From 1ac39c69f238cb949b88865daff155760b05e1e5 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Tue, 21 Dec 2021 19:24:27 +0100
Subject: [PATCH] Move entries to a different time

---
 CHANGELOG.md            |  1 +
 src/eval/command.rs     | 39 +++++++++++++++++++++++++++++++--------
 src/eval/date.rs        | 21 +++++++++++++++++----
 src/eval/delta.rs       |  8 ++++----
 src/files/commands.rs   |  3 ++-
 src/files/format.rs     |  9 ++++++++-
 src/files/grammar.pest  |  2 +-
 src/files/parse.rs      | 20 +++++++++++++++++---
 src/files/primitives.rs | 22 ++++++++++++++++++----
 9 files changed, 99 insertions(+), 26 deletions(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index c0b9fae..d12e3d9 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 
 ### Added
 - `REMIND` statement
+- `MOVE` entries to a different time
 
 ## 0.1.0 - 2021-12-20
 
diff --git a/src/eval/command.rs b/src/eval/command.rs
index 8bdac96..b277a7d 100644
--- a/src/eval/command.rs
+++ b/src/eval/command.rs
@@ -1,11 +1,11 @@
 use std::collections::HashMap;
 
-use chrono::NaiveDate;
+use chrono::{Duration, NaiveDate};
 
 use crate::files::commands::{
     self, BirthdaySpec, Command, Done, DoneDate, Note, Spec, Statement, Task,
 };
-use crate::files::primitives::{Span, Spanned};
+use crate::files::primitives::{Span, Spanned, Time};
 use crate::files::SourcedCommand;
 
 use super::date::Dates;
@@ -220,7 +220,12 @@ impl<'a> CommandState<'a> {
             Statement::From(date) => self.from = *date,
             Statement::Until(date) => self.until = *date,
             Statement::Except(date) => self.eval_except(*date),
-            Statement::Move { span, from, to } => self.eval_move(*span, *from, *to)?,
+            Statement::Move {
+                span,
+                from,
+                to,
+                to_time,
+            } => self.eval_move(*span, *from, *to, *to_time)?,
             Statement::Remind(delta) => self.eval_remind(delta),
         }
         Ok(())
@@ -242,13 +247,31 @@ impl<'a> CommandState<'a> {
         self.dated.remove(&date);
     }
 
-    fn eval_move(&mut self, span: Span, from: NaiveDate, to: NaiveDate) -> Result<()> {
+    fn eval_move(
+        &mut self,
+        span: Span,
+        from: NaiveDate,
+        to: Option<NaiveDate>,
+        to_time: Option<Time>,
+    ) -> Result<()> {
         if let Some(mut entry) = self.dated.remove(&from) {
-            if let Some(dates) = entry.dates {
-                let delta = to - from;
-                entry.dates = Some(dates.move_by(delta));
+            let mut dates = entry.dates.expect("comes from self.dated");
+
+            // Determine delta
+            let mut delta = Duration::zero();
+            if let Some(to) = to {
+                delta = delta + (to - dates.root());
             }
-            self.dated.insert(to, entry);
+            if let Some(to_time) = to_time {
+                if let Some((root, _)) = dates.times() {
+                    delta = delta + Duration::minutes(root.minutes_to(to_time));
+                }
+            }
+
+            dates = dates.move_by(delta);
+            entry.dates = Some(dates);
+            self.dated.insert(dates.root(), entry);
+
             Ok(())
         } else {
             Err(Error::MoveWithoutSource {
diff --git a/src/eval/date.rs b/src/eval/date.rs
index 61b2908..da8ce25 100644
--- a/src/eval/date.rs
+++ b/src/eval/date.rs
@@ -103,11 +103,24 @@ impl Dates {
     }
 
     pub fn move_by(&self, delta: Duration) -> Self {
-        Self {
-            root: self.root + delta,
-            other: self.other + delta,
-            times: self.times,
+        let mut result = *self;
+
+        // Modify dates
+        result.root += delta;
+        result.other += delta;
+
+        // Modify times if necessary (may further modify dates)
+        const MINUTES_PER_DAY: i64 = 24 * 60;
+        let minutes = delta.num_minutes() % MINUTES_PER_DAY; // May be negative
+        if let Some(times) = self.times {
+            let (root_days, root) = times.root.add_minutes(minutes);
+            let (other_days, other) = times.other.add_minutes(minutes);
+            result.root += Duration::days(root_days);
+            result.other += Duration::days(other_days);
+            result.times = Some(Times { root, other });
         }
+
+        result
     }
 }
 
diff --git a/src/eval/delta.rs b/src/eval/delta.rs
index ecde59b..dcc1706 100644
--- a/src/eval/delta.rs
+++ b/src/eval/delta.rs
@@ -258,8 +258,8 @@ impl DeltaEval {
             None => return Err(self.err_time(span)),
         };
 
-        let (days, time) = time.add_hours(amount);
-        self.curr += Duration::days(days.into());
+        let (days, time) = time.add_hours(amount.into());
+        self.curr += Duration::days(days);
         self.curr_time = Some(time);
         Ok(())
     }
@@ -270,8 +270,8 @@ impl DeltaEval {
             None => return Err(self.err_time(span)),
         };
 
-        let (days, time) = time.add_minutes(amount);
-        self.curr += Duration::days(days.into());
+        let (days, time) = time.add_minutes(amount.into());
+        self.curr += Duration::days(days);
         self.curr_time = Some(time);
         Ok(())
     }
diff --git a/src/files/commands.rs b/src/files/commands.rs
index a699ce3..90983d0 100644
--- a/src/files/commands.rs
+++ b/src/files/commands.rs
@@ -265,7 +265,8 @@ pub enum Statement {
     Move {
         span: Span,
         from: NaiveDate,
-        to: NaiveDate,
+        to: Option<NaiveDate>,
+        to_time: Option<Time>,
     },
     Remind(Option<Spanned<Delta>>),
 }
diff --git a/src/files/format.rs b/src/files/format.rs
index a7764f4..e169142 100644
--- a/src/files/format.rs
+++ b/src/files/format.rs
@@ -220,7 +220,14 @@ impl fmt::Display for Statement {
             Statement::Until(Some(date)) => writeln!(f, "UNTIL {}", date),
             Statement::Until(None) => writeln!(f, "UNTIL *"),
             Statement::Except(date) => writeln!(f, "EXCEPT {}", date),
-            Statement::Move { from, to, .. } => writeln!(f, "MOVE {} TO {}", from, to),
+            Statement::Move {
+                from, to, to_time, ..
+            } => match (to, to_time) {
+                (None, None) => unreachable!(),
+                (Some(to), None) => writeln!(f, "MOVE {} TO {}", from, to),
+                (None, Some(to_time)) => writeln!(f, "MOVE {} TO {}", from, to_time),
+                (Some(to), Some(to_time)) => writeln!(f, "MOVE {} TO {} {}", from, to, to_time),
+            },
             Statement::Remind(Some(delta)) => writeln!(f, "REMIND {}", delta),
             Statement::Remind(None) => writeln!(f, "REMIND *"),
         }
diff --git a/src/files/grammar.pest b/src/files/grammar.pest
index d071cbb..a2712be 100644
--- a/src/files/grammar.pest
+++ b/src/files/grammar.pest
@@ -106,7 +106,7 @@ stmt_bdate = !{ "BDATE" ~ bdatum ~ eol }
 stmt_from = !{ "FROM" ~ (datum | "*") ~ eol }
 stmt_until = !{ "UNTIL" ~ (datum | "*") ~ eol }
 stmt_except = !{ "EXCEPT" ~ datum ~ eol }
-stmt_move = !{ "MOVE" ~ datum ~ "TO" ~ datum ~ eol }
+stmt_move = !{ "MOVE" ~ datum ~ "TO" ~ (datum ~ time? | time) ~ eol }
 stmt_remind = !{ "REMIND" ~ (delta | "*") ~ eol }
 
 statements = { (stmt_date | stmt_bdate | stmt_from | stmt_until | stmt_except | stmt_move | stmt_remind)* }
diff --git a/src/files/parse.rs b/src/files/parse.rs
index cfcaaf6..3e43ab0 100644
--- a/src/files/parse.rs
+++ b/src/files/parse.rs
@@ -618,9 +618,23 @@ fn parse_stmt_move(p: Pair<'_, Rule>) -> Result<Statement> {
     let span = (&p.as_span()).into();
     let mut p = p.into_inner();
     let from = parse_datum(p.next().unwrap())?.value;
-    let to = parse_datum(p.next().unwrap())?.value;
-    assert_eq!(p.next(), None);
-    Ok(Statement::Move { span, from, to })
+
+    let mut to = None;
+    let mut to_time = None;
+    for p in p {
+        match p.as_rule() {
+            Rule::datum => to = Some(parse_datum(p)?.value),
+            Rule::time => to_time = Some(parse_time(p)?.value),
+            _ => unreachable!(),
+        }
+    }
+
+    Ok(Statement::Move {
+        span,
+        from,
+        to,
+        to_time,
+    })
 }
 
 fn parse_stmt_remind(p: Pair<'_, Rule>) -> Result<Statement> {
diff --git a/src/files/primitives.rs b/src/files/primitives.rs
index d41a2fb..a31b297 100644
--- a/src/files/primitives.rs
+++ b/src/files/primitives.rs
@@ -98,10 +98,15 @@ impl Time {
         true
     }
 
-    pub fn add_minutes(&self, amount: i32) -> (i32, Self) {
+    /// How many minutes into the day this time is.
+    fn minutes(&self) -> i64 {
+        (self.hour as i64) * 60 + (self.min as i64)
+    }
+
+    pub fn add_minutes(&self, amount: i64) -> (i64, Self) {
         match amount.cmp(&0) {
             Ordering::Less => {
-                let mut mins = (self.hour as i32) * 60 + (self.min as i32) + amount;
+                let mut mins = self.minutes() + amount;
 
                 let days = mins.div_euclid(60 * 24);
                 mins = mins.rem_euclid(60 * 24);
@@ -111,7 +116,7 @@ impl Time {
                 (days, Self::new(hour, min))
             }
             Ordering::Greater => {
-                let mut mins = (self.hour as i32) * 60 + (self.min as i32) + amount;
+                let mut mins = self.minutes() + amount;
 
                 let mut days = mins.div_euclid(60 * 24);
                 mins = mins.rem_euclid(60 * 24);
@@ -130,9 +135,18 @@ impl Time {
         }
     }
 
-    pub fn add_hours(&self, amount: i32) -> (i32, Self) {
+    pub fn add_hours(&self, amount: i64) -> (i64, Self) {
         self.add_minutes(amount * 60)
     }
+
+    /// `a.minutes_to(b)` returns the minutes from `a` to `b`, meaning it is
+    /// greater than 0 if `a` is earlier than `b`.
+    ///
+    /// May return weird amounts if [`Self::in_normal_range`] is not true for
+    /// both.
+    pub fn minutes_to(&self, other: Self) -> i64 {
+        other.minutes() - self.minutes()
+    }
 }
 
 #[derive(Debug, Clone, Copy)]