Refactor commandline processing

This reduces the amount of code duplication, and similar flow
is used for both wsl and non-wsl code paths.

src/bridge/mod.rs

@@ -29,8 +29,12 @@ fn set_windows_creation_flags(cmd: &mut Command) {
     cmd.creation_flags(0x0800_0000); // CREATE_NO_WINDOW
 }
 
+fn build_nvim_cmd_with_args(bin: &str) -> Command {
+    let mut args = Vec::<String>::new();
+    args.push("--embed".to_string());
+    args.extend(SETTINGS.get::<CmdLineSettings>().neovim_args);
+
     #[cfg(windows)]
-fn platform_build_nvim_cmd(bin: &str) -> Option<Command> {
     if SETTINGS.get::<CmdLineSettings>().wsl {
         let mut cmd = Command::new("wsl");
         cmd.args(&[
@@ -38,62 +42,63 @@ fn platform_build_nvim_cmd(bin: &str) -> Option<Command> {
             "-c",
             "let \\$PATH=system(\"\\$SHELL -lic 'echo \\$PATH' 2>/dev/null\")",
         ]);
-        Some(cmd)
-    } else if Path::new(&bin).exists() {
-        Some(Command::new(bin))
-    } else {
-        None
+        cmd.args(args);
+        return cmd;
     }
+    let mut cmd = Command::new(bin);
+    cmd.args(args);
+    cmd
 }
 
-#[cfg(unix)]
-fn platform_build_nvim_cmd(bin: &str) -> Option<Command> {
-    if Path::new(&bin).exists() {
-        Some(Command::new(bin))
+fn platform_exists(bin: &str) -> bool {
+    #[cfg(windows)]
+    if SETTINGS.get::<CmdLineSettings>().wsl {
+        if let Ok(output) = std::process::Command::new("wsl")
+            .args(&["$SHELL", "-lic"])
+            .arg(format!("exists -x {}", bin))
+            .output()
+        {
+            return output.status.success();
         } else {
-        None
-    }
+            error!("wsl exists failed");
+            std::process::exit(1);
         }
-
-fn build_nvim_cmd() -> Command {
-    if let Some(path) = SETTINGS.get::<CmdLineSettings>().neovim_bin {
-        if let Some(cmd) = platform_build_nvim_cmd(&path) {
-            return cmd;
-        } else {
-            warn!("NEOVIM_BIN is invalid falling back to first bin in PATH");
     }
+    Path::new(&bin).exists()
 }
+
+fn platform_which(bin: &str) -> Option<String> {
     #[cfg(windows)]
     if SETTINGS.get::<CmdLineSettings>().wsl {
         if let Ok(output) = std::process::Command::new("wsl")
-            .args(&["$SHELL", "-lic", "which nvim"])
+            .args(&["$SHELL", "-lic"])
+            .arg(format!("which {}", bin))
             .output()
         {
             if output.status.success() {
-                let path = String::from_utf8(output.stdout).unwrap();
-                let mut cmd = Command::new("wsl");
-                cmd.args(&[
-                    path.trim(),
-                    "-c",
-                    "let \\$PATH=system(\"\\$SHELL -lic 'echo \\$PATH' 2>/dev/null\")",
-                ]);
-                return cmd;
+                return Some(String::from_utf8(output.stdout).unwrap());
             } else {
-                error!("nvim not found in WSL path");
-                std::process::exit(1);
+                return None;
+            }
         }
+    }
+    if let Ok(path) = which::which(bin) {
+        path.into_os_string().into_string().ok()
     } else {
-            error!("wsl which nvim failed");
-            std::process::exit(1);
+        None
     }
 }
-    if let Ok(path) = which::which("nvim") {
-        if let Some(cmd) = platform_build_nvim_cmd(path.to_str().unwrap()) {
-            cmd
+
+fn build_nvim_cmd() -> Command {
+    if let Some(path) = SETTINGS.get::<CmdLineSettings>().neovim_bin {
+        if platform_exists(&path) {
+            return build_nvim_cmd_with_args(&path);
         } else {
-            error!("nvim does not have proper permissions!");
-            std::process::exit(1);
+            warn!("NEOVIM_BIN is invalid falling back to first bin in PATH");
         }
+    }
+    if let Some(path) = platform_which("nvim") {
+        build_nvim_cmd_with_args(&path)
     } else {
         error!("nvim not found!");
         std::process::exit(1);
@@ -123,9 +128,6 @@ pub fn build_neovide_command(channel: u64, num_args: u64, command: &str, event:
 pub fn create_nvim_command() -> Command {
     let mut cmd = build_nvim_cmd();
 
-    cmd.arg("--embed")
-        .args(SETTINGS.get::<CmdLineSettings>().neovim_args.iter());
-
     info!("Starting neovim with: {:?}", cmd);
 
     #[cfg(not(debug_assertions))]