//! OxygenFlow's cheap checks as one WASI module (#96): what

//! `.flow/jobs/{layout,todos,size,summary}.sh` did in an Alpine microVM, so

//! that any runner offering the WASM tier (a phone, plex, windows-1) can take

//! them. The job's files are preopened as `/src`, which is also the current

//! directory, so every path here is relative to the workspace.

//!

//! - `layout PATH...`: each path is a file; fails naming the first missing.

//! - `todos DIR...`: the lines holding a note marker, counted, the first 20

//!   listed; never fails.

//! - `size DIR`: lines of Rust in each crate directory under DIR.

//! - `summary`: one line naming `$PROJECT`.

//! - `changelog FILE [MANIFEST]`: the changelog's shape: `## Unreleased`

//!   first if at all, then `## X.Y.Z (YYYY-MM-DD)` sections, newest first,

//!   none empty; with a manifest (`Cargo.toml`, `*.properties`,

//!   `package.json`), its version has a section, as a release needs.

use std::fs;

use std::io::{self, Write};

use std::path::{Path, PathBuf};

use std::process::ExitCode;

/// The note markers, spelt in pieces so this file does not count itself.

const MARKERS: [&str; 3] = [concat!("TO", "DO"), concat!("FIX", "ME"), concat!("X", "XX")];

/// How many noted lines `todos` lists.

const LISTED: usize = 20;

const USAGE: &str = "usage: flow-checks layout PATH... | todos DIR... | size DIR | summary | changelog FILE [MANIFEST]";

fn main() -> ExitCode {

    let args: Vec<String> = std::env::args().skip(1).collect();

    let root = Path::new(".");

    let mut out = io::stdout().lock();

    let done = match args.split_first() {

        Some((cmd, rest)) => match cmd.as_str() {

            "layout" => layout(root, rest, &mut out),

            "todos" => todos(root, rest, &mut out),

            "size" => match rest {

                [dir] => size(root, dir, &mut out),

                _ => Err(USAGE.to_string()),

            },

            "summary" => summary(std::env::var("PROJECT").ok().as_deref(), &mut out),

            "changelog" => match rest {

                [file] => changelog(root, file, None, &mut out),

                [file, manifest] => changelog(root, file, Some(manifest), &mut out),

                _ => Err(USAGE.to_string()),

            },

            _ => Err(USAGE.to_string()),

        },

        None => Err(USAGE.to_string()),

    };

    match done {

        Ok(()) => ExitCode::SUCCESS,

        Err(e) => {

            eprintln!("{e}");

            ExitCode::FAILURE

        }

    }

}

type Done = Result<(), String>;

fn emit(out: &mut impl Write, line: &str) -> Done {

    writeln!(out, "{line}").map_err(|e| format!("write: {e}"))

}

/// The workspace has the files it should.

fn layout(root: &Path, paths: &[String], out: &mut impl Write) -> Done {

    if paths.is_empty() {

        return Err(USAGE.to_string());

    }

    for p in paths {

        if !root.join(p).is_file() {

            return Err(format!("missing: {p}"));

        }

        emit(out, &format!("found {p}"))?;

    }

    Ok(())

}

/// Notes left in the code, for the log.

fn todos(root: &Path, dirs: &[String], out: &mut impl Write) -> Done {

    if dirs.is_empty() {

        return Err(USAGE.to_string());

    }

    let mut noted = Vec::new();

    for d in dirs {

        for file in files(&root.join(d))? {

            // Text only, as grep reports a binary file rather than its lines.

            let Ok(text) = fs::read_to_string(&file) else { continue };

            let name = shown(root, &file);

            for (i, line) in text.lines().enumerate() {

                if MARKERS.iter().any(|m| line.contains(m)) {

                    noted.push(format!("{name}:{}:{line}", i + 1));

                }

            }

        }

    }

    emit(out, &format!("{} {} notes in {}", noted.len(), MARKERS.join("/"), shown_dirs(dirs)))?;

    for line in noted.iter().take(LISTED) {

        emit(out, line)?;

    }

    Ok(())

}

/// Lines of Rust per crate: each directory directly under `dir`.

fn size(root: &Path, dir: &str, out: &mut impl Write) -> Done {

    for krate in entries(&root.join(dir))?.into_iter().filter(|p| p.is_dir()) {

        let mut lines = 0;

        for file in files(&krate)?.into_iter().filter(|f| f.extension().is_some_and(|e| e == "rs")) {

            let bytes = fs::read(&file).map_err(|e| format!("{}: {e}", file.display()))?;

            lines += bytes.iter().filter(|&&b| b == b'\n').count();

        }

        emit(out, &format!("{:<24} {lines:>6} lines", format!("{}/", shown(root, &krate))))?;

    }

    Ok(())

}

fn summary(project: Option<&str>, out: &mut impl Write) -> Done {

    emit(out, &format!("{}: every check passed on this state.", project.unwrap_or("This project")))

}

/// A directory's entries, sorted by name so every runner prints the same.

/// A version as three numbers, or `None`.

fn version(s: &str) -> Option<(u64, u64, u64)> {

    let mut parts = s.split('.').map(|p| p.parse::<u64>().ok());

    let v = (parts.next()??, parts.next()??, parts.next()??);

    parts.next().is_none().then_some(v)

}

/// A `YYYY-MM-DD` date with a real month and day.

fn is_date(s: &str) -> bool {

    let b = s.as_bytes();

    b.len() == 10

        && b[4] == b'-'

        && b[7] == b'-'

        && s[..4].parse::<u32>().is_ok()

        && s[5..7].parse::<u32>().is_ok_and(|m| (1..=12).contains(&m))

        && s[8..].parse::<u32>().is_ok_and(|d| (1..=31).contains(&d))

}

/// The version a manifest declares: `version = "…"` in `Cargo.toml`'s

/// `[package]` or `[workspace.package]`, a `….version=` key of a

/// `.properties` file, or `"version"` in a `package.json`.

fn manifest_version(path: &str, text: &str) -> Option<String> {

    let unquote = |v: &str| v.trim().trim_matches('"').trim_end_matches(',').trim_matches('"').to_string();

    if path.ends_with(".properties") {

        return text.lines().find_map(|l| {

            let (k, v) = l.split_once('=')?;

            (k.trim() == "version" || k.trim().ends_with(".version")).then(|| v.trim().to_string())

        });

    }

    if path.ends_with(".json") {

        return text.lines().find_map(|l| l.trim().strip_prefix("\"version\":").map(unquote));

    }

    let mut section = "";

    for l in text.lines() {

        let l = l.trim();

        if l.starts_with('[') {

            section = l;

        } else if matches!(section, "[package]" | "[workspace.package]") {

            if let Some(v) = l.strip_prefix("version").and_then(|r| r.trim_start().strip_prefix('=')) {

                return Some(unquote(v));

            }

        }

    }

    None

}

/// The changelog's shape, and the manifest's version in it.

fn changelog(root: &Path, file: &str, manifest: Option<&String>, out: &mut impl Write) -> Done {

    let text = fs::read_to_string(root.join(file)).map_err(|e| format!("{file}: {e}"))?;

    let mut sections: Vec<(usize, String, usize)> = Vec::new(); // (line, heading, entries)

    for (i, line) in text.lines().enumerate() {

        if let Some(h) = line.strip_prefix("## ") {

            sections.push((i + 1, h.trim().to_string(), 0));

        } else if let Some(last) = sections.last_mut() {

            if line.trim_start().starts_with("- ") || line.trim_start().starts_with("* ") {

                last.2 += 1;

            }

        }

    }

    let mut problems = Vec::new();

    let mut last: Option<(u64, u64, u64)> = None;

    let mut released = Vec::new();

    for (k, (line, h, n)) in sections.iter().enumerate() {

        if h == "Unreleased" {

            if k != 0 {

                problems.push(format!("{file}:{line}: ## Unreleased comes first"));

            }

            continue;

        }

        let (v, rest) = h.split_once(' ').unwrap_or((h.as_str(), ""));

        let date = rest.trim().strip_prefix('(').and_then(|r| r.strip_suffix(')'));

        match (version(v), date) {

            (Some(ver), Some(d)) if is_date(d) => {

                if last.is_some_and(|l| ver >= l) {

                    problems.push(format!("{file}:{line}: {v} is not older than the section above it"));

                }

                last = Some(ver);

                released.push(v.to_string());

                if *n == 0 {

                    problems.push(format!("{file}:{line}: ## {h} has no entries"));

                }

            }

            _ => problems.push(format!("{file}:{line}: \"## {h}\" is not \"## X.Y.Z (YYYY-MM-DD)\" or \"## Unreleased\"")),

        }

    }

    let mut said = format!("changelog: {} released section{}", released.len(), if released.len() == 1 { "" } else { "s" });

    if let Some(m) = manifest {

        let mtext = fs::read_to_string(root.join(m)).map_err(|e| format!("{m}: {e}"))?;

        match manifest_version(m, &mtext) {

            Some(v) if released.contains(&v) => said.push_str(&format!(", {m} at {v} has its section")),

            Some(v) => problems.push(format!(

                "{m} says version {v}, but {file} has no \"## {v} (YYYY-MM-DD)\" section: a release of it would have no notes"

            )),

            None => problems.push(format!("{m}: no version found")),

        }

    }

    if problems.is_empty() {

        return emit(out, &said);

    }

    Err(problems.join("\n"))

}

fn entries(dir: &Path) -> Result<Vec<PathBuf>, String> {

    let read = fs::read_dir(dir).map_err(|e| format!("{}: {e}", dir.display()))?;

    let mut all = read.map(|e| e.map(|e| e.path())).collect::<Result<Vec<_>, _>>().map_err(|e| format!("{}: {e}", dir.display()))?;

    all.sort();

    Ok(all)

}

/// Every file under `dir`, depth first, in name order; links are not followed.

fn files(dir: &Path) -> Result<Vec<PathBuf>, String> {

    let mut found = Vec::new();

    for p in entries(dir)? {

        let kind = fs::symlink_metadata(&p).map_err(|e| format!("{}: {e}", p.display()))?.file_type();

        if kind.is_dir() {

            found.extend(files(&p)?);

        } else if kind.is_file() {

            found.push(p);

        }

    }

    Ok(found)

}

/// A path as the workspace names it, with `/` between its parts.

fn shown(root: &Path, p: &Path) -> String {

    let rel = p.strip_prefix(root).unwrap_or(p);

    rel.components().map(|c| c.as_os_str().to_string_lossy()).collect::<Vec<_>>().join("/")

}

fn shown_dirs(dirs: &[String]) -> String {

    dirs.iter().map(|d| format!("{}/", d.trim_end_matches('/'))).collect::<Vec<_>>().join(" ")

}

#[cfg(test)]

mod tests {

    use super::*;

    fn tree(files: &[(&str, &str)]) -> tempfile::TempDir {

        let dir = tempfile::tempdir().unwrap();

        for (path, text) in files {

            let p = dir.path().join(path);

            fs::create_dir_all(p.parent().unwrap()).unwrap();

            fs::write(p, text).unwrap();

        }

        dir

    }

    fn run(f: impl FnOnce(&mut Vec<u8>) -> Done) -> (Done, String) {

        let mut out = Vec::new();

        let done = f(&mut out);

        (done, String::from_utf8(out).unwrap())

    }

    fn args(a: &[&str]) -> Vec<String> {

        a.iter().map(|s| s.to_string()).collect()

    }

    #[test]

    fn changelog_shape_and_the_manifest_version() {

        let good = "# Changelog\n\nIntro.\n\n## Unreleased\n\n## 0.2.0 (2026-11-03)\n\n- **New.**\n\n## 0.1.9 (2026-10-01)\n\n- Old.\n";

        let dir = tree(&[

            ("CHANGELOG.md", good),

            ("Cargo.toml", "[workspace]\nmembers = []\n\n[workspace.package]\nversion = \"0.2.0\"\n"),

            ("gradle.properties", "android.useAndroidX=true\noxygenhub.version=0.1.9\n"),

            ("package.json", "{\n  \"name\": \"x\",\n  \"version\": \"0.3.0\",\n}\n"),

        ]);

        let r = |m: Option<&str>| run(|o| changelog(dir.path(), "CHANGELOG.md", m.map(String::from).as_ref(), o));

        let (done, out) = r(None);

        assert_eq!((done, out.trim()), (Ok(()), "changelog: 2 released sections"));

        assert!(r(Some("Cargo.toml")).1.contains("Cargo.toml at 0.2.0 has its section"));

        assert!(r(Some("gradle.properties")).0.is_ok(), "an older release's section counts");

        let e = r(Some("package.json")).0.unwrap_err();

        assert!(e.contains("version 0.3.0") && e.contains("no \"## 0.3.0 (YYYY-MM-DD)\""), "{e}");

        let bad = "## 0.1.0 (2026-10-01)\n\n- a\n\n## Unreleased\n\n## 0.2.0 (2026-13-01)\n\n- b\n\n## 0.0.9 (2026-09-01)\n\n## v1\n";

        let dir = tree(&[("CHANGELOG.md", bad)]);

        let e = run(|o| changelog(dir.path(), "CHANGELOG.md", None, o)).0.unwrap_err();

        assert!(e.contains(":5: ## Unreleased comes first"), "{e}");

        assert!(e.contains(":7: \"## 0.2.0 (2026-13-01)\" is not"), "a month 13: {e}");

        assert!(e.contains(":11: ## 0.0.9 (2026-09-01) has no entries"), "{e}");

        assert!(e.contains(":13: \"## v1\""), "{e}");

        let order = "## 0.1.0 (2026-10-01)\n\n- a\n\n## 0.2.0 (2026-11-01)\n\n- b\n";

        let dir = tree(&[("CHANGELOG.md", order)]);

        let e = run(|o| changelog(dir.path(), "CHANGELOG.md", None, o)).0.unwrap_err();

        assert!(e.contains("0.2.0 is not older than the section above it"), "{e}");

    }

    #[test]

    fn layout_lists_what_it_found_and_fails_on_the_first_missing() {

        let t = tree(&[("Cargo.toml", ""), ("docs/m0.md", "")]);

        let (done, out) = run(|o| layout(t.path(), &args(&["Cargo.toml", "docs/m0.md"]), o));

        assert_eq!(done, Ok(()));

        assert_eq!(out, "found Cargo.toml\nfound docs/m0.md\n");

        let (done, out) = run(|o| layout(t.path(), &args(&["Cargo.toml", "nope.rs", "docs/m0.md"]), o));

        assert_eq!(done, Err("missing: nope.rs".to_string()));

        assert_eq!(out, "found Cargo.toml\n");

        // A directory is not the file asked for.

        assert!(layout(t.path(), &args(&["docs"]), &mut Vec::new()).is_err());

    }

    #[test]

    fn todos_counts_every_marked_line_and_lists_the_first_twenty() {

        let marker = MARKERS[0];

        let many: String = (0..25).map(|i| format!("// {marker} {i}\n")).collect();

        let t = tree(&[

            ("crates/a/src/lib.rs", &format!("fn a() {{}}\n// {} later\n", MARKERS[1])),

            ("crates/b/src/many.rs", &many),

            ("crates/b/blob.bin", "\u{0}"),

        ]);

        // Invalid UTF-8 is skipped, as grep skips a binary file's lines.

        fs::write(t.path().join("crates/b/blob.bin"), [0xff, 0xfe, b'T']).unwrap();

        let (done, out) = run(|o| todos(t.path(), &args(&["crates"]), o));

        assert_eq!(done, Ok(()));

        let lines: Vec<&str> = out.lines().collect();

        assert_eq!(lines[0], format!("26 {} notes in crates/", MARKERS.join("/")));

        assert_eq!(lines[1], format!("crates/a/src/lib.rs:2:// {} later", MARKERS[1]));

        assert_eq!(lines[2], format!("crates/b/src/many.rs:1:// {marker} 0"));

        assert_eq!(lines.len(), 1 + LISTED);

    }

    #[test]

    fn size_counts_rust_lines_per_crate_in_name_order() {

        let t = tree(&[

            ("crates/zeta/src/main.rs", "a\nb\nc\n"),

            ("crates/alpha/src/lib.rs", "a\n"),

            ("crates/alpha/src/deep/mod.rs", "a\nb\n"),

            ("crates/alpha/README.md", "not rust\n"),

            ("crates/loose.txt", "a file, not a crate\n"),

        ]);

        let (done, out) = run(|o| size(t.path(), "crates", o));

        assert_eq!(done, Ok(()));

        assert_eq!(out, format!("{:<24} {:>6} lines\n{:<24} {:>6} lines\n", "crates/alpha/", 3, "crates/zeta/", 3));

    }

    #[test]

    fn summary_names_the_project() {

        let (_, out) = run(|o| summary(Some("OxygenFlow"), o));

        assert_eq!(out, "OxygenFlow: every check passed on this state.\n");

    }

}