1 files changed, 198 insertions, 0 deletions
diff --git a/lib/astal/io/variable.vala b/lib/astal/io/variable.vala
new file mode 100644
index 0000000..312a27a
--- /dev/null
+++ b/lib/astal/io/variable.vala
@@ -0,0 +1,198 @@
+/*
+ * Base class for [[email protected]] mainly meant to be used
+ * in higher level language bindings such as Lua and Gjs.
+ */
+public class AstalIO.VariableBase : Object {
+    public signal void changed ();
+    public signal void dropped ();
+    public signal void error (string err);
+
+    // lua-lgi crashes when using its emitting mechanism
+    public void emit_changed() { changed(); }
+    public void emit_dropped() { dropped(); }
+    public void emit_error(string err) { this.error(err); }
+
+    ~VariableBase() {
+        dropped();
+    }
+}
+
+public class AstalIO.Variable : VariableBase {
+    public Value value { owned get; set; }
+
+    private uint poll_id = 0;
+    private Process? watch_proc;
+
+    private uint poll_interval { get; set; default = 1000; }
+    private string[] poll_exec { get; set; }
+    private Closure? poll_transform { get; set; }
+    private Closure? poll_fn { get; set; }
+
+    private Closure? watch_transform { get; set; }
+    private string[] watch_exec { get; set; }
+
+    public Variable(Value init) {
+        Object(value: init);
+    }
+
+    public Variable poll(
+        uint interval,
+        string exec,
+        Closure? transform
+    ) throws Error {
+        string[] argv;
+        Shell.parse_argv(exec, out argv);
+        return pollv(interval, argv, transform);
+    }
+
+    public Variable pollv(
+        uint interval,
+        string[] execv,
+        Closure? transform
+    ) throws Error {
+        if (is_polling())
+            stop_poll();
+
+        poll_interval = interval;
+        poll_exec = execv;
+        poll_transform = transform;
+        poll_fn = null;
+        start_poll();
+        return this;
+    }
+
+    public Variable pollfn(
+        uint interval,
+        Closure fn
+    ) throws Error {
+        if (is_polling())
+            stop_poll();
+
+        poll_interval = interval;
+        poll_fn = fn;
+        poll_exec = null;
+        start_poll();
+        return this;
+    }
+
+    public Variable watch(
+        string exec,
+        Closure? transform
+    ) throws Error {
+        string[] argv;
+        Shell.parse_argv(exec, out argv);
+        return watchv(argv, transform);
+    }
+
+    public Variable watchv(
+        string[] execv,
+        Closure? transform
+    ) throws Error {
+        if (is_watching())
+            stop_watch();
+
+        watch_exec = execv;
+        watch_transform = transform;
+        start_watch();
+        return this;
+    }
+
+    construct {
+        notify["value"].connect(() => changed());
+        dropped.connect(() => {
+            if (is_polling())
+                stop_poll();
+
+            if (is_watching())
+                stop_watch();
+        });
+    }
+
+    private void set_closure(string val, Closure? transform) {
+        if (transform != null) {
+            var str = Value(typeof(string));
+            str.set_string(val);
+
+            var ret_val = Value(this.value.type());
+            transform.invoke(ref ret_val, { str, this.value });
+            this.value = ret_val;
+        }
+        else {
+            if (this.value.type() == Type.STRING && this.value.get_string() == val)
+                return;
+
+            var str = Value(typeof(string));
+            str.set_string(val);
+            this.value = str;
+        }
+    }
+
+    private void set_fn() {
+        var ret_val = Value(this.value.type());
+        poll_fn.invoke(ref ret_val, { this.value });
+        this.value = ret_val;
+    }
+
+    public void start_poll() throws Error {
+        return_if_fail(poll_id == 0);
+
+        if (poll_fn != null) {
+            set_fn();
+            poll_id = Timeout.add(poll_interval, () => {
+                set_fn();
+                return Source.CONTINUE;
+            }, Priority.DEFAULT);
+        }
+        if (poll_exec != null) {
+            Process.exec_asyncv.begin(poll_exec, (_, res) => {
+                try {
+                    var str = Process.exec_asyncv.end(res);
+                    set_closure(str, poll_transform);
+                } catch (Error err) {
+                    this.error(err.message);
+                }
+            });
+            poll_id = Timeout.add(poll_interval, () => {
+                Process.exec_asyncv.begin(poll_exec, (_, res) => {
+                    try {
+                        var str = Process.exec_asyncv.end(res);
+                        set_closure(str, poll_transform);
+                    } catch (Error err) {
+                        this.error(err.message);
+                        Source.remove(poll_id);
+                        poll_id = 0;
+                    }
+                });
+                return Source.CONTINUE;
+            }, Priority.DEFAULT);
+        }
+    }
+
+    public void start_watch() throws Error {
+        return_if_fail(watch_proc == null);
+        return_if_fail(watch_exec != null);
+
+        watch_proc = new Process.subprocessv(watch_exec);
+        watch_proc.stdout.connect((str) => set_closure(str, watch_transform));
+        watch_proc.stderr.connect((str) => this.error(str));
+    }
+
+    public void stop_poll() {
+        return_if_fail(poll_id != 0);
+        Source.remove(poll_id);
+        poll_id = 0;
+    }
+
+    public void stop_watch() {
+        return_if_fail(watch_proc != null);
+        watch_proc.kill();
+        watch_proc = null;
+    }
+
+    public bool is_polling() { return poll_id > 0; }
+    public bool is_watching() { return watch_proc != null; }
+
+    ~Variable() {
+        dropped();
+    }
+}