feat(config): add rudimentary config syntax checks

This commit attempts to introduce miette to provide users with quick
feedback when there may be syntax errors such as trailing commas in
their komorebi.json configuration file.

The lines and columns reported by serde_json don't actually line up with
the visualization of where we want to indicate a syntax error on the
miette Report. Some hackery has been done, but this should be improved
upon. Notably, this hackery does not accurately reflect the location of
a syntax error when the syntax error is a missing comma after a string
value.

komorebic/src/main.rs

@@ -22,6 +22,10 @@ use fs_tail::TailedFile;
 use heck::ToKebabCase;
 use komorebi_core::resolve_home_path;
 use lazy_static::lazy_static;
+use miette::NamedSource;
+use miette::Report;
+use miette::SourceOffset;
+use miette::SourceSpan;
 use paste::paste;
 use sysinfo::SystemExt;
 use uds_windows::UnixListener;
@@ -82,6 +86,17 @@ trait AhkFunction {
     fn generate_ahk_function() -> String;
 }
 
+#[derive(thiserror::Error, Debug, miette::Diagnostic)]
+#[error("{message}")]
+#[diagnostic(code(komorebi::configuration), help("try fixing this syntax error"))]
+struct ConfigurationError {
+    message: String,
+    #[source_code]
+    src: NamedSource,
+    #[label("This bit here")]
+    bad_bit: SourceSpan,
+}
+
 #[derive(Copy, Clone, ValueEnum)]
 enum BooleanState {
     Enable,
@@ -1261,6 +1276,30 @@ fn main() -> Result<()> {
                 .join("whkdrc");
 
             if static_config.exists() {
+                let config_source = std::fs::read_to_string(&static_config)?;
+                let lines: Vec<_> = config_source.lines().collect();
+                let parsed_config = serde_json::from_str::<serde_json::Value>(&config_source);
+                if let Err(serde_error) = parsed_config {
+                    let line = lines[serde_error.line() - 2];
+
+                    let offset = SourceOffset::from_location(
+                        config_source.clone(),
+                        serde_error.line() - 1,
+                        line.len(),
+                    );
+
+                    let error_string = serde_error.to_string();
+                    let msgs: Vec<_> = error_string.split(" at ").collect();
+
+                    let diagnostic = ConfigurationError {
+                        message: msgs[0].to_string(),
+                        src: NamedSource::new("komorebi.json", config_source.clone()),
+                        bad_bit: SourceSpan::new(offset, 2.into()),
+                    };
+
+                    println!("{:?}", Report::new(diagnostic));
+                }
+
                 println!("Found komorebi.json; this file can be passed to the start command with the --config flag\n");
                 if config_whkd.exists() {
                     println!("Found ~/.config/whkdrc; key bindings will be loaded from here when whkd is started, and you can start it automatically using the --whkd flag\n");