From e5a744a3c32ccb4520f934595e317d5737bc008c Mon Sep 17 00:00:00 2001
From: Melody Horn / boringcactus <melody@boringcactus.com>
Date: Fri, 18 Jun 2021 15:18:50 -0600
Subject: correctly gather model info

---
 tosin-macros/src/lib.rs | 57 ++++++++++++++++++++++++++++++++++++++++++++++---
 1 file changed, 54 insertions(+), 3 deletions(-)

(limited to 'tosin-macros')

diff --git a/tosin-macros/src/lib.rs b/tosin-macros/src/lib.rs
index 86750e1..7028274 100644
--- a/tosin-macros/src/lib.rs
+++ b/tosin-macros/src/lib.rs
@@ -2,6 +2,7 @@
 
 extern crate proc_macro;
 
+use std::collections::HashMap;
 use std::fs;
 
 use proc_macro::TokenStream;
@@ -17,14 +18,64 @@ pub fn model_derive(input: TokenStream) -> TokenStream {
     impl_model(&ast)
 }
 
+fn to_field_spec(field: &syn::Field) -> impl quote::ToTokens {
+    fn parse_type(ty: &str) -> syn::Type {
+        syn::parse_str(ty).unwrap()
+    }
+    let field_name = &field.ident;
+    let field_type = &field.ty;
+    let model_options: HashMap<syn::Path, syn::Lit> = field.attrs.iter()
+        .filter_map(|attr| attr.parse_meta().ok())
+        .filter_map(|meta| if let syn::Meta::List(meta) = meta { Some(meta) } else { None })
+        .filter(|meta| meta.path.get_ident().map_or(false, |path| path == "model"))
+        .flat_map(|model| {
+            model.nested.into_iter().filter_map(|item| {
+                if let syn::NestedMeta::Meta(syn::Meta::NameValue(data)) = item {
+                    Some((data.path, data.lit))
+                } else {
+                    None
+                }
+            })
+        })
+        .collect();
+    if field_type == &parse_type("Option<Id>") {
+        quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
+    } else if field_type == &parse_type("Id") {
+        // TODO foreign key constraint
+        quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
+    } else if field_type == &parse_type("usize") {
+        // TODO default
+        quote! { ::tosin::db::models::Field::IntField { name: stringify!(#field_name) } }
+    } 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) } }
+        } else {
+            quote! { ::tosin::db::models::Field::CharField { name: stringify!(#field_name), max_length: None } }
+        }
+    } else if field_type == &parse_type("time::PrimitiveDateTime") {
+        quote! { ::tosin::db::models::Field::DateTimeField { name: stringify!(#field_name) } }
+    } else {
+        use quote::ToTokens;
+        panic!("can't handle {}", field.to_token_stream())
+    }
+}
+
 fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
     let name = &ast.ident;
+    let fields = if let syn::Data::Struct(ast) = &ast.data {
+        ast.fields.iter()
+            .map(to_field_spec)
+    } else {
+        panic!("not on a struct");
+    };
     let gen = quote! {
-        use tosin::db::models::ModelMeta;
         impl #name {
-            pub const META: ModelMeta = ModelMeta {
+            pub const META: ::tosin::db::models::ModelMeta = ::tosin::db::models::ModelMeta {
                 name: stringify!(#name),
-                fields: &[],
+                fields: &[ #(#fields),* ],
             };
         }
     };
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