From 8852f0b7090c612f1d04a60becb55bbe56441eda Mon Sep 17 00:00:00 2001
From: Melody Horn / boringcactus <melody@boringcactus.com>
Date: Wed, 23 Jun 2021 21:07:56 -0600
Subject: start impling diesel::Queryable for Models

---
 tosin-macros/src/lib.rs | 97 +++++++++++++++++++++++++++++++++++--------------
 1 file changed, 70 insertions(+), 27 deletions(-)

(limited to 'tosin-macros/src')

diff --git a/tosin-macros/src/lib.rs b/tosin-macros/src/lib.rs
index c9e352c..131888c 100644
--- a/tosin-macros/src/lib.rs
+++ b/tosin-macros/src/lib.rs
@@ -18,9 +18,35 @@ pub fn model_derive(input: TokenStream) -> TokenStream {
     impl_model(&ast)
 }
 
-// TODO clean all this shit up
+struct FieldInfo<T: quote::ToTokens> {
+    tosin_field: T,
+    diesel_column: T,
+    diesel_type: T,
+}
+
+struct FieldsInfo<T: quote::ToTokens> {
+    tosin_fields: Vec<T>,
+    diesel_columns: Vec<T>,
+    diesel_types: Vec<T>,
+}
 
-fn to_field_spec(field: &syn::Field) -> (impl quote::ToTokens, impl quote::ToTokens) {
+impl<T: quote::ToTokens> std::iter::FromIterator<FieldInfo<T>> for FieldsInfo<T> {
+    fn from_iter<I: IntoIterator<Item=FieldInfo<T>>>(iter: I) -> Self {
+        let mut result = Self {
+            tosin_fields: vec![],
+            diesel_columns: vec![],
+            diesel_types: vec![],
+        };
+        for info in iter {
+            result.tosin_fields.push(info.tosin_field);
+            result.diesel_columns.push(info.diesel_column);
+            result.diesel_types.push(info.diesel_type);
+        }
+        result
+    }
+}
+
+fn to_field_spec(field: &syn::Field) -> FieldInfo<impl quote::ToTokens> {
     fn parse_type(ty: &str) -> syn::Type {
         syn::parse_str(ty).unwrap()
     }
@@ -41,42 +67,48 @@ fn to_field_spec(field: &syn::Field) -> (impl quote::ToTokens, impl quote::ToTok
         })
         .collect();
     if field_type == &parse_type("Option<Id>") {
-        ( 
-            quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
-            quote! { #field_name -> Integer }
-        )
+        FieldInfo {
+            tosin_field: quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
+            diesel_column: quote! { #field_name -> Integer },
+            diesel_type: quote! { ::tosin::db::sql_types::Integer },
+        }
     } else if field_type == &parse_type("Id") {
         // TODO foreign key constraint
-        ( 
-            quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
-            quote! { #field_name -> Integer }
-        )
+        FieldInfo {
+            tosin_field: quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
+            diesel_column: quote! { #field_name -> Integer },
+            diesel_type: quote! { ::tosin::db::sql_types::Integer },
+        }
     } else if field_type == &parse_type("usize") {
         // TODO default
-        ( 
-            quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
-            quote! { #field_name -> Integer }
-        )
+        FieldInfo {
+            tosin_field: quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } },
+            diesel_column: quote! { #field_name -> Integer },
+            diesel_type: quote! { ::tosin::db::sql_types::Integer },
+        }
     } else if field_type == &parse_type("String") {
         let max_length = model_options.iter()
             .find(|(name, _value)| name.get_ident().map_or(false, |path| path == "max_length"))
             .map(|(_name, value)| value);
         if let Some(max_length) = max_length {
-            (
-                quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: Some(#max_length) } },
-                quote! { #field_name -> Text }
-            )
+            FieldInfo {
+                tosin_field: quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: Some(#max_length) } },
+                diesel_column: quote! { #field_name -> Text },
+                diesel_type: quote! { ::tosin::db::sql_types::Text }
+            }
         } else {
-            (
-                quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: None } },
-                quote! { #field_name -> Text }
-            )
+            FieldInfo {
+                tosin_field: quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: None } },
+                diesel_column: quote! { #field_name -> Text },
+                diesel_type: quote! { ::tosin::db::sql_types::Text }
+            }
         }
     } else if field_type == &parse_type("time::PrimitiveDateTime") {
-        (
-            quote! { ::tosin::db::models::Field::DateTimeField { name: stringify!(#field_name) } },
-            quote! { #field_name -> Timestamp }
-        )
+        FieldInfo {
+            tosin_field: quote! { ::tosin::db::models::Field::DateTimeField { name: stringify!(#field_name) } },
+            diesel_column: quote! { #field_name -> Timestamp },
+            diesel_type: quote! { ::tosin::db::sql_types::Timestamp }
+        }
     } else {
         use quote::ToTokens;
         panic!("can't handle {}", field.to_token_stream())
@@ -91,7 +123,8 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
     } else {
         panic!("not on a struct");
     };
-    let (tosin_fields, diesel_columns): (Vec<_>, Vec<_>) = ast_data.fields.iter().map(to_field_spec).unzip();
+    let real_types: Vec<_> = ast_data.fields.iter().map(|field| &field.ty).collect();
+    let FieldsInfo { tosin_fields, diesel_columns, diesel_types } = ast_data.fields.iter().map(to_field_spec).collect();
     let gen = quote! {
         impl #name {
             pub const META: ::tosin::db::models::ModelMeta = ::tosin::db::models::ModelMeta {
@@ -100,6 +133,16 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
             };
         }
 
+        impl<__DB: tosin::db::diesel_backend::Backend, __ST> tosin::db::Queryable<__ST, __DB> for #name
+        where (#(#real_types),*): tosin::db::Queryable<__ST, __DB> {
+            type Row = <(#(#real_types),*) as tosin::db::Queryable<__ST, __DB>>::Row;
+
+            fn build(row: Self::Row) -> Self {
+                let row: (#(#real_types),*) = tosin::db::Queryable::build(row);
+                todo!()
+            }
+        }
+
         // this means users need #[macro_use] extern crate diesel; but fuck doing it ourselves
         table! {
             #lowercase_name {
-- 
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