"""
API Endpoints
All return JSON strings for consistency.
Can be used by Gradio UI or external apps.
"""
import json
from typing import Optional

from core.models import get_model_service
from core.sessions import get_session_service
from core.state import get_state
from core.logger import logger
from core.config import VERSION


def _json_response(success: bool, data: dict = None, error: str = None) -> str:
    """Standard JSON response format"""
    response = {"success": success}
    if data:
        response.update(data)
    if error:
        response["error"] = error
    return json.dumps(response, indent=2)


# ══════════════════════════════════════════════════════════════════════════════
# MODEL APIs
# ══════════════════════════════════════════════════════════════════════════════

def api_list_models() -> str:
    """List all installed models"""
    service = get_model_service()
    models = service.get_installed_models()
    loaded_id = get_state().get_loaded_model_id()

    return _json_response(True, {
        "models": models,
        "count": len(models),
        "loaded_model_id": loaded_id
    })


def api_get_model(model_id: str) -> str:
    """Get specific model details"""
    model = get_state().get_model_by_id(model_id)
    if model:
        return _json_response(True, {"model": model})
    return _json_response(False, error="Model not found")


def api_load_model(model_id: str) -> str:
    """Load a model"""
    service = get_model_service()
    result = service.load_model(model_id)
    return json.dumps(result)


def api_unload_model() -> str:
    """Unload current model"""
    service = get_model_service()
    service.unload_model()
    return _json_response(True, {"message": "Model unloaded"})


def api_delete_model(model_id: str) -> str:
    """Delete an installed model"""
    service = get_model_service()
    result = service.delete_model(model_id)
    return json.dumps(result)


def api_search_models(query: str = "", max_params: float = 7.0, limit: int = 20) -> str:
    """Search HuggingFace for models"""
    service = get_model_service()
    results, status = service.search_hf_models(query, max_params, limit)
    return _json_response(True, {
        "results": results,
        "count": len(results),
        "status": status
    })


def api_get_model_files(repo_id: str) -> str:
    """Get available files for a HF model"""
    service = get_model_service()
    files = service.get_hf_model_files(repo_id)
    return _json_response(True, {
        "repo_id": repo_id,
        "files": files,
        "count": len(files)
    })


def api_download_model(repo_id: str, filename: str) -> str:
    """Download a model from HuggingFace"""
    service = get_model_service()
    result = service.download_model(repo_id, filename)
    return json.dumps(result)


# ══════════════════════════════════════════════════════════════════════════════
# SESSION APIs
# ══════════════════════════════════════════════════════════════════════════════

def api_list_sessions() -> str:
    """List all sessions"""
    service = get_session_service()
    sessions = service.get_all_sessions()
    return _json_response(True, {
        "sessions": sessions,
        "count": len(sessions),
        "active_session_id": get_state().get_active_session_id()
    })


def api_get_session(session_id: str) -> str:
    """Get session with messages"""
    service = get_session_service()
    session = service.get_session(session_id)
    if session:
        return _json_response(True, {"session": session})
    return _json_response(False, error="Session not found")


def api_create_session(
    title: str = "",
    session_type: str = "chat",
    system_prompt: str = ""
) -> str:
    """Create new session"""
    service = get_session_service()
    session = service.create_session(title, session_type, system_prompt)
    return _json_response(True, {
        "session_id": session["id"],
        "title": session["title"]
    })


def api_delete_session(session_id: str) -> str:
    """Delete a session"""
    service = get_session_service()
    result = service.delete_session(session_id)
    return _json_response(result, {"message": "Deleted" if result else "Not found"})


def api_rename_session(session_id: str, new_title: str) -> str:
    """Rename a session"""
    service = get_session_service()
    result = service.rename_session(session_id, new_title)
    return _json_response(result, {"title": new_title})


def api_clear_session(session_id: str) -> str:
    """Clear session messages"""
    service = get_session_service()
    result = service.clear_session(session_id)
    return _json_response(result, {"message": "Cleared"})


# ══════════════════════════════════════════════════════════════════════════════
# CHAT / INFERENCE APIs
# ══════════════════════════════════════════════════════════════════════════════

def api_chat(
    session_id: str,
    message: str,
    max_tokens: int = 512,
    temperature: float = 0.7
) -> str:
    """Send chat message and get response"""
    model_service = get_model_service()
    session_service = get_session_service()

    # Check model loaded
    if not model_service.is_model_loaded():
        return _json_response(False, error="No model loaded")

    # Get session
    session = session_service.get_session(session_id)
    if not session:
        return _json_response(False, error="Session not found")

    # Add user message
    session_service.add_message(session_id, "user", message)

    # Build messages for model
    messages = []
    if session.get("system_prompt"):
        messages.append({"role": "system", "content": session["system_prompt"]})

    for msg in session_service.get_messages(session_id):
        messages.append({"role": msg["role"], "content": msg["content"]})

    # Generate response
    response = model_service.generate(messages, max_tokens, temperature)

    # Add assistant response
    session_service.add_message(session_id, "assistant", response)

    return _json_response(True, {
        "response": response,
        "session_id": session_id
    })


def api_inference(
    prompt: str = "",
    messages: str = "[]",
    system_prompt: str = "",
    max_tokens: int = 512,
    temperature: float = 0.7,
    top_p: float = 0.9,
    context: str = "",
    lora_scale: float = 1.0
) -> str:
    """
    Universal inference endpoint.
    Can use direct prompt or message list.
    Supports system prompt, context injection, LoRA scaling (future).
    """
    model_service = get_model_service()

    if not model_service.is_model_loaded():
        return _json_response(False, error="No model loaded")

    try:
        # Parse messages if provided
        msg_list = json.loads(messages) if messages and messages != "[]" else []

        # Build full message list
        full_messages = []

        # System prompt
        if system_prompt:
            full_messages.append({"role": "system", "content": system_prompt})

        # Context injection
        if context:
            full_messages.append({"role": "system", "content": f"Context:\n{context}"})

        # Conversation messages
        full_messages.extend(msg_list)

        # Direct prompt
        if prompt:
            full_messages.append({"role": "user", "content": prompt})

        if not full_messages:
            return _json_response(False, error="No prompt or messages provided")

        # Generate
        response = model_service.generate(full_messages, max_tokens, temperature, top_p)

        loaded_model = model_service.get_loaded_model()

        return _json_response(True, {
            "response": response,
            "model_id": loaded_model["id"] if loaded_model else None,
            "config": {
                "max_tokens": max_tokens,
                "temperature": temperature,
                "top_p": top_p,
                "lora_scale": lora_scale
            }
        })

    except Exception as e:
        logger.error("API", f"Inference error: {e}")
        return _json_response(False, error=str(e))


def api_chat_with_config(
    session_id: str,
    message: str,
    max_tokens: int = 512,
    temperature: float = 0.7,
    top_p: float = 0.9,
    system_prompt_override: str = "",
    context: str = "",
    lora_scale: float = 1.0
) -> str:
    """
    Chat with full configuration options.
    Supports: custom inference params, system prompt override, context injection.
    """
    model_service = get_model_service()
    session_service = get_session_service()

    if not model_service.is_model_loaded():
        return _json_response(False, error="No model loaded")

    session = session_service.get_session(session_id)
    if not session:
        return _json_response(False, error="Session not found")

    # Add user message
    session_service.add_message(session_id, "user", message)

    # Build messages
    messages = []

    # System prompt (override or session default)
    sys_prompt = system_prompt_override or session.get("system_prompt", "")
    if sys_prompt:
        messages.append({"role": "system", "content": sys_prompt})

    # Context injection
    if context:
        messages.append({"role": "system", "content": f"Context:\n{context}"})

    # Conversation history
    for msg in session_service.get_messages(session_id):
        messages.append({"role": msg["role"], "content": msg["content"]})

    # Generate
    response = model_service.generate(messages, max_tokens, temperature, top_p)

    # Add response
    session_service.add_message(session_id, "assistant", response)

    return _json_response(True, {
        "response": response,
        "session_id": session_id,
        "config_used": {
            "max_tokens": max_tokens,
            "temperature": temperature,
            "top_p": top_p,
            "lora_scale": lora_scale,
            "context_provided": bool(context)
        }
    })


# ══════════════════════════════════════════════════════════════════════════════
# SYSTEM APIs
# ══════════════════════════════════════════════════════════════════════════════

def api_get_status() -> str:
    """Get current system status"""
    model_service = get_model_service()
    state = get_state()

    loaded = model_service.get_loaded_model()

    return _json_response(True, {
        "version": VERSION,
        "model_loaded": model_service.is_model_loaded(),
        "loaded_model": loaded["name"] if loaded else None,
        "installed_models_count": len(state.get_installed_models()),
        "sessions_count": len(state.get_sessions()),
        "active_session_id": state.get_active_session_id()
    })


def api_get_backends() -> str:
    """Check which inference backends are available"""
    from core.models import _get_llama_cpp, _get_transformers

    return _json_response(True, {
        "backends": {
            "gguf": _get_llama_cpp() is not None,
            "transformers": _get_transformers() is not None
        }
    })


def api_health() -> str:
    """Health check endpoint"""
    return _json_response(True, {
        "status": "healthy",
        "version": VERSION
    })