Add about internal page

crates/ely_app/build.rs

@@ -0,0 +1,122 @@
+use std::{
+    env,
+    error::Error,
+    fs,
+    io::{self, Write},
+    path::{Path, PathBuf},
+    process::Command,
+};
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let manifest_dir = PathBuf::from(env::var("CARGO_MANIFEST_DIR")?);
+    let workspace_root = workspace_root(&manifest_dir)?;
+    let workspace_manifest_path = workspace_root.join("Cargo.toml");
+    let git_head_path = workspace_root.join(".git/HEAD");
+    let workspace_manifest = read_workspace_manifest(&workspace_manifest_path)?;
+    let workspace = table(&workspace_manifest, "workspace")?;
+    let package = table(workspace, "package")?;
+    let dependencies = table(workspace, "dependencies")?;
+
+    emit_cargo_directive(format!("cargo:rerun-if-changed={}", workspace_manifest_path.display()))?;
+    emit_cargo_directive(format!("cargo:rerun-if-changed={}", git_head_path.display()))?;
+    if let Some(ref_path) = git_head_ref(&git_head_path)? {
+        emit_cargo_directive(format!(
+            "cargo:rerun-if-changed={}",
+            workspace_root.join(".git").join(ref_path).display()
+        ))?;
+    }
+
+    emit_env("ELY_BUILD_REVISION", &git_revision(workspace_root)?)?;
+    emit_env("ELY_WORKSPACE_LICENSE", string_value(package, "license")?)?;
+    emit_env("ELY_GPUI_VERSION", dependency_version(dependencies, "gpui")?)?;
+    emit_env("ELY_GPUI_COMPONENT_VERSION", dependency_version(dependencies, "gpui-component")?)?;
+    emit_env("ELY_SERVO_VERSION", dependency_version(dependencies, "servo")?)?;
+    Ok(())
+}
+
+fn workspace_root(manifest_dir: &Path) -> Result<&Path, Box<dyn Error>> {
+    let crates_dir = manifest_dir
+        .parent()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, "missing crates directory"))?;
+    crates_dir
+        .parent()
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, "missing workspace root"))
+        .map_err(Into::into)
+}
+
+fn read_workspace_manifest(path: &Path) -> Result<toml::Table, Box<dyn Error>> {
+    let manifest = fs::read_to_string(path)?;
+    manifest.parse::<toml::Table>().map_err(Into::into)
+}
+
+fn table<'a>(value: &'a toml::Table, key: &str) -> Result<&'a toml::Table, Box<dyn Error>> {
+    value
+        .get(key)
+        .and_then(toml::Value::as_table)
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, format!("missing {key} table")))
+        .map_err(Into::into)
+}
+
+fn string_value<'a>(value: &'a toml::Table, key: &str) -> Result<&'a str, Box<dyn Error>> {
+    value
+        .get(key)
+        .and_then(toml::Value::as_str)
+        .ok_or_else(|| io::Error::new(io::ErrorKind::InvalidData, format!("missing {key} value")))
+        .map_err(Into::into)
+}
+
+fn dependency_version<'a>(
+    dependencies: &'a toml::Table,
+    name: &str,
+) -> Result<&'a str, Box<dyn Error>> {
+    let dependency = dependencies.get(name).ok_or_else(|| {
+        io::Error::new(io::ErrorKind::InvalidData, format!("missing {name} dependency"))
+    })?;
+    match dependency {
+        toml::Value::String(version) => Ok(version),
+        toml::Value::Table(table) => string_value(table, "version"),
+        _ => Err(io::Error::new(
+            io::ErrorKind::InvalidData,
+            format!("invalid {name} dependency version"),
+        )
+        .into()),
+    }
+}
+
+fn git_revision(workspace_root: &Path) -> Result<String, Box<dyn Error>> {
+    let output = Command::new("git")
+        .args(["rev-parse", "--short=12", "HEAD"])
+        .current_dir(workspace_root)
+        .output()?;
+    if !output.status.success() {
+        return Err(
+            io::Error::new(io::ErrorKind::InvalidData, "git revision is unavailable").into()
+        );
+    }
+    let revision = String::from_utf8(output.stdout)?.trim().to_string();
+    if revision.is_empty() {
+        return Err(io::Error::new(io::ErrorKind::InvalidData, "git revision is empty").into());
+    }
+    Ok(revision)
+}
+
+fn git_head_ref(git_head_path: &Path) -> Result<Option<String>, Box<dyn Error>> {
+    let head = fs::read_to_string(git_head_path)?;
+    let Some(ref_path) = head.trim().strip_prefix("ref: ") else {
+        return Ok(None);
+    };
+    Ok(Some(ref_path.to_string()))
+}
+
+fn emit_env(key: &str, value: &str) -> Result<(), Box<dyn Error>> {
+    if value.trim().is_empty() {
+        return Err(io::Error::new(io::ErrorKind::InvalidData, format!("{key} is empty")).into());
+    }
+    emit_cargo_directive(format!("cargo:rustc-env={key}={value}"))?;
+    Ok(())
+}
+
+fn emit_cargo_directive(directive: impl AsRef<str>) -> Result<(), Box<dyn Error>> {
+    writeln!(io::stdout(), "{}", directive.as_ref())?;
+    Ok(())
+}