From 6f85995379286b583daa3bcc8c469b29b8b32f83 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Thu, 27 Apr 2023 20:34:46 +0200
Subject: [PATCH] Derive Document for simple enums

---
 cove-config/src/doc.rs     |  2 +-
 cove-config/src/euph.rs    | 18 +++---------------
 cove-macro/src/document.rs | 39 +++++++++++++++++++++++++++++++-------
 3 files changed, 36 insertions(+), 23 deletions(-)

diff --git a/cove-config/src/doc.rs b/cove-config/src/doc.rs
index da27b89..2149b77 100644
--- a/cove-config/src/doc.rs
+++ b/cove-config/src/doc.rs
@@ -7,7 +7,7 @@ use cove_input::KeyBinding;
 pub use cove_macro::Document;
 use serde::Serialize;
 
-pub(crate) fn toml_value_as_markdown<T: Serialize>(value: &T) -> String {
+pub fn toml_value_as_markdown<T: Serialize>(value: &T) -> String {
     let mut result = String::new();
     value
         .serialize(toml::ser::ValueSerializer::new(&mut result))
diff --git a/cove-config/src/euph.rs b/cove-config/src/euph.rs
index d2fa84a..0584933 100644
--- a/cove-config/src/euph.rs
+++ b/cove-config/src/euph.rs
@@ -1,10 +1,10 @@
 use std::collections::HashMap;
 
-use serde::Deserialize;
+use serde::{Deserialize, Serialize};
 
-use crate::doc::{Doc, Document};
+use crate::doc::Document;
 
-#[derive(Debug, Clone, Copy, Default, Deserialize)]
+#[derive(Debug, Clone, Copy, Default, Serialize, Deserialize, Document)]
 #[serde(rename_all = "snake_case")]
 pub enum RoomsSortOrder {
     #[default]
@@ -12,18 +12,6 @@ pub enum RoomsSortOrder {
     Importance,
 }
 
-impl Document for RoomsSortOrder {
-    fn doc() -> Doc {
-        let mut doc = String::doc();
-        doc.value_info.values = Some(vec![
-            // TODO Generate by serializing
-            "`alphabet`".to_string(),
-            "`importance`".to_string(),
-        ]);
-        doc
-    }
-}
-
 // TODO Mark favourite rooms via printable ascii characters
 #[derive(Debug, Clone, Default, Deserialize, Document)]
 pub struct EuphRoom {
diff --git a/cove-macro/src/document.rs b/cove-macro/src/document.rs
index e6845d2..75a0cfc 100644
--- a/cove-macro/src/document.rs
+++ b/cove-macro/src/document.rs
@@ -1,7 +1,7 @@
 use proc_macro2::TokenStream;
 use quote::quote;
 use syn::spanned::Spanned;
-use syn::{Data, DeriveInput, ExprPath, Field, LitStr, Type};
+use syn::{Data, DataEnum, DataStruct, DeriveInput, ExprPath, Field, Ident, LitStr, Type};
 
 use crate::util::{self, docstring};
 
@@ -75,11 +75,7 @@ impl FieldInfo {
     }
 }
 
-pub fn derive_impl(input: DeriveInput) -> syn::Result<TokenStream> {
-    let Data::Struct(data) = input.data else {
-        return Err(syn::Error::new(input.span(), "must be a struct"));
-    };
-
+fn from_struct(ident: Ident, data: DataStruct) -> syn::Result<TokenStream> {
     let mut fields = vec![];
     for field in data.fields {
         let Some(ident) = field.ident.as_ref() else {
@@ -129,7 +125,6 @@ pub fn derive_impl(input: DeriveInput) -> syn::Result<TokenStream> {
         });
     }
 
-    let ident = input.ident;
     let tokens = quote!(
         impl crate::doc::Document for #ident {
             fn doc() -> crate::doc::Doc {
@@ -145,3 +140,33 @@ pub fn derive_impl(input: DeriveInput) -> syn::Result<TokenStream> {
 
     Ok(tokens)
 }
+
+fn from_enum(ident: Ident, data: DataEnum) -> syn::Result<TokenStream> {
+    let mut values = vec![];
+    for variant in data.variants {
+        let ident = variant.ident;
+        values.push(quote! {
+            crate::doc::toml_value_as_markdown(&Self::#ident)
+        });
+    }
+
+    let tokens = quote!(
+        impl crate::doc::Document for #ident {
+            fn doc() -> crate::doc::Doc {
+                let mut doc = <String as crate::doc::Document>::doc();
+                doc.value_info.values = Some(vec![ #( #values ),* ]);
+                doc
+            }
+        }
+    );
+
+    Ok(tokens)
+}
+
+pub fn derive_impl(input: DeriveInput) -> syn::Result<TokenStream> {
+    match input.data {
+        Data::Struct(data) => from_struct(input.ident, data),
+        Data::Enum(data) => from_enum(input.ident, data),
+        Data::Union(_) => util::bail(input.span(), "must be an enum or a struct"),
+    }
+}