make path changes LSP spec conform (#8949)

Currently, helix implements operations which change the paths of files
incorrectly and inconsistently. This PR ensures that we do the following
whenever a buffer is renamed (`:move` and workspace edits)

* always send did_open/did_close notifications
* send will_rename/did_rename requests correctly
  * send them to all LSP servers not just those that are active for a
    buffer
  * also send these requests for paths that are not yet open in a buffer (if
    triggered from workspace edit).
  * only send these if the server registered interests in the path
* autodetect language, indent, line ending, ..

This PR also centralizes the infrastructure for path setting and
therefore `:w <path>` benefits from similar fixed (but without didRename)

3 files changed, 320 insertions, 2 deletions

diff --git a/helix-view/src/document.rs b/helix-view/src/document.rs
index 88653948..33137c6c 100644
--- a/helix-view/src/document.rs
+++ b/helix-view/src/document.rs
@@ -1041,6 +1041,9 @@ impl Document {
         self.encoding
     }
 
+    /// sets the document path without sending events to various
+    /// observers (like LSP), in most cases `Editor::set_doc_path`
+    /// should be used instead
     pub fn set_path(&mut self, path: Option<&Path>) {
         let path = path.map(helix_stdx::path::canonicalize);
 
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index eca488e7..db0d4030 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -23,7 +23,8 @@ use std::{
     borrow::Cow,
     cell::Cell,
     collections::{BTreeMap, HashMap},
-    io::stdin,
+    fs,
+    io::{self, stdin},
     num::NonZeroUsize,
     path::{Path, PathBuf},
     pin::Pin,
@@ -45,6 +46,7 @@ use helix_core::{
 };
 use helix_dap as dap;
 use helix_lsp::lsp;
+use helix_stdx::path::canonicalize;
 
 use serde::{ser::SerializeMap, Deserialize, Deserializer, Serialize, Serializer};
 
@@ -1215,6 +1217,90 @@ impl Editor {
         self.launch_language_servers(doc_id)
     }
 
+    /// moves/renames a path, invoking any event handlers (currently only lsp)
+    /// and calling `set_doc_path` if the file is open in the editor
+    pub fn move_path(&mut self, old_path: &Path, new_path: &Path) -> io::Result<()> {
+        let new_path = canonicalize(new_path);
+        // sanity check
+        if old_path == new_path {
+            return Ok(());
+        }
+        let is_dir = old_path.is_dir();
+        let language_servers: Vec<_> = self
+            .language_servers
+            .iter_clients()
+            .filter(|client| client.is_initialized())
+            .cloned()
+            .collect();
+        for language_server in language_servers {
+            let Some(request) = language_server.will_rename(old_path, &new_path, is_dir) else {
+                continue;
+            };
+            let edit = match helix_lsp::block_on(request) {
+                Ok(edit) => edit,
+                Err(err) => {
+                    log::error!("invalid willRename response: {err:?}");
+                    continue;
+                }
+            };
+            if let Err(err) = self.apply_workspace_edit(language_server.offset_encoding(), &edit) {
+                log::error!("failed to apply workspace edit: {err:?}")
+            }
+        }
+        fs::rename(old_path, &new_path)?;
+        if let Some(doc) = self.document_by_path(old_path) {
+            self.set_doc_path(doc.id(), &new_path);
+        }
+        let is_dir = new_path.is_dir();
+        for ls in self.language_servers.iter_clients() {
+            if let Some(notification) = ls.did_rename(old_path, &new_path, is_dir) {
+                tokio::spawn(notification);
+            };
+        }
+        self.language_servers
+            .file_event_handler
+            .file_changed(old_path.to_owned());
+        self.language_servers
+            .file_event_handler
+            .file_changed(new_path);
+        Ok(())
+    }
+
+    pub fn set_doc_path(&mut self, doc_id: DocumentId, path: &Path) {
+        let doc = doc_mut!(self, &doc_id);
+        let old_path = doc.path();
+
+        if let Some(old_path) = old_path {
+            // sanity check, should not occur but some callers (like an LSP) may
+            // create bogus calls
+            if old_path == path {
+                return;
+            }
+            // if we are open in LSPs send did_close notification
+            for language_server in doc.language_servers() {
+                tokio::spawn(language_server.text_document_did_close(doc.identifier()));
+            }
+        }
+        // we need to clear the list of language servers here so that
+        // refresh_doc_language/refresh_language_servers doesn't resend
+        // text_document_did_close. Since we called `text_document_did_close`
+        // we have fully unregistered this document from its LS
+        doc.language_servers.clear();
+        doc.set_path(Some(path));
+        self.refresh_doc_language(doc_id)
+    }
+
+    pub fn refresh_doc_language(&mut self, doc_id: DocumentId) {
+        let loader = self.syn_loader.clone();
+        let doc = doc_mut!(self, &doc_id);
+        doc.detect_language(loader);
+        doc.detect_indent_and_line_ending();
+        self.refresh_language_servers(doc_id);
+        let doc = doc_mut!(self, &doc_id);
+        let diagnostics = Editor::doc_diagnostics(&self.language_servers, &self.diagnostics, doc);
+        doc.replace_diagnostics(diagnostics, &[], None);
+    }
+
     /// Launch a language server for a given document
     fn launch_language_servers(&mut self, doc_id: DocumentId) {
         if !self.config().lsp.enable {
@@ -1257,7 +1343,7 @@ impl Editor {
                 .collect::<HashMap<_, _>>()
         });
 
-        if language_servers.is_empty() {
+        if language_servers.is_empty() && doc.language_servers.is_empty() {
             return;
         }
 
diff --git a/helix-view/src/handlers/lsp.rs b/helix-view/src/handlers/lsp.rs
index 1dae45dd..beb106b2 100644
--- a/helix-view/src/handlers/lsp.rs
+++ b/helix-view/src/handlers/lsp.rs
@@ -1,4 +1,8 @@
+use crate::editor::Action;
+use crate::Editor;
 use crate::{DocumentId, ViewId};
+use helix_lsp::util::generate_transaction_from_edits;
+use helix_lsp::{lsp, OffsetEncoding};
 
 pub enum CompletionEvent {
     /// Auto completion was triggered by typing a word char
@@ -39,3 +43,228 @@ pub enum SignatureHelpEvent {
     Cancel,
     RequestComplete { open: bool },
 }
+
+#[derive(Debug)]
+pub struct ApplyEditError {
+    pub kind: ApplyEditErrorKind,
+    pub failed_change_idx: usize,
+}
+
+#[derive(Debug)]
+pub enum ApplyEditErrorKind {
+    DocumentChanged,
+    FileNotFound,
+    UnknownURISchema,
+    IoError(std::io::Error),
+    // TODO: check edits before applying and propagate failure
+    // InvalidEdit,
+}
+
+impl ToString for ApplyEditErrorKind {
+    fn to_string(&self) -> String {
+        match self {
+            ApplyEditErrorKind::DocumentChanged => "document has changed".to_string(),
+            ApplyEditErrorKind::FileNotFound => "file not found".to_string(),
+            ApplyEditErrorKind::UnknownURISchema => "URI schema not supported".to_string(),
+            ApplyEditErrorKind::IoError(err) => err.to_string(),
+        }
+    }
+}
+
+impl Editor {
+    fn apply_text_edits(
+        &mut self,
+        uri: &helix_lsp::Url,
+        version: Option<i32>,
+        text_edits: Vec<lsp::TextEdit>,
+        offset_encoding: OffsetEncoding,
+    ) -> Result<(), ApplyEditErrorKind> {
+        let path = match uri.to_file_path() {
+            Ok(path) => path,
+            Err(_) => {
+                let err = format!("unable to convert URI to filepath: {}", uri);
+                log::error!("{}", err);
+                self.set_error(err);
+                return Err(ApplyEditErrorKind::UnknownURISchema);
+            }
+        };
+
+        let doc_id = match self.open(&path, Action::Load) {
+            Ok(doc_id) => doc_id,
+            Err(err) => {
+                let err = format!("failed to open document: {}: {}", uri, err);
+                log::error!("{}", err);
+                self.set_error(err);
+                return Err(ApplyEditErrorKind::FileNotFound);
+            }
+        };
+
+        let doc = doc_mut!(self, &doc_id);
+        if let Some(version) = version {
+            if version != doc.version() {
+                let err = format!("outdated workspace edit for {path:?}");
+                log::error!("{err}, expected {} but got {version}", doc.version());
+                self.set_error(err);
+                return Err(ApplyEditErrorKind::DocumentChanged);
+            }
+        }
+
+        // Need to determine a view for apply/append_changes_to_history
+        let view_id = self.get_synced_view_id(doc_id);
+        let doc = doc_mut!(self, &doc_id);
+
+        let transaction = generate_transaction_from_edits(doc.text(), text_edits, offset_encoding);
+        let view = view_mut!(self, view_id);
+        doc.apply(&transaction, view.id);
+        doc.append_changes_to_history(view);
+        Ok(())
+    }
+
+    // TODO make this transactional (and set failureMode to transactional)
+    pub fn apply_workspace_edit(
+        &mut self,
+        offset_encoding: OffsetEncoding,
+        workspace_edit: &lsp::WorkspaceEdit,
+    ) -> Result<(), ApplyEditError> {
+        if let Some(ref document_changes) = workspace_edit.document_changes {
+            match document_changes {
+                lsp::DocumentChanges::Edits(document_edits) => {
+                    for (i, document_edit) in document_edits.iter().enumerate() {
+                        let edits = document_edit
+                            .edits
+                            .iter()
+                            .map(|edit| match edit {
+                                lsp::OneOf::Left(text_edit) => text_edit,
+                                lsp::OneOf::Right(annotated_text_edit) => {
+                                    &annotated_text_edit.text_edit
+                                }
+                            })
+                            .cloned()
+                            .collect();
+                        self.apply_text_edits(
+                            &document_edit.text_document.uri,
+                            document_edit.text_document.version,
+                            edits,
+                            offset_encoding,
+                        )
+                        .map_err(|kind| ApplyEditError {
+                            kind,
+                            failed_change_idx: i,
+                        })?;
+                    }
+                }
+                lsp::DocumentChanges::Operations(operations) => {
+                    log::debug!("document changes - operations: {:?}", operations);
+                    for (i, operation) in operations.iter().enumerate() {
+                        match operation {
+                            lsp::DocumentChangeOperation::Op(op) => {
+                                self.apply_document_resource_op(op).map_err(|io| {
+                                    ApplyEditError {
+                                        kind: ApplyEditErrorKind::IoError(io),
+                                        failed_change_idx: i,
+                                    }
+                                })?;
+                            }
+
+                            lsp::DocumentChangeOperation::Edit(document_edit) => {
+                                let edits = document_edit
+                                    .edits
+                                    .iter()
+                                    .map(|edit| match edit {
+                                        lsp::OneOf::Left(text_edit) => text_edit,
+                                        lsp::OneOf::Right(annotated_text_edit) => {
+                                            &annotated_text_edit.text_edit
+                                        }
+                                    })
+                                    .cloned()
+                                    .collect();
+                                self.apply_text_edits(
+                                    &document_edit.text_document.uri,
+                                    document_edit.text_document.version,
+                                    edits,
+                                    offset_encoding,
+                                )
+                                .map_err(|kind| {
+                                    ApplyEditError {
+                                        kind,
+                                        failed_change_idx: i,
+                                    }
+                                })?;
+                            }
+                        }
+                    }
+                }
+            }
+
+            return Ok(());
+        }
+
+        if let Some(ref changes) = workspace_edit.changes {
+            log::debug!("workspace changes: {:?}", changes);
+            for (i, (uri, text_edits)) in changes.iter().enumerate() {
+                let text_edits = text_edits.to_vec();
+                self.apply_text_edits(uri, None, text_edits, offset_encoding)
+                    .map_err(|kind| ApplyEditError {
+                        kind,
+                        failed_change_idx: i,
+                    })?;
+            }
+        }
+
+        Ok(())
+    }
+
+    fn apply_document_resource_op(&mut self, op: &lsp::ResourceOp) -> std::io::Result<()> {
+        use lsp::ResourceOp;
+        use std::fs;
+        match op {
+            ResourceOp::Create(op) => {
+                let path = op.uri.to_file_path().unwrap();
+                let ignore_if_exists = op.options.as_ref().map_or(false, |options| {
+                    !options.overwrite.unwrap_or(false) && options.ignore_if_exists.unwrap_or(false)
+                });
+                if !ignore_if_exists || !path.exists() {
+                    // Create directory if it does not exist
+                    if let Some(dir) = path.parent() {
+                        if !dir.is_dir() {
+                            fs::create_dir_all(dir)?;
+                        }
+                    }
+
+                    fs::write(&path, [])?;
+                    self.language_servers.file_event_handler.file_changed(path);
+                }
+            }
+            ResourceOp::Delete(op) => {
+                let path = op.uri.to_file_path().unwrap();
+                if path.is_dir() {
+                    let recursive = op
+                        .options
+                        .as_ref()
+                        .and_then(|options| options.recursive)
+                        .unwrap_or(false);
+
+                    if recursive {
+                        fs::remove_dir_all(&path)?
+                    } else {
+                        fs::remove_dir(&path)?
+                    }
+                    self.language_servers.file_event_handler.file_changed(path);
+                } else if path.is_file() {
+                    fs::remove_file(&path)?;
+                }
+            }
+            ResourceOp::Rename(op) => {
+                let from = op.old_uri.to_file_path().unwrap();
+                let to = op.new_uri.to_file_path().unwrap();
+                let ignore_if_exists = op.options.as_ref().map_or(false, |options| {
+                    !options.overwrite.unwrap_or(false) && options.ignore_if_exists.unwrap_or(false)
+                });
+                if !ignore_if_exists || !to.exists() {
+                    self.move_path(&from, &to)?;
+                }
+            }
+        }
+        Ok(())
+    }
+}