usage_type: {usage_type_str}")
        else:
            await manager.update_config(provider, config)

            return {
                "success": True,
                "message": f"LLM configuration updated to {provider}",
            }

    except ValueError as e:
        logger.error(f"[AC-ASA-16] Invalid LLM config: {e}")
        return {
            "success": False,
            "message": str(e),
        }


@router.post("/test")
async def test_connection(
    body: dict[str, Any] | None = None,
    tenant_id: str = Depends(get_tenant_id),
) -> dict[str, Any]:
    """
    Test LLM connection.
    [AC-ASA-17, AC-ASA-18] Tests connection and returns response.

    Request body format:
    {
        "test_prompt": "optional test prompt",
        "provider": "optional provider to test",
        "config": "optional config to test",
        "usage_type": "optional usage type to test"
    }
    """
    body = body or {}

    test_prompt = body.get("test_prompt", "你好，请简单介绍一下自己。")
    provider = body.get("provider")
    config = body.get("config")
    usage_type_str = body.get("usage_type")

    logger.info(
        f"[AC-ASA-17] Testing LLM connection for tenant={tenant_id}, "
        f"provider={provider or 'current'}, usage_type={usage_type_str or 'default'}"
    )

    manager = get_llm_config_manager()

    usage_type = None
    if usage_type_str:
        try:
            usage_type = LLMUsageType(usage_type_str)
        except ValueError:
            return {
                "success": False,
                "error": f"Invalid usage_type: {usage_type_str}",
            }

    result = await manager.test_connection(
        test_prompt=test_prompt,
        provider=provider,
        config=config,
        usage_type=usage_type,
    )

    return result


def _mask_secrets(config: dict[str, Any]) -> dict[str, Any]:
    """Mask secret fields in config for display."""
    masked = {}
    for key, value in config.items():
        if key in ("api_key", "password", "secret"):
            if value:
                masked[key] = f"{str(value)[:4]}***"
            else:
                masked[key] = ""
        else:
            masked[key] = value
    return masked