From 3163f33887b0826b54524b0f00464e5aecdb3b14 Mon Sep 17 00:00:00 2001
From: Filip Tibell <filip.tibell@gmail.com>
Date: Wed, 8 Mar 2023 19:23:47 +0100
Subject: [PATCH] Add support for shebang at the top of a script

---
 CHANGELOG.md                      | 12 ++++++++++++
 packages/cli/src/cli.rs           |  4 ++--
 packages/cli/src/utils/files.rs   | 18 ++++++++++++++++++
 packages/cli/src/utils/listing.rs |  5 +++--
 4 files changed, 35 insertions(+), 4 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ef69fd7..c5d4504 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -8,6 +8,18 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## Unreleased
+
+### Added
+
+-   Added support for shebangs at the top of a script, meaning scripts such as this one will now run without throwing a syntax error:
+
+    ```lua
+    #!/usr/bin/env lune
+
+    print("Hello, world!")
+    ```
+
 ## `0.5.5` - March 8th, 2023
 
 ### Added
diff --git a/packages/cli/src/cli.rs b/packages/cli/src/cli.rs
index 97fe11b..3c0723a 100644
--- a/packages/cli/src/cli.rs
+++ b/packages/cli/src/cli.rs
@@ -15,7 +15,7 @@ use crate::{
         generate_selene_defs_from_definitions, generate_wiki_dir_from_definitions,
     },
     utils::{
-        files::discover_script_file_path_including_lune_dirs,
+        files::{discover_script_file_path_including_lune_dirs, strip_shebang},
         listing::{find_lune_scripts, print_lune_scripts, sort_lune_scripts},
     },
 };
@@ -177,7 +177,7 @@ impl Cli {
         // Create a new lune object with all globals & run the script
         let result = Lune::new()
             .with_args(self.script_args)
-            .try_run(&script_display_name, &script_contents)
+            .try_run(&script_display_name, strip_shebang(script_contents))
             .await;
         Ok(match result {
             Err(err) => {
diff --git a/packages/cli/src/utils/files.rs b/packages/cli/src/utils/files.rs
index 88f4796..d7548a5 100644
--- a/packages/cli/src/utils/files.rs
+++ b/packages/cli/src/utils/files.rs
@@ -157,3 +157,21 @@ pub fn parse_lune_description_from_file(contents: &str) -> Option<String> {
         Some(unindented_lines)
     }
 }
+
+pub fn strip_shebang(mut contents: Vec<u8>) -> Vec<u8> {
+    if contents.starts_with(b"#!") {
+        if let Some(first_newline_idx) =
+            contents
+                .iter()
+                .enumerate()
+                .find_map(|(idx, c)| if *c == b'\n' { Some(idx) } else { None })
+        {
+            // NOTE: We keep the newline here on purpose to preserve
+            // correct line numbers in stack traces, the only reason
+            // we strip the shebang is to get the lua script to parse
+            // and the extra newline is not really a problem for that
+            contents.drain(..first_newline_idx);
+        }
+    }
+    contents
+}
diff --git a/packages/cli/src/utils/listing.rs b/packages/cli/src/utils/listing.rs
index 307c980..23d43c8 100644
--- a/packages/cli/src/utils/listing.rs
+++ b/packages/cli/src/utils/listing.rs
@@ -23,16 +23,17 @@ pub async fn find_lune_scripts() -> Result<Vec<(String, String)>> {
             while let Some(entry) = dir.next_entry().await? {
                 let meta = entry.metadata().await?;
                 if meta.is_file() {
-                    let contents = fs::read_to_string(entry.path()).await?;
+                    let contents = fs::read(entry.path()).await?;
                     files.push((entry, meta, contents));
                 }
             }
             let parsed: Vec<_> = files
                 .iter()
                 .map(|(entry, _, contents)| {
+                    let contents_str = String::from_utf8_lossy(contents);
                     let file_path = entry.path().with_extension("");
                     let file_name = file_path.file_name().unwrap().to_string_lossy();
-                    let description = parse_lune_description_from_file(contents);
+                    let description = parse_lune_description_from_file(&contents_str);
                     (file_name.to_string(), description.unwrap_or_default())
                 })
                 .collect();