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//! Executables and Rust crate for handling OCI images without container runtime.
//!
//! See [README.md at GitHub](https://github.com/termoshtt/ocipkg) for usage of the executables.
//! This reference describes the crate part.
//!

pub mod distribution;
pub mod error;
pub mod image;
pub mod local;

mod digest;
mod image_name;

pub use digest::Digest;
pub use image_name::ImageName;

use crate::error::*;
use std::fs;

const STATIC_PREFIX: &str = if cfg!(target_os = "windows") {
    ""
} else {
    "lib"
};

const STATIC_EXTENSION: &str = if cfg!(target_os = "windows") {
    "lib"
} else {
    "a"
};

/// Get and link package in `build.rs` with [cargo link instructions](https://doc.rust-lang.org/cargo/reference/build-scripts.html#outputs-of-the-build-script).
///
/// This is aimed to use in [build script](https://doc.rust-lang.org/cargo/reference/build-scripts.html) a.k.a. `build.rs`.
pub fn link_package(image_name: &str) -> Result<()> {
    let image_name = ImageName::parse(image_name)?;
    let dir = local::image_dir(&image_name)?;
    if !dir.exists() {
        distribution::get_image(&image_name)?;
    }
    println!("cargo:rustc-link-search={}", dir.display());
    for path in fs::read_dir(&dir)?.filter_map(|entry| {
        let path = entry.ok()?.path();
        path.is_file().then(|| path)
    }) {
        let name = path
            .file_stem()
            .unwrap()
            .to_str()
            .expect("Non UTF-8 is not supported");
        let name = if let Some(name) = name.strip_prefix(STATIC_PREFIX) {
            name
        } else {
            continue;
        };
        if let Some(ext) = path.extension() {
            if ext == STATIC_EXTENSION {
                println!("cargo:rustc-link-lib=static={}", name);
            }
        }
    }
    println!("cargo:rerun-if-changed={}", dir.display());
    println!("cargo:rerun-if-env-changed=XDG_DATA_HOME");
    Ok(())
}