From 1586b05bbd72a3896113f3613717549452242fa9 Mon Sep 17 00:00:00 2001
From: Sayan Nandan <nandansayan@outlook.com>
Date: Sun, 2 Apr 2023 08:31:24 -0700
Subject: [PATCH] Add `drop model` exec without advanced params

---
 server/src/engine/core/model/mod.rs       | 20 ++++++++++++++++++++
 server/src/engine/core/tests/model/alt.rs | 19 +++++++++++++++++--
 server/src/engine/error.rs                |  2 ++
 3 files changed, 39 insertions(+), 2 deletions(-)

diff --git a/server/src/engine/core/model/mod.rs b/server/src/engine/core/model/mod.rs
index 5aecd4f8..d30daa6e 100644
--- a/server/src/engine/core/model/mod.rs
+++ b/server/src/engine/core/model/mod.rs
@@ -42,6 +42,7 @@ use {
         mem::VInline,
         ql::ddl::{
             crt::CreateModel,
+            drop::DropModel,
             syn::{FieldSpec, LayerSpec},
         },
     },
@@ -105,6 +106,10 @@ impl ModelView {
             Ok(())
         }
     }
+    pub fn is_empty_atomic(&self) -> bool {
+        // TODO(@ohsayan): change this!
+        true
+    }
 }
 
 impl ModelView {
@@ -167,6 +172,21 @@ impl ModelView {
         };
         space._create_model(ItemID::new(model_name.as_str()), model)
     }
+    pub fn exec_drop(gns: &super::GlobalNS, stmt: DropModel) -> DatabaseResult<()> {
+        let Some((space, model)) = stmt.entity.into_full() else {
+            return Err(DatabaseError::ExpectedEntity);
+        };
+        let spaces = gns.spaces().read();
+        let Some(space) =  spaces.st_get(space.as_bytes()) else {
+            return Err(DatabaseError::DdlSpaceNotFound);
+        };
+        let mut w_space = space.models().write();
+        match w_space.st_delete_if(model.as_bytes(), |mdl| !mdl.is_empty_atomic()) {
+            Some(true) => Ok(()),
+            Some(false) => Err(DatabaseError::DdlModelViewNotEmpty),
+            None => Err(DatabaseError::DdlModelNotFound),
+        }
+    }
 }
 
 /*
diff --git a/server/src/engine/core/tests/model/alt.rs b/server/src/engine/core/tests/model/alt.rs
index 482a1eb2..efac130b 100644
--- a/server/src/engine/core/tests/model/alt.rs
+++ b/server/src/engine/core/tests/model/alt.rs
@@ -343,9 +343,9 @@ mod plan {
 }
 
 mod exec {
-    use crate::engine::{core::GlobalNS, idx::STIndex};
+    use crate::engine::{core::GlobalNS, error::DatabaseError, idx::STIndex};
     #[test]
-    fn exec_simple_alter() {
+    fn simple_alter() {
         let gns = GlobalNS::empty();
         super::exec_plan(
             &gns,
@@ -359,4 +359,19 @@ mod exec {
         )
         .unwrap();
     }
+    #[test]
+    fn failing_alter_nullable_switch_need_lock() {
+        let gns = GlobalNS::empty();
+        assert_eq!(
+            super::exec_plan(
+                &gns,
+                true,
+                "create model myspace.mymodel(username: string, null gh_handle: string)",
+                "alter model myspace.mymodel update gh_handle { nullable: false }",
+                |_| {},
+            )
+            .unwrap_err(),
+            DatabaseError::NeedLock
+        );
+    }
 }
diff --git a/server/src/engine/error.rs b/server/src/engine/error.rs
index e7858e62..0c4ffb81 100644
--- a/server/src/engine/error.rs
+++ b/server/src/engine/error.rs
@@ -117,4 +117,6 @@ pub enum DatabaseError {
     DdlModelAlterBadTypedef,
     /// didn't find the model
     DdlModelNotFound,
+    /// attempted a remove, but the model view is nonempty
+    DdlModelViewNotEmpty,
 }