From a4c1595619986938aec698edb5e17286e3839e42 Mon Sep 17 00:00:00 2001
From: Melody Horn / boringcactus <melody@boringcactus.com>
Date: Fri, 18 Jun 2021 16:03:24 -0600
Subject: actually make migrations

---
 Cargo.toml                 |  2 ++
 src/cli/make_migrations.rs | 65 ++++++++++++++++++++++++++++++++++++++++++++--
 2 files changed, 65 insertions(+), 2 deletions(-)

diff --git a/Cargo.toml b/Cargo.toml
index ed90c9c..76282f6 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -10,7 +10,9 @@ edition = "2018"
 barrel = { version = "0.6.5", features = ["sqlite3"] }
 diesel = { version = "1.4.4", features = ["sqlite"] }
 hyper = { version = "0.14", features = ["full"] }
+quote = "1.0"
 structopt = "0.3.21"
+syn = { version = "1.0", features = ["full", "extra-traits"] }
 time = "0.2.27"
 tokio = { version = "1", features = ["full"] }
 tosin-macros = { version = "0.1.0", path = "./tosin-macros" }
diff --git a/src/cli/make_migrations.rs b/src/cli/make_migrations.rs
index 767639f..f4edf94 100644
--- a/src/cli/make_migrations.rs
+++ b/src/cli/make_migrations.rs
@@ -1,5 +1,8 @@
 use std::collections::HashMap;
+use std::fs;
+use std::path::PathBuf;
 
+use quote::{quote, ToTokens};
 use structopt::StructOpt;
 
 use crate::{Settings, UrlMap, db::backend::Connectable};
@@ -21,6 +24,36 @@ struct TableState {
     fields: Vec<Field>,
 }
 
+impl AppTablesState {
+    fn changes_to(self, dest: AppTablesState) -> Vec<impl ToTokens> {
+        let mut result = vec![];
+        for table in dest.db.keys() {
+            if !self.db.contains_key(table) {
+                let fields = &dest.db[table].fields.iter().map(|field| {
+                    match field {
+                        Field::CharField { name, max_length: Some(max_length) } => quote! { Field::CharField { name: #name, max_length: Some(#max_length) } },
+                        Field::CharField { name, max_length: None } => quote! { Field::CharField { name: #name, max_length: None } },
+
+                        Field::DateTimeField { name } => quote! { Field::DateTimeField { name: #name } },
+                        
+                        Field::IntField { name } => quote! { Field::IntField { name: #name } },
+                    }
+                }).collect::<Vec<_>>();
+                result.push(quote! {
+                    DatabaseChange::CreateModel {
+                        name: #table,
+                        fields: &[
+                            #(#fields),*
+                        ],
+                        options: &[],
+                    }
+                });
+            }
+        }
+        result
+    }
+}
+
 impl From<&[ModelMeta]> for AppTablesState {
     fn from(models: &[ModelMeta]) -> Self {
         let mut db = HashMap::new();
@@ -59,8 +92,36 @@ impl MakeMigrations {
         for app in settings.installed_apps {
             let expected_table_state = AppTablesState::from(app.models);
             let actual_table_state = AppTablesState::from(app.migrations);
-            dbg!(expected_table_state, actual_table_state);
-            todo!();
+            let next_id = app.migrations.iter().map(|m| m.id).max().map_or(1, |x| x + 1);
+            let name = "auto"; // TODO names
+            let changes = actual_table_state.changes_to(expected_table_state);
+            if changes.is_empty() { continue; }
+            let migration = quote! {
+                Migration {
+                    id: #next_id,
+                    name: #name,
+                    prereqs: &[], // TODO
+                    changes: &[ #(#changes),* ],
+                }
+            };
+            let file = quote! {
+                use crate::db::migration::Migration;
+
+                pub const MIGRATION: Migration = #migration;
+            };
+            let file_name = format!("m_{:04}_{}.rs", next_id, name);
+            let file_text = file.into_token_stream().to_string();
+            let app_folder = app.name.split("::")
+                .skip(1)
+                .collect::<PathBuf>();
+            // TODO don't explode if running in a weird place
+            let file_path = PathBuf::from("src")
+                .join(app_folder)
+                .join("migrations")
+                .join(file_name);
+            println!("Saving migration to {}...", file_path.display());
+            fs::write(file_path, file_text).unwrap();
+            // TODO cargo fmt
         }
     }
 }
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