//! # terminal-garden
//!
//! The first face of the bus: a renderer, not a collector.
//! Git is the cleanest signal in the suite — discrete, unambiguous, no privacy
//! questions — so the garden proves the bus before anything reads the shell.
//!
//! Like every renderer, the garden is thin: connect to the socket → read the
//! git aggregates → fold them into per-repo plots → render. It never touches a
//! sensor. The mapping (commits → growth, staleness → wilt) lives in the
//! `terminal-garden` library so it can be unit-tested; this binary is just the
//! subscriber loop.
//!
//! Usage:
//! ```text
//!   terminal-garden [--socket <path>]
//! ```
//! Socket defaults to `$XDG_RUNTIME_DIR/signald.sock`, falling back to
//! `~/.local/state/signald/sock`.

use std::collections::BTreeMap;
use std::io::BufReader;
use std::os::unix::net::UnixStream;
use std::path::PathBuf;

use signal_schema::{wire, Signal, SignalName};
use terminal_garden::{plots_from_signals, render};

/// The `name`s the garden cares about: the git aggregates.
const SUBSCRIBE: &[SignalName] = &[
    SignalName::CommitsWindow,
    SignalName::CommitsToday,
    SignalName::BranchCount,
    SignalName::DaysSinceLastCommit,
];

fn main() {
    let socket = parse_socket();
    if let Err(e) = run(&socket) {
        eprintln!("terminal-garden: could not read signald at {}: {e}", socket.display());
        eprintln!("terminal-garden: is signald running? (signald --socket {})", socket.display());
        std::process::exit(1);
    }
}

/// Connect and render live: the daemon replays the last-value cache on connect,
/// then streams updates. We keep the latest value of each metric (keyed by name
/// and repo tag) and re-render the garden on every frame. `Ok(())` is a clean EOF
/// (the daemon closed the stream). Frames this build cannot decode are skipped,
/// so an older renderer keeps working against a newer daemon.
fn run(socket: &PathBuf) -> std::io::Result<()> {
    let stream = UnixStream::connect(socket)?;
    let mut reader = BufReader::new(stream);

    // Keyed by (metric name, repo tag) so per-repo signals coexist and updates
    // replace prior values rather than accumulating.
    let mut latest: BTreeMap<(u8, Option<String>), Signal> = BTreeMap::new();
    loop {
        let sig = match wire::read_frame(&mut reader)? {
            wire::Frame::Signal(sig) => sig,
            // A record this build does not understand: a newer daemon, or a
            // metric appended after this renderer was built. Keep rendering.
            wire::Frame::Skipped => continue,
            wire::Frame::Eof => break,
        };
        if !SUBSCRIBE.contains(&sig.name) {
            continue;
        }
        let key = (sig.name.to_u8(), sig.tag.as_ref().map(|t| t.as_str().to_string()));
        latest.insert(key, sig);

        let signals: Vec<Signal> = latest.values().cloned().collect();
        let plots = plots_from_signals(&signals);
        // Clear + home so the garden redraws in place as signals change.
        print!("\x1b[2J\x1b[H{}", render(&plots));
    }
    Ok(())
}

fn parse_socket() -> PathBuf {
    let mut args = std::env::args().skip(1);
    while let Some(arg) = args.next() {
        if arg == "--socket" {
            if let Some(path) = args.next() {
                return PathBuf::from(path);
            }
        }
    }
    default_socket_path()
}

/// `$XDG_RUNTIME_DIR/signald.sock`, else `$HOME/.local/state/signald/sock`.
///
/// Split from the environment so it can be tested without mutating it. The
/// same resolution is duplicated in the other binary and in
/// `shell-hooks/signald-hooks.zsh`; the README's "Paths" table is the one
/// place they are written down, and the tests below pin them to it.
fn socket_path_from(xdg_runtime_dir: Option<&str>, home: Option<&str>) -> PathBuf {
    if let Some(dir) = xdg_runtime_dir {
        return PathBuf::from(dir).join("signald.sock");
    }
    PathBuf::from(home.unwrap_or(".")).join(".local/state/signald/sock")
}

fn default_socket_path() -> PathBuf {
    socket_path_from(
        std::env::var("XDG_RUNTIME_DIR").ok().as_deref(),
        std::env::var("HOME").ok().as_deref(),
    )
}

#[cfg(test)]
mod path_tests {
    use super::*;

    /// Pinned to the README "Paths" table. If this changes, the table and
    /// `shell-hooks/signald-hooks.zsh` change with it.
    #[test]
    fn socket_default_follows_xdg_then_home() {
        assert_eq!(
            socket_path_from(Some("/run/user/501"), Some("/Users/x")),
            PathBuf::from("/run/user/501/signald.sock")
        );
        assert_eq!(
            socket_path_from(None, Some("/Users/x")),
            PathBuf::from("/Users/x/.local/state/signald/sock")
        );
    }
}