feat: add proper support for config files

cbundl.toml

@@ -1,3 +1,7 @@
-no-format = true
-formatter = "/home/kat/.nix-profile/bin/clang-format"
-deterministic = true
+[bundle]
+output = "test/frob/final.c"
+deterministic = false
+
+[formatter]
+# enable = true
+# path = "clang-format"

src/config.rs

@@ -0,0 +1,207 @@
+use std::fs;
+use std::io;
+use std::path::{Path, PathBuf};
+
+use clap::parser::ValueSource;
+use clap::{CommandFactory, Parser};
+use eyre::{Context, Result};
+use serde::Deserialize;
+
+use crate::consts::{
+    CRATE_DESCRIPTION, DEFAULT_CONFIG_FILES, DEFAULT_FORMATTER, LONG_VERSION, SHORT_VERSION,
+};
+use crate::display::display_path;
+
+#[derive(Debug, Clone, Parser)]
+#[command(
+    version = SHORT_VERSION,
+    long_version = LONG_VERSION,
+    about = CRATE_DESCRIPTION,
+    long_about = None
+)]
+struct Args {
+    #[arg(
+        long,
+        help = "Don't load any configuration file. (Overrides `--config`)"
+    )]
+    no_config: bool,
+
+    #[arg(long, help = "Specify an alternate configuration file")]
+    config: Option<PathBuf>,
+
+    #[arg(long, help = "Don't pass the resulting bundle through the formatter.")]
+    no_format: bool,
+
+    #[arg(
+        long,
+        help = "Code formatter executable.",
+        long_help = "Code formatter. Must format the code from stdin and write it to stdout.",
+        value_name = "exe",
+        default_value = DEFAULT_FORMATTER
+    )]
+    formatter: PathBuf,
+
+    #[arg(long = "deterministic", help = "Output a deterministic bundle.")]
+    deterministic: bool,
+
+    #[arg(
+        short = 'o',
+        long = "output",
+        help = "Specify where to write the resulting bundle.",
+        value_name = "path",
+        default_value = "-"
+    )]
+    output_file: PathBuf,
+
+    #[arg(help = "Path to the entry source file.", value_name = "path")]
+    entry: PathBuf,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct File {
+    bundle: Option<BundleSection>,
+    formatter: Option<FormatterSection>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct BundleSection {
+    deterministic: Option<bool>,
+
+    #[serde(rename = "output")]
+    output_file: Option<PathBuf>,
+}
+
+#[derive(Debug, Clone, Deserialize)]
+struct FormatterSection {
+    enable: Option<bool>,
+    path: Option<PathBuf>,
+}
+
+impl File {
+    fn read(path: &Path) -> Option<Result<Self>> {
+        let x = match fs::read_to_string(path) {
+            Ok(x) => x,
+            Err(e) if e.kind() == io::ErrorKind::NotFound => return None,
+            Err(e) => return Some(Err(e).context("failed to read file")),
+        };
+
+        let x = toml::from_str(&x).context("failed to parse file");
+        Some(x)
+    }
+
+    fn read_many<'a, I>(paths: I) -> Option<Self>
+    where
+        I: Iterator<Item = &'a Path>,
+    {
+        for path in paths {
+            match Self::read(path) {
+                Some(r) => {
+                    match r
+                        .with_context(|| format!("failed to read config `{}`", display_path(path)))
+                    {
+                        Ok(x) => return Some(x),
+                        Err(e) => {
+                            warn!("{e:#}");
+                            continue;
+                        }
+                    }
+                }
+                None => continue,
+            }
+        }
+
+        None
+    }
+}
+
+#[derive(Debug, Clone)]
+pub struct Config {
+    pub no_format: bool,
+    pub formatter: PathBuf,
+    pub deterministic: bool,
+    pub output_file: Option<PathBuf>,
+    pub entry: PathBuf,
+}
+
+impl Config {
+    pub fn new() -> Result<Self> {
+        let args = Args::command().get_matches();
+
+        let file = if args.get_flag("no_config") {
+            None
+        } else if let Some(config) = args.get_one::<&PathBuf>("config") {
+            let x = File::read(config)
+                .ok_or_else(|| io::Error::from(io::ErrorKind::NotFound))
+                .with_context(|| format!("failed to read config `{}`", display_path(config)))??;
+
+            Some(x)
+        } else {
+            File::read_many(DEFAULT_CONFIG_FILES.iter().copied().map(Path::new))
+        };
+
+        let no_format = if let ValueSource::CommandLine = args.value_source("no_format").unwrap() {
+            args.get_flag("no_format")
+        } else if let Some(x) = file
+            .as_ref()
+            .and_then(|x| x.formatter.as_ref())
+            .and_then(|x| x.enable)
+        {
+            !x
+        } else {
+            false
+        };
+
+        let formatter = if let ValueSource::CommandLine = args.value_source("formatter").unwrap() {
+            args.get_one::<PathBuf>("formatter").unwrap().clone()
+        } else if let Some(x) = file
+            .as_ref()
+            .and_then(|x| x.formatter.as_ref())
+            .and_then(|x| x.path.as_ref())
+        {
+            x.clone()
+        } else {
+            PathBuf::from(DEFAULT_FORMATTER)
+        };
+
+        let deterministic =
+            if let ValueSource::CommandLine = args.value_source("deterministic").unwrap() {
+                args.get_flag("deterministic")
+            } else if let Some(x) = file
+                .as_ref()
+                .and_then(|x| x.bundle.as_ref())
+                .and_then(|x| x.deterministic)
+            {
+                x
+            } else {
+                false
+            };
+
+        let output_file =
+            if let ValueSource::CommandLine = args.value_source("output_file").unwrap() {
+                let x = args.get_one::<PathBuf>("output_file").unwrap();
+                (!path_is_stdio(x)).then(|| x.clone())
+            } else if let Some(x) = file
+                .as_ref()
+                .and_then(|x| x.bundle.as_ref())
+                .and_then(|x| x.output_file.as_ref())
+            {
+                Some(x.to_owned())
+            } else {
+                None
+            };
+
+        let entry = args.get_one::<PathBuf>("entry").unwrap().clone();
+
+        Ok(Self {
+            no_format,
+            formatter,
+            deterministic,
+            output_file,
+            entry,
+        })
+    }
+}
+
+fn path_is_stdio(path: &Path) -> bool {
+    path.as_os_str().as_encoded_bytes().eq(b"-")
+}