// SPDX-FileCopyrightText: Copyright (c) 2024-2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
// SPDX-License-Identifier: Apache-2.0

use std::fmt::Display;
use std::path::PathBuf;

use pyo3::{exceptions::PyException, prelude::*};

use dynamo_llm::entrypoint::input::Input;
use dynamo_llm::entrypoint::EngineConfig as RsEngineConfig;
use dynamo_llm::local_model::{LocalModel, LocalModelBuilder};
use dynamo_runtime::protocols::Endpoint as EndpointId;

#[pyclass(eq, eq_int)]
#[derive(Clone, Debug, PartialEq)]
#[repr(i32)]
pub enum EngineType {
    Echo = 1,
    MistralRs = 2,
    LlamaCpp = 3,
    Dynamic = 4,
}

#[pyclass]
#[derive(Clone, Debug)]
pub(crate) struct EntrypointArgs {
    engine_type: EngineType,
    model_path: Option<PathBuf>,
    model_name: Option<String>,
    model_config: Option<PathBuf>,
    endpoint_id: Option<EndpointId>,
    context_length: Option<u32>,
    template_file: Option<PathBuf>,
    //router_config: Option<RouterConfig>,
    kv_cache_block_size: Option<u32>,
    http_port: Option<u16>,
}

#[pymethods]
impl EntrypointArgs {
    #[allow(clippy::too_many_arguments)]
    #[new]
    #[pyo3(signature = (engine_type, model_path=None, model_name=None, model_config=None, endpoint_id=None, context_length=None, template_file=None, kv_cache_block_size=None, http_port=None))]
    pub fn new(
        engine_type: EngineType,
        model_path: Option<PathBuf>,
        model_name: Option<String>, // e.g. "dyn://namespace.component.endpoint"
        model_config: Option<PathBuf>,
        endpoint_id: Option<String>,
        context_length: Option<u32>,
        template_file: Option<PathBuf>,
        //router_config: Option<RouterConfig>,
        kv_cache_block_size: Option<u32>,
        http_port: Option<u16>,
    ) -> PyResult<Self> {
        let endpoint_id_obj: Option<EndpointId> = match endpoint_id {
            Some(eid) => Some(eid.parse().map_err(|_| {
                PyErr::new::<pyo3::exceptions::PyValueError, _>(format!(
                    "Invalid endpoint_id format: {eid}"
                ))
            })?),
            None => None,
        };
        Ok(EntrypointArgs {
            engine_type,
            model_path,
            model_name,
            model_config,
            endpoint_id: endpoint_id_obj,
            context_length,
            template_file,
            //router_config,
            kv_cache_block_size,
            http_port,
        })
    }
}

#[pyclass]
#[derive(Clone)]
pub(crate) struct EngineConfig {
    inner: RsEngineConfig,
}

#[pyfunction]
#[pyo3(signature = (distributed_runtime, args))]
pub fn make_engine<'p>(
    py: Python<'p>,
    distributed_runtime: super::DistributedRuntime,
    args: EntrypointArgs,
) -> PyResult<Bound<'p, PyAny>> {
    let mut builder = LocalModelBuilder::default();
    builder
        .model_path(args.model_path)
        .model_name(args.model_name)
        .model_config(args.model_config)
        .endpoint_id(args.endpoint_id)
        .context_length(args.context_length)
        .request_template(args.template_file)
        .kv_cache_block_size(args.kv_cache_block_size)
        .http_port(args.http_port);
    pyo3_async_runtimes::tokio::future_into_py(py, async move {
        let local_model = builder.build().await.map_err(to_pyerr)?;
        let inner = select_engine(distributed_runtime, args.engine_type, local_model)
            .await
            .map_err(to_pyerr)?;
        Ok(EngineConfig { inner })
    })
}

async fn select_engine(
    #[allow(unused_variables)] distributed_runtime: super::DistributedRuntime,
    engine_type: EngineType,
    local_model: LocalModel,
) -> anyhow::Result<RsEngineConfig> {
    let inner = match engine_type {
        EngineType::Echo => {
            // There is no validation for the echo engine
            RsEngineConfig::StaticFull {
                model: Box::new(local_model),
                engine: dynamo_llm::engines::make_engine_full(),
            }
        }
        EngineType::Dynamic => RsEngineConfig::Dynamic(Box::new(local_model)),
        EngineType::MistralRs => {
            #[cfg(feature = "mistralrs")]
            {
                RsEngineConfig::StaticFull {
                    engine: dynamo_engine_mistralrs::make_engine(&local_model).await?,
                    model: Box::new(local_model),
                }
            }
            #[cfg(not(feature = "mistralrs"))]
            {
                anyhow::bail!(
                    "mistralrs engine is not enabled. Rebuild bindings with `--features mistralrs`"
                );
            }
        }
        EngineType::LlamaCpp => {
            #[cfg(feature = "llamacpp")]
            {
                RsEngineConfig::StaticCore {
                    engine: dynamo_engine_llamacpp::make_engine(
                        distributed_runtime.inner.primary_token(),
                        &local_model,
                    )
                    .await?,
                    model: Box::new(local_model),
                }
            }
            #[cfg(not(feature = "llamacpp"))]
            {
                anyhow::bail!(
                    "llamacpp engine is not enabled. Rebuild bindings with `--features llamacpp`"
                );
            }
        }
    };

    Ok(inner)
}

#[pyfunction]
#[pyo3(signature = (distributed_runtime, input, engine_config))]
pub fn run_input<'p>(
    py: Python<'p>,
    distributed_runtime: super::DistributedRuntime,
    input: &str,
    engine_config: EngineConfig,
) -> PyResult<Bound<'p, PyAny>> {
    let input_enum: Input = input.parse().map_err(to_pyerr)?;
    pyo3_async_runtimes::tokio::future_into_py(py, async move {
        dynamo_llm::entrypoint::input::run_input(
            either::Either::Right(distributed_runtime.inner.clone()),
            input_enum,
            engine_config.inner,
        )
        .await
        .map_err(to_pyerr)?;
        Ok(())
    })
}

pub fn to_pyerr<E>(err: E) -> PyErr
where
    E: Display,
{
    PyException::new_err(format!("{}", err))
}