use std::ffi::{CStr, CString};
use std::os::raw::c_char;
use std::path::Path;
use tokio::net::UnixStream;
use tonic::transport::{Endpoint, Uri};
use tower::service_fn;

// Generated by tonic-build
pub mod workload {
    tonic::include_proto!("_");
}

use workload::spiffe_workload_api_client::SpiffeWorkloadApiClient;
use workload::X509svidRequest;

#[repr(C)]
pub struct SvidResponseC {
    spiffe_id: *mut c_char,
    x509_svid: *mut u8,
    x509_svid_len: usize,
    x509_svid_key: *mut u8,
    x509_svid_key_len: usize,
    bundle: *mut u8,
    bundle_len: usize,
    error: *mut c_char,
}

impl SvidResponseC {
    fn with_error(err_msg: &str) -> Self {
        let err_c = match CString::new(err_msg) {
            Ok(c) => c.into_raw(),
            Err(_) => std::ptr::null_mut(),
        };
        SvidResponseC {
            spiffe_id: std::ptr::null_mut(),
            x509_svid: std::ptr::null_mut(),
            x509_svid_len: 0,
            x509_svid_key: std::ptr::null_mut(),
            x509_svid_key_len: 0,
            bundle: std::ptr::null_mut(),
            bundle_len: 0,
            error: err_c,
        }
    }
}

async fn fetch_svid_async(socket_path: &str) -> Result<SvidResponseC, Box<dyn std::error::Error>> {
    let path = Path::new(socket_path).to_path_buf();
    
    let channel = Endpoint::try_from("http://[::]:50051")?
        .connect_with_connector(service_fn(move |_: Uri| {
            let path_clone = path.clone();
            async move { UnixStream::connect(path_clone).await }
        }))
        .await?;

    let mut client = SpiffeWorkloadApiClient::new(channel);

    let request = tonic::Request::new(X509svidRequest {});
    let mut stream = client.fetch_x509svid(request).await?.into_inner();

    if let Some(response) = stream.message().await? {
        if let Some(svid) = response.svids.first() {
            let spiffe_id_c = CString::new(svid.spiffe_id.clone())?.into_raw();

            let mut svid_box = svid.x509_svid.clone().into_boxed_slice();
            let x509_svid = svid_box.as_mut_ptr();
            let x509_svid_len = svid_box.len();
            std::mem::forget(svid_box);

            let mut key_box = svid.x509_svid_key.clone().into_boxed_slice();
            let x509_svid_key = key_box.as_mut_ptr();
            let x509_svid_key_len = key_box.len();
            std::mem::forget(key_box);

            let mut bundle_box = svid.bundle.clone().into_boxed_slice();
            let bundle = bundle_box.as_mut_ptr();
            let bundle_len = bundle_box.len();
            std::mem::forget(bundle_box);

            return Ok(SvidResponseC {
                spiffe_id: spiffe_id_c,
                x509_svid,
                x509_svid_len,
                x509_svid_key,
                x509_svid_key_len,
                bundle,
                bundle_len,
                error: std::ptr::null_mut(),
            });
        }
    }

    Err("No SVID received from Workload API".into())
}

#[no_mangle]
pub extern "C" fn fetch_svid(socket_path_ptr: *const c_char) -> *mut SvidResponseC {
    if socket_path_ptr.is_null() {
        let resp = Box::new(SvidResponseC::with_error("socket_path_ptr is null"));
        return Box::into_raw(resp);
    }

    let socket_path = unsafe {
        match CStr::from_ptr(socket_path_ptr).to_str() {
            Ok(s) => s.to_string(),
            Err(e) => {
                let resp = Box::new(SvidResponseC::with_error(&format!("Invalid UTF-8 in socket path: {}", e)));
                return Box::into_raw(resp);
            }
        }
    };

    let rt = match tokio::runtime::Builder::new_current_thread().enable_all().build() {
        Ok(rt) => rt,
        Err(e) => {
            let resp = Box::new(SvidResponseC::with_error(&format!("Failed to build tokio runtime: {}", e)));
            return Box::into_raw(resp);
        }
    };

    let result = match rt.block_on(fetch_svid_async(&socket_path)) {
        Ok(data) => data,
        Err(e) => SvidResponseC::with_error(&e.to_string()),
    };

    Box::into_raw(Box::new(result))
}

#[no_mangle]
pub extern "C" fn free_svid(ptr: *mut SvidResponseC) {
    if ptr.is_null() {
        return;
    }

    unsafe {
        let mut resp = Box::from_raw(ptr);

        if !resp.spiffe_id.is_null() {
            let _ = CString::from_raw(resp.spiffe_id);
            resp.spiffe_id = std::ptr::null_mut();
        }

        if !resp.error.is_null() {
            let _ = CString::from_raw(resp.error);
            resp.error = std::ptr::null_mut();
        }

        if !resp.x509_svid.is_null() && resp.x509_svid_len > 0 {
            let _ = Box::from_raw(std::ptr::slice_from_raw_parts_mut(resp.x509_svid, resp.x509_svid_len));
            resp.x509_svid = std::ptr::null_mut();
            resp.x509_svid_len = 0;
        }

        if !resp.x509_svid_key.is_null() && resp.x509_svid_key_len > 0 {
            let _ = Box::from_raw(std::ptr::slice_from_raw_parts_mut(resp.x509_svid_key, resp.x509_svid_key_len));
            resp.x509_svid_key = std::ptr::null_mut();
            resp.x509_svid_key_len = 0;
        }

        if !resp.bundle.is_null() && resp.bundle_len > 0 {
            let _ = Box::from_raw(std::ptr::slice_from_raw_parts_mut(resp.bundle, resp.bundle_len));
            resp.bundle = std::ptr::null_mut();
            resp.bundle_len = 0;
        }
    }
}