Streamline configuration

Fixes triggermulti deserialization
Add 'generate-dhall' argument, which generates dhall for the config
enums.

Cargo.lock

@@ -160,6 +160,19 @@ version = "1.0.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
 
+[[package]]
+name = "chrono"
+version = "0.4.19"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "670ad68c9088c2a963aaa298cb369688cf3f9465ce5e2d4ca10e6e0098a1ce73"
+dependencies = [
+ "libc",
+ "num-integer",
+ "num-traits",
+ "time",
+ "winapi",
+]
+
 [[package]]
 name = "concurrent-queue"
 version = "1.2.2"
@@ -667,7 +680,7 @@ checksum = "713d550d9b44d89174e066b7a6217ae06234c10cb47819a88290d2b353c31799"
 dependencies = [
  "libc",
  "log",
- "wasi",
+ "wasi 0.11.0+wasi-snapshot-preview1",
  "windows-sys",
 ]
 
@@ -700,6 +713,25 @@ dependencies = [
  "version_check",
 ]
 
+[[package]]
+name = "num-integer"
+version = "0.1.45"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "225d3389fb3509a24c93f5c29eb6bde2586b98d9f016636dff58d7c6f7569cd9"
+dependencies = [
+ "autocfg",
+ "num-traits",
+]
+
+[[package]]
+name = "num-traits"
+version = "0.2.15"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "578ede34cf02f8924ab9447f50c28075b4d3e5b269972345e7e0372b38c6cdcd"
+dependencies = [
+ "autocfg",
+]
+
 [[package]]
 name = "num_cpus"
 version = "1.13.1"
@@ -1019,6 +1051,7 @@ name = "sampad"
 version = "0.1.0"
 dependencies = [
  "bitvec",
+ "chrono",
  "hidapi",
  "rumqttc",
  "serde",
@@ -1270,6 +1303,17 @@ dependencies = [
  "once_cell",
 ]
 
+[[package]]
+name = "time"
+version = "0.1.44"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "6db9e6914ab8b1ae1c260a4ae7a49b6c5611b40328a735b21862567685e73255"
+dependencies = [
+ "libc",
+ "wasi 0.10.0+wasi-snapshot-preview1",
+ "winapi",
+]
+
 [[package]]
 name = "tinyvec"
 version = "1.6.0"
@@ -1510,6 +1554,12 @@ dependencies = [
  "try-lock",
 ]
 
+[[package]]
+name = "wasi"
+version = "0.10.0+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "1a143597ca7c7793eff794def352d41792a93c481eb1042423ff7ff72ba2c31f"
+
 [[package]]
 name = "wasi"
 version = "0.11.0+wasi-snapshot-preview1"

Cargo.toml

@@ -11,3 +11,4 @@ serde = "1"
 serde_dhall = "0.11"
 tracing = "0.1.35"
 tracing-subscriber = "0.3.14"
+chrono = "0.4.19"

build.rs

@@ -0,0 +1,13 @@
+use std::error::Error;
+use std::process::Command;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let hash = Command::new("git")
+        .arg("rev-parse")
+        .arg("--short")
+        .arg("HEAD")
+        .output()?
+        .stdout;
+    println!("cargo:rustc-env=VERSION={}", std::str::from_utf8(&hash)?);
+    Ok(())
+}

src/config.rs

@@ -1,5 +1,7 @@
+use crate::StdError;
+use chrono::Utc;
 use serde::Deserialize;
-use serde_dhall::StaticType;
+use serde_dhall::{SimpleType, StaticType};
 use std::collections::HashMap;
 use std::error::Error;
 use std::fmt;
@@ -24,7 +26,11 @@ impl fmt::Display for Action {
     }
 }
 
-#[derive(Deserialize, StaticType, Debug)]
+// Newtype wrapper around a Vec of actions.
+// serde(transparent) and the imp StaticType below ensures we ignore the outer struct and
+// transparently deserialize into the inner vec.
+#[derive(Deserialize, Debug)]
+#[serde(transparent)]
 pub struct Actions(Vec<Action>);
 
 impl Actions {
@@ -40,6 +46,12 @@ impl fmt::Display for Actions {
     }
 }
 
+impl StaticType for Actions {
+    fn static_type() -> SimpleType {
+        SimpleType::List(Box::new(Action::static_type()))
+    }
+}
+
 #[derive(Deserialize, StaticType, Debug)]
 pub enum Mapping {
     NOP,                   // Do nothing.
@@ -87,16 +99,25 @@ pub struct Config {
 
 impl Config {
     pub fn from_file(p: &Path) -> Result<Self, Box<dyn Error>> {
-        match serde_dhall::from_file(p)
+        serde_dhall::from_file(p)
-            .with_builtin_type("Mapping".to_string(), Mapping::static_type())
-            .with_builtin_type("Action".to_string(), Action::static_type())
             .parse::<Self>()
-        {
+            .map_err(|e| e.into())
-            Ok(c) => Ok(c),
-            Err(e) => {
-                println!("{}", e);
-                Err(Box::new(e))
-            }
     }
+
+    pub fn generate_prelude() -> StdError<()> {
+        let mut m = HashMap::new();
+        m.insert("Action".to_string(), Action::static_type());
+        m.insert("Mapping".to_string(), Mapping::static_type());
+        println!(
+            "-- Sampad Dhall types, autogenerated by git#{} on {}",
+            option_env!("VERSION").unwrap_or("unknown"),
+            Utc::now(),
+        );
+        println!(
+            "{{ Action = {}, Mapping = {} }}",
+            Action::static_type(),
+            Mapping::static_type()
+        );
+        Ok(())
     }
 }

src/main.rs

@@ -5,11 +5,14 @@ use config::{Action, Config, Mapping};
 use hidapi::HidApi;
 use rumqttc::{Client, MqttOptions, QoS};
 use std::collections::HashMap;
+use std::env;
 use std::error::Error;
 use std::path::Path;
 use std::thread;
 use tracing::{event, Level};
 
+type StdError<T> = Result<T, Box<dyn Error>>;
+
 struct State<'a> {
     mqtt_servers: HashMap<String, Client>,
     conf: &'a Config,
@@ -107,7 +110,19 @@ impl<'a> State<'a> {
     }
 }
 
-fn main() -> Result<(), Box<dyn Error>> {
+fn main() -> StdError<()> {
+    let args: Vec<_> = env::args().collect();
+    if let [prog, args @ ..] = &args[..] {
+        if args == ["generate-dhall"] {
+            return Config::generate_prelude();
+        } else if args.len() > 0 {
+            eprintln!("Usage: {} [generate-dhall]", prog);
+            return Err("Invalid usage".into());
+        }
+    } else {
+        unreachable!();
+    }
+
     tracing_subscriber::fmt::init();
     event!(Level::INFO, "Starting...");
     let conf = Config::from_file(Path::new("./config.dhall"))?;

types.dhall

@@ -0,0 +1,22 @@
+-- Sampad Dhall types, autogenerated by git#96d9ca3 on 2022-07-11 13:54:53.099283885 UTC
+{ Action =
+    < ActivateLayer : Text
+    | MQTTPub : { payload : Text, topic : Text }
+    | Print : Text
+    >
+, Mapping =
+    < NOP
+    | Passthrough
+    | Trigger :
+        < ActivateLayer : Text
+        | MQTTPub : { payload : Text, topic : Text }
+        | Print : Text
+        >
+    | TriggerMulti :
+        List
+          < ActivateLayer : Text
+          | MQTTPub : { payload : Text, topic : Text }
+          | Print : Text
+          >
+    >
+}