use std::sync::LazyLock;
use std::time::Duration;
use serde::Deserialize;
use tokio::process::Command;
use tokio::time::sleep;

#[derive(Deserialize)]
struct ServerConfig {
    llama_server: LlamaServerConfig,
}

#[derive(Deserialize)]
struct LlamaServerConfig {
    binary: String,
    model_path: String,
    host: String,
    port: u16,
    context_size: u32,
}

static SERVER_CONFIG: LazyLock<ServerConfig> = LazyLock::new(|| {
    toml::from_str(include_str!("server.toml")).expect("Could not parse server.toml")
});

static HTTP_CLIENT: LazyLock<reqwest::Client> = LazyLock::new(reqwest::Client::new);

pub(crate) fn url() -> String {
    format!("http://{}:{}", SERVER_CONFIG.llama_server.host, SERVER_CONFIG.llama_server.port)
}

async fn is_healthy(health_url: &str) -> bool {
    HTTP_CLIENT.get(health_url).send().await.is_ok_and(|r| r.status().is_success())
}

/// Checks whether llama-server is already serving on the configured host/port,
/// and if not, spawns it from the configured binary/model path and waits for
/// it to report healthy before returning.
pub(crate) async fn ensure_running() -> anyhow::Result<()> {
    let base_url = url();
    let health_url = format!("{base_url}/health");

    if is_healthy(&health_url).await {
        return Ok(());
    }

    println!("llama-server not running at {base_url}, starting it...");

    Command::new(&SERVER_CONFIG.llama_server.binary)
        .args([
            "-m", &SERVER_CONFIG.llama_server.model_path,
            "--jinja",
            "-c", &SERVER_CONFIG.llama_server.context_size.to_string(),
            "--host", &SERVER_CONFIG.llama_server.host,
            "--port", &SERVER_CONFIG.llama_server.port.to_string(),
        ])
        .spawn()
        .map_err(|e| anyhow::anyhow!("failed to spawn llama-server at {}: {e}", SERVER_CONFIG.llama_server.binary))?;

    for _ in 0..60 {
        if is_healthy(&health_url).await {
            println!("llama-server is up.");
            return Ok(());
        }
        sleep(Duration::from_secs(1)).await;
    }

    anyhow::bail!("llama-server did not become healthy within 60s")
}