ahk-cli 0.3.0

//! The runner: a script on stdin, a report on stdout.
//!
//! This is the binary that runs on the lab box. The MCP hands it a script
//! over stdin -- in memory, never a file -- and reads the report back.
//!
//! ```sh
//! echo 'Msg "hello"' | ahk
//! ```
//!
//! The exit code is 0 when the script finished, 1 when it failed, and 2
//! when it did not parse; the report is on stdout either way.
//!
//! The `--surface` flag is the other way round: it prints the table of
//! the names of v2 with the state of each one, and it does not read a
//! script.

use std::io::Read;
use std::path::{Path, PathBuf};
use std::time::Duration;

use ahk_cli::{json, report};

use ahk::dialect::{self, Dialect};
use ahk::parse_with;
use ahk::runtime::Runtime;
use ahk::surface;
use ahk_box::LabDesktop;

/// Where the runtime says it is running.
///
/// A script that types forever has to be stoppable from outside, and the
/// only thing that can stop it is the process. The pid file is how the
/// `ahk_stop` tool finds it -- and how a human finds it, with `cat`.
///
/// `XDG_CACHE_HOME` is the first choice, then the cache directory of the
/// home directory. A host with neither -- a Windows one that nobody
/// configured -- gets the temporary directory, and never the working
/// directory: the file has to be where the stop looks for it, and the
/// working directory changes from one call to the next.
fn pid_file() -> PathBuf {
    let base = match std::env::var_os("XDG_CACHE_HOME") {
        Some(base) => PathBuf::from(base),
        None => match std::env::var_os("HOME").or_else(|| std::env::var_os("USERPROFILE")) {
            Some(home) => PathBuf::from(home).join(".cache"),
            None => std::env::temp_dir(),
        },
    };
    base.join("ahk").join("run.pid")
}

fn write_pid_file() {
    let path = pid_file();
    if let Some(parent) = path.parent() {
        let _ = std::fs::create_dir_all(parent);
    }
    let _ = std::fs::write(&path, format!("{}\n", std::process::id()));
}

fn clear_pid_file() {
    let _ = std::fs::remove_file(pid_file());
}

/// How much stack the run of a script gets.
///
/// The frames of the tree are heavier than the ones of v2, and a script
/// that recurses needs a stack that the recursion rail fits in.
const STACK_BYTES: usize = 128 * 1024 * 1024;
/// How much of that stack the run may use.
const STACK_BUDGET: usize = 64 * 1024 * 1024;

fn main() -> std::process::ExitCode {
    let dialect = the_dialect();
    // The flag is answered before the script is read: the command is
    // about the tree, and it must not wait for a script that is not
    // coming.
    if std::env::args()
        .skip(1)
        .any(|argument| argument == "--surface")
    {
        // The behaviour is the call of every name that has a probe: the
        // state says what a name is, and the probe says whether it works.
        let behaviour = std::env::args()
            .skip(1)
            .any(|argument| argument == "--behavior" || argument == "--behaviour");
        // The JSON is for the CI, and the text is for a human.
        if std::env::args()
            .skip(1)
            .any(|argument| argument == "--json")
        {
            print_surface_json(dialect, behaviour);
        } else {
            print_surface(dialect, behaviour);
        }
        return std::process::ExitCode::from(0);
    }

    let mut source = String::new();
    if let Err(error) = std::io::stdin().read_to_string(&mut source) {
        eprintln!("cannot read the script: {error}");
        return std::process::ExitCode::from(2);
    }
    let timeout = std::env::args()
        .skip(1)
        .find_map(|argument| {
            argument
                .strip_prefix("--timeout=")
                .and_then(|value| value.parse::<f64>().ok())
        })
        .unwrap_or(60.0);

    // The includes are resolved here and not in the language: the
    // language crate does no I/O, and the runner is the one that has a
    // disk to read from.
    let source = match resolve_includes(&source, Path::new("."), &mut Vec::new()) {
        Ok(source) => source,
        Err(error) => {
            let report = report::the_failure_of_the_load(&error, 0, 0);
            println!("{report}");
            return std::process::ExitCode::from(2);
        }
    };

    let statements = match parse_with(&source, dialect) {
        Ok(statements) => statements,
        Err(error) => {
            let report = report::the_failure_of_the_load(&error.message, error.line, error.column);
            println!("{report}");
            return std::process::ExitCode::from(2);
        }
    };

    // From here on, the run can be stopped from outside: the pid file says
    // which process to kill.
    write_pid_file();
    let _guard = PidGuard;

    // The script runs on a thread with a stack of its own: the tree's
    // frames are heavier than the ones of v2, and the recursion rail has
    // to fit in the stack of the run. The report is written down there,
    // because a value of the runtime is not `Send` and cannot travel.
    let handle = std::thread::Builder::new()
        .stack_size(STACK_BYTES)
        .spawn(move || {
            // `YOKO_DESKTOP=x11` selects the X11 backend (XTEST + XGetImage)
            // instead of the uinput one: a FreeBSD box has no /dev/uinput,
            // and a Wayland box has no X11 focus for uinput to reach. Both
            // are the same AHK language, with a different desktop.
            #[cfg(any(target_os = "linux", target_os = "freebsd"))]
            let x11 =
                ahk_box::desktop_kind().eq_ignore_ascii_case("x11") && ahk_box::x11_available();
            #[cfg(any(target_os = "linux", target_os = "freebsd"))]
            let mut x11_desktop = ahk_box::x11::X11Desktop::new();
            let mut lab_desktop = LabDesktop::new();
            lab_desktop.ensure_session_env();
            #[cfg(any(target_os = "linux", target_os = "freebsd"))]
            let desktop: &mut dyn ahk::desktop::Desktop = if x11 {
                &mut x11_desktop
            } else {
                &mut lab_desktop
            };
            #[cfg(not(any(target_os = "linux", target_os = "freebsd")))]
            let desktop: &mut dyn ahk::desktop::Desktop = &mut lab_desktop;
            let report = Runtime::new(desktop, Duration::from_secs_f64(timeout))
                .with_stack_budget(STACK_BUDGET)
                .with_source(&source)
                .with_dialect(dialect)
                .run(&statements);
            let mut notes = report.notes.clone();
            notes.extend(lab_desktop.notes().iter().cloned());
            let payload = report::the_report(&report, &notes);
            (payload, report.ok)
        })
        .expect("the thread of the run starts");
    let (payload, ok) = match handle.join() {
        Ok(pair) => pair,
        Err(_) => {
            eprintln!("the run of the script died");
            return std::process::ExitCode::from(1);
        }
    };
    println!("{payload}");
    // The exit code goes out through the return, and not through
    // `process::exit`: that one leaves without running the destructors, and
    // the guard that removes the pid file is a destructor.
    std::process::ExitCode::from(if ok { 0 } else { 1 })
}

/// The dialect that the run speaks.
///
/// The v2 is the dialect of the tree, and it is the one of every run that
/// does not ask for another one. The `--dialect=v1` asks for the legacy
/// dialect of AutoHotkey, which is measured on the binary of v1.1.37.02.
fn the_dialect() -> &'static dyn Dialect {
    let asked = std::env::args().skip(1).find_map(|argument| {
        argument
            .strip_prefix("--dialect=")
            .map(|value| value.to_lowercase())
    });
    match asked.as_deref() {
        Some("v1") => dialect::v1(),
        // The mechanisms of v2.1 beside the v2.0.19: the names and the tables
        // are the ones of the v2, and the mechanisms that the v2.1 adds are the
        // ones that the gate turns on.
        Some("v2.1") | Some("v2_1") => dialect::v2_1(),
        // The dialect of KeySharp: the v2.1 mechanisms and the extensions of
        // KeySharp beside them. The refusal names the dialects the tree
        // speaks, and this one is the third of them.
        Some("ks") => dialect::ks(),
        // The KeySharp without the mechanisms of the v2.1: the two
        // switches of the dialect are orthogonal, and this is the fourth
        // combination of them.
        Some("ks20") | Some("ks2.0") => dialect::ks_20(),
        Some("v2") | None => dialect::v2(),
        Some(other) => {
            eprintln!(
                "the dialect {other} is not one this tree speaks: the tree speaks v1, v2, v2.1, ks and ks20."
            );
            std::process::exit(2);
        }
    }
}

/// Print the surface of v2 and where every name of it stands here.
///
/// The report is a line for every name of the surface and a summary at
/// the end: the number is the point of the command, and it is what makes
/// "what is missing" a measurement and not an opinion.
fn print_surface(dialect: &'static dyn Dialect, behaviour: bool) {
    let entries = surface::entries_of(dialect);
    let mut out = String::new();
    for entry in &entries {
        out.push_str(&entry.line());
        if behaviour {
            if let Some(answer) = ahk::behavior::behaviour_of(dialect, &entry.full_name()) {
                out.push_str("\tbehaviour=");
                out.push_str(&answer);
            }
        }
        out.push('\n');
    }
    out.push_str(&surface::summary_of(&entries, dialect).text());
    out.push('\n');
    print!("{out}");
}

/// Print the surface of the dialect as JSON.
///
/// The text of the surface is for a human, and the JSON is for the CI: the
/// numbers of the summary and the state of every name, with the reason of
/// the ones that are refused or that are pending.
///
/// The plan of the v1 dialect asks for this shape: "the JSON, for the CI,
/// is a piece of F5".
fn print_surface_json(dialect: &'static dyn Dialect, behaviour: bool) {
    let entries = surface::entries_of(dialect);
    let summary = surface::summary_of(&entries, dialect);
    let mut report = json::Object::new(64 * 1024);
    report.text("dialect", summary.dialect);
    report.number("total", summary.total as i64);
    report.number("values", summary.values as i64);
    report.number("refusals", summary.refusals as i64);
    report.number("pending", summary.pending as i64);
    report.field("entries", |out| {
        out.push('[');
        for (index, entry) in entries.iter().enumerate() {
            if index > 0 {
                out.push(',');
            }
            let mut row = json::Object::new(96);
            row.text("name", entry.name);
            row.text("kind", entry.kind.as_str());
            row.text(
                "state",
                match entry.state {
                    surface::State::Value => "value",
                    surface::State::Refusal(_) => "refusal",
                    surface::State::Pending(_) => "pending",
                },
            );
            if !entry.class.is_empty() {
                row.text("class", entry.class);
            }
            if let surface::State::Refusal(reason) | surface::State::Pending(reason) = entry.state {
                row.text("reason", reason);
            }
            if behaviour {
                if let Some(answer) = ahk::behavior::behaviour_of(dialect, &entry.full_name()) {
                    row.text("behavior", &answer);
                }
            }
            out.push_str(&row.finish());
        }
        out.push(']');
    });
    println!("{}", report.finish());
}

/// The source with the includes put in place of the lines that ask for
/// them.
///
/// A `#Include "path"` line is replaced by the text of the file, and the
/// path is taken from the directory of the file that asks for it. An
/// include that is already in the tree is not put in twice; the
/// `#IncludeAgain` line puts its file in every time it asks for it, which
/// is the difference between the two directives.
///
/// The nesting is counted: a file that includes itself, or a group of files
/// that include one another, is refused with the reason instead of making
/// the runner recurse until the stack is gone.
fn resolve_includes(source: &str, base: &Path, seen: &mut Vec<PathBuf>) -> Result<String, String> {
    resolve_includes_at(source, base, seen, 0)
}

/// How deep the includes may nest.
const MAX_INCLUDE_DEPTH: usize = 64;

/// `resolve_includes`, with the depth of the nesting the tree is in.
fn resolve_includes_at(
    source: &str,
    base: &Path,
    seen: &mut Vec<PathBuf>,
    depth: usize,
) -> Result<String, String> {
    if depth > MAX_INCLUDE_DEPTH {
        return Err(format!(
            "the includes nest more than {MAX_INCLUDE_DEPTH} deep: a file includes itself, or a group of them includes one another."
        ));
    }
    let mut out = String::with_capacity(source.len());
    for line in source.lines() {
        let Some((again, argument)) = the_include_of(line) else {
            out.push_str(line);
            out.push('\n');
            continue;
        };
        // The path is in quotes, or it is the rest of the line.
        let path = argument
            .strip_prefix('"')
            .and_then(|rest| rest.strip_suffix('"'))
            .unwrap_or(argument)
            .trim();
        if path.is_empty() {
            return Err("an include needs a path.".to_string());
        }
        let path = base.join(path);
        let path = match path.canonicalize() {
            Ok(path) => path,
            Err(_) => return Err(format!("the include \"{path:?}\" cannot be found.")),
        };
        if !again && seen.contains(&path) {
            // The file is already in the tree, and `#Include` puts it in
            // once: the line becomes nothing.
            out.push('\n');
            continue;
        }
        let text = std::fs::read_to_string(&path)
            .map_err(|error| format!("the include \"{path:?}\" cannot be read: {error}"))?;
        let directory = path.parent().unwrap_or(Path::new(".")).to_path_buf();
        // The file is in the tree now, and a later `#Include` of it is
        // skipped. `#IncludeAgain` ignores this list and asks again.
        if !seen.contains(&path) {
            seen.push(path);
        }
        out.push_str(&resolve_includes_at(&text, &directory, seen, depth + 1)?);
        out.push('\n');
    }
    Ok(out)
}

/// The include that the line asks for: whether it is `#IncludeAgain`, and
/// its argument.
///
/// The directive is matched by its whole name, because `#Include` is a
/// prefix of `#IncludeAgain` and the two are not the same line. A line
/// whose directive is neither is a line of the script, and it is left as it
/// is.
fn the_include_of(line: &str) -> Option<(bool, &str)> {
    let trimmed = line.trim();
    let rest = trimmed.strip_prefix('#')?;
    let end = rest
        .find(|character: char| character.is_whitespace())
        .unwrap_or(rest.len());
    let (name, argument) = rest.split_at(end);
    let again = if name.eq_ignore_ascii_case("include") {
        false
    } else if name.eq_ignore_ascii_case("includeagain") {
        true
    } else {
        return None;
    };
    Some((again, argument.trim()))
}

/// Removes the pid file when the run ends, however it ends.
struct PidGuard;

impl Drop for PidGuard {
    fn drop(&mut self) {
        clear_pid_file();
    }
}