From 5237560b6192e6a8647c9ae02e6037fc66d6c482 Mon Sep 17 00:00:00 2001
From: PoiScript <poiscript@gmail.com>
Date: Thu, 21 Dec 2023 02:57:13 +0800
Subject: [PATCH] feat(lsp): completion support

---
 orgize-lsp/src/completion.rs | 75 ++++++++++++++++++++++++++++++++++++
 orgize-lsp/src/main.rs       | 15 ++++++--
 2 files changed, 87 insertions(+), 3 deletions(-)
 create mode 100644 orgize-lsp/src/completion.rs

diff --git a/orgize-lsp/src/completion.rs b/orgize-lsp/src/completion.rs
new file mode 100644
index 0000000..5b48c9c
--- /dev/null
+++ b/orgize-lsp/src/completion.rs
@@ -0,0 +1,75 @@
+use tower_lsp::lsp_types::{
+    CompletionItem, CompletionItemKind, CompletionParams, CompletionResponse, CompletionTextEdit,
+    Position, Range, TextEdit,
+};
+
+use crate::Backend;
+
+pub fn completion(params: CompletionParams, backend: &Backend) -> Option<CompletionResponse> {
+    let uri = params.text_document_position.text_document.uri.to_string();
+
+    let Some(doc) = backend.documents.get(&uri) else {
+        return None;
+    };
+
+    let offset = doc.offset_of(params.text_document_position.position) as usize;
+
+    if offset < 2 {
+        return None;
+    }
+
+    let filter_text = doc.text.get((offset - 2)..offset)?;
+
+    let (label, new_text) = match filter_text {
+        "<a" => (
+            "ASCI export block",
+            "#+BEGIN_EXPORT ascii\n\n#+END_EXPORT\n",
+        ),
+        "<c" => ("Center block", "#+BEGIN_CENTER\n\n#+END_CENTER\n"),
+        "<C" => ("Comment block", "#+BEGIN_COMMENT\n\n#+END_COMMENT\n"),
+        "<e" => ("Example block", "#+BEGIN_EXAMPLE\n\n#+END_EXAMPLE\n"),
+        "<E" => ("Export block", "#+BEGIN_EXPORT\n\n#+END_EXPORT\n"),
+        "<h" => ("HTML export block", "#+BEGIN_EXPORT html\n\n#+END_EXPORT\n"),
+        "<l" => (
+            "LaTeX export block",
+            "#+BEGIN_EXPORT latex\n\n#+END_EXPORT\n",
+        ),
+        "<q" => ("Quote block", "#+BEGIN_QUOTE\n\n#+END_QUOTE\n"),
+        "<s" => ("Source block", "#+BEGIN_SRC\n\n#+END_SRC\n"),
+        "<v" => ("Verse block", "#+BEGIN_VERSE\n\n#+END_VERSE\n"),
+        _ => return None,
+    };
+
+    let end = params.text_document_position.position;
+
+    Some(CompletionResponse::Array(vec![CompletionItem {
+        label: label.into(),
+        kind: Some(CompletionItemKind::TEXT),
+        insert_text: Some(new_text.into()),
+        filter_text: Some(filter_text.into()),
+        text_edit: Some(CompletionTextEdit::Edit(TextEdit {
+            new_text: new_text.into(),
+            range: Range {
+                start: Position::new(end.line, end.character - 2),
+                end,
+            },
+        })),
+        ..Default::default()
+    }]))
+}
+
+pub fn trigger_characters() -> Vec<String> {
+    vec![
+        "<a".into(),
+        "<c".into(),
+        "<C".into(),
+        "<e".into(),
+        "<E".into(),
+        "<h".into(),
+        "<l".into(),
+        "<q".into(),
+        "<s".into(),
+        "<v".into(),
+        "<I".into(),
+    ]
+}
diff --git a/orgize-lsp/src/main.rs b/orgize-lsp/src/main.rs
index deecff7..fade10e 100644
--- a/orgize-lsp/src/main.rs
+++ b/orgize-lsp/src/main.rs
@@ -1,5 +1,6 @@
 mod code_lens;
 mod commands;
+mod completion;
 mod document_link;
 mod document_link_resolve;
 mod document_symbol;
@@ -83,6 +84,11 @@ impl LanguageServer for Backend {
                 }),
                 document_formatting_provider: Some(OneOf::Left(true)),
                 document_symbol_provider: Some(OneOf::Left(true)),
+                completion_provider: Some(CompletionOptions {
+                    resolve_provider: Some(false),
+                    trigger_characters: Some(completion::trigger_characters()),
+                    ..Default::default()
+                }),
                 ..ServerCapabilities::default()
             },
         })
@@ -133,8 +139,12 @@ impl LanguageServer for Backend {
 
     async fn did_change_watched_files(&self, _: DidChangeWatchedFilesParams) {}
 
-    async fn completion(&self, _: CompletionParams) -> Result<Option<CompletionResponse>> {
-        Ok(None)
+    async fn completion(&self, params: CompletionParams) -> Result<Option<CompletionResponse>> {
+        Ok(completion::completion(params, &self))
+    }
+
+    async fn completion_resolve(&self, params: CompletionItem) -> Result<CompletionItem> {
+        Ok(params)
     }
 
     async fn semantic_tokens_full(
@@ -265,7 +275,6 @@ impl LanguageServer for Backend {
 
         let mut t = DocumentSymbolTraverser::new(&doc);
         doc.traverse(&mut t);
-        dbg!(&t.symbols);
         Ok(Some(DocumentSymbolResponse::Nested(t.symbols)))
     }
 }