use anyhow::{Context, Result};
use clap::Parser;
use std::net::SocketAddr;
use std::path::PathBuf;
use tokio::sync::mpsc;
use tracing::info;

mod api;
mod models;
mod storage;
mod ws_client;

use api::build_router;
use models::AppState;
use storage::StorageWriter;
use ws_client::spawn_connection;

/// Sina Finance WebSocket real-time data API.
///
/// Connects to wss://hq.sinajs.cn/wskt, keeps latest stock tick data in memory,
/// exposes a REST API, and also persists raw records to daily CSV files.
#[derive(Parser)]
#[command(name = "sina-realtime-api", version)]
struct Cli {
    /// Stock list file — one code per line, e.g. sz300394 (lines starting with # are ignored)
    #[arg(short, long, default_value = "stocks_100.txt")]
    stocks: PathBuf,

    /// Directory for output CSV files
    #[arg(short, long, default_value = "data")]
    output: PathBuf,

    /// Max stocks per WebSocket connection (tune based on URL length / server limits)
    #[arg(long, default_value_t = 500)]
    chunk_size: usize,

    /// Internal channel buffer (records in flight between WS tasks and storage)
    #[arg(long, default_value_t = 131_072)]
    buffer: usize,

    /// API host. Hugging Face Spaces should use 0.0.0.0.
    #[arg(long, default_value = "0.0.0.0")]
    api_host: String,

    /// API port. If omitted, reads PORT env var, then falls back to 7860.
    #[arg(long)]
    api_port: Option<u16>,
}

#[tokio::main]
async fn main() -> Result<()> {
    tracing_subscriber::fmt()
        .with_env_filter(
            tracing_subscriber::EnvFilter::try_from_default_env()
                .unwrap_or_else(|_| "sina_realtime_collector=info,tower_http=warn".into()),
        )
        .init();

    let cli = Cli::parse();

    // Load and validate stock list
    let content = std::fs::read_to_string(&cli.stocks)
        .with_context(|| format!("Cannot read stock list: {:?}", cli.stocks))?;

    let stocks: Vec<String> = content
        .lines()
        .map(|l| l.trim().to_string())
        .filter(|l| !l.is_empty() && !l.starts_with('#'))
        .collect();

    anyhow::ensure!(!stocks.is_empty(), "Stock list is empty");
    info!("Loaded {} stocks from {:?}", stocks.len(), cli.stocks);

    std::fs::create_dir_all(&cli.output)
        .with_context(|| format!("Cannot create output dir: {:?}", cli.output))?;

    let started_at = chrono::Local::now()
        .format("%Y-%m-%dT%H:%M:%S%.3f")
        .to_string();
    let state = AppState::new(stocks.clone(), started_at);

    // Shared channel: WS tasks -> storage/API-state task
    let (tx, rx) = mpsc::channel::<String>(cli.buffer);

    // Storage also updates the latest-quote in-memory map used by the API.
    let storage_state = state.clone();
    let output_dir = cli.output.clone();
    let storage_handle = tokio::spawn(async move {
        if let Err(e) = StorageWriter::run(rx, output_dir, storage_state).await {
            tracing::error!("Storage error: {e:#}");
        }
    });

    // Split stocks into chunks, one WebSocket connection per chunk.
    let chunks: Vec<Vec<String>> = stocks
        .chunks(cli.chunk_size)
        .map(|c| c.to_vec())
        .collect();

    info!(
        "Starting {} connection(s) (~{} stocks each)",
        chunks.len(),
        cli.chunk_size
    );

    let mut conn_handles = Vec::with_capacity(chunks.len());
    for (i, chunk) in chunks.into_iter().enumerate() {
        let tx = tx.clone();
        conn_handles.push(tokio::spawn(spawn_connection(chunk, tx, i)));
    }
    drop(tx);

    let port = cli
        .api_port
        .or_else(|| std::env::var("PORT").ok().and_then(|v| v.parse::<u16>().ok()))
        .unwrap_or(7860);
    let addr: SocketAddr = format!("{}:{}", cli.api_host, port)
        .parse()
        .with_context(|| format!("Invalid API bind address: {}:{}", cli.api_host, port))?;

    let app = build_router(state);
    let listener = tokio::net::TcpListener::bind(addr).await?;
    info!("API listening on http://{addr}");

    let server_result = axum::serve(listener, app)
        .with_graceful_shutdown(shutdown_signal())
        .await;

    for h in conn_handles {
        h.abort();
    }
    storage_handle.abort();

    server_result?;
    Ok(())
}

async fn shutdown_signal() {
    if let Err(e) = tokio::signal::ctrl_c().await {
        tracing::warn!("Failed to listen for shutdown signal: {e}");
    }
    info!("Shutdown signal received");
}