use std::collections::HashMap;
use std::net::{IpAddr, SocketAddr};
use std::sync::{Arc, LazyLock};

use axum::extract::{ConnectInfo, Path, Query, State};
use axum::http::header::{CACHE_CONTROL, CONTENT_TYPE};
use axum::http::{HeaderValue, StatusCode};
use axum::response::{IntoResponse, Response};
use axum::routing::{get, post};
use axum::{Json, Router};
use llmfit_core::fit::{
    FitLevel, InferenceRuntime, ModelFit, SortColumn, backend_compatible,
    rank_models_by_fit_opts_col,
};
use llmfit_core::hardware::{GpuBackend, SystemSpecs};
use llmfit_core::models::{LlmModel, ModelDatabase, UseCase};
use llmfit_core::plan::{PlanRequest, estimate_model_plan};
use llmfit_core::providers::{
    DockerModelRunnerProvider, LlamaCppProvider, LmStudioProvider, MlxProvider, ModelProvider,
    OllamaProvider, PullEvent, VllmProvider,
};
use serde::{Deserialize, Serialize};

use crate::serve_shared;

include!(concat!(env!("OUT_DIR"), "/web_assets.rs"));

static ASSET_MAP: LazyLock<HashMap<&'static str, &'static EmbeddedAsset>> =
    LazyLock::new(|| EMBEDDED_WEB_ASSETS.iter().map(|a| (a.path, a)).collect());

struct AppState {
    node_name: String,
    os: String,
    specs: SystemSpecs,
    models: Vec<LlmModel>,
    context_limit: Option<u32>,
    active_download: tokio::sync::RwLock<Option<ActiveDownload>>,
    download_counter: std::sync::atomic::AtomicU32,
}

struct ActiveDownload {
    id: String,
    model_name: String,
    runtime: String,
    status: String,
    progress_pct: f64,
    message: String,
}

#[derive(Debug, Serialize)]
struct InstalledModel {
    name: String,
    runtime: String,
}

#[derive(Debug, Deserialize)]
struct HardwareOverrideQuery {
    #[serde(alias = "ram")]
    ram_gb: Option<f64>,
    #[serde(alias = "memory")]
    vram_gb: Option<f64>,
    cpu_cores: Option<usize>,
}

#[derive(Debug, Deserialize)]
struct ModelsQuery {
    limit: Option<usize>,
    #[serde(alias = "n")]
    top: Option<usize>,
    perfect: Option<bool>,
    min_fit: Option<String>,
    runtime: Option<String>,
    use_case: Option<String>,
    provider: Option<String>,
    search: Option<String>,
    sort: Option<String>,
    include_too_tight: Option<bool>,
    max_context: Option<u32>,
    force_runtime: Option<String>,
    license: Option<String>,
    #[serde(alias = "ram")]
    ram_gb: Option<f64>,
    #[serde(alias = "memory")]
    vram_gb: Option<f64>,
    cpu_cores: Option<usize>,
}

#[derive(Debug, Serialize)]
struct NodeInfo {
    name: String,
    os: String,
}

#[derive(Debug, Serialize)]
struct ApiEnvelope {
    node: NodeInfo,
    system: serde_json::Value,
    total_models: usize,
    returned_models: usize,
    filters: serde_json::Value,
    models: Vec<serde_json::Value>,
}

#[derive(Debug)]
struct ApiError {
    status: StatusCode,
    message: String,
}

impl ApiError {
    fn new(status: StatusCode, message: impl Into<String>) -> Self {
        Self {
            status,
            message: message.into(),
        }
    }

    fn bad_request(message: impl Into<String>) -> Self {
        Self::new(StatusCode::BAD_REQUEST, message)
    }

    fn internal(message: impl Into<String>) -> Self {
        Self::new(StatusCode::INTERNAL_SERVER_ERROR, message)
    }
}

impl IntoResponse for ApiError {
    fn into_response(self) -> Response {
        (
            self.status,
            Json(serde_json::json!({
                "error": self.message,
            })),
        )
            .into_response()
    }
}

type ApiResult<T> = Result<T, ApiError>;

pub fn run_serve(
    host: &str,
    port: u16,
    unix_socket: Option<&std::path::Path>,
    overrides: &super::HardwareOverrides,
    context_limit: Option<u32>,
) -> Result<(), String> {
    let specs = super::detect_specs(overrides);
    let db = ModelDatabase::new();
    let all_models = db.get_all_models().clone();

    let node_name = std::env::var("HOSTNAME")
        .ok()
        .filter(|v| !v.trim().is_empty())
        .unwrap_or_else(|| "unknown-node".to_string());

    let state = Arc::new(AppState {
        node_name,
        os: std::env::consts::OS.to_string(),
        specs,
        models: all_models,
        context_limit,
        active_download: tokio::sync::RwLock::new(None),
        download_counter: std::sync::atomic::AtomicU32::new(0),
    });

    let app = build_router(state);

    let runtime = tokio::runtime::Builder::new_multi_thread()
        .enable_all()
        .build()
        .map_err(|e| format!("failed to start tokio runtime: {e}"))?;

    match unix_socket {
        Some(path) => {
            #[cfg(unix)]
            {
                println!("llmfit dashboard listening on unix://{}", path.display());
                println!("  GET /health");
                println!("  GET /api/v1/system");
                println!("  GET /api/v1/models?limit=20&min_fit=marginal&sort=score");
                runtime
                    .block_on(async move {
                        if let Some(parent) = path.parent() {
                            let _ = std::fs::create_dir_all(parent);
                        }
                        // A stale file from a previous instance blocks bind
                        // (the path can outlive the process, e.g. a pod
                        // volume across container restarts).
                        let _ = std::fs::remove_file(path);
                        let listener = tokio::net::UnixListener::bind(path).map_err(|e| {
                            ApiError::internal(format!("bind failed on {}: {e}", path.display()))
                        })?;
                        // Same-host peers only; group-accessible, not world.
                        use std::os::unix::fs::PermissionsExt;
                        let _ =
                            std::fs::set_permissions(path, std::fs::Permissions::from_mode(0o660));
                        axum::serve(listener, app.into_make_service())
                            .with_graceful_shutdown(async {
                                let _ = tokio::signal::ctrl_c().await;
                            })
                            .await
                            .map_err(|e| ApiError::internal(format!("server error: {e}")))
                    })
                    .map_err(|e| e.message)
            }
            #[cfg(not(unix))]
            {
                let _ = path;
                Err("--unix-socket is only supported on unix platforms".to_string())
            }
        }
        None => {
            let ip: IpAddr = host
                .parse()
                .map_err(|_| format!("invalid --host value: '{host}'"))?;
            let addr = SocketAddr::new(ip, port);

            println!("llmfit dashboard listening on http://{}/", addr);
            println!("  API models: http://{}/api/v1/models", addr);
            println!("  GET /health");
            println!("  GET /api/v1/system");
            println!("  GET /api/v1/models?limit=20&min_fit=marginal&sort=score");
            println!("  GET /api/v1/models/top?limit=5&use_case=coding&min_fit=good");
            println!("  GET /api/v1/models/<name>");

            runtime
                .block_on(async move {
                    let listener = tokio::net::TcpListener::bind(addr)
                        .await
                        .map_err(|e| ApiError::internal(format!("bind failed on {addr}: {e}")))?;

                    axum::serve(
                        listener,
                        app.into_make_service_with_connect_info::<SocketAddr>(),
                    )
                    .with_graceful_shutdown(async {
                        let _ = tokio::signal::ctrl_c().await;
                    })
                    .await
                    .map_err(|e| ApiError::internal(format!("server error: {e}")))
                })
                .map_err(|e| e.message)
        }
    }
}

fn build_router(state: Arc<AppState>) -> Router {
    Router::new()
        .route("/", get(web_index))
        .route("/assets/{*path}", get(web_asset))
        .route("/health", get(health))
        .route("/api/v1/system", get(system))
        .route("/api/v1/models", get(models))
        .route("/api/v1/models/top", get(top_models))
        .route("/api/v1/models/{name}", get(model_by_name))
        .route("/api/v1/runtimes", get(runtimes))
        .route("/api/v1/installed", get(installed))
        .route("/api/v1/download", post(start_download))
        .route("/api/v1/download/{id}/status", get(download_status))
        .route("/api/v1/plan", post(plan_estimate))
        .route("/{*path}", get(spa_fallback))
        .with_state(state)
}

async fn health(State(state): State<Arc<AppState>>) -> Json<serde_json::Value> {
    Json(serde_json::json!({
        "status": "ok",
        "node": {
            "name": state.node_name,
            "os": state.os,
        }
    }))
}

async fn system(
    State(state): State<Arc<AppState>>,
    Query(overrides): Query<HardwareOverrideQuery>,
) -> ApiResult<Json<serde_json::Value>> {
    let specs = effective_specs(&state.specs, &overrides)?;

    Ok(Json(serde_json::json!({
        "node": {
            "name": state.node_name,
            "os": state.os,
        },
        "system": system_json(&specs),
    })))
}

async fn web_index() -> Response {
    serve_web_path("/index.html")
}

async fn web_asset(Path(path): Path<String>) -> Response {
    let asset_path = format!("/assets/{}", path.trim_start_matches('/'));
    serve_web_path(&asset_path)
}

async fn spa_fallback(Path(path): Path<String>) -> Response {
    if path.starts_with("api/") || path == "health" || path.starts_with("assets/") {
        return StatusCode::NOT_FOUND.into_response();
    }
    serve_web_path("/index.html")
}

fn serve_web_path(path: &str) -> Response {
    let Some(asset) = find_web_asset(path) else {
        return StatusCode::NOT_FOUND.into_response();
    };

    let mut response = asset.bytes.to_vec().into_response();
    response
        .headers_mut()
        .insert(CONTENT_TYPE, HeaderValue::from_static(asset.content_type));
    let cache_value = if path.starts_with("/assets/") {
        "public, max-age=31536000, immutable"
    } else {
        "no-cache"
    };
    response
        .headers_mut()
        .insert(CACHE_CONTROL, HeaderValue::from_static(cache_value));
    response
}

fn find_web_asset(path: &str) -> Option<&'static EmbeddedAsset> {
    ASSET_MAP.get(path).copied()
}

async fn models(
    State(state): State<Arc<AppState>>,
    Query(query): Query<ModelsQuery>,
) -> ApiResult<Json<ApiEnvelope>> {
    let specs = effective_specs(&state.specs, &query.hardware_overrides())?;
    let mut fits = filtered_fits(&state, &specs, &query, false)?;
    let total_models = fits.len();

    let limit = query.limit.or(query.top).unwrap_or(usize::MAX);
    if limit < fits.len() {
        fits.truncate(limit);
    }

    let envelope = ApiEnvelope {
        node: NodeInfo {
            name: state.node_name.clone(),
            os: state.os.clone(),
        },
        system: system_json(&specs),
        total_models,
        returned_models: fits.len(),
        filters: active_filters_json(&query, false),
        models: fits.iter().map(fit_to_json).collect(),
    };

    Ok(Json(envelope))
}

async fn top_models(
    State(state): State<Arc<AppState>>,
    Query(query): Query<ModelsQuery>,
) -> ApiResult<Json<ApiEnvelope>> {
    let specs = effective_specs(&state.specs, &query.hardware_overrides())?;
    let mut fits = filtered_fits(&state, &specs, &query, true)?;
    let total_models = fits.len();

    let limit = query.limit.or(query.top).unwrap_or(5);
    if limit < fits.len() {
        fits.truncate(limit);
    }

    let envelope = ApiEnvelope {
        node: NodeInfo {
            name: state.node_name.clone(),
            os: state.os.clone(),
        },
        system: system_json(&specs),
        total_models,
        returned_models: fits.len(),
        filters: active_filters_json(&query, true),
        models: fits.iter().map(fit_to_json).collect(),
    };

    Ok(Json(envelope))
}

async fn model_by_name(
    State(state): State<Arc<AppState>>,
    Path(name): Path<String>,
    Query(query): Query<ModelsQuery>,
) -> ApiResult<Json<ApiEnvelope>> {
    let mut scoped = query;
    scoped.search = Some(name);

    let specs = effective_specs(&state.specs, &scoped.hardware_overrides())?;
    let mut fits = filtered_fits(&state, &specs, &scoped, false)?;
    let total_models = fits.len();

    let limit = scoped.limit.or(scoped.top).unwrap_or(20);
    if limit < fits.len() {
        fits.truncate(limit);
    }

    let envelope = ApiEnvelope {
        node: NodeInfo {
            name: state.node_name.clone(),
            os: state.os.clone(),
        },
        system: system_json(&specs),
        total_models,
        returned_models: fits.len(),
        filters: active_filters_json(&scoped, false),
        models: fits.iter().map(fit_to_json).collect(),
    };

    Ok(Json(envelope))
}

#[derive(Deserialize)]
struct DownloadBody {
    model: String,
    runtime: String,
}

#[derive(Deserialize)]
struct PlanBody {
    model: String,
    context: u32,
    quant: Option<String>,
    target_tps: Option<f64>,
    #[serde(default)]
    kv_quant: Option<String>,
    #[serde(alias = "ram")]
    ram_gb: Option<f64>,
    #[serde(alias = "memory")]
    vram_gb: Option<f64>,
    cpu_cores: Option<usize>,
}

impl ModelsQuery {
    fn hardware_overrides(&self) -> HardwareOverrideQuery {
        HardwareOverrideQuery {
            ram_gb: self.ram_gb,
            vram_gb: self.vram_gb,
            cpu_cores: self.cpu_cores,
        }
    }
}

impl PlanBody {
    fn hardware_overrides(&self) -> HardwareOverrideQuery {
        HardwareOverrideQuery {
            ram_gb: self.ram_gb,
            vram_gb: self.vram_gb,
            cpu_cores: self.cpu_cores,
        }
    }
}

async fn runtimes(State(_state): State<Arc<AppState>>) -> Json<serde_json::Value> {
    let mut set = tokio::task::JoinSet::new();

    set.spawn_blocking(|| ("ollama", OllamaProvider::new().is_available()));
    set.spawn_blocking(|| ("mlx", MlxProvider::new().is_available()));
    set.spawn_blocking(|| ("llamacpp", LlamaCppProvider::new().is_available()));
    set.spawn_blocking(|| {
        (
            "docker_model_runner",
            DockerModelRunnerProvider::new().is_available(),
        )
    });
    set.spawn_blocking(|| ("lmstudio", LmStudioProvider::new().is_available()));
    set.spawn_blocking(|| ("vllm", VllmProvider::new().is_available()));

    let mut runtimes = Vec::new();
    let mut warnings = Vec::new();
    while let Some(result) = set.join_next().await {
        match result {
            Ok((name, available)) => {
                runtimes.push(serde_json::json!({ "name": name, "installed": available }));
            }
            Err(e) => {
                warnings.push(format!("provider check failed: {e}"));
            }
        }
    }

    Json(serde_json::json!({ "runtimes": runtimes, "warnings": warnings }))
}

async fn installed(State(_state): State<Arc<AppState>>) -> Json<serde_json::Value> {
    let mut set = tokio::task::JoinSet::new();

    set.spawn_blocking(|| {
        let p = OllamaProvider::new();
        ("ollama", p.is_available(), p.installed_models())
    });
    set.spawn_blocking(|| {
        let p = MlxProvider::new();
        ("mlx", p.is_available(), p.installed_models())
    });
    set.spawn_blocking(|| {
        let p = LlamaCppProvider::new();
        ("llamacpp", p.is_available(), p.installed_models())
    });
    set.spawn_blocking(|| {
        let p = DockerModelRunnerProvider::new();
        (
            "docker_model_runner",
            p.is_available(),
            p.installed_models(),
        )
    });
    set.spawn_blocking(|| {
        let p = LmStudioProvider::new();
        ("lmstudio", p.is_available(), p.installed_models())
    });
    set.spawn_blocking(|| {
        let p = VllmProvider::new();
        ("vllm", p.is_available(), p.installed_models())
    });

    let mut models = Vec::new();
    let mut warnings = Vec::new();
    while let Some(result) = set.join_next().await {
        match result {
            Ok((name, available, installed_set)) => {
                if !available {
                    continue;
                }
                for model_name in installed_set {
                    models.push(InstalledModel {
                        name: model_name,
                        runtime: name.to_string(),
                    });
                }
            }
            Err(e) => {
                warnings.push(format!("provider check failed: {e}"));
            }
        }
    }

    Json(serde_json::json!({
        "models": models,
        "warnings": warnings,
    }))
}

async fn start_download(
    State(state): State<Arc<AppState>>,
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    Json(body): Json<DownloadBody>,
) -> ApiResult<Json<serde_json::Value>> {
    if !addr.ip().is_loopback() {
        return Err(ApiError::new(
            StatusCode::FORBIDDEN,
            "Downloads restricted to localhost",
        ));
    }

    {
        let dl = state.active_download.read().await;
        if let Some(ref d) = *dl
            && d.status == "pulling"
        {
            return Err(ApiError::bad_request(format!(
                "download '{}' already in progress; wait for it to complete or error",
                d.id
            )));
        }
    }

    let id = {
        let n = state
            .download_counter
            .fetch_add(1, std::sync::atomic::Ordering::Relaxed);
        format!("dl-{n}")
    };

    {
        let mut dl = state.active_download.write().await;
        *dl = Some(ActiveDownload {
            id: id.clone(),
            model_name: body.model.clone(),
            runtime: body.runtime.clone(),
            status: "pulling".to_string(),
            progress_pct: 0.0,
            message: "starting".to_string(),
        });
    }

    let download_id = id.clone();
    let model_name = body.model.clone();
    let runtime = body.runtime.clone();
    let state_bg = Arc::clone(&state);

    // Use a tokio mpsc channel to relay PullEvents from the blocking thread
    // into the async task that updates the RwLock.
    let (event_tx, mut event_rx) = tokio::sync::mpsc::unbounded_channel::<PullEvent>();

    // Blocking thread: start the pull and forward events over the tokio channel.
    tokio::task::spawn_blocking(move || {
        let handle_result = match runtime.as_str() {
            "ollama" => OllamaProvider::new().start_pull(&model_name),
            "mlx" => MlxProvider::new().start_pull(&model_name),
            "llamacpp" => LlamaCppProvider::new().start_pull(&model_name),
            "docker_model_runner" => DockerModelRunnerProvider::new().start_pull(&model_name),
            "lmstudio" => LmStudioProvider::new().start_pull(&model_name),
            "vllm" => VllmProvider::new().start_pull(&model_name),
            other => {
                let _ = event_tx.send(PullEvent::Error(format!("unknown runtime: {other}")));
                return;
            }
        };

        match handle_result {
            Ok(handle) => loop {
                match handle.receiver.recv() {
                    Ok(event @ PullEvent::Progress { .. }) => {
                        if event_tx.send(event).is_err() {
                            return;
                        }
                    }
                    Ok(PullEvent::Done) => {
                        let _ = event_tx.send(PullEvent::Done);
                        return;
                    }
                    Ok(PullEvent::Error(e)) => {
                        let _ = event_tx.send(PullEvent::Error(e));
                        return;
                    }
                    Err(_) => {
                        let _ = event_tx.send(PullEvent::Error(
                            "download channel closed unexpectedly".to_string(),
                        ));
                        return;
                    }
                }
            },
            Err(e) => {
                let _ = event_tx.send(PullEvent::Error(e));
            }
        }
    });

    // Async task: consume events from the channel and update shared state.
    tokio::task::spawn(async move {
        while let Some(event) = event_rx.recv().await {
            let mut dl = state_bg.active_download.write().await;
            if let Some(ref mut d) = *dl {
                if d.id != download_id {
                    break;
                }
                match event {
                    PullEvent::Progress { status, percent } => {
                        d.status = "pulling".to_string();
                        d.progress_pct = percent.unwrap_or(d.progress_pct);
                        d.message = status;
                    }
                    PullEvent::Done => {
                        d.status = "done".to_string();
                        d.progress_pct = 100.0;
                        d.message = "completed".to_string();
                        break;
                    }
                    PullEvent::Error(e) => {
                        d.status = "error".to_string();
                        d.message = e;
                        break;
                    }
                }
            }
        }
    });

    Ok(Json(serde_json::json!({
        "id": id,
        "model": body.model,
        "runtime": body.runtime,
        "status": "pulling",
    })))
}

async fn download_status(
    State(state): State<Arc<AppState>>,
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    Path(id): Path<String>,
) -> ApiResult<Json<serde_json::Value>> {
    if !addr.ip().is_loopback() {
        return Err(ApiError::new(
            StatusCode::FORBIDDEN,
            "Download status restricted to localhost",
        ));
    }
    let dl = state.active_download.read().await;
    match dl.as_ref() {
        Some(d) if d.id == id => Ok(Json(serde_json::json!({
            "id": d.id,
            "model": d.model_name,
            "runtime": d.runtime,
            "status": d.status,
            "progress_pct": d.progress_pct,
            "message": d.message,
        }))),
        _ => Err(ApiError::new(
            StatusCode::NOT_FOUND,
            format!("no download with id '{id}'"),
        )),
    }
}

async fn plan_estimate(
    State(state): State<Arc<AppState>>,
    ConnectInfo(addr): ConnectInfo<SocketAddr>,
    Json(body): Json<PlanBody>,
) -> ApiResult<Json<serde_json::Value>> {
    if !addr.ip().is_loopback() {
        return Err(ApiError::new(
            StatusCode::FORBIDDEN,
            "Plan restricted to localhost",
        ));
    }

    let model = state
        .models
        .iter()
        .find(|m| m.name.eq_ignore_ascii_case(&body.model))
        .ok_or_else(|| ApiError::bad_request(format!("model '{}' not found", body.model)))?;

    let kv_quant = match body.kv_quant.as_deref() {
        Some(s) => Some(llmfit_core::models::KvQuant::parse(s).ok_or_else(|| {
            ApiError::bad_request(format!(
                "Unsupported kv_quant '{}'. Valid: fp16, fp8, q8_0, q4_0, tq",
                s
            ))
        })?),
        None => None,
    };

    let overrides = body.hardware_overrides();
    let request = PlanRequest {
        context: body.context,
        quant: body.quant,
        target_tps: body.target_tps,
        kv_quant,
    };
    let specs = effective_specs(&state.specs, &overrides)?;

    match estimate_model_plan(model, &request, &specs) {
        Ok(estimate) => Ok(Json(serde_json::json!(estimate))),
        Err(e) => Err(ApiError::bad_request(e)),
    }
}

fn filtered_fits(
    state: &AppState,
    specs: &SystemSpecs,
    query: &ModelsQuery,
    top_only: bool,
) -> Result<Vec<ModelFit>, ApiError> {
    let sort_column = parse_sort(query.sort.as_deref())?;
    let min_fit = parse_min_fit(query.min_fit.as_deref())?;
    let runtime_filter = parse_runtime(query.runtime.as_deref())?;
    let use_case_filter = parse_use_case(query.use_case.as_deref())?;

    let context_limit = query.max_context.or(state.context_limit);
    let forced_rt = parse_force_runtime(query.force_runtime.as_deref())?;
    let mut fits: Vec<ModelFit> = state
        .models
        .iter()
        .filter(|m| backend_compatible(m, specs))
        .map(|m| ModelFit::analyze_with_forced_runtime(m, specs, context_limit, forced_rt))
        .collect();

    let is_apple_silicon = specs.backend == GpuBackend::Metal && specs.unified_memory;
    if !is_apple_silicon {
        fits.retain(|f| !f.model.is_mlx_only());
    }

    if let Some(provider) = query.provider.as_ref() {
        let provider_lower = provider.to_lowercase();
        fits.retain(|f| f.model.provider.to_lowercase().contains(&provider_lower));
    }

    if let Some(search) = query.search.as_ref() {
        let search_lower = search.to_lowercase();
        fits.retain(|f| {
            f.model.name.to_lowercase().contains(&search_lower)
                || f.model.provider.to_lowercase().contains(&search_lower)
                || f.model
                    .parameter_count
                    .to_lowercase()
                    .contains(&search_lower)
                || f.model.use_case.to_lowercase().contains(&search_lower)
                || f.use_case.label().to_lowercase().contains(&search_lower)
        });
    }

    if query.perfect.unwrap_or(false) {
        fits.retain(|f| f.fit_level == FitLevel::Perfect);
    } else {
        fits.retain(|f| fit_at_least(f.fit_level, min_fit));
    }

    match runtime_filter {
        RuntimeFilter::Any => {}
        RuntimeFilter::Mlx => fits.retain(|f| f.runtime == InferenceRuntime::Mlx),
        RuntimeFilter::Vllm => fits.retain(|f| f.runtime == InferenceRuntime::Vllm),
        RuntimeFilter::LlamaCpp => {
            fits.retain(|f| f.runtime == InferenceRuntime::LlamaCpp);
        }
    }

    if let Some(use_case) = use_case_filter {
        fits.retain(|f| f.use_case == use_case);
    }

    if let Some(ref lic_str) = query.license {
        fits.retain(|f| llmfit_core::models::matches_license_filter(&f.model.license, lic_str));
    }

    let include_too_tight = query.include_too_tight.unwrap_or(!top_only);
    if top_only || !include_too_tight {
        fits.retain(|f| f.fit_level != FitLevel::TooTight);
    }

    Ok(rank_models_by_fit_opts_col(fits, false, sort_column))
}

fn effective_specs(
    base_specs: &SystemSpecs,
    overrides: &HardwareOverrideQuery,
) -> Result<SystemSpecs, ApiError> {
    let mut specs = base_specs.clone();

    if let Some(ram_gb) = overrides.ram_gb {
        if !ram_gb.is_finite() || ram_gb <= 0.0 {
            return Err(ApiError::bad_request(
                "invalid ram_gb value: expected a positive number",
            ));
        }
        specs = specs.with_ram_override(ram_gb);
    }

    if let Some(vram_gb) = overrides.vram_gb {
        if !vram_gb.is_finite() || vram_gb < 0.0 {
            return Err(ApiError::bad_request(
                "invalid vram_gb value: expected a non-negative number",
            ));
        }
        specs = specs.with_gpu_memory_override(vram_gb);
    }

    if let Some(cpu_cores) = overrides.cpu_cores {
        if cpu_cores == 0 {
            return Err(ApiError::bad_request(
                "invalid cpu_cores value: expected a positive integer",
            ));
        }
        specs = specs.with_cpu_core_override(cpu_cores);
    }

    Ok(specs)
}

#[derive(Debug, Clone, Copy)]
enum RuntimeFilter {
    Any,
    Mlx,
    LlamaCpp,
    Vllm,
}

fn parse_sort(raw: Option<&str>) -> Result<SortColumn, ApiError> {
    let value = raw.unwrap_or("score").trim().to_lowercase();
    let sort = match value.as_str() {
        "score" => SortColumn::Score,
        "tps" | "tokens" | "throughput" => SortColumn::Tps,
        "params" | "parameters" => SortColumn::Params,
        "mem" | "memory" | "mem_pct" | "utilization" => SortColumn::MemPct,
        "ctx" | "context" => SortColumn::Ctx,
        "date" | "release" | "released" => SortColumn::ReleaseDate,
        "use" | "use_case" | "usecase" => SortColumn::UseCase,
        _ => {
            return Err(ApiError::bad_request(
                "invalid sort value: use score|tps|params|mem|ctx|date|use_case",
            ));
        }
    };
    Ok(sort)
}

fn parse_min_fit(raw: Option<&str>) -> Result<FitLevel, ApiError> {
    let value = raw.unwrap_or("marginal").trim().to_lowercase();
    let min_fit = match value.as_str() {
        "perfect" => FitLevel::Perfect,
        "good" => FitLevel::Good,
        "marginal" => FitLevel::Marginal,
        "too_tight" | "tootight" | "tight" => FitLevel::TooTight,
        _ => {
            return Err(ApiError::bad_request(
                "invalid min_fit value: use perfect|good|marginal|too_tight",
            ));
        }
    };
    Ok(min_fit)
}

fn parse_runtime(raw: Option<&str>) -> Result<RuntimeFilter, ApiError> {
    let Some(value) = raw else {
        return Ok(RuntimeFilter::Any);
    };

    let runtime = match value.trim().to_lowercase().as_str() {
        "any" => RuntimeFilter::Any,
        "mlx" => RuntimeFilter::Mlx,
        "llamacpp" | "llama.cpp" | "llama_cpp" => RuntimeFilter::LlamaCpp,
        "vllm" => RuntimeFilter::Vllm,
        _ => {
            return Err(ApiError::bad_request(
                "invalid runtime value: use any|mlx|llamacpp|vllm",
            ));
        }
    };
    Ok(runtime)
}

fn parse_force_runtime(
    raw: Option<&str>,
) -> Result<Option<llmfit_core::fit::InferenceRuntime>, ApiError> {
    let Some(value) = raw else {
        return Ok(None);
    };
    match value.trim().to_lowercase().as_str() {
        "mlx" => Ok(Some(llmfit_core::fit::InferenceRuntime::Mlx)),
        "llamacpp" | "llama.cpp" | "llama_cpp" => {
            Ok(Some(llmfit_core::fit::InferenceRuntime::LlamaCpp))
        }
        "vllm" => Ok(Some(llmfit_core::fit::InferenceRuntime::Vllm)),
        _ => Err(ApiError::bad_request(
            "invalid force_runtime value: use mlx|llamacpp|vllm",
        )),
    }
}

fn parse_use_case(raw: Option<&str>) -> Result<Option<UseCase>, ApiError> {
    let Some(value) = raw else {
        return Ok(None);
    };

    let use_case = match value.trim().to_lowercase().as_str() {
        "coding" | "code" => UseCase::Coding,
        "reasoning" | "reason" => UseCase::Reasoning,
        "chat" => UseCase::Chat,
        "multimodal" | "vision" => UseCase::Multimodal,
        "embedding" | "embed" => UseCase::Embedding,
        "general" => UseCase::General,
        _ => {
            return Err(ApiError::bad_request(
                "invalid use_case value: use general|coding|reasoning|chat|multimodal|embedding",
            ));
        }
    };
    Ok(Some(use_case))
}

fn fit_at_least(actual: FitLevel, minimum: FitLevel) -> bool {
    let rank = |fit: FitLevel| match fit {
        FitLevel::Perfect => 3,
        FitLevel::Good => 2,
        FitLevel::Marginal => 1,
        FitLevel::TooTight => 0,
    };
    rank(actual) >= rank(minimum)
}

fn active_filters_json(query: &ModelsQuery, top_only: bool) -> serde_json::Value {
    serde_json::json!({
        "limit": query.limit.or(query.top),
        "perfect": query.perfect,
        "min_fit": query.min_fit,
        "runtime": query.runtime,
        "use_case": query.use_case,
        "provider": query.provider,
        "search": query.search,
        "sort": query.sort,
        "max_context": query.max_context,
        "include_too_tight": query.include_too_tight,
        "ram_gb": query.ram_gb,
        "vram_gb": query.vram_gb,
        "cpu_cores": query.cpu_cores,
        "top_only": top_only,
    })
}

fn system_json(specs: &SystemSpecs) -> serde_json::Value {
    serve_shared::system_json(specs)
}

fn fit_to_json(fit: &ModelFit) -> serde_json::Value {
    serve_shared::fit_to_json(fit)
}

#[cfg(test)]
mod tests {
    use super::*;
    use axum::body::Body;
    use axum::http::Request;
    use http_body_util::BodyExt as _;
    use std::future::Future;
    use tower::ServiceExt;

    fn test_state() -> Arc<AppState> {
        let db = ModelDatabase::new();
        Arc::new(AppState {
            node_name: "test-node".to_string(),
            os: "test-os".to_string(),
            specs: SystemSpecs::detect(),
            models: db.get_all_models().clone(),
            context_limit: None,
            active_download: tokio::sync::RwLock::new(None),
            download_counter: std::sync::atomic::AtomicU32::new(0),
        })
    }

    fn test_router() -> Router {
        build_router(test_state())
    }

    fn find_asset_path_with_ext(ext: &str) -> Option<&'static EmbeddedAsset> {
        EMBEDDED_WEB_ASSETS
            .iter()
            .find(|asset| asset.path.starts_with("/assets/") && asset.path.ends_with(ext))
    }

    fn run_async<T>(future: impl Future<Output = T>) -> T {
        tokio::runtime::Builder::new_current_thread()
            .enable_all()
            .build()
            .expect("tokio runtime")
            .block_on(future)
    }

    #[test]
    fn root_serves_index_html() {
        run_async(async {
            let response = test_router()
                .oneshot(Request::builder().uri("/").body(Body::empty()).unwrap())
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            assert_eq!(
                response.headers().get(CONTENT_TYPE).unwrap(),
                "text/html; charset=utf-8"
            );
        });
    }

    #[test]
    fn assets_route_serves_embedded_file_with_content_type() {
        let Some(asset) = find_asset_path_with_ext(".js")
            .or_else(|| find_asset_path_with_ext(".css"))
            .or_else(|| find_asset_path_with_ext(".svg"))
        else {
            panic!("no embedded assets available under /assets/");
        };

        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri(asset.path)
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            assert_eq!(
                response.headers().get(CONTENT_TYPE).unwrap(),
                asset.content_type
            );
        });
    }

    #[test]
    fn unknown_non_api_routes_fallback_to_index() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/dashboard/models")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            assert_eq!(
                response.headers().get(CONTENT_TYPE).unwrap(),
                "text/html; charset=utf-8"
            );
        });
    }

    #[test]
    fn existing_api_route_response_shape_is_preserved() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/api/v1/system")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            let bytes = response.into_body().collect().await.unwrap().to_bytes();
            let value: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
            assert!(value.get("node").is_some());
            assert!(value.get("system").is_some());
            for gpu in value["system"]["gpus"].as_array().unwrap() {
                assert!(gpu.get("memory_bandwidth_gbps").is_some());
            }
        });
    }

    #[test]
    fn system_endpoint_applies_hardware_overrides() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/api/v1/system?ram_gb=64&vram_gb=24&cpu_cores=16")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            let bytes = response.into_body().collect().await.unwrap().to_bytes();
            let value: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
            assert_eq!(value["system"]["total_ram_gb"], 64.0);
            assert_eq!(value["system"]["gpu_vram_gb"], 24.0);
            assert_eq!(value["system"]["cpu_cores"], 16);
        });
    }

    #[test]
    fn models_endpoint_returns_effective_simulated_system() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/api/v1/models?limit=1&ram_gb=48&vram_gb=12&cpu_cores=8")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::OK);
            let bytes = response.into_body().collect().await.unwrap().to_bytes();
            let value: serde_json::Value = serde_json::from_slice(&bytes).unwrap();
            assert_eq!(value["filters"]["ram_gb"], 48.0);
            assert_eq!(value["filters"]["vram_gb"], 12.0);
            assert_eq!(value["filters"]["cpu_cores"], 8);
            assert_eq!(value["system"]["total_ram_gb"], 48.0);
            assert_eq!(value["system"]["gpu_vram_gb"], 12.0);
            assert_eq!(value["system"]["cpu_cores"], 8);
        });
    }

    #[test]
    fn invalid_cpu_override_returns_bad_request() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/api/v1/system?cpu_cores=0")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::BAD_REQUEST);
        });
    }

    #[test]
    fn unknown_api_paths_do_not_fallback_to_html() {
        run_async(async {
            let response = test_router()
                .oneshot(
                    Request::builder()
                        .uri("/api/v1/not-found")
                        .body(Body::empty())
                        .unwrap(),
                )
                .await
                .unwrap();

            assert_eq!(response.status(), StatusCode::NOT_FOUND);
        });
    }
}
