From e08161c790e9ca86da762b53cc7153547c69843e Mon Sep 17 00:00:00 2001
From: Gustavo Shigueo <gustavo.gsmn@gmail.com>
Date: Thu, 25 Jul 2024 15:20:38 -0300
Subject: [PATCH] Fix JSDoc formatting for Rust block comments (#342)

---
 macros/src/utils.rs             | 46 +++++++++++++++++++++------------
 ts-rs/tests/integration/docs.rs | 44 ++++++++++++++++++++++++++++---
 2 files changed, 70 insertions(+), 20 deletions(-)

diff --git a/macros/src/utils.rs b/macros/src/utils.rs
index 07ce47a2..445487ff 100644
--- a/macros/src/utils.rs
+++ b/macros/src/utils.rs
@@ -3,8 +3,8 @@ use std::collections::HashMap;
 use proc_macro2::{Ident, TokenStream};
 use quote::quote;
 use syn::{
-    spanned::Spanned, Attribute, Error, Expr, ExprLit, GenericParam, Generics, Lit, Meta, Path,
-    Result, Type,
+    spanned::Spanned, Attribute, Error, Expr, ExprLit, GenericParam, Generics, Lit, Path, Result,
+    Type,
 };
 
 use super::attr::{Attr, Serde};
@@ -140,30 +140,42 @@ where
 
 /// Return doc comments parsed and formatted as JSDoc.
 pub fn parse_docs(attrs: &[Attribute]) -> Result<String> {
-    let lines = attrs
+    let doc_attrs = attrs
         .iter()
-        .filter_map(|a| match a.meta {
-            Meta::NameValue(ref x) if x.path.is_ident("doc") => Some(x),
-            _ => None,
-        })
+        .filter_map(|attr| attr.meta.require_name_value().ok())
+        .filter(|attr| attr.path.is_ident("doc"))
         .map(|attr| match attr.value {
             Expr::Lit(ExprLit {
                 lit: Lit::Str(ref str),
                 ..
             }) => Ok(str.value()),
-            _ => syn_err!(attr.span(); "doc attribute with non literal expression found"),
-        })
-        .map(|attr| {
-            attr.map(|line| match line.trim() {
-                "" => " *".to_owned(),
-                _ => format!(" *{}", line.trim_end()),
-            })
+            _ => syn_err!(attr.span(); "doc  with non literal expression found"),
         })
         .collect::<Result<Vec<_>>>()?;
 
-    Ok(match lines.is_empty() {
-        true => "".to_owned(),
-        false => format!("/**\n{}\n */\n", lines.join("\n")),
+    Ok(match doc_attrs.len() {
+        // No docs
+        0 => String::new(),
+
+        // Multi-line block doc comment (/** ... */)
+        1 if doc_attrs[0].contains('\n') => format!("/**{}*/\n", &doc_attrs[0]),
+
+        // Regular doc comment(s) (///) or single line block doc comment
+        _ => {
+            let mut buffer = String::from("/**\n");
+            let mut lines = doc_attrs.iter().peekable();
+
+            while let Some(line) = lines.next() {
+                buffer.push_str(" *");
+                buffer.push_str(line);
+
+                if lines.peek().is_some() {
+                    buffer.push('\n');
+                }
+            }
+            buffer.push_str("\n */\n");
+            buffer
+        }
     })
 }
 
diff --git a/ts-rs/tests/integration/docs.rs b/ts-rs/tests/integration/docs.rs
index 5fec1b92..9c5ebc07 100644
--- a/ts-rs/tests/integration/docs.rs
+++ b/ts-rs/tests/integration/docs.rs
@@ -4,8 +4,6 @@ use std::{concat, fs};
 
 use ts_rs::TS;
 
-/* ============================================================================================== */
-
 /// Doc comment.
 /// Supports new lines.
 ///
@@ -93,7 +91,16 @@ struct G {
     f: F,
 }
 
-/* ============================================================================================== */
+#[derive(TS)]
+#[ts(export_to = "docs/")]
+/**
+ * Block doc comment
+ *
+ * works
+ */
+struct H {
+    foo: i32,
+}
 
 #[test]
 fn export_a() {
@@ -387,3 +394,34 @@ fn export_g() {
 
     assert_eq!(actual_content, expected_content);
 }
+
+#[test]
+fn export_h() {
+    H::export().unwrap();
+
+    let expected_content = if cfg!(feature = "format") {
+        concat!(
+            "// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.\n\n",
+            "/**\n",
+            " * Block doc comment\n",
+            " *\n",
+            " * works\n",
+            " */\n",
+            "export type H = { foo: number };\n",
+        )
+    } else {
+        concat!(
+            "// This file was generated by [ts-rs](https://github.com/Aleph-Alpha/ts-rs). Do not edit this file manually.\n\n",
+            "/**\n",
+            " * Block doc comment\n",
+            " *\n",
+            " * works\n",
+            " */\n",
+            "export type H = { foo: number, };\n",
+        )
+    };
+
+    let actual_content = fs::read_to_string(H::default_output_path().unwrap()).unwrap();
+
+    assert_eq!(actual_content, expected_content);
+}