From e992ac7ad05e0f10b8c229ccf51dfdc871dd97e1 Mon Sep 17 00:00:00 2001
From: Wez Furlong <wez@wezfurlong.org>
Date: Sat, 6 Mar 2021 14:25:36 -0800
Subject: [PATCH] lua: add `wezterm.battery_info()` function

Queries the system battery information and returns an array of
battery information.

Each element is a lua table with the following entries:

* state_of_charge: expressed as percents
* vendor: the battery manufacturer
* model: the battery model
* serial: the battery serial number
* time_to_full: how long until the battery is full
* time_to_empty: how long until the battery is empty
* state: "Charging", "Discharging", "Empty", "Full", "Unknown"

I haven't run this on a system with a battery yet, so I'm holding
off from showing an example until I've got a work one.

refs: https://github.com/wez/wezterm/issues/500
---
 Cargo.lock        | 49 +++++++++++++++++++++++++++++++++++++++++++++++
 config/Cargo.toml |  1 +
 config/src/lua.rs | 47 +++++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 97 insertions(+)

diff --git a/Cargo.lock b/Cargo.lock
index f048cd75c..486fe1ea4 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -346,6 +346,23 @@ checksum = "904dfeac50f3cdaba28fc6f57fdcddb75f49ed61346676a78c4ffe55877802fd"
 name = "base91"
 version = "0.1.0"
 
+[[package]]
+name = "battery"
+version = "0.7.8"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b4b624268937c0e0a3edb7c27843f9e547c320d730c610d3b8e6e8e95b2026e4"
+dependencies = [
+ "cfg-if 1.0.0",
+ "core-foundation 0.7.0",
+ "lazycell",
+ "libc",
+ "mach",
+ "nix 0.19.1",
+ "num-traits 0.2.14",
+ "uom",
+ "winapi 0.3.9",
+]
+
 [[package]]
 name = "bintree"
 version = "0.1.0"
@@ -673,6 +690,7 @@ name = "config"
 version = "0.1.0"
 dependencies = [
  "anyhow",
+ "battery",
  "bitflags",
  "bstr 0.2.15",
  "chrono",
@@ -1937,6 +1955,15 @@ dependencies = [
  "cc",
 ]
 
+[[package]]
+name = "mach"
+version = "0.3.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b823e83b2affd8f40a9ee8c29dbc56404c1e34cd2710921f2801e2cf29527afa"
+dependencies = [
+ "libc",
+]
+
 [[package]]
 name = "malloc_buf"
 version = "0.0.6"
@@ -2211,6 +2238,18 @@ dependencies = [
  "libc",
 ]
 
+[[package]]
+name = "nix"
+version = "0.19.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b2ccba0cfe4fdf15982d1674c69b1fd80bad427d293849982668dfe454bd61f2"
+dependencies = [
+ "bitflags",
+ "cc",
+ "cfg-if 1.0.0",
+ "libc",
+]
+
 [[package]]
 name = "nix"
 version = "0.20.0"
@@ -4007,6 +4046,16 @@ version = "0.7.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "a156c684c91ea7d62626509bce3cb4e1d9ed5c4d978f7b4352658f96a4c26b4a"
 
+[[package]]
+name = "uom"
+version = "0.30.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e76503e636584f1e10b9b3b9498538279561adcef5412927ba00c2b32c4ce5ed"
+dependencies = [
+ "num-traits 0.2.14",
+ "typenum",
+]
+
 [[package]]
 name = "url"
 version = "2.2.1"
diff --git a/config/Cargo.toml b/config/Cargo.toml
index 317a60b1c..7f4110528 100644
--- a/config/Cargo.toml
+++ b/config/Cargo.toml
@@ -15,6 +15,7 @@ pretty_env_logger = "0.4"
 
 [dependencies]
 anyhow = "1.0"
+battery = "0.7"
 bitflags = "1.0"
 bstr = "0.2"
 chrono = {version="0.4", features=["unstable-locales"]}
diff --git a/config/src/lua.rs b/config/src/lua.rs
index 06240b73b..ee73d5cea 100644
--- a/config/src/lua.rs
+++ b/config/src/lua.rs
@@ -134,6 +134,7 @@ pub fn make_lua_context(config_dir: &Path) -> anyhow::Result<Lua> {
         wezterm_mod.set("sleep_ms", lua.create_async_function(sleep_ms)?)?;
         wezterm_mod.set("format", lua.create_function(format)?)?;
         wezterm_mod.set("strftime", lua.create_function(strftime)?)?;
+        wezterm_mod.set("battery_info", lua.create_function(battery_info)?)?;
 
         package.set("path", path_array.join(";"))?;
 
@@ -254,6 +255,52 @@ fn format<'lua>(_: &'lua Lua, items: Vec<FormatItem>) -> mlua::Result<String> {
     String::from_utf8(target.target).map_err(|e| mlua::Error::external(e))
 }
 
+#[derive(Serialize, Deserialize, Debug)]
+struct BatteryInfo {
+    state_of_charge: f32,
+    vendor: String,
+    model: String,
+    state: String,
+    serial: String,
+    time_to_full: Option<f32>,
+    time_to_empty: Option<f32>,
+}
+impl_lua_conversion!(BatteryInfo);
+
+fn opt_string(s: Option<&str>) -> String {
+    match s {
+        Some(s) => s,
+        None => "unknown",
+    }
+    .to_string()
+}
+
+fn battery_info<'lua>(_: &'lua Lua, _: ()) -> mlua::Result<Vec<BatteryInfo>> {
+    use battery::{Manager, State};
+    let manager = Manager::new().map_err(|e| mlua::Error::external(e))?;
+    let mut result = vec![];
+    for b in manager.batteries().map_err(|e| mlua::Error::external(e))? {
+        let bat = b.map_err(|e| mlua::Error::external(e))?;
+        result.push(BatteryInfo {
+            state_of_charge: bat.state_of_charge().value,
+            vendor: opt_string(bat.vendor()),
+            model: opt_string(bat.model()),
+            serial: opt_string(bat.serial_number()),
+            state: match bat.state() {
+                State::Charging => "charging",
+                State::Discharging => "Discharging",
+                State::Empty => "Empty",
+                State::Full => "Full",
+                State::Unknown | _ => "Unknown",
+            }
+            .to_string(),
+            time_to_full: bat.time_to_full().map(|q| q.value),
+            time_to_empty: bat.time_to_empty().map(|q| q.value),
+        })
+    }
+    Ok(result)
+}
+
 async fn sleep_ms<'lua>(_: &'lua Lua, milliseconds: u64) -> mlua::Result<()> {
     let duration = std::time::Duration::from_millis(milliseconds);
     smol::Timer::after(duration).await;