support monitor lid option to disable closed monitors

src/lid.rs

@@ -0,0 +1,45 @@
+use std::fs::File;
+use std::io::Read;
+use std::path::PathBuf;
+use crate::config::Monitor;
+
+pub fn is_lid_closed(monitor: &Monitor) -> bool {
+    if let Some(lid) = &monitor.lid {
+        is_acpi_closed(lid)
+    } else {
+        false
+    }
+}
+
+/// Determine if the lid is closed.
+/// lid is the name of a directory in /proc/acpi/button/lid/.
+fn is_acpi_closed(lid: &String) -> bool {
+    let mut path_buf = PathBuf::from("/proc/acpi/button/lid");
+    path_buf.push(&lid);
+    path_buf.push("state");
+
+    if let Ok(ok) = path_buf.try_exists() {
+        if ok {
+            File::open(path_buf).is_ok_and(|mut file| {
+                let mut str = String::new();
+                if let Ok(_size) = file.read_to_string(&mut str) {
+                    is_state_closed(str)
+                } else {
+                    // error reading file
+                    false
+                }
+            })
+        } else {
+            // no file
+            false
+        }
+    } else {
+        // error checking for file
+        false
+    }
+}
+
+/// Parse a /proc/acpi/button/lid/*/state file and return true if the lid is closed
+fn is_state_closed(str:String) -> bool {
+    str.contains("closed")
+}