// Build script for Subplot, locates and builds the embedded resource set from
// the share directory

use anyhow::Result;
use std::io::Write;
use std::path::{Component, Path, PathBuf};
use walkdir::WalkDir;

fn path_ignore(path: &Path) -> bool {
    // We have a number of rules for ignoring any given path.
    path.components().any(|component| {
        match component {
            Component::Prefix(_) => true,
            Component::RootDir => true,
            Component::CurDir => true,
            Component::ParentDir => true,
            Component::Normal(part) => {
                if let Some(part) = part.to_str() {
                    // We don't want dot files, tilde files, bak files
                    // or the python cache.  Add other things here if
                    // there's stuff ending up in the resources tree
                    // which we don't want.
                    part.starts_with('.')
                        || part.ends_with('~')
                        || part.ends_with(".bak")
                        || part == "__pycache__"
                } else {
                    // We don't want any non-unicode paths
                    true
                }
            }
        }
    })
}

fn gather_share_files() -> Result<Vec<PathBuf>> {
    let base_path = Path::new(env!("CARGO_MANIFEST_DIR")).join("share");
    println!("cargo:rerun-if-changed={}", base_path.display());
    let mut ret = Vec::new();
    for entry in WalkDir::new(&base_path) {
        let entry = entry?;
        let entry_path = entry.path().strip_prefix(&base_path)?;
        if entry_path.components().count() == 0 || path_ignore(entry_path) {
            continue;
        }
        // If this path part is a directory, we want to watch it but we don't
        // represent directories in the resources tree
        if entry.file_type().is_dir() {
            println!("cargo:rerun-if-changed={}", entry.path().display());
            continue;
        }
        // If this is a symlink we need cargo to watch the target of the link
        // even though we'll treat it as a basic file when we embed it
        if entry.file_type().is_symlink() {
            let target = std::fs::read_link(entry.path())?;
            println!("cargo:rerun-if-changed={}", target.display());
        }
        println!("cargo:rerun-if-changed={}", entry.path().display());
        ret.push(entry_path.into());
    }

    Ok(ret)
}

fn write_out_resource_file<'a>(paths: impl Iterator<Item = &'a Path>) -> Result<()> {
    let mut out_path: PathBuf = std::env::var("OUT_DIR")?.into();
    out_path.push("embedded_files.inc");
    let mut fh = std::fs::File::create(out_path)?;
    writeln!(fh, "&[")?;
    for entry in paths {
        let sharepath = Path::new("/share").join(entry);
        writeln!(
            fh,
            r#"({:?}, include_bytes!(concat!(env!("CARGO_MANIFEST_DIR"), {:?}))),"#,
            entry.display(),
            sharepath.display()
        )?;
    }
    writeln!(fh, "]")?;
    fh.flush()?;
    Ok(())
}

fn main() {
    println!("cargo:rerun-if-env-changed=DEB_BUILD_OPTIONS");
    let paths = if std::env::var("DEB_BUILD_OPTIONS").is_err() {
        println!("cargo:rustc-env=FALLBACK_PATH=");
        gather_share_files().expect("Unable to scan the share tree")
    } else {
        println!("cargo:rustc-env=FALLBACK_PATH=/usr/share/subplot");
        vec![]
    };
    write_out_resource_file(paths.iter().map(PathBuf::as_path))
        .expect("Unable to write the resource file out");
}