From 92bf14bb7cc0c10f67a9a67e7512138c15db6ec0 Mon Sep 17 00:00:00 2001
From: Melody Horn / boringcactus <melody@boringcactus.com>
Date: Mon, 14 Jun 2021 20:54:57 -0600
Subject: start working on migrations

---
 README.md                                      |  5 +++++
 src/apps.rs                                    |  4 +++-
 src/contrib/admin/migrations/m_0001_initial.rs | 10 +++++++++
 src/contrib/admin/migrations/mod.rs            |  3 +++
 src/contrib/admin/mod.rs                       |  3 ++-
 src/db/migration/mod.rs                        | 12 ++++++++++
 src/db/mod.rs                                  |  1 +
 tosin-macros/Cargo.toml                        |  2 +-
 tosin-macros/src/lib.rs                        | 31 ++++++++++++++++++++++++++
 9 files changed, 68 insertions(+), 3 deletions(-)
 create mode 100644 src/contrib/admin/migrations/m_0001_initial.rs
 create mode 100644 src/contrib/admin/migrations/mod.rs
 create mode 100644 src/db/migration/mod.rs

diff --git a/README.md b/README.md
index 870d4e4..8834f67 100644
--- a/README.md
+++ b/README.md
@@ -6,6 +6,11 @@ it's like Django, but for Rust.
 
 painfully WIP, not usable.
 
+## stable rust pls
+
+needs [proc_macro_span](https://github.com/rust-lang/rust/issues/54725) (or at least `SourceFile`) stabilized before it'll work on stable Rust.
+that could probably be worked around with a build script, but i do not want to do that.
+
 ## name
 
 Django is named after a guitarist that one of the original developers liked, so i've named Tosin similarly.
diff --git a/src/apps.rs b/src/apps.rs
index 26c6124..785ce8c 100644
--- a/src/apps.rs
+++ b/src/apps.rs
@@ -1,3 +1,5 @@
-pub struct AppConfig {
+use crate::db::migration::Migration;
 
+pub struct AppConfig {
+    pub migrations: &'static [Migration],
 }
diff --git a/src/contrib/admin/migrations/m_0001_initial.rs b/src/contrib/admin/migrations/m_0001_initial.rs
new file mode 100644
index 0000000..6fed631
--- /dev/null
+++ b/src/contrib/admin/migrations/m_0001_initial.rs
@@ -0,0 +1,10 @@
+use crate::db::migration::{Migration, DatabaseChange};
+
+pub const MIGRATION: Migration = Migration {
+    id: 1,
+    name: "initial",
+    prereqs: &[],
+    changes: &[
+        DatabaseChange::CreateModel,
+    ],
+};
diff --git a/src/contrib/admin/migrations/mod.rs b/src/contrib/admin/migrations/mod.rs
new file mode 100644
index 0000000..5ecbb82
--- /dev/null
+++ b/src/contrib/admin/migrations/mod.rs
@@ -0,0 +1,3 @@
+use crate::db::migration::{Migration, gather};
+
+gather!();
diff --git a/src/contrib/admin/mod.rs b/src/contrib/admin/mod.rs
index 0f7e880..5098a4a 100644
--- a/src/contrib/admin/mod.rs
+++ b/src/contrib/admin/mod.rs
@@ -1,7 +1,8 @@
 use crate::apps::AppConfig;
 
+mod migrations;
 pub mod site;
 
 pub const APP: AppConfig = AppConfig {
-
+    migrations: migrations::migrations,
 };
diff --git a/src/db/migration/mod.rs b/src/db/migration/mod.rs
new file mode 100644
index 0000000..d53f46b
--- /dev/null
+++ b/src/db/migration/mod.rs
@@ -0,0 +1,12 @@
+pub use tosin_macros::gather_migrations as gather;
+
+pub struct Migration {
+    pub id: usize,
+    pub name: &'static str,
+    pub prereqs: &'static [(&'static str, usize)],
+    pub changes: &'static [DatabaseChange],
+}
+
+pub enum DatabaseChange {
+    CreateModel,
+}
diff --git a/src/db/mod.rs b/src/db/mod.rs
index b6528f5..05c38df 100644
--- a/src/db/mod.rs
+++ b/src/db/mod.rs
@@ -1,2 +1,3 @@
 pub mod backend;
+pub mod migration;
 pub mod models;
diff --git a/tosin-macros/Cargo.toml b/tosin-macros/Cargo.toml
index 4a58a20..836461c 100644
--- a/tosin-macros/Cargo.toml
+++ b/tosin-macros/Cargo.toml
@@ -10,5 +10,5 @@ edition = "2018"
 proc-macro = true
 
 [dependencies]
-syn = "1.0"
+syn = { version = "1.0", features = ["full", "extra-traits"] }
 quote = "1.0"
diff --git a/tosin-macros/src/lib.rs b/tosin-macros/src/lib.rs
index c0651fa..7efbac6 100644
--- a/tosin-macros/src/lib.rs
+++ b/tosin-macros/src/lib.rs
@@ -1,3 +1,5 @@
+#![feature(proc_macro_span)]
+
 extern crate proc_macro;
 
 use proc_macro::TokenStream;
@@ -24,3 +26,32 @@ fn impl_model(ast: &syn::DeriveInput) -> TokenStream {
     };
     gen.into()
 }
+
+#[proc_macro]
+pub fn gather_migrations(_input: TokenStream) -> TokenStream {
+    let call_site = proc_macro::Span::call_site();
+    let call_site_file = call_site.source_file();
+    let call_site_path = call_site_file.path();
+    if !call_site_file.is_real() {
+        panic!("call site does not have a real path");
+    }
+
+    let migrations_dir = call_site_path.parent().unwrap();
+    let migrations: Vec<syn::Ident> = migrations_dir.read_dir()
+        .unwrap()
+        .map(Result::unwrap)
+        .map(|x| x.path().file_stem().unwrap().to_string_lossy().into_owned())
+        .filter(|x| x != "mod")
+        .map(|x| syn::parse_str(&x).unwrap())
+        .collect();
+
+    let gen = quote! {
+        #( mod #migrations; )*
+
+        pub const migrations: &[Migration] = &[
+            #(#migrations::MIGRATION),*
+        ];
+    };
+
+    gen.into()
+}
-- 
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