Add buttons to interract with last month

src/main.rs

@@ -11,7 +11,7 @@ use iced::{
     font, subscription, theme,
     widget::{
         button, column, component, horizontal_rule, horizontal_space, row, rule, scrollable, text,
-        text_input,
+        text_input, Row,
     },
     window, Alignment, Application, Command, Event, Length, Renderer, Settings, Theme,
 };
@@ -635,6 +635,7 @@ enum Message {
     EditEarings2(f64),
     SetDate(ReportDate),
     Load(ReportDate),
+    InitFrom(ReportDate),
 }
 
 struct Glaurung {
@@ -670,6 +671,24 @@ struct ReportDate {
     pub month: u8,
 }
 
+impl std::ops::Add<u64> for ReportDate {
+    type Output = Self;
+
+    fn add(self, rhs: u64) -> Self::Output {
+        let mut new_month = self.month + (rhs % 12) as u8;
+        let mut new_year = self.year + rhs / 12;
+        if new_month > 12 {
+            new_month -= 12;
+            new_year += 1;
+        }
+
+        Self {
+            year: new_year,
+            month: new_month,
+        }
+    }
+}
+
 impl std::fmt::Display for ReportDate {
     fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
         write!(f, "{}-{}", self.year, self.month)
@@ -754,6 +773,18 @@ impl Glaurung {
         self.earnings_2 = report.earnings_2;
     }
 
+    fn init_from(&mut self, report: Report) {
+        self.recurring = report.recurring;
+        self.savings = report.savings;
+        self.earnings_1 = 0.;
+        self.earnings_2 = 0.;
+        self.variable = report
+            .variable
+            .into_keys()
+            .map(|k| (k, Default::default()))
+            .collect();
+    }
+
     fn report(&self) -> Report {
         Report {
             savings: self.savings.clone(),
@@ -872,6 +903,11 @@ impl Application for Glaurung {
                 self.date = Some(d);
                 self.load(self.archive.get(&d).cloned().unwrap_or_default());
             }
+            Message::InitFrom(d) => {
+                if let Some(report) = self.archive.get(&d) {
+                    self.init_from(report.clone())
+                }
+            }
         }
 
         Command::none()
@@ -986,6 +1022,35 @@ impl Application for Glaurung {
             None => "No month set".to_string(),
         };
 
+        let mut save_buttons = Row::new();
+
+        if let Some(&last) = self.archive.keys().next_back() {
+            let next_month = last + 1;
+            save_buttons = save_buttons.push(
+                button(text(&format!("Archive as {next_month}")))
+                    .on_press(Message::SetDate(next_month)),
+            );
+        }
+
+        save_buttons = save_buttons
+            .push(component(DatePicker {
+                label: "Archive",
+                confirm: "Archive",
+                title: "Set report date",
+                on_pick: Message::SetDate,
+            }))
+            .push(component(DatePicker {
+                label: "Load",
+                confirm: "Load",
+                title: "Load archived report",
+                on_pick: Message::Load,
+            }));
+
+        if let Some(&last) = self.archive.keys().next_back() {
+            save_buttons = save_buttons
+                .push(button(text("Init from last month")).on_press(Message::InitFrom(last)));
+        }
+
         scrollable(
             column![
                 text(date).size(TEXT_H1),
@@ -1039,21 +1104,7 @@ impl Application for Glaurung {
                     on_add: Message::AddSaving,
                 }),
                 per_person,
-                row![
-                    component(DatePicker {
-                        label: "Archive",
-                        confirm: "Archive",
-                        title: "Set report date",
-                        on_pick: Message::SetDate
-                    }),
-                    component(DatePicker {
-                        label: "Load",
-                        confirm: "Load",
-                        title: "Load archived report",
-                        on_pick: Message::Load
-                    })
-                ]
-                .spacing(5)
+                save_buttons.spacing(5),
             ]
             .align_items(Alignment::Center)
             .padding(15),