Show BibTeX entry when completing citations

src/completion/factory.rs

@@ -1,4 +1,6 @@
-use lsp_types::{CompletionItem, CompletionItemKind, InsertTextFormat, Uri};
+use crate::formatting::{BibtexFormatter, BibtexFormattingOptions};
+use crate::syntax::bibtex::{BibtexEntry, BibtexToken};
+use lsp_types::*;
 use serde::{Deserialize, Serialize};
 use std::borrow::Cow;
 use std::path::Path;
@@ -36,11 +38,7 @@ pub enum CompletionItemData {
     Class,
     EntryKind,
     FieldName,
-    Citation {
-        #[serde(with = "url_serde")]
-        uri: Uri,
-        key: String,
-    },
+    Citation,
     CommandSymbol,
     ArgumentSymbol,
 }
@@ -162,11 +160,18 @@ pub fn create_class(name: Cow<'static, str>) -> CompletionItem {
     }
 }
 
-pub fn create_citation(uri: Uri, key: String) -> CompletionItem {
+pub fn create_citation(entry: &BibtexEntry, key: &str) -> CompletionItem {
+    let mut formatter = BibtexFormatter::new(BibtexFormattingOptions::new(2, true, 35));
+    formatter.format_entry(entry);
+    let markdown = format!("```bibtex\n{}\n```", formatter.output);
     CompletionItem {
-        label: Cow::from(key.clone()),
+        label: Cow::from(key.to_owned()),
         kind: Some(CompletionItemKind::Field),
-        data: Some(CompletionItemData::Citation { uri, key }.into()),
+        data: Some(CompletionItemData::Citation.into()),
+        documentation: Some(Documentation::MarkupContent(MarkupContent {
+            kind: MarkupKind::Markdown,
+            value: Cow::from(markdown),
+        })),
         ..CompletionItem::default()
     }
 }

src/completion/latex/citation.rs

@@ -21,10 +21,7 @@ impl LatexCitationCompletionProvider {
                         for declaration in &tree.root.children {
                             if let BibtexDeclaration::Entry(entry) = declaration {
                                 if let Some(key) = &entry.key {
-                                    items.push(factory::create_citation(
-                                        document.uri.clone(),
-                                        key.text().to_owned(),
-                                    ));
+                                    items.push(factory::create_citation(entry, key.text()));
                                 }
                             }
                         }

src/formatting.rs

@@ -33,7 +33,7 @@ impl Default for BibtexFormattingOptions {
 pub struct BibtexFormatter {
     pub options: BibtexFormattingOptions,
     indent: String,
-    output: String,
+    pub output: String,
 }
 
 impl BibtexFormatter {
@@ -61,39 +61,45 @@ impl BibtexFormatter {
                 let text = comment.token.text();
                 self.output.push_str(text);
             }
-            BibtexDeclaration::Preamble(preamble) => {
-                self.format_token(&preamble.kind);
-                self.output.push('{');
-                if let Some(ref content) = preamble.content {
-                    self.format_content(content, self.output.chars().count());
-                    self.output.push('}');
-                }
-            }
-            BibtexDeclaration::String(string) => {
-                self.format_token(&string.kind);
-                self.output.push('{');
-                if let Some(ref name) = string.name {
-                    self.output.push_str(name.text());
-                    self.output.push_str(" = ");
-                    if let Some(ref value) = string.value {
-                        self.format_content(value, self.output.chars().count());
-                        self.output.push('}');
-                    }
-                }
+            BibtexDeclaration::Preamble(preamble) => self.format_preamble(preamble),
+            BibtexDeclaration::String(string) => self.format_string(string),
+            BibtexDeclaration::Entry(entry) => self.format_entry(entry),
+        }
+    }
+
+    pub fn format_preamble(&mut self, preamble: &BibtexPreamble) {
+        self.format_token(&preamble.kind);
+        self.output.push('{');
+        if let Some(ref content) = preamble.content {
+            self.format_content(content, self.output.chars().count());
+            self.output.push('}');
+        }
+    }
+
+    pub fn format_string(&mut self, string: &BibtexString) {
+        self.format_token(&string.kind);
+        self.output.push('{');
+        if let Some(ref name) = string.name {
+            self.output.push_str(name.text());
+            self.output.push_str(" = ");
+            if let Some(ref value) = string.value {
+                self.format_content(value, self.output.chars().count());
+                self.output.push('}');
             }
-            BibtexDeclaration::Entry(entry) => {
-                self.format_token(&entry.kind);
-                self.output.push('{');
-                if let Some(ref key) = entry.key {
-                    self.output.push_str(key.text());
-                    self.output.push(',');
-                    self.output.push('\n');
-                    for field in &entry.fields {
-                        self.format_field(field);
-                    }
-                    self.output.push('}');
-                }
+        }
+    }
+
+    pub fn format_entry(&mut self, entry: &BibtexEntry) {
+        self.format_token(&entry.kind);
+        self.output.push('{');
+        if let Some(ref key) = entry.key {
+            self.output.push_str(key.text());
+            self.output.push(',');
+            self.output.push('\n');
+            for field in &entry.fields {
+                self.format_field(field);
             }
+            self.output.push('}');
         }
     }
 

src/syntax/bibtex/ast.rs

@@ -252,6 +252,10 @@ impl BibtexEntry {
             right,
         }
     }
+
+    pub fn is_comment(&self) -> bool {
+        self.kind.text().to_lowercase() == "@comment"
+    }
 }
 
 impl SyntaxNode for BibtexEntry {