resource: Support setting the template name

Signed-off-by: Daniel Silverstone <dsilvers@digital-scurf.org>

1 files changed, 32 insertions, 0 deletions

diff --git a/src/resource.rs b/src/resource.rs
index 2c1df0a..d8fab16 100644
--- a/src/resource.rs
+++ b/src/resource.rs
@@ -41,6 +41,7 @@ lazy_static! {
         let ret = Vec::new();
         Mutex::new(ret)
     };
+    static ref TEMPLATE_NAME: Mutex<Option<String>> = Mutex::new(None);
 }
 
 static EMBEDDED_FILES: &[(&str, &[u8])] = include!(concat!(env!("OUT_DIR"), "/embedded_files.inc"));
@@ -53,10 +54,41 @@ pub fn add_search_path<P: AsRef<Path>>(path: P) {
         .push(path.as_ref().into());
 }
 
+/// Set the template name, for use in searching for content...
+pub fn set_template(template: &str) {
+    *TEMPLATE_NAME.lock().expect("Unable to lock TEMPLATE_NAME") = Some(template.to_string());
+}
+
 /// Open a file for reading, honouring search paths established during
 /// startup, and falling back to potentially embedded file content
 pub fn open<P: AsRef<Path>>(subpath: P) -> io::Result<Box<dyn Read>> {
     let subpath = subpath.as_ref();
+    match internal_open(subpath) {
+        Ok(r) => Ok(r),
+        Err(e) => {
+            let template = TEMPLATE_NAME.lock().expect("Unable to lock TEMPLATE_NAME");
+            if let Some(templ) = template.as_deref() {
+                let subpath = Path::new(templ).join(subpath);
+                match internal_open(&subpath) {
+                    Ok(r) => Ok(r),
+                    Err(sub_e) => {
+                        if sub_e.kind() != io::ErrorKind::NotFound
+                            && e.kind() == io::ErrorKind::NotFound
+                        {
+                            Err(sub_e)
+                        } else {
+                            Err(e)
+                        }
+                    }
+                }
+            } else {
+                Err(e)
+            }
+        }
+    }
+}
+
+fn internal_open(subpath: &Path) -> io::Result<Box<dyn Read>> {
     let search_paths = SEARCH_PATHS.lock().expect("Unable to lock SEARCH_PATHS");
     let search_paths = search_paths.iter().map(|p| p.as_path());
     let search_paths = std::iter::empty()