feat(nav): Complete file paths and flag unresolved web file references

Path completion in href/src/url()/@import, Markdown links and path-like strings, folders first. HTML and CSS paths that name no file get a 'Cannot resolve file' warning. File references resolve in the backend like IDEA's: relative to the file, /-rooted against the project and resource roots.

src-tauri/src/commands/mod.rs

@@ -104,6 +104,9 @@ pub fn builder() -> tauri_specta::Builder<tauri::Wry> {
         nav::mark_recent,
         nav::recent_files,
         nav::web_goto,
+        nav::fs_resolve_reference,
+        nav::path_completions,
+        nav::web_unresolved_references,
         search::search_start,
         search::replace_in_files,
         search::replace_preview,

src-tauri/src/commands/nav.rs

@@ -1,8 +1,9 @@
 use super::doc::blocking;
-use crate::state::AppState;
-use ide_core::{DocId, IdeResult, Location, Pos};
+use crate::state::{AppState, Project};
+use ide_core::{DocId, IdeResult, IpcPath, Location, Pos};
 use ide_index::{FileMatch, IndexStatus, SymbolFilter, SymbolMatch};
-use ide_language::WebReference;
+use ide_language::{FileReference, WebReference};
+use ide_workspace::file_refs::{self, PathCompletion};
 use serde::{Deserialize, Serialize};
 use specta::Type;
 use std::path::PathBuf;
@@ -96,3 +97,74 @@ pub async fn web_goto(window: Window, state: State<'_, AppState>, doc: DocId, po
     })
     .await
 }
+
+/// The project root and its resource roots (served at `/`), for file references.
+fn reference_roots(project: &Project) -> (PathBuf, Vec<PathBuf>) {
+    let resources = project.roots().resource_dirs().iter().map(|d| project.root.join(d)).collect();
+    (project.root.clone(), resources)
+}
+
+/// The existing file or directory a path written in `from` names (`href`, `url()`, a string literal).
+#[tauri::command]
+#[specta::specta]
+pub async fn fs_resolve_reference(
+    window: Window,
+    state: State<'_, AppState>,
+    from: IpcPath,
+    value: String,
+) -> IdeResult<Option<IpcPath>> {
+    let project = state.project(window.label()).ok();
+    blocking(move || {
+        let (root, resources) = project.as_deref().map(reference_roots).unzip();
+        let resources = resources.unwrap_or_default();
+        Ok(file_refs::resolve(&value, &from, root.as_deref(), &resources).map(Into::into))
+    })
+    .await
+}
+
+/// Files and folders that continue `prefix`, a path being typed in `from`.
+#[tauri::command]
+#[specta::specta]
+pub async fn path_completions(
+    window: Window,
+    state: State<'_, AppState>,
+    from: IpcPath,
+    prefix: String,
+) -> IdeResult<Vec<PathCompletion>> {
+    let project = state.project(window.label()).ok();
+    blocking(move || {
+        let (root, resources) = project.as_deref().map(reference_roots).unzip();
+        let resources = resources.unwrap_or_default();
+        Ok(file_refs::complete(&prefix, &from, root.as_deref(), &resources))
+    })
+    .await
+}
+
+/// Paths in an HTML document or stylesheet that name no existing file.
+#[tauri::command]
+#[specta::specta]
+pub async fn web_unresolved_references(
+    window: Window,
+    state: State<'_, AppState>,
+    doc: DocId,
+) -> IdeResult<Vec<FileReference>> {
+    let project = state.project(window.label())?;
+    let syntax = state.syntax();
+    blocking(move || {
+        let snap = project.documents.snapshot(doc)?;
+        if snap.large {
+            return Ok(Vec::new());
+        }
+        let (root, resources) = reference_roots(&project);
+        Ok(syntax
+            .web_file_references(&snap.language, &snap.text)
+            .into_iter()
+            .filter(|r| {
+                file_refs::is_file_reference(&r.value)
+                    && !file_refs::path_part(&r.value).is_empty()
+                    && file_refs::resolve(&r.value, &snap.path, Some(&root), &resources).is_none()
+            })
+            .collect())
+    })
+    .await
+}