Update settings at runtime (#798)

* feat: Update settings at runtime

fix the clippy warning

* update the documentation

* use to_value instead of to_vec+from_value

* drop the equal

* remove an useless comment

* apply suggestion

4 files changed, 81 insertions, 4 deletions

diff --git a/book/src/generated/typable-cmd.md b/book/src/generated/typable-cmd.md
index bb21fd6b..f12082bb 100644
--- a/book/src/generated/typable-cmd.md
+++ b/book/src/generated/typable-cmd.md
@@ -41,3 +41,4 @@
 | `:hsplit`, `:hs`, `:sp` | Open the file in a horizontal split. |
 | `:tutor` | Open the tutorial. |
 | `:goto`, `:g` | Go to line number. |
+| `:set-option`, `:set` | Set a config option at runtime |
diff --git a/helix-term/src/commands.rs b/helix-term/src/commands.rs
index ee6a5989..7b1235f8 100644
--- a/helix-term/src/commands.rs
+++ b/helix-term/src/commands.rs
@@ -2637,6 +2637,36 @@ pub mod cmd {
         let (view, doc) = current!(cx.editor);
 
         view.ensure_cursor_in_view(doc, line);
+        Ok(())
+    }
+
+    fn setting(
+        cx: &mut compositor::Context,
+        args: &[Cow<str>],
+        _event: PromptEvent,
+    ) -> anyhow::Result<()> {
+        let runtime_config = &mut cx.editor.config;
+
+        if args.len() != 2 {
+            anyhow::bail!("Bad arguments. Usage: `:set key field`");
+        }
+
+        let (key, arg) = (&args[0].to_lowercase(), &args[1]);
+
+        match key.as_ref() {
+            "scrolloff" => runtime_config.scrolloff = arg.parse()?,
+            "scroll-lines" => runtime_config.scroll_lines = arg.parse()?,
+            "mouse" => runtime_config.mouse = arg.parse()?,
+            "line-number" => runtime_config.line_number = arg.parse()?,
+            "middle-click_paste" => runtime_config.middle_click_paste = arg.parse()?,
+            "smart-case" => runtime_config.smart_case = arg.parse()?,
+            "auto-pairs" => runtime_config.auto_pairs = arg.parse()?,
+            "auto-completion" => runtime_config.auto_completion = arg.parse()?,
+            "completion-trigger-len" => runtime_config.completion_trigger_len = arg.parse()?,
+            "auto-info" => runtime_config.auto_info = arg.parse()?,
+            "true-color" => runtime_config.true_color = arg.parse()?,
+            _ => anyhow::bail!("Unknown key `{}`.", args[0]),
+        }
 
         Ok(())
     }
@@ -2928,6 +2958,13 @@ pub mod cmd {
             doc: "Go to line number.",
             fun: goto_line_number,
             completer: None,
+        },
+        TypableCommand {
+            name: "set-option",
+            aliases: &["set"],
+            doc: "Set a config option at runtime",
+            fun: setting,
+            completer: Some(completers::setting),
         }
     ];
 
diff --git a/helix-term/src/ui/mod.rs b/helix-term/src/ui/mod.rs
index f57e2e2b..9e096311 100644
--- a/helix-term/src/ui/mod.rs
+++ b/helix-term/src/ui/mod.rs
@@ -174,7 +174,9 @@ pub mod completers {
     use crate::ui::prompt::Completion;
     use fuzzy_matcher::skim::SkimMatcherV2 as Matcher;
     use fuzzy_matcher::FuzzyMatcher;
+    use helix_view::editor::Config;
     use helix_view::theme;
+    use once_cell::sync::Lazy;
     use std::borrow::Cow;
     use std::cmp::Reverse;
 
@@ -208,6 +210,31 @@ pub mod completers {
         names
     }
 
+    pub fn setting(input: &str) -> Vec<Completion> {
+        static KEYS: Lazy<Vec<String>> = Lazy::new(|| {
+            serde_json::to_value(Config::default())
+                .unwrap()
+                .as_object()
+                .unwrap()
+                .keys()
+                .cloned()
+                .collect()
+        });
+
+        let matcher = Matcher::default();
+
+        let mut matches: Vec<_> = KEYS
+            .iter()
+            .filter_map(|name| matcher.fuzzy_match(name, input).map(|score| (name, score)))
+            .collect();
+
+        matches.sort_unstable_by_key(|(_file, score)| Reverse(*score));
+        matches
+            .into_iter()
+            .map(|(name, _)| ((0..), name.into()))
+            .collect()
+    }
+
     pub fn filename(input: &str) -> Vec<Completion> {
         filename_impl(input, |entry| {
             let is_dir = entry.file_type().map_or(false, |entry| entry.is_dir());
diff --git a/helix-view/src/editor.rs b/helix-view/src/editor.rs
index fd6eb4d5..f4b0f73e 100644
--- a/helix-view/src/editor.rs
+++ b/helix-view/src/editor.rs
@@ -27,7 +27,7 @@ pub use helix_core::register::Registers;
 use helix_core::syntax;
 use helix_core::{Position, Selection};
 
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 
 fn deserialize_duration_millis<'de, D>(deserializer: D) -> Result<Duration, D::Error>
 where
@@ -37,7 +37,7 @@ where
     Ok(Duration::from_millis(millis))
 }
 
-#[derive(Debug, Clone, PartialEq, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
 pub struct FilePickerConfig {
     /// IgnoreOptions
@@ -77,7 +77,7 @@ impl Default for FilePickerConfig {
     }
 }
 
-#[derive(Debug, Clone, PartialEq, Deserialize)]
+#[derive(Debug, Clone, PartialEq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case", default, deny_unknown_fields)]
 pub struct Config {
     /// Padding to keep between the edge of the screen and the cursor when scrolling. Defaults to 5.
@@ -109,7 +109,7 @@ pub struct Config {
     pub true_color: bool,
 }
 
-#[derive(Debug, Copy, Clone, PartialEq, Eq, Deserialize)]
+#[derive(Debug, Copy, Clone, PartialEq, Eq, Serialize, Deserialize)]
 #[serde(rename_all = "kebab-case")]
 pub enum LineNumber {
     /// Show absolute line number
@@ -119,6 +119,18 @@ pub enum LineNumber {
     Relative,
 }
 
+impl std::str::FromStr for LineNumber {
+    type Err = anyhow::Error;
+
+    fn from_str(s: &str) -> Result<Self, Self::Err> {
+        match s.to_lowercase().as_str() {
+            "absolute" | "abs" => Ok(Self::Absolute),
+            "relative" | "rel" => Ok(Self::Relative),
+            _ => anyhow::bail!("Line number can only be `absolute` or `relative`."),
+        }
+    }
+}
+
 impl Default for Config {
     fn default() -> Self {
         Self {