what-stack 0.1.1

use std::path::Path;

use self::ConfigMatch::{
    AllOf, Exact, Extension, FileToken, NodeDependency, NodeRuntimeDependency, Prefix,
    PrefixWithNodeDependency,
};
use super::files::ProjectFiles;
use super::python;
use crate::ecosystem::Ecosystem as E;
use crate::{StackLabel, labels};

/// How a config rule recognizes its project files.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ConfigMatch {
    /// A root entry with exactly this name.
    Exact(&'static str),
    /// A root entry named like the prefix plus a common config suffix, such as
    /// `next.config.mjs`.
    Prefix(&'static str),
    /// Every listed path exists. Nested paths such as `bin/rails` use `/`.
    AllOf(&'static [&'static str]),
    /// A root entry with this file extension.
    Extension(&'static str),
    /// `package.json` lists any of these packages under `"dependencies"` or
    /// `"devDependencies"`.
    NodeDependency(&'static [&'static str]),
    /// A [`Prefix`] config file plus a [`NodeDependency`] on any of the
    /// packages, for config names that several tools share.
    PrefixWithNodeDependency(&'static str, &'static [&'static str]),
    /// `package.json` lists any of these packages under `"dependencies"`. A
    /// package that only appears in `"devDependencies"` (a test server, a
    /// mock) does not describe what the project runs.
    NodeRuntimeDependency(&'static [&'static str]),
    /// The named root file mentions the token outside comment lines.
    FileToken(&'static str, &'static str),
}

/// One config rule: matcher, label, and the ecosystem of the label.
pub type ConfigRule = (ConfigMatch, StackLabel, E);

/// Rules checked before Python detection, in priority order.
pub const CONFIG_RULES: &[ConfigRule] = &[
    (Prefix("next.config"), labels::NEXT_JS, E::Node),
    (Prefix("nuxt.config"), labels::NUXT, E::Node),
    (Exact("angular.json"), labels::ANGULAR, E::Node),
    // Plain Svelte with Vite also has `svelte.config.js`; only SvelteKit
    // depends on `@sveltejs/kit`.
    (
        PrefixWithNodeDependency("svelte.config", &["@sveltejs/kit"]),
        labels::SVELTEKIT,
        E::Node,
    ),
    (Prefix("astro.config"), labels::ASTRO, E::Node),
    // React Router v7 framework mode and Remix both build with Vite, so they
    // come before `vite.config`.
    (Prefix("react-router.config"), labels::REACT_ROUTER, E::Node),
    (Prefix("remix.config"), labels::REMIX, E::Node),
    (NodeDependency(REMIX_PACKAGES), labels::REMIX, E::Node),
    (Exact("nest-cli.json"), labels::NESTJS, E::Node),
    (NodeDependency(&["@nestjs/core"]), labels::NESTJS, E::Node),
    // Next.js 13 and later need no config file.
    (NodeDependency(&["next"]), labels::NEXT_JS, E::Node),
    (Prefix("vite.config"), labels::VITE, E::Node),
    (Prefix("gatsby-config"), labels::GATSBY, E::Node),
    (Prefix("vue.config"), labels::VUE_CLI, E::Node),
    (Prefix("webpack.config"), labels::WEBPACK, E::Node),
    (Exact("Cargo.toml"), labels::RUST, E::Rust),
    (Exact("go.mod"), labels::GO, E::Go),
    (Exact("go.work"), labels::GO, E::Go),
    // The Spring Boot parent POM, starters, and Gradle plugin all use this
    // group id.
    (
        FileToken("pom.xml", SPRING_BOOT_GROUP),
        labels::SPRING_BOOT,
        E::Jvm,
    ),
    (
        FileToken("build.gradle.kts", SPRING_BOOT_GROUP),
        labels::SPRING_BOOT,
        E::Jvm,
    ),
    (
        FileToken("build.gradle", SPRING_BOOT_GROUP),
        labels::SPRING_BOOT,
        E::Jvm,
    ),
    (Exact("pom.xml"), labels::JAVA_MAVEN, E::Jvm),
    (Exact("build.gradle.kts"), labels::KOTLIN_GRADLE, E::Jvm),
    (Exact("build.gradle"), labels::JAVA_GRADLE, E::Jvm),
    // Root of a multi-module Gradle build without its own build script.
    (Exact("settings.gradle.kts"), labels::KOTLIN_GRADLE, E::Jvm),
    (Exact("settings.gradle"), labels::JAVA_GRADLE, E::Jvm),
    (
        AllOf(&["artisan", "composer.json"]),
        labels::LARAVEL,
        E::Php,
    ),
    (
        AllOf(&["composer.json", "symfony.lock"]),
        labels::SYMFONY,
        E::Php,
    ),
    (
        AllOf(&["composer.json", "bin/console"]),
        labels::SYMFONY,
        E::Php,
    ),
    (Exact("composer.json"), labels::PHP, E::Php),
    (FileToken("mix.exs", ":phoenix"), labels::PHOENIX, E::Beam),
    (Exact("mix.exs"), labels::ELIXIR, E::Beam),
    (Exact("deno.json"), labels::DENO, E::Deno),
    (Exact("deno.jsonc"), labels::DENO, E::Deno),
];

const SPRING_BOOT_GROUP: &str = "org.springframework.boot";

/// Remix application packages. `@remix-run/router` is left out: it is the
/// routing core of React Router 6 and appears in plain React apps.
const REMIX_PACKAGES: &[&str] = &[
    "@remix-run/dev",
    "@remix-run/react",
    "@remix-run/node",
    "@remix-run/serve",
    "@remix-run/cloudflare",
];

/// Rules checked after Python detection, in priority order.
pub const LATE_CONFIG_RULES: &[ConfigRule] = &[
    (
        AllOf(&["Gemfile", "config.ru", "bin/rails"]),
        labels::RAILS,
        E::Ruby,
    ),
    (AllOf(&["Gemfile", "config.ru"]), labels::RUBY_RACK, E::Ruby),
    (Extension("csproj"), labels::DOTNET, E::DotNet),
    (Extension("fsproj"), labels::DOTNET_FSHARP, E::DotNet),
    // A solution root whose projects live in subdirectories.
    (Extension("sln"), labels::DOTNET, E::DotNet),
    (Extension("slnx"), labels::DOTNET, E::DotNet),
    // Express is the weakest signal of all: many projects use it beside a
    // framework, a bundler, or another language's build that describes them
    // better, so it comes after every other rule, including Python detection.
    (
        NodeRuntimeDependency(&["express"]),
        labels::EXPRESS,
        E::Node,
    ),
];

/// Detect a stack label from configuration files in a project root.
///
/// The function scans only `project_root` and checks built-in rules in a fixed
/// priority order. More specific frontend framework config files are evaluated
/// before generic runtime markers such as `Cargo.toml` or `go.mod`. Node
/// projects are also recognized from `package.json` dependencies: `next`
/// (`Next.js` without a config file), `@nestjs/core` (`NestJS`, also from
/// `nest-cli.json`), Remix packages such as `@remix-run/react` (`Remix`, even
/// with `vite.config.ts`), and `express` under `"dependencies"` (`Express`,
/// only when no other rule matches, so a repo with `package.json` and
/// `Cargo.toml`, `go.mod`, or a `.csproj` keeps the label of that build).
/// `react-router.config.ts` is `React Router`, and `svelte.config.js` is
/// `SvelteKit` only when `package.json` lists `@sveltejs/kit` (plain Svelte
/// with Vite is `Vite`). Python
/// projects get a second pass that can identify `Django`, `Flask`, `FastAPI`,
/// `Starlette`, and `Litestar` from entry files or dependency files. Ruby
/// projects need `Gemfile` and `config.ru` (`Ruby (Rack)`), plus `bin/rails`
/// for `Rails`. PHP projects with `artisan` next to `composer.json` are
/// `Laravel`, and those with `symfony.lock` or `bin/console` are `Symfony`.
/// Maven and Gradle builds that use `org.springframework.boot` are
/// `Spring Boot`, and a `mix.exs` that depends on `:phoenix` is `Phoenix`; a
/// multi-module Gradle root with only `settings.gradle` or
/// `settings.gradle.kts` is a Gradle project.
///
/// This function knows nothing about the process, so it uses the same rules
/// [`StackDetector`](crate::StackDetector) applies to an unknown process.
/// Python entry files such as `server.py` alone do not make a Python project
/// when `package.json` is present without a Python dependency file. The
/// detector narrows the rules to the process's ecosystem: a `php` process in a
/// Laravel project with `vite.config.js` is `Laravel`, while a `node` process
/// there is `Vite`.
///
/// # Examples
///
/// ```no_run
/// use std::path::Path;
/// use what_stack::detect_from_config;
///
/// let label = detect_from_config(Path::new("/workspace/api"));
/// println!("{label:?}");
/// ```
///
/// # Performance
///
/// Directory entries are read once into a small in-memory set. Source and
/// dependency files used for Python detection are capped to the first 64 KiB.
/// Python frameworks come from entry files and from dependency manifests
/// (`pyproject.toml`, `requirements.txt`, `requirements-dev.txt`, `Pipfile`,
/// `setup.py`), ignoring `#` comment lines. Lock files (`uv.lock`,
/// `poetry.lock`) list transitive dependencies, so they only confirm a
/// framework a manifest names and never add one.
#[must_use]
pub fn detect_from_config(project_root: &Path) -> Option<StackLabel> {
    detect_for_scope(project_root, ConfigScope::All)
}

/// Which config rules apply to a process.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum ConfigScope {
    /// Unknown process: every rule, in the order of [`detect_from_config`].
    All,
    /// Unknown process whose executable lies inside the project: a compiled
    /// project binary is far more likely than a Node or Python program, so
    /// rules of compiled ecosystems (see [`E::is_compiled`]) are tried first,
    /// then every rule in the usual order.
    CompiledFirst,
    /// Unknown process whose executable lies in the project's `node_modules`,
    /// such as the native binary of esbuild, turbo, Biome, or SWC: a Node
    /// build tool, so Node rules are tried first, then every rule in the usual
    /// order.
    NodeFirst,
    /// A process of a known ecosystem, either from its name or because its
    /// executable was built by that ecosystem's tools: only the rules the
    /// ecosystem accepts (see [`E::accepts_config`]). A Python process gets
    /// only framework labels (see [`python::detect_python_project`]).
    Ecosystem(E),
}

/// Config detection limited to `scope`.
pub fn detect_for_scope(project_root: &Path, scope: ConfigScope) -> Option<StackLabel> {
    let files = ProjectFiles::read(project_root)?;

    match scope {
        ConfigScope::All => detect_with(project_root, &files, |_| true, false),
        ConfigScope::CompiledFirst => detect_with(project_root, &files, E::is_compiled, false)
            .or_else(|| detect_with(project_root, &files, |_| true, false)),
        ConfigScope::NodeFirst => detect_with(project_root, &files, |rule| rule == E::Node, false)
            .or_else(|| detect_with(project_root, &files, |_| true, false)),
        ConfigScope::Ecosystem(process) => detect_with(
            project_root,
            &files,
            |rule| process.accepts_config(rule),
            process == E::Python,
        ),
    }
}

fn detect_with(
    project_root: &Path,
    files: &ProjectFiles,
    in_scope: impl Fn(E) -> bool + Copy,
    python_process: bool,
) -> Option<StackLabel> {
    detect_from_rules(project_root, files, CONFIG_RULES, in_scope)
        .or_else(|| {
            in_scope(E::Python)
                .then(|| python::detect_python_project(project_root, files, python_process))
                .flatten()
        })
        .or_else(|| detect_from_rules(project_root, files, LATE_CONFIG_RULES, in_scope))
}

fn detect_from_rules(
    project_root: &Path,
    files: &ProjectFiles,
    rules: &[ConfigRule],
    in_scope: impl Fn(E) -> bool,
) -> Option<StackLabel> {
    rules
        .iter()
        .filter(|(_, _, ecosystem)| in_scope(*ecosystem))
        .find(|(matcher, _, _)| rule_matches(project_root, files, *matcher))
        .map(|(_, label, _)| label.clone())
}

fn rule_matches(project_root: &Path, files: &ProjectFiles, matcher: ConfigMatch) -> bool {
    match matcher {
        Exact(name) => files.contains_exact(name),
        Prefix(prefix) => files.contains_prefix(prefix),
        AllOf(paths) => paths
            .iter()
            .all(|path| files.contains_path(project_root, path)),
        Extension(extension) => files.contains_extension(extension),
        NodeDependency(packages) => files.node_dependencies(project_root).has_any(packages),
        NodeRuntimeDependency(packages) => {
            files.node_dependencies(project_root).has_runtime(packages)
        }
        PrefixWithNodeDependency(prefix, packages) => {
            files.contains_prefix(prefix) && files.node_dependencies(project_root).has_any(packages)
        }
        FileToken(file_name, token) => files.mentions_token(project_root, file_name, token),
    }
}