#![allow(dead_code)]

use axum::body::Body;
use axum::http::header;
use axum::response::Response;
use axum::routing::{get, post};
use axum::{Json, Router};
use cortex_core::config::{
    EvictionSettings, EvictionStrategy, GatewayConfig, GatewaySettings, NodeConfig,
};
use cortex_core::node::{ModelEntry, ModelStatus};
use cortex_gateway::state::CortexState;
use futures::{StreamExt, stream};
use serde_json::{Value, json};
use std::sync::Arc;
use std::time::Duration;
use tokio::net::TcpListener;

/// Spawns a mock mistral.rs backend on a random port.
/// Returns the base URL (e.g. "http://127.0.0.1:12345").
pub async fn spawn_mock_backend() -> String {
    let app = Router::new()
        .route("/v1/chat/completions", post(mock_chat_completions))
        .route("/v1/models", get(mock_list_models));

    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = listener.local_addr().unwrap();
    tokio::spawn(async move {
        axum::serve(listener, app).await.unwrap();
    });

    format!("http://{addr}")
}

async fn mock_chat_completions(Json(body): Json<Value>) -> Json<Value> {
    let model = body
        .get("model")
        .and_then(|v| v.as_str())
        .unwrap_or("unknown");

    Json(json!({
        "id": "chatcmpl-test-001",
        "object": "chat.completion",
        "created": 1700000000_u64,
        "model": model,
        "choices": [{
            "index": 0,
            "message": {
                "role": "assistant",
                "content": "Hello from mock backend"
            },
            "finish_reason": "stop"
        }],
        "usage": {
            "prompt_tokens": 10,
            "completion_tokens": 5,
            "total_tokens": 15
        }
    }))
}

async fn mock_list_models() -> Json<Value> {
    Json(json!({
        "object": "list",
        "data": [{
            "id": "test-model",
            "object": "model",
            "status": "loaded"
        }]
    }))
}

/// Spawns a mock mistral.rs backend that returns SSE streaming responses.
/// Each chunk is delayed by `chunk_delay` to prove the proxy streams incrementally.
pub async fn spawn_streaming_mock_backend(chunk_count: usize, chunk_delay: Duration) -> String {
    let app = Router::new()
        .route(
            "/v1/chat/completions",
            post(move |Json(body): Json<Value>| async move {
                let model = body
                    .get("model")
                    .and_then(|v| v.as_str())
                    .unwrap_or("unknown")
                    .to_string();

                let chunks: Vec<String> = (0..chunk_count)
                    .map(|i| {
                        let content = format!("token{i}");
                        let chunk = json!({
                            "id": "chatcmpl-stream-001",
                            "object": "chat.completion.chunk",
                            "created": 1700000000_u64,
                            "model": model,
                            "choices": [{
                                "index": 0,
                                "delta": { "content": content },
                                "finish_reason": null
                            }]
                        });
                        format!("data: {chunk}\n\n")
                    })
                    .collect();

                let delay = chunk_delay;
                let stream = stream::iter(
                    chunks
                        .into_iter()
                        .chain(std::iter::once("data: [DONE]\n\n".to_string())),
                )
                .then(move |chunk| async move {
                    tokio::time::sleep(delay).await;
                    Ok::<_, std::convert::Infallible>(chunk)
                });

                Response::builder()
                    .header(header::CONTENT_TYPE, "text/event-stream")
                    .header(header::CACHE_CONTROL, "no-cache")
                    .body(Body::from_stream(stream))
                    .unwrap()
            }),
        )
        .route("/v1/models", get(mock_list_models));

    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = listener.local_addr().unwrap();
    tokio::spawn(async move {
        axum::serve(listener, app).await.unwrap();
    });

    format!("http://{addr}")
}

/// Spawns a mock backend with a custom `/v1/models` response.
pub async fn spawn_mock_backend_with_models(models_response: Value) -> String {
    let app = Router::new()
        .route("/v1/chat/completions", post(mock_chat_completions))
        .route(
            "/v1/models",
            get(move || {
                let resp = models_response.clone();
                async move { Json(resp) }
            }),
        );

    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = listener.local_addr().unwrap();
    tokio::spawn(async move {
        axum::serve(listener, app).await.unwrap();
    });

    format!("http://{addr}")
}

/// Spawns the cortex gateway with a single node pointing at `mock_url`.
/// The node is pre-seeded as healthy with one loaded model ("test-model").
/// Returns the gateway's base URL.
pub async fn spawn_gateway(mock_url: &str) -> String {
    let (_, url) = spawn_gateway_with_state(mock_url).await;
    url
}

/// Like `spawn_gateway` but also returns the shared `CortexState` so tests
/// can call `poll_once` or inspect state directly.
pub async fn spawn_gateway_with_state(mock_url: &str) -> (Arc<CortexState>, String) {
    let config = GatewayConfig {
        gateway: GatewaySettings {
            listen: "127.0.0.1:0".into(),
            metrics_listen: "127.0.0.1:0".into(),
        },
        eviction: EvictionSettings {
            strategy: EvictionStrategy::Lru,
            defrag_after_cycles: 0,
        },
        nodes: vec![NodeConfig {
            name: "mock-node".into(),
            endpoint: mock_url.to_string(),
            vram_mb: 24000,
            pinned: vec![],
        }],
    };

    let fleet = Arc::new(CortexState::from_config(&config));

    // Seed the node as healthy with a loaded model.
    // (Bypasses the poller, which is not running in tests.)
    {
        let mut nodes = fleet.nodes.write().await;
        let node = nodes.get_mut("mock-node").expect("node must exist");
        node.healthy = true;
        node.models.insert(
            "test-model".into(),
            ModelEntry {
                id: "test-model".into(),
                status: ModelStatus::Loaded,
                last_accessed: None,
                vram_estimate_mb: Some(8000),
            },
        );
    }

    let app = cortex_gateway::build_app(Arc::clone(&fleet));

    let listener = TcpListener::bind("127.0.0.1:0").await.unwrap();
    let addr = listener.local_addr().unwrap();
    tokio::spawn(async move {
        axum::serve(listener, app).await.unwrap();
    });

    (fleet, format!("http://{addr}"))
}