lay groundwork for make-migrations

1 files changed, 66 insertions, 0 deletions

diff --git a/src/cli/make_migrations.rs b/src/cli/make_migrations.rs
new file mode 100644
index 0000000..767639f
--- /dev/null
+++ b/src/cli/make_migrations.rs
@@ -0,0 +1,66 @@
+use std::collections::HashMap;
+
+use structopt::StructOpt;
+
+use crate::{Settings, UrlMap, db::backend::Connectable};
+use crate::db::migration::{Migration, DatabaseChange, CreateModelOption};
+use crate::db::models::{Field, ModelMeta};
+
+#[derive(StructOpt)]
+/// Generate migrations
+pub struct MakeMigrations {
+}
+
+#[derive(Debug)]
+struct AppTablesState {
+    db: HashMap<&'static str, TableState>,
+}
+
+#[derive(Debug)]
+struct TableState {
+    fields: Vec<Field>,
+}
+
+impl From<&[ModelMeta]> for AppTablesState {
+    fn from(models: &[ModelMeta]) -> Self {
+        let mut db = HashMap::new();
+        for model in models {
+            db.insert(model.name, TableState { fields: model.fields.into() });
+        }
+        Self { db }
+    }
+}
+
+impl From<&[Migration]> for AppTablesState {
+    fn from(migrations: &[Migration]) -> Self {
+        let mut db = HashMap::new();
+        for migration in migrations {
+            for change in migration.changes {
+                match change {
+                    DatabaseChange::CreateModel { name, fields, options } => {
+                        if db.contains_key(name) {
+                            if options.contains(&CreateModelOption::IfNotExist) {
+                                continue;
+                            } else {
+                                panic!("double-created table {}", name);
+                            }
+                        }
+                        db.insert(*name, TableState { fields: (*fields).into() });
+                    }
+                }
+            }
+        }
+        Self { db }
+    }
+}
+
+impl MakeMigrations {
+    pub fn execute(self, _urls: UrlMap, settings: Settings<impl Connectable>) {
+        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!();
+        }
+    }
+}