remove treehouse-format crate and collapse everything into src

src/generate/dir_helper.rs

@@ -0,0 +1,37 @@
+use handlebars::{Context, Handlebars, Helper, HelperDef, RenderContext, RenderError, ScopedJson};
+use serde_json::Value;
+
+use crate::vfs::{self, DynDir, VPath};
+
+pub struct DirHelper {
+    site: String,
+    dir: DynDir,
+}
+
+impl DirHelper {
+    pub fn new(site: &str, dir: DynDir) -> Self {
+        Self {
+            site: site.to_owned(),
+            dir,
+        }
+    }
+}
+
+impl HelperDef for DirHelper {
+    fn call_inner<'reg: 'rc, 'rc>(
+        &self,
+        h: &Helper<'reg, 'rc>,
+        _: &'reg Handlebars<'reg>,
+        _: &'rc Context,
+        _: &mut RenderContext<'reg, 'rc>,
+    ) -> Result<ScopedJson<'reg, 'rc>, RenderError> {
+        if let Some(path) = h.param(0).and_then(|v| v.value().as_str()) {
+            let vpath = VPath::try_new(path).map_err(|e| RenderError::new(e.to_string()))?;
+            let url = vfs::url(&self.site, &self.dir, vpath)
+                .ok_or_else(|| RenderError::new("path is not anchored anywhere"))?;
+            Ok(ScopedJson::Derived(Value::String(url)))
+        } else {
+            Err(RenderError::new("missing path string"))
+        }
+    }
+}