mock_worker.rs

// Mock worker for testing - these functions are used by integration tests
#![allow(dead_code)]

use axum::{
    extract::{Json, Path, State},
    http::StatusCode,
    response::sse::{Event, KeepAlive},
    response::{IntoResponse, Response, Sse},
    routing::{get, post},
    Router,
};
use futures_util::stream::{self, StreamExt};
use serde_json::json;
use std::collections::{HashMap, HashSet};
use std::convert::Infallible;
use std::sync::{Arc, Mutex, OnceLock};
use std::time::{SystemTime, UNIX_EPOCH};
use tokio::sync::RwLock;
use uuid::Uuid;

/// Configuration for mock worker behavior
#[derive(Clone)]
pub struct MockWorkerConfig {
    pub port: u16,
    pub worker_type: WorkerType,
    pub health_status: HealthStatus,
    pub response_delay_ms: u64,
    pub fail_rate: f32,
}

#[derive(Clone, Debug)]
pub enum WorkerType {
    Regular,
    Prefill,
    Decode,
}

#[derive(Clone, Debug)]
pub enum HealthStatus {
    Healthy,
    Unhealthy,
    Degraded,
}

/// Mock worker server for testing
pub struct MockWorker {
    config: Arc<RwLock<MockWorkerConfig>>,
    shutdown_handle: Option<tokio::task::JoinHandle<()>>,
    shutdown_tx: Option<tokio::sync::oneshot::Sender<()>>,
}

impl MockWorker {
    pub fn new(config: MockWorkerConfig) -> Self {
        Self {
            config: Arc::new(RwLock::new(config)),
            shutdown_handle: None,
            shutdown_tx: None,
        }
    }

    /// Start the mock worker server
    pub async fn start(&mut self) -> Result<String, Box<dyn std::error::Error>> {
        let config = self.config.clone();
        let port = config.read().await.port;

        // If port is 0, find an available port
        let port = if port == 0 {
            let listener = std::net::TcpListener::bind("127.0.0.1:0")?;
            let port = listener.local_addr()?.port();
            drop(listener);
            config.write().await.port = port;
            port
        } else {
            port
        };

        let app = Router::new()
            .route("/health", get(health_handler))
            .route("/health_generate", get(health_generate_handler))
            .route("/get_server_info", get(server_info_handler))
            .route("/get_model_info", get(model_info_handler))
            .route("/generate", post(generate_handler))
            .route("/v1/chat/completions", post(chat_completions_handler))
            .route("/v1/completions", post(completions_handler))
            .route("/v1/rerank", post(rerank_handler))
            .route("/v1/responses", post(responses_handler))
            .route("/v1/responses/{response_id}", get(responses_get_handler))
            .route(
                "/v1/responses/{response_id}/cancel",
                post(responses_cancel_handler),
            )
            .route("/flush_cache", post(flush_cache_handler))
            .route("/v1/models", get(v1_models_handler))
            .with_state(config);

        let (shutdown_tx, shutdown_rx) = tokio::sync::oneshot::channel::<()>();
        self.shutdown_tx = Some(shutdown_tx);

        // Spawn the server in a separate task
        let handle = tokio::spawn(async move {
            let listener = match tokio::net::TcpListener::bind(("127.0.0.1", port)).await {
                Ok(l) => l,
                Err(e) => {
                    eprintln!("Failed to bind to port {}: {}", port, e);
                    return;
                }
            };

            let server = axum::serve(listener, app).with_graceful_shutdown(async move {
                let _ = shutdown_rx.await;
            });

            if let Err(e) = server.await {
                eprintln!("Server error: {}", e);
            }
        });

        self.shutdown_handle = Some(handle);

        // Wait for the server to start
        tokio::time::sleep(tokio::time::Duration::from_millis(100)).await;

        let url = format!("http://127.0.0.1:{}", port);
        Ok(url)
    }

    /// Stop the mock worker server
    pub async fn stop(&mut self) {
        if let Some(shutdown_tx) = self.shutdown_tx.take() {
            let _ = shutdown_tx.send(());
        }

        if let Some(handle) = self.shutdown_handle.take() {
            // Wait for the server to shut down
            let _ = tokio::time::timeout(tokio::time::Duration::from_secs(5), handle).await;
        }
    }
}

impl Drop for MockWorker {
    fn drop(&mut self) {
        // Clean shutdown when dropped
        if let Some(shutdown_tx) = self.shutdown_tx.take() {
            let _ = shutdown_tx.send(());
        }
    }
}

// Handler implementations

/// Check if request should fail based on configured fail_rate
async fn should_fail(config: &MockWorkerConfig) -> bool {
    rand::random::<f32>() < config.fail_rate
}

async fn health_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    match config.health_status {
        HealthStatus::Healthy => Json(json!({
            "status": "healthy",
            "timestamp": SystemTime::now().duration_since(UNIX_EPOCH).unwrap().as_secs(),
            "worker_type": format!("{:?}", config.worker_type),
        }))
        .into_response(),
        HealthStatus::Unhealthy => (
            StatusCode::SERVICE_UNAVAILABLE,
            Json(json!({
                "status": "unhealthy",
                "error": "Worker is not responding"
            })),
        )
            .into_response(),
        HealthStatus::Degraded => Json(json!({
            "status": "degraded",
            "warning": "High load detected"
        }))
        .into_response(),
    }
}

async fn health_generate_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": "Random failure for testing"
            })),
        )
            .into_response();
    }

    if matches!(config.health_status, HealthStatus::Healthy) {
        Json(json!({
            "status": "ok",
            "queue_length": 0,
            "processing_time_ms": config.response_delay_ms
        }))
        .into_response()
    } else {
        (
            StatusCode::SERVICE_UNAVAILABLE,
            Json(json!({
                "error": "Generation service unavailable"
            })),
        )
            .into_response()
    }
}

async fn server_info_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": "Random failure for testing"
            })),
        )
            .into_response();
    }

    Json(json!({
        "model_path": "mock-model-path",
        "tokenizer_path": "mock-tokenizer-path",
        "port": config.port,
        "host": "127.0.0.1",
        "max_num_batched_tokens": 32768,
        "max_prefill_tokens": 16384,
        "mem_fraction_static": 0.88,
        "tp_size": 1,
        "dp_size": 1,
        "stream_interval": 8,
        "dtype": "float16",
        "device": "cuda",
        "enable_flashinfer": true,
        "enable_p2p_check": true,
        "context_length": 32768,
        "chat_template": null,
        "disable_radix_cache": false,
        "enable_torch_compile": false,
        "trust_remote_code": false,
        "show_time_cost": false,
        "waiting_queue_size": 0,
        "running_queue_size": 0,
        "req_to_token_ratio": 1.2,
        "min_running_requests": 0,
        "max_running_requests": 2048,
        "max_req_num": 8192,
        "max_batch_tokens": 32768,
        "schedule_policy": "lpm",
        "schedule_conservativeness": 1.0,
        "version": "0.3.0",
        "internal_states": [{
            "waiting_queue_size": 0,
            "running_queue_size": 0
        }]
    }))
    .into_response()
}

async fn model_info_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": "Random failure for testing"
            })),
        )
            .into_response();
    }

    Json(json!({
        "model_path": "mock-model-path",
        "tokenizer_path": "mock-tokenizer-path",
        "is_generation": true,
        "preferred_sampling_params": {
            "temperature": 0.7,
            "top_p": 0.9,
            "top_k": 40,
            "max_tokens": 2048
        }
    }))
    .into_response()
}

async fn generate_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Json(payload): Json<serde_json::Value>,
) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": "Random failure for testing"
            })),
        )
            .into_response();
    }

    if config.response_delay_ms > 0 {
        tokio::time::sleep(tokio::time::Duration::from_millis(config.response_delay_ms)).await;
    }

    let is_stream = payload
        .get("stream")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);

    if is_stream {
        let stream_delay = config.response_delay_ms;

        // Check if it's a batch request
        let is_batch = payload.get("text").and_then(|t| t.as_array()).is_some();

        let batch_size = if is_batch {
            payload
                .get("text")
                .and_then(|t| t.as_array())
                .map(|arr| arr.len())
                .unwrap_or(1)
        } else {
            1
        };

        let mut events = Vec::new();

        // Generate events for each item in batch
        for i in 0..batch_size {
            let timestamp_start = SystemTime::now()
                .duration_since(UNIX_EPOCH)
                .unwrap()
                .as_secs_f64();

            let data = json!({
                "text": format!("Mock response {}", i + 1),
                "meta_info": {
                    "prompt_tokens": 10,
                    "completion_tokens": 5,
                    "completion_tokens_wo_jump_forward": 5,
                    "input_token_logprobs": null,
                    "output_token_logprobs": null,
                    "first_token_latency": stream_delay as f64 / 1000.0,
                    "time_to_first_token": stream_delay as f64 / 1000.0,
                    "time_per_output_token": 0.01,
                    "end_time": timestamp_start + (stream_delay as f64 / 1000.0),
                    "start_time": timestamp_start,
                    "finish_reason": {
                        "type": "stop",
                        "reason": "length"
                    }
                },
                "stage": "mid"
            });

            events.push(Ok::<_, Infallible>(Event::default().data(data.to_string())));
        }

        // Add [DONE] event
        events.push(Ok(Event::default().data("[DONE]")));

        let stream = stream::iter(events);

        Sse::new(stream)
            .keep_alive(KeepAlive::default())
            .into_response()
    } else {
        Json(json!({
            "text": "This is a mock response.",
            "meta_info": {
                "prompt_tokens": 10,
                "completion_tokens": 5,
                "completion_tokens_wo_jump_forward": 5,
                "input_token_logprobs": null,
                "output_token_logprobs": null,
                "first_token_latency": config.response_delay_ms as f64 / 1000.0,
                "time_to_first_token": config.response_delay_ms as f64 / 1000.0,
                "time_per_output_token": 0.01,
                "finish_reason": {
                    "type": "stop",
                    "reason": "length"
                }
            }
        }))
        .into_response()
    }
}

async fn chat_completions_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Json(payload): Json<serde_json::Value>,
) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": {
                    "message": "Random failure for testing",
                    "type": "internal_error",
                    "code": "internal_error"
                }
            })),
        )
            .into_response();
    }

    if config.response_delay_ms > 0 {
        tokio::time::sleep(tokio::time::Duration::from_millis(config.response_delay_ms)).await;
    }

    let is_stream = payload
        .get("stream")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);

    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs();

    if is_stream {
        let request_id = format!("chatcmpl-{}", Uuid::new_v4());

        let stream = stream::once(async move {
            let chunk = json!({
                "id": request_id,
                "object": "chat.completion.chunk",
                "created": timestamp,
                "model": "mock-model",
                "choices": [{
                    "index": 0,
                    "delta": {
                        "content": "This is a mock chat response."
                    },
                    "finish_reason": null
                }]
            });

            Ok::<_, Infallible>(Event::default().data(chunk.to_string()))
        })
        .chain(stream::once(async { Ok(Event::default().data("[DONE]")) }));

        Sse::new(stream)
            .keep_alive(KeepAlive::default())
            .into_response()
    } else {
        Json(json!({
            "id": format!("chatcmpl-{}", Uuid::new_v4()),
            "object": "chat.completion",
            "created": timestamp,
            "model": "mock-model",
            "choices": [{
                "index": 0,
                "message": {
                    "role": "assistant",
                    "content": "This is a mock chat response."
                },
                "finish_reason": "stop"
            }],
            "usage": {
                "prompt_tokens": 10,
                "completion_tokens": 5,
                "total_tokens": 15
            }
        }))
        .into_response()
    }
}

async fn completions_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Json(payload): Json<serde_json::Value>,
) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": {
                    "message": "Random failure for testing",
                    "type": "internal_error",
                    "code": "internal_error"
                }
            })),
        )
            .into_response();
    }

    if config.response_delay_ms > 0 {
        tokio::time::sleep(tokio::time::Duration::from_millis(config.response_delay_ms)).await;
    }

    let is_stream = payload
        .get("stream")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);

    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs();

    if is_stream {
        let request_id = format!("cmpl-{}", Uuid::new_v4());

        let stream = stream::once(async move {
            let chunk = json!({
                "id": request_id,
                "object": "text_completion",
                "created": timestamp,
                "model": "mock-model",
                "choices": [{
                    "text": "This is a mock completion.",
                    "index": 0,
                    "logprobs": null,
                    "finish_reason": null
                }]
            });

            Ok::<_, Infallible>(Event::default().data(chunk.to_string()))
        })
        .chain(stream::once(async { Ok(Event::default().data("[DONE]")) }));

        Sse::new(stream)
            .keep_alive(KeepAlive::default())
            .into_response()
    } else {
        Json(json!({
            "id": format!("cmpl-{}", Uuid::new_v4()),
            "object": "text_completion",
            "created": timestamp,
            "model": "mock-model",
            "choices": [{
                "text": "This is a mock completion.",
                "index": 0,
                "logprobs": null,
                "finish_reason": "stop"
            }],
            "usage": {
                "prompt_tokens": 10,
                "completion_tokens": 5,
                "total_tokens": 15
            }
        }))
        .into_response()
    }
}

async fn responses_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Json(payload): Json<serde_json::Value>,
) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": {
                    "message": "Random failure for testing",
                    "type": "internal_error",
                    "code": "internal_error"
                }
            })),
        )
            .into_response();
    }

    if config.response_delay_ms > 0 {
        tokio::time::sleep(tokio::time::Duration::from_millis(config.response_delay_ms)).await;
    }

    let is_stream = payload
        .get("stream")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);

    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs() as i64;

    // Background storage simulation
    let is_background = payload
        .get("background")
        .and_then(|v| v.as_bool())
        .unwrap_or(false);
    let req_id = payload
        .get("request_id")
        .and_then(|v| v.as_str())
        .map(|s| s.to_string());
    if is_background {
        if let Some(id) = &req_id {
            store_response_for_port(config.port, id);
        }
    }

    if is_stream {
        let request_id = format!("resp-{}", Uuid::new_v4());

        // Check if this is an MCP tool call scenario
        let has_tools = payload
            .get("tools")
            .and_then(|v| v.as_array())
            .map(|arr| {
                arr.iter().any(|tool| {
                    tool.get("type")
                        .and_then(|t| t.as_str())
                        .map(|t| t == "function")
                        .unwrap_or(false)
                })
            })
            .unwrap_or(false);
        let has_function_output = payload
            .get("input")
            .and_then(|v| v.as_array())
            .map(|items| {
                items.iter().any(|item| {
                    item.get("type")
                        .and_then(|t| t.as_str())
                        .map(|t| t == "function_call_output")
                        .unwrap_or(false)
                })
            })
            .unwrap_or(false);

        if has_tools && !has_function_output {
            // First turn: emit streaming tool call events
            let call_id = format!(
                "call_{}",
                Uuid::new_v4().to_string().split('-').next().unwrap()
            );
            let rid = request_id.clone();

            let events = vec![
                // response.created
                Ok::<_, Infallible>(
                    Event::default().event("response.created").data(
                        json!({
                            "type": "response.created",
                            "response": {
                                "id": rid.clone(),
                                "object": "response",
                                "created_at": timestamp,
                                "model": "mock-model",
                                "status": "in_progress"
                            }
                        })
                        .to_string(),
                    ),
                ),
                // response.in_progress
                Ok(Event::default().event("response.in_progress").data(
                    json!({
                        "type": "response.in_progress",
                        "response": {
                            "id": rid.clone(),
                            "object": "response",
                            "created_at": timestamp,
                            "model": "mock-model",
                            "status": "in_progress"
                        }
                    })
                    .to_string(),
                )),
                // response.output_item.added with function_tool_call
                Ok(Event::default().event("response.output_item.added").data(
                    json!({
                        "type": "response.output_item.added",
                        "output_index": 0,
                        "item": {
                            "id": call_id.clone(),
                            "type": "function_tool_call",
                            "name": "brave_web_search",
                            "arguments": "",
                            "status": "in_progress"
                        }
                    })
                    .to_string(),
                )),
                // response.function_call_arguments.delta events
                Ok(Event::default()
                    .event("response.function_call_arguments.delta")
                    .data(
                        json!({
                            "type": "response.function_call_arguments.delta",
                            "output_index": 0,
                            "item_id": call_id.clone(),
                            "delta": "{\"query\""
                        })
                        .to_string(),
                    )),
                Ok(Event::default()
                    .event("response.function_call_arguments.delta")
                    .data(
                        json!({
                            "type": "response.function_call_arguments.delta",
                            "output_index": 0,
                            "item_id": call_id.clone(),
                            "delta": ":\"SGLang"
                        })
                        .to_string(),
                    )),
                Ok(Event::default()
                    .event("response.function_call_arguments.delta")
                    .data(
                        json!({
                            "type": "response.function_call_arguments.delta",
                            "output_index": 0,
                            "item_id": call_id.clone(),
                            "delta": " router MCP"
                        })
                        .to_string(),
                    )),
                Ok(Event::default()
                    .event("response.function_call_arguments.delta")
                    .data(
                        json!({
                            "type": "response.function_call_arguments.delta",
                            "output_index": 0,
                            "item_id": call_id.clone(),
                            "delta": " integration\"}"
                        })
                        .to_string(),
                    )),
                // response.function_call_arguments.done
                Ok(Event::default()
                    .event("response.function_call_arguments.done")
                    .data(
                        json!({
                            "type": "response.function_call_arguments.done",
                            "output_index": 0,
                            "item_id": call_id.clone()
                        })
                        .to_string(),
                    )),
                // response.output_item.done
                Ok(Event::default().event("response.output_item.done").data(
                    json!({
                        "type": "response.output_item.done",
                        "output_index": 0,
                        "item": {
                            "id": call_id.clone(),
                            "type": "function_tool_call",
                            "name": "brave_web_search",
                            "arguments": "{\"query\":\"SGLang router MCP integration\"}",
                            "status": "completed"
                        }
                    })
                    .to_string(),
                )),
                // response.completed
                Ok(Event::default().event("response.completed").data(
                    json!({
                        "type": "response.completed",
                        "response": {
                            "id": rid,
                            "object": "response",
                            "created_at": timestamp,
                            "model": "mock-model",
                            "status": "completed"
                        }
                    })
                    .to_string(),
                )),
                // [DONE]
                Ok(Event::default().data("[DONE]")),
            ];

            let stream = stream::iter(events);
            Sse::new(stream)
                .keep_alive(KeepAlive::default())
                .into_response()
        } else if has_tools && has_function_output {
            // Second turn: emit streaming text response
            let rid = request_id.clone();
            let msg_id = format!(
                "msg_{}",
                Uuid::new_v4().to_string().split('-').next().unwrap()
            );

            let events = vec![
                // response.created
                Ok::<_, Infallible>(
                    Event::default().event("response.created").data(
                        json!({
                            "type": "response.created",
                            "response": {
                                "id": rid.clone(),
                                "object": "response",
                                "created_at": timestamp,
                                "model": "mock-model",
                                "status": "in_progress"
                            }
                        })
                        .to_string(),
                    ),
                ),
                // response.in_progress
                Ok(Event::default().event("response.in_progress").data(
                    json!({
                        "type": "response.in_progress",
                        "response": {
                            "id": rid.clone(),
                            "object": "response",
                            "created_at": timestamp,
                            "model": "mock-model",
                            "status": "in_progress"
                        }
                    })
                    .to_string(),
                )),
                // response.output_item.added with message
                Ok(Event::default().event("response.output_item.added").data(
                    json!({
                        "type": "response.output_item.added",
                        "output_index": 0,
                        "item": {
                            "id": msg_id.clone(),
                            "type": "message",
                            "role": "assistant",
                            "content": []
                        }
                    })
                    .to_string(),
                )),
                // response.content_part.added
                Ok(Event::default().event("response.content_part.added").data(
                    json!({
                        "type": "response.content_part.added",
                        "output_index": 0,
                        "item_id": msg_id.clone(),
                        "part": {
                            "type": "output_text",
                            "text": ""
                        }
                    })
                    .to_string(),
                )),
                // response.output_text.delta events
                Ok(Event::default().event("response.output_text.delta").data(
                    json!({
                        "type": "response.output_text.delta",
                        "output_index": 0,
                        "content_index": 0,
                        "delta": "Tool result"
                    })
                    .to_string(),
                )),
                Ok(Event::default().event("response.output_text.delta").data(
                    json!({
                        "type": "response.output_text.delta",
                        "output_index": 0,
                        "content_index": 0,
                        "delta": " consumed;"
                    })
                    .to_string(),
                )),
                Ok(Event::default().event("response.output_text.delta").data(
                    json!({
                        "type": "response.output_text.delta",
                        "output_index": 0,
                        "content_index": 0,
                        "delta": " here is the final answer."
                    })
                    .to_string(),
                )),
                // response.output_text.done
                Ok(Event::default().event("response.output_text.done").data(
                    json!({
                        "type": "response.output_text.done",
                        "output_index": 0,
                        "content_index": 0,
                        "text": "Tool result consumed; here is the final answer."
                    })
                    .to_string(),
                )),
                // response.output_item.done
                Ok(Event::default().event("response.output_item.done").data(
                    json!({
                        "type": "response.output_item.done",
                        "output_index": 0,
                        "item": {
                            "id": msg_id,
                            "type": "message",
                            "role": "assistant",
                            "content": [{
                                "type": "output_text",
                                "text": "Tool result consumed; here is the final answer."
                            }]
                        }
                    })
                    .to_string(),
                )),
                // response.completed
                Ok(Event::default().event("response.completed").data(
                    json!({
                        "type": "response.completed",
                        "response": {
                            "id": rid,
                            "object": "response",
                            "created_at": timestamp,
                            "model": "mock-model",
                            "status": "completed",
                            "usage": {
                                "input_tokens": 12,
                                "output_tokens": 7,
                                "total_tokens": 19
                            }
                        }
                    })
                    .to_string(),
                )),
                // [DONE]
                Ok(Event::default().data("[DONE]")),
            ];

            let stream = stream::iter(events);
            Sse::new(stream)
                .keep_alive(KeepAlive::default())
                .into_response()
        } else {
            // Default streaming response
            let stream = stream::once(async move {
                let chunk = json!({
                    "id": request_id,
                    "object": "response",
                    "created_at": timestamp,
                    "model": "mock-model",
                    "status": "in_progress",
                    "output": [{
                        "type": "message",
                        "role": "assistant",
                        "content": [{
                            "type": "output_text",
                            "text": "This is a mock responses streamed output."
                        }]
                    }]
                });
                Ok::<_, Infallible>(Event::default().data(chunk.to_string()))
            })
            .chain(stream::once(async { Ok(Event::default().data("[DONE]")) }));

            Sse::new(stream)
                .keep_alive(KeepAlive::default())
                .into_response()
        }
    } else if is_background {
        let rid = req_id.unwrap_or_else(|| format!("resp-{}", Uuid::new_v4()));
        Json(json!({
            "id": rid,
            "object": "response",
            "created_at": timestamp,
            "model": "mock-model",
            "output": [],
            "status": "queued",
            "usage": null
        }))
        .into_response()
    } else {
        // If tools are provided and this is the first call (no previous_response_id),
        // emit a single function_tool_call to trigger the router's MCP flow.
        let has_tools = payload
            .get("tools")
            .and_then(|v| v.as_array())
            .map(|arr| {
                arr.iter().any(|tool| {
                    tool.get("type")
                        .and_then(|t| t.as_str())
                        .map(|t| t == "function")
                        .unwrap_or(false)
                })
            })
            .unwrap_or(false);
        let has_function_output = payload
            .get("input")
            .and_then(|v| v.as_array())
            .map(|items| {
                items.iter().any(|item| {
                    item.get("type")
                        .and_then(|t| t.as_str())
                        .map(|t| t == "function_call_output")
                        .unwrap_or(false)
                })
            })
            .unwrap_or(false);

        if has_tools && !has_function_output {
            let rid = format!("resp-{}", Uuid::new_v4());
            Json(json!({
                "id": rid,
                "object": "response",
                "created_at": timestamp,
                "model": "mock-model",
                "output": [{
                    "type": "function_tool_call",
                    "id": "call_1",
                    "name": "brave_web_search",
                    "arguments": "{\"query\":\"SGLang router MCP integration\"}",
                    "status": "in_progress"
                }],
                "status": "in_progress",
                "usage": null
            }))
            .into_response()
        } else if has_tools && has_function_output {
            Json(json!({
                "id": format!("resp-{}", Uuid::new_v4()),
                "object": "response",
                "created_at": timestamp,
                "model": "mock-model",
                "output": [{
                    "type": "message",
                    "role": "assistant",
                    "content": [{
                        "type": "output_text",
                        "text": "Tool result consumed; here is the final answer."
                    }]
                }],
                "status": "completed",
                "usage": {
                    "input_tokens": 12,
                    "output_tokens": 7,
                    "total_tokens": 19
                }
            }))
            .into_response()
        } else {
            Json(json!({
                "id": format!("resp-{}", Uuid::new_v4()),
                "object": "response",
                "created_at": timestamp,
                "model": "mock-model",
                "output": [{
                    "type": "message",
                    "role": "assistant",
                    "content": [{
                        "type": "output_text",
                        "text": "This is a mock responses output."
                    }]
                }],
                "status": "completed",
                "usage": {
                    "input_tokens": 10,
                    "output_tokens": 5,
                    "total_tokens": 15
                }
            }))
            .into_response()
        }
    }
}

async fn flush_cache_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": "Random failure for testing"
            })),
        )
            .into_response();
    }

    Json(json!({
        "message": "Cache flushed successfully"
    }))
    .into_response()
}

async fn v1_models_handler(State(config): State<Arc<RwLock<MockWorkerConfig>>>) -> Response {
    let config = config.read().await;

    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({
                "error": {
                    "message": "Random failure for testing",
                    "type": "internal_error",
                    "code": "internal_error"
                }
            })),
        )
            .into_response();
    }

    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs();

    Json(json!({
        "object": "list",
        "data": [{
            "id": "mock-model",
            "object": "model",
            "created": timestamp,
            "owned_by": "organization-owner"
        }]
    }))
    .into_response()
}

async fn responses_get_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Path(response_id): Path<String>,
) -> Response {
    let config = config.read().await;
    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({ "error": "Random failure for testing" })),
        )
            .into_response();
    }
    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs() as i64;
    // Only return 200 if this worker "stores" the response id
    if response_exists_for_port(config.port, &response_id) {
        Json(json!({
            "id": response_id,
            "object": "response",
            "created_at": timestamp,
            "model": "mock-model",
            "output": [],
            "status": "completed",
            "usage": {
                "input_tokens": 0,
                "output_tokens": 0,
                "total_tokens": 0
            }
        }))
        .into_response()
    } else {
        StatusCode::NOT_FOUND.into_response()
    }
}

async fn responses_cancel_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Path(response_id): Path<String>,
) -> Response {
    let config = config.read().await;
    if should_fail(&config).await {
        return (
            StatusCode::INTERNAL_SERVER_ERROR,
            Json(json!({ "error": "Random failure for testing" })),
        )
            .into_response();
    }
    let timestamp = SystemTime::now()
        .duration_since(UNIX_EPOCH)
        .unwrap()
        .as_secs() as i64;
    if response_exists_for_port(config.port, &response_id) {
        Json(json!({
            "id": response_id,
            "object": "response",
            "created_at": timestamp,
            "model": "mock-model",
            "output": [],
            "status": "cancelled",
            "usage": null
        }))
        .into_response()
    } else {
        StatusCode::NOT_FOUND.into_response()
    }
}

// --- Simple in-memory response store per worker port (for tests) ---
static RESP_STORE: OnceLock<Mutex<HashMap<u16, HashSet<String>>>> = OnceLock::new();

fn get_store() -> &'static Mutex<HashMap<u16, HashSet<String>>> {
    RESP_STORE.get_or_init(|| Mutex::new(HashMap::new()))
}

fn store_response_for_port(port: u16, response_id: &str) {
    let mut map = get_store().lock().unwrap();
    map.entry(port).or_default().insert(response_id.to_string());
}

fn response_exists_for_port(port: u16, response_id: &str) -> bool {
    let map = get_store().lock().unwrap();
    map.get(&port)
        .map(|set| set.contains(response_id))
        .unwrap_or(false)
}

// Minimal rerank handler returning mock results; router shapes final response
async fn rerank_handler(
    State(config): State<Arc<RwLock<MockWorkerConfig>>>,
    Json(payload): Json<serde_json::Value>,
) -> impl IntoResponse {
    let config = config.read().await;

    // Simulate response delay
    if config.response_delay_ms > 0 {
        tokio::time::sleep(tokio::time::Duration::from_millis(config.response_delay_ms)).await;
    }

    // Simulate failure rate
    if rand::random::<f32>() < config.fail_rate {
        return (StatusCode::INTERNAL_SERVER_ERROR, "Simulated failure").into_response();
    }

    // Extract documents from the request to create mock results
    let empty_vec = vec![];
    let documents = payload
        .get("documents")
        .and_then(|d| d.as_array())
        .unwrap_or(&empty_vec);

    // Create mock rerank results with scores based on document index
    let mut mock_results = Vec::new();
    for (i, doc) in documents.iter().enumerate() {
        let score = 0.95 - (i as f32 * 0.1); // Decreasing scores
        let result = serde_json::json!({
            "score": score,
            "document": doc.as_str().unwrap_or(""),
            "index": i,
            "meta_info": {
                "confidence": if score > 0.9 { "high" } else { "medium" }
            }
        });
        mock_results.push(result);
    }

    // Sort by score (highest first) to simulate proper ranking
    mock_results.sort_by(|a, b| {
        b["score"]
            .as_f64()
            .unwrap()
            .partial_cmp(&a["score"].as_f64().unwrap())
            .unwrap()
    });

    (StatusCode::OK, Json(mock_results)).into_response()
}

impl Default for MockWorkerConfig {
    fn default() -> Self {
        Self {
            port: 0,
            worker_type: WorkerType::Regular,
            health_status: HealthStatus::Healthy,
            response_delay_ms: 0,
            fail_rate: 0.0,
        }
    }
}