From 5506149efc190cef14961b523db182c8dd99a937 Mon Sep 17 00:00:00 2001
From: Pierre Hubert <pierre.git@communiquons.org>
Date: Sat, 5 Aug 2023 12:10:23 +0200
Subject: [PATCH] Add loop protection

---
 .../src/controllers/members_controller.rs     | 14 ++++
 geneit_backend/src/models.rs                  |  2 +-
 .../src/services/members_service.rs           | 83 +++++++++++++++++++
 3 files changed, 98 insertions(+), 1 deletion(-)

diff --git a/geneit_backend/src/controllers/members_controller.rs b/geneit_backend/src/controllers/members_controller.rs
index 1f83427..dafab9f 100644
--- a/geneit_backend/src/controllers/members_controller.rs
+++ b/geneit_backend/src/controllers/members_controller.rs
@@ -262,6 +262,20 @@ pub async fn update(m: FamilyAndMemberInPath, req: web::Json<MemberRequest>) ->
         return Ok(HttpResponse::BadRequest().body(e.to_string()));
     }
 
+    // Check for potential loops
+    let members = members_service::get_all_of_family(member.family_id()).await?;
+    let mut members_ref = Vec::with_capacity(members.len());
+    members_ref.push(&member);
+    for m in &members {
+        if m.id() != member.id() {
+            members_ref.push(m);
+        }
+    }
+    if members_service::loop_detection::detect_loop(&members_ref) {
+        log::warn!("Membership update rejected due to detected loop!");
+        return Ok(HttpResponse::NotAcceptable().json("Loop detected!"));
+    }
+
     members_service::update(&mut member).await?;
 
     Ok(HttpResponse::Accepted().finish())
diff --git a/geneit_backend/src/models.rs b/geneit_backend/src/models.rs
index 7532a90..f31bc62 100644
--- a/geneit_backend/src/models.rs
+++ b/geneit_backend/src/models.rs
@@ -118,7 +118,7 @@ pub struct FamilyMembership {
 }
 
 /// Member ID holder
-#[derive(Debug, Clone, Copy, serde::Serialize, serde::Deserialize)]
+#[derive(Debug, Clone, Copy, serde::Serialize, serde::Deserialize, Eq, PartialEq, Hash)]
 pub struct MemberID(pub i32);
 
 #[derive(serde::Serialize, serde::Deserialize)]
diff --git a/geneit_backend/src/services/members_service.rs b/geneit_backend/src/services/members_service.rs
index 63c0de8..59214eb 100644
--- a/geneit_backend/src/services/members_service.rs
+++ b/geneit_backend/src/services/members_service.rs
@@ -106,3 +106,86 @@ pub async fn delete_all_family(family_id: FamilyID) -> anyhow::Result<()> {
     }
     Ok(())
 }
+
+pub mod loop_detection {
+    use crate::models::{Member, MemberID};
+    use std::collections::HashMap;
+
+    #[derive(Debug)]
+    struct LoopStack<'a> {
+        curr: MemberID,
+        prev: Option<&'a LoopStack<'a>>,
+    }
+
+    impl<'a> LoopStack<'a> {
+        pub fn contains(&self, id: MemberID) -> bool {
+            if let Some(ls) = &self.prev {
+                if ls.contains(id) {
+                    return true;
+                }
+            }
+
+            self.curr == id
+        }
+    }
+
+    fn detect_loop_control(
+        members: &HashMap<MemberID, &&Member>,
+        curr_stack: &LoopStack,
+        next: Option<MemberID>,
+    ) -> bool {
+        match next {
+            None => false,
+            Some(id) => {
+                if curr_stack.contains(id) {
+                    log::debug!("Loop detected! {:?}", curr_stack);
+                    return true;
+                }
+
+                detect_loop_recurse(
+                    members,
+                    &LoopStack {
+                        curr: id,
+                        prev: Some(curr_stack),
+                    },
+                )
+            }
+        }
+    }
+
+    /// Recurse loop detection
+    fn detect_loop_recurse(members: &HashMap<MemberID, &&Member>, curr_stack: &LoopStack) -> bool {
+        let member = match members.get(&curr_stack.curr) {
+            Some(m) => m,
+            None => {
+                log::warn!("Member {:?} not found in the tree for loop detection, this should never happen!", curr_stack.curr);
+                return false;
+            }
+        };
+
+        detect_loop_control(members, curr_stack, member.mother())
+            || detect_loop_control(members, curr_stack, member.father())
+    }
+
+    /// Detect loops in members hierarchy
+    pub fn detect_loop(members: &[&Member]) -> bool {
+        let mut map = HashMap::new();
+        for m in members {
+            map.insert(m.id(), m);
+        }
+
+        for m in members {
+            if detect_loop_recurse(
+                &map,
+                &LoopStack {
+                    curr: m.id(),
+                    prev: None,
+                },
+            ) {
+                return true;
+            }
+        }
+
+        false
+    }
+}