From 27a73171cf97c24c7785787eb7661405334329de Mon Sep 17 00:00:00 2001
From: Profpatsch <mail@profpatsch.de>
Date: Sat, 2 Jan 2021 17:08:27 +0100
Subject: feat(Profpatsch/netencode): add netencode-mustache
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A little executable, combining the netencode and mustache libraries to
make easy templating from the command line possible.

Combined with the nix netencode generators, it’s now trivial to
populate a mustache template with (nearly) arbitrary data.

Yay.

Change-Id: I5b892c38fbc33dd826a26174dd9567f0b72e6322
Reviewed-on: https://cl.tvl.fyi/c/depot/+/2320
Reviewed-by: Profpatsch <mail@profpatsch.de>
Tested-by: BuildkiteCI
---
 users/Profpatsch/netencode/default.nix           | 51 +++++++++++++++++
 users/Profpatsch/netencode/netencode-mustache.rs | 71 ++++++++++++++++++++++++
 users/Profpatsch/netencode/netencode.rs          |  2 +-
 3 files changed, 123 insertions(+), 1 deletion(-)
 create mode 100644 users/Profpatsch/netencode/netencode-mustache.rs

diff --git a/users/Profpatsch/netencode/default.nix b/users/Profpatsch/netencode/default.nix
index 4a06cd700e..80ff73aff5 100644
--- a/users/Profpatsch/netencode/default.nix
+++ b/users/Profpatsch/netencode/default.nix
@@ -40,9 +40,60 @@ let
 
   netencode-rs = netencode-rs-common false;
 
+  gen = import ./netencode.nix;
+
+  cfg-if = pkgs.buildRustCrate {
+    pname = "cfg-if";
+    version = "1.0.0";
+    crateName = "cfg-if";
+    sha256 = "1fzidq152hnxhg4lj6r2gv4jpnn8yivp27z6q6xy7w6v0dp6bai9";
+  };
+
+  log = pkgs.buildRustCrate {
+    pname = "log";
+    version = "0.4.11";
+    crateName = "log";
+    sha256 = "0m6xhqxsps5mgd7r91g5mqkndbh8zbjd58p7w75r330zl4n40l07";
+    dependencies = [ cfg-if ];
+  };
+
+  serde_derive = pkgs.buildRustCrate {
+    pname = "serde";
+    version = "1.0.118";
+    crateName = "serde";
+    sha256 = "1kbi2csphq8m4z77fpd6v8jih10j7867wniqnlxnk308mrnxi4r2";
+  };
+
+  serde = pkgs.buildRustCrate {
+    pname = "serde";
+    version = "1.0.118";
+    crateName = "serde";
+    sha256 = "1kbi2csphq8m4z77fpd6v8jih10j7867wniqnlxnk308mrnxi4r2";
+    features = [ "std" ];
+  };
+
+  mustache = pkgs.buildRustCrate {
+    pname = "mustache";
+    version = "0.9.0";
+    crateName = "mustache";
+    sha256 = "1zgl8l15i19lzp90icgwyi6zqdd31b9vm8w129f41d1zd0hs7ayq";
+    dependencies = [ log serde ];
+  };
+
+  netencode-mustache = imports.writers.rustSimple {
+    name = "netencode_mustache";
+    dependencies = [
+      netencode-rs
+      mustache
+    ];
+  } (builtins.readFile ./netencode-mustache.rs);
+
+
 in {
   inherit
    netencode-rs
    netencode-rs-tests
+   netencode-mustache
+   gen
    ;
 }
diff --git a/users/Profpatsch/netencode/netencode-mustache.rs b/users/Profpatsch/netencode/netencode-mustache.rs
new file mode 100644
index 0000000000..796c7a68d4
--- /dev/null
+++ b/users/Profpatsch/netencode/netencode-mustache.rs
@@ -0,0 +1,71 @@
+extern crate netencode;
+extern crate mustache;
+
+use mustache::{Data};
+use netencode::{T};
+use std::collections::HashMap;
+use std::os::unix::ffi::{OsStrExt};
+use std::io::{Read};
+
+fn arglib_netencode(env: Option<&std::ffi::OsStr>) -> Result<T, String> {
+    let env = match env {
+        None => std::ffi::OsStr::from_bytes("ARGLIB_NETENCODE".as_bytes()),
+        Some(a) => a
+    };
+    match std::env::var_os(env) {
+        None => Err(format!("could not read args, envvar {} not set", env.to_string_lossy())),
+        // TODO: good error handling for the different parser errors
+        Some(soup) => match netencode::parse::t_t(soup.as_bytes()) {
+            Ok((remainder, t)) => match remainder.is_empty() {
+                true => Ok(t),
+                false => Err(format!("there was some unparsed bytes remaining: {:?}", remainder))
+            },
+            Err(err) => Err(format!("parsing error: {:?}", err))
+        }
+    }
+}
+
+
+fn netencode_to_mustache_data_dwim(t: T) -> Data {
+    match t {
+        // TODO: good idea?
+        T::Unit => Data::Null,
+        T::N1(b) => Data::Bool(b),
+        T::N3(u) => Data::String(u.to_string()),
+        T::N6(u) => Data::String(u.to_string()),
+        T::N7(u) => Data::String(u.to_string()),
+        T::I3(i) => Data::String(i.to_string()),
+        T::I6(i) => Data::String(i.to_string()),
+        T::I7(i) => Data::String(i.to_string()),
+        T::Text(s) => Data::String(s),
+        T::Binary(b) => unimplemented!(),
+        T::Sum(tag) => unimplemented!(),
+        T::Record(xs) => Data::Map(
+            xs.into_iter()
+                .map(|(key, val)| (key, netencode_to_mustache_data_dwim(*val)))
+                .collect::<HashMap<_,_>>()
+        ),
+        T::List(xs) => Data::Vec(
+            xs.into_iter()
+                .map(|x| netencode_to_mustache_data_dwim(x))
+                .collect::<Vec<_>>()
+        ),
+    }
+}
+
+pub fn from_stdin() -> () {
+    let data = netencode_to_mustache_data_dwim(
+        arglib_netencode(None).unwrap()
+    );
+    let mut stdin = String::new();
+    std::io::stdin().read_to_string(&mut stdin).unwrap();
+    mustache::compile_str(&stdin)
+        .and_then(|templ| templ.render_data(
+            &mut std::io::stdout(),
+            &data
+        )).unwrap()
+}
+
+pub fn main() {
+    from_stdin()
+}
diff --git a/users/Profpatsch/netencode/netencode.rs b/users/Profpatsch/netencode/netencode.rs
index 57b0a09493..9c999a7cbb 100644
--- a/users/Profpatsch/netencode/netencode.rs
+++ b/users/Profpatsch/netencode/netencode.rs
@@ -338,7 +338,7 @@ pub mod parse {
         ))(s)
     }
 
-    fn t_t(s: &[u8]) -> IResult<&[u8], T>  {
+    pub fn t_t(s: &[u8]) -> IResult<&[u8], T>  {
         alt((
             text,
             binary(),
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