Added a mutation to edit specific member details

docs/mutations.md

@@ -2,6 +2,7 @@
 
 ## Contents
 - [addMember](#addmember)
+- [editMember](#editmember)
 - [markAttendance](#markattendance)
 - [addAttendance](#addattendance)
 
@@ -41,6 +42,58 @@ discordId: String
 
 ---
 
+### editMember
+Edit details of an existing member.
+
+#### GraphQL Mutation
+```graphql
+mutation {
+    editMember(id:0,hostel:"hostel",year:2,macaddress:"mac_address",discordId:"discord_id",hmacSignature:"hmac_signature") {
+    id
+    hostel
+    discord_id
+    }
+}
+```
+
+#### Arguments (all required)
+```graphql
+id: Int!
+hostel: String!
+year: Int!
+macaddress: String!
+discordId: String!
+hmacSignature: String!
+```
+
+**Note:** Follow the below format if you want to leave some fields unchanged
+- `''` (*empty string*) for type `String`
+    - Feilds: `hostel,macaddress,discordId`
+- `0` for type `Int`
+    - Feilds: `year`
+
+For example, If you want to update only `discordId`:
+
+```graphql
+mutation {
+    editMember(id:1,hostel:"",year:0,macaddress:"",discordId:"discord_id",hmacSignature:"hmac_signature") {
+        id
+        hostel
+        discord_id
+    }
+}
+```
+
+Note: `id` and `hmacSignature` can't be empty
+
+#### HMAC Format
+
+```
+"{secret_key}{id}{hostel}{year}{macaddress}{discord_id}"
+```
+
+---
+
 ### markAttendance
 Record attendance for a member.
 

src/graphql/mutations.rs

@@ -53,6 +53,60 @@ impl MutationRoot {
         Ok(member)
     }
 
+    async fn edit_member(
+        &self,
+        ctx: &Context<'_>,
+        id: i32,
+        hostel: String,
+        year: i32,
+        macaddress: String,
+        discord_id: String,
+        hmac_signature: String,
+    ) -> Result<Member,sqlx::Error> {
+        let pool = ctx.data::<Arc<PgPool>>().expect("Pool not found in context");
+
+        let secret_key = ctx.data::<String>().expect("HMAC secret not found in context");
+
+        let mut mac = HmacSha256::new_from_slice(secret_key.as_bytes()).expect("HMAC can take key of any size");
+
+        let message = format!("{}{}{}{}{}", id, hostel, year, macaddress, discord_id);
+        mac.update(message.as_bytes());
+
+        let expected_signature = mac.finalize().into_bytes();
+
+        // Convert the received HMAC signature from the client to bytes for comparison
+        let received_signature = hex::decode(hmac_signature)
+            .map_err(|_| sqlx::Error::Protocol("Invalid HMAC signature".into()))?;
+
+
+        if expected_signature.as_slice() != received_signature.as_slice() {
+
+            return Err(sqlx::Error::Protocol("HMAC verification failed".into()));
+        }
+
+        let member = sqlx::query_as::<_, Member>(
+            "
+            UPDATE Member
+            SET
+                hostel = CASE WHEN $1 = '' THEN hostel ELSE $1 END,
+                year = CASE WHEN $2 = 0 THEN year ELSE $2 END,
+                macaddress = CASE WHEN $3 = '' THEN macaddress ELSE $3 END,
+                discord_id = CASE WHEN $4 = '' THEN discord_id ELSE $4 END
+            WHERE id = $5
+            RETURNING *
+            "
+        )
+
+        .bind(hostel)
+        .bind(year)
+        .bind(macaddress)
+        .bind(discord_id)
+        .bind(id)
+        .fetch_one(pool.as_ref())
+        .await?;
+
+        Ok(member)
+    }
 
     //Mutation for adding attendance to the Attendance table
     async fn add_attendance(