feat: implement Ord for the task model

src/models/task.rs

@@ -1,10 +1,12 @@
-use chrono::NaiveDateTime;
 use crate::models::category::Category;
+use crate::models::subtask::Subtask;
 use crate::schema::tasks;
+use crate::utils::reverse_ord_option::ReverseOrdOption;
+use chrono::NaiveDateTime;
 use diesel::prelude::*;
 use serde::{Deserialize, Serialize};
+use std::cmp::Ordering;
 use validator::Validate;
-use crate::models::subtask::Subtask;
 
 const TITLE_LENGTH_MIN: u64 = 1;
 const TITLE_LENGTH_MAX: u64 = 255;
@@ -52,6 +54,40 @@ impl Task {
     }
 }
 
+impl Eq for Task {}
+
+impl PartialOrd<Self> for Task {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for Task {
+    fn cmp(&self, other: &Self) -> Ordering {
+        match (&self.category, &other.category) {
+            (Category::Inbox, Category::Inbox) => self.created_at.cmp(&other.created_at),
+            (
+                Category::Calendar { date: self_date, time: self_time, .. },
+                Category::Calendar { date: other_date, time: other_time, .. }
+            ) => self_date.cmp(other_date)
+                .then(ReverseOrdOption::from(
+                    &self_time.as_ref().map(|calendar_time| calendar_time.time())
+                ).cmp(&ReverseOrdOption::from(
+                        &other_time.as_ref().map(|calendar_time| calendar_time.time())
+                )))
+                .then(ReverseOrdOption::from(&self.deadline()).cmp(
+                    &ReverseOrdOption::from(&other.deadline())
+                ))
+                .then(self.created_at.cmp(&other.created_at)),
+            (Category::Done, Category::Done) | (Category::Trash, Category::Trash)
+            => self.updated_at.cmp(&other.updated_at).reverse(),
+            (_, _) => ReverseOrdOption::from(&self.deadline()).cmp(
+                &ReverseOrdOption::from(&other.deadline())
+            ).then(self.created_at.cmp(&other.created_at)),
+        }
+    }
+}
+
 #[derive(Serialize, Deserialize, PartialEq, Clone, Debug)]
 pub struct TaskWithSubtasks {
     task: Task,
@@ -72,6 +108,20 @@ impl TaskWithSubtasks {
     }
 }
 
+impl Eq for TaskWithSubtasks {}
+
+impl PartialOrd<Self> for TaskWithSubtasks {
+    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {
+        Some(self.cmp(other))
+    }
+}
+
+impl Ord for TaskWithSubtasks {
+    fn cmp(&self, other: &Self) -> Ordering {
+        self.task().cmp(other.task())
+    }
+}
+
 #[derive(Insertable, Serialize, Deserialize, Validate, Clone, Debug)]
 #[diesel(table_name = tasks)]
 pub struct NewTask {