//! Finds printers and prints `printers.toml` blocks for them.
//!
//! ```text
//! cargo run --example discover_printers -- all [a.b.c.0/24]   # everything safe
//! cargo run --example discover_printers -- listen [seconds]   # passive SSDP (Bambu)
//! cargo run --example discover_printers -- raw [seconds]      # ... and dump every datagram
//! cargo run --example discover_printers -- identify <host>... # one known address
//! cargo run --example discover_printers -- sweep <a.b.c.0/24> # every address on a segment
//! cargo run --example discover_printers -- serial             # USB/serial ports, passive
//! cargo run --example discover_printers -- serial-probe <port> [baud] --yes-reset-the-printer
//! ```
//!
//! Everything except `serial-probe` is **read-only and sends no credentials**.
//! `listen` only receives. `identify` and `sweep` open a connection and read
//! what the far end volunteers - a TLS certificate, an HTTP identity endpoint
//! - without a session or a key. `serial` reads sysfs and opens no device.
//!
//! **`serial-probe` resets the printer**, because opening a serial port
//! toggles DTR on an Arduino-based board. That ruins a print in progress, so
//! it refuses to run without `--yes-reset-the-printer`, the same shape as
//! `bambu_print_probe`'s `--yes-start-a-real-print`.
//!
//! Which network subcommand to use depends on where the gateway sits.
//! `listen` learns the most about a Bambu printer - the model and the
//! operator's own name come only from SSDP - but multicast does not cross a
//! router, so it finds nothing unless this host is on the printers' segment.
//! `sweep` works from anywhere that can route to them, and covers Bambu,
//! Klipper and PrusaLink. `all` does both and merges the result.
//!
//! It deliberately does not write `printers.toml`: a Bambu access code is on
//! the printer's screen and a PrusaLink API key is in its web UI, so every
//! block printed here is incomplete by construction. `fleet::load` rejects an
//! entry whose credential is empty, which means pasting one in and forgetting
//! to finish it fails loudly at the next start rather than quietly.

use std::collections::HashSet;
use std::time::Duration;

use continuum_proxy::discovery::{self, Candidate, net, serial};

/// Long enough to catch Bambu's announcement interval a few times over.
const LISTEN_SECONDS: u64 = 15;

/// Per-host probe budget. Generous for a LAN, but a sweep spends it on every
/// address that is not there, so the batching in `sweep_hosts` matters more.
const PROBE_TIMEOUT: Duration = Duration::from_secs(3);

/// A serial handshake has to wait out a board reset before it can even ask.
const SERIAL_TIMEOUT: Duration = Duration::from_secs(10);

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

    let args: Vec<String> = std::env::args().skip(1).collect();
    let Some(command) = args.first().map(String::as_str) else {
        anyhow::bail!(usage());
    };

    let found = match command {
        "all" => {
            let mut found = listen(LISTEN_SECONDS, false).await?;
            match args.get(1) {
                Some(subnet) => found.extend(sweep(subnet).await?),
                // Without a subnet the sweep is skipped rather than guessed:
                // picking one would mean probing a network nobody named.
                None => println!("(no subnet given, so no sweep - pass one like 192.168.0.0/24 to include it)"),
            }
            found.extend(list_serial()?);
            found
        }
        "listen" | "raw" => {
            let seconds = args.get(1).and_then(|s| s.parse().ok()).unwrap_or(LISTEN_SECONDS);
            listen(seconds, command == "raw").await?
        }
        "identify" => {
            let hosts = &args[1..];
            if hosts.is_empty() {
                anyhow::bail!("identify needs at least one host");
            }
            let mut found = Vec::new();
            for host in hosts {
                let candidates = net::identify_any(host, PROBE_TIMEOUT).await;
                if candidates.is_empty() {
                    // Named explicitly, unlike in a sweep: the operator asked
                    // about this address, so silence is the wrong answer.
                    eprintln!("{host}: nothing answered as a Bambu, Klipper or PrusaLink printer");
                }
                for candidate in &candidates {
                    println!("{host}: {} - {}", candidate.vendor.toml_value(), describe(candidate));
                }
                found.extend(candidates);
            }
            found
        }
        "sweep" => {
            let subnet = args.get(1).ok_or_else(|| anyhow::anyhow!("sweep needs a subnet, e.g. 192.168.0.0/24"))?;
            sweep(subnet).await?
        }
        "serial" => list_serial()?,
        "serial-probe" => {
            let port = args.get(1).ok_or_else(|| anyhow::anyhow!("serial-probe needs a port, e.g. /dev/ttyACM0"))?;
            let baud = args.get(2).and_then(|s| s.parse().ok()).unwrap_or(serial::DEFAULT_BAUD_RATE);
            if !args.iter().any(|a| a == "--yes-reset-the-printer") {
                anyhow::bail!(
                    "opening {port} will RESET the printer on it - on an Arduino-based board the \
                     port open toggles DTR, which reboots the machine and ruins any print in \
                     progress. Re-run with --yes-reset-the-printer if nothing is printing. \
                     `serial` (no probe) lists ports without opening any."
                );
            }
            println!("opening {port} at {baud} baud - this resets the board; waiting for it to boot ...");
            vec![serial::probe_m115(port, baud, SERIAL_TIMEOUT).await?]
        }
        other => anyhow::bail!("unknown command {other:?}\n{}", usage()),
    };

    report(discovery::merge(found));
    Ok(())
}

fn usage() -> String {
    "usage: discover_printers all [subnet] | listen [seconds] | raw [seconds] | identify <host>... \
     | sweep <a.b.c.0/24> | serial | serial-probe <port> [baud] --yes-reset-the-printer"
        .to_string()
}

async fn sweep(subnet: &str) -> anyhow::Result<Vec<Candidate>> {
    // Expanded before anything is printed, so a refused subnet says so
    // instead of first claiming to be probing it.
    let hosts = net::hosts_in_subnet(subnet)?;
    println!(
        "probing {} addresses in {subnet} - Bambu on {}, Klipper on {}, PrusaLink on {} ...",
        hosts.len(),
        net::BAMBU_MQTT_PORT,
        net::MOONRAKER_PORT,
        net::PRUSALINK_PORT
    );
    Ok(net::sweep_hosts(&hosts, PROBE_TIMEOUT).await)
}

async fn listen(seconds: u64, raw: bool) -> anyhow::Result<Vec<Candidate>> {
    let window = Duration::from_secs(seconds);
    println!("listening {seconds}s on {:?} for {} ...", discovery::SSDP_PORTS, discovery::SSDP_GROUP);

    // Both ports at once, because which one a printer announces on depends on
    // its firmware and the operator has no way to know which.
    let listeners = discovery::SSDP_PORTS.map(|port| discovery::listen_ssdp(port, window, raw));
    let mut found: Vec<Candidate> = Vec::new();
    for result in futures_util::future::join_all(listeners).await {
        match result {
            Ok(candidates) => found.extend(candidates),
            // One port being unavailable - held by another process, or a
            // kernel that will not join the group - must not lose the other.
            Err(err) => eprintln!("warning: {err}"),
        }
    }
    Ok(found)
}

fn list_serial() -> anyhow::Result<Vec<Candidate>> {
    let ports = serial::list_ports()?;
    if ports.is_empty() {
        println!("no USB/serial ports found.");
        return Ok(Vec::new());
    }
    println!("{} serial port(s):", ports.len());
    for port in &ports {
        let confidence = if port.is_probably_a_printer() { "printer" } else { "maybe" };
        println!("  {} [{confidence}] {}", port.path, port.to_candidate().detail.unwrap_or_default());
    }
    // USB descriptors describe the bridge chip, so for anything but a Prusa
    // this is as far as passive detection goes - and the operator should know
    // that the next step has a cost.
    if ports.iter().any(|port| !port.is_probably_a_printer()) {
        println!(
            "\nUSB alone cannot tell a printer from any other serial device. `serial-probe <port>`\n\
             asks the board directly with M115, but opening the port RESETS it - don't while printing."
        );
    }
    Ok(ports.iter().map(serial::SerialDevice::to_candidate).collect())
}

fn describe(candidate: &Candidate) -> String {
    let mut parts = Vec::new();
    if let Some(serial) = &candidate.serial {
        parts.push(format!("serial {serial}"));
    }
    if let Some(name) = &candidate.name {
        parts.push(name.clone());
    }
    if let Some(detail) = &candidate.detail {
        parts.push(detail.clone());
    }
    if parts.is_empty() { "no details available".to_string() } else { parts.join(", ") }
}

fn report(found: Vec<Candidate>) {
    if found.is_empty() {
        println!(
            "\nNo printers found.\n\
             If that was `listen`: multicast does not cross a router, so a gateway on a\n\
             different subnet from its printers will never hear them - use\n\
             `sweep <their subnet>/24` instead. If it was `sweep`: check the subnet, and\n\
             that the printers have LAN mode (Bambu) or their API enabled."
        );
        return;
    }

    println!("\n{} printer(s) found. Paste into printers.toml and add each credential:\n", found.len());
    let mut used: HashSet<String> = HashSet::new();
    for candidate in &found {
        // Two of the same model suggest the same id, and a duplicate `id`
        // would silently give the fleet two printers it cannot tell apart.
        let base = candidate.suggested_id();
        let mut id = base.clone();
        let mut n = 2;
        while !used.insert(id.clone()) {
            id = format!("{base}-{n}");
            n += 1;
        }
        println!("{}", candidate.to_toml_entry(&id));
    }

    if found.iter().any(|c| !c.vendor.driver_is_implemented()) {
        println!(
            "Note: some of these vendors' clients in printer/ are still stubs - those entries\n\
             are marked, and a gateway will connect to them and do nothing useful yet."
        );
    }
}