From 279bf4a4d104a7e0e9d5b73120b6132e58e7aaa6 Mon Sep 17 00:00:00 2001
From: Joscha <joscha@plugh.de>
Date: Sat, 18 Dec 2021 22:21:17 +0100
Subject: [PATCH] Parse range for --range

---
 src/files.rs           |  1 +
 src/files/arguments.rs | 94 ++++++++++++++++++++++++++++++++++++++++++
 src/files/grammar.pest |  5 +++
 src/files/parse.rs     |  6 +--
 4 files changed, 103 insertions(+), 3 deletions(-)
 create mode 100644 src/files/arguments.rs

diff --git a/src/files.rs b/src/files.rs
index 7ec38c0..38cc135 100644
--- a/src/files.rs
+++ b/src/files.rs
@@ -8,6 +8,7 @@ use tzfile::Tz;
 use self::commands::{Command, Done, File};
 pub use self::error::{Error, Result};
 
+pub mod arguments;
 pub mod commands;
 mod error;
 mod format;
diff --git a/src/files/arguments.rs b/src/files/arguments.rs
new file mode 100644
index 0000000..0878692
--- /dev/null
+++ b/src/files/arguments.rs
@@ -0,0 +1,94 @@
+use std::str::FromStr;
+
+use chrono::NaiveDate;
+use pest::iterators::Pair;
+use pest::Parser;
+
+use super::commands::Delta;
+use super::parse::{self, Error, Result, Rule, TodayfileParser};
+
+#[derive(Debug)]
+pub enum RangeDate {
+    Date(NaiveDate),
+    Today,
+}
+
+#[derive(Debug)]
+pub struct Range {
+    pub start: RangeDate,
+    pub start_delta: Option<Delta>,
+    pub end: Option<RangeDate>,
+    pub end_delta: Option<Delta>,
+}
+
+/* Parsing */
+
+fn parse_range_date(p: Pair<'_, Rule>) -> Result<RangeDate> {
+    assert!(matches!(p.as_rule(), Rule::datum | Rule::today));
+    Ok(match p.as_rule() {
+        Rule::datum => RangeDate::Date(parse::parse_datum(p)?.value),
+        Rule::today => RangeDate::Today,
+        _ => unreachable!(),
+    })
+}
+
+fn parse_range_start(p: Pair<'_, Rule>) -> Result<(RangeDate, Option<Delta>)> {
+    assert_eq!(p.as_rule(), Rule::range_start);
+    let mut p = p.into_inner();
+
+    let start = parse_range_date(p.next().unwrap())?;
+    let start_delta = match p.next() {
+        None => None,
+        Some(p) => Some(parse::parse_delta(p)?.value),
+    };
+
+    assert_eq!(p.next(), None);
+
+    Ok((start, start_delta))
+}
+
+fn parse_range_end(p: Pair<'_, Rule>) -> Result<(Option<RangeDate>, Option<Delta>)> {
+    assert_eq!(p.as_rule(), Rule::range_end);
+
+    let mut end = None;
+    let mut end_delta = None;
+
+    for p in p.into_inner() {
+        match p.as_rule() {
+            Rule::datum | Rule::today => end = Some(parse_range_date(p)?),
+            Rule::delta => end_delta = Some(parse::parse_delta(p)?.value),
+            _ => unreachable!(),
+        }
+    }
+
+    Ok((end, end_delta))
+}
+
+fn parse_range(p: Pair<'_, Rule>) -> Result<Range> {
+    assert_eq!(p.as_rule(), Rule::range);
+    let mut p = p.into_inner();
+
+    let (start, start_delta) = parse_range_start(p.next().unwrap())?;
+    let (end, end_delta) = parse_range_end(p.next().unwrap())?;
+
+    assert_eq!(p.next(), None);
+
+    Ok(Range {
+        start,
+        start_delta,
+        end,
+        end_delta,
+    })
+}
+
+impl FromStr for Range {
+    type Err = Error;
+
+    fn from_str(s: &str) -> Result<Self> {
+        let mut pairs = TodayfileParser::parse(Rule::range, s)?;
+        let p = pairs.next().unwrap();
+        assert_eq!(pairs.next(), None);
+
+        parse_range(p)
+    }
+}
diff --git a/src/files/grammar.pest b/src/files/grammar.pest
index 32186a2..227e32b 100644
--- a/src/files/grammar.pest
+++ b/src/files/grammar.pest
@@ -142,3 +142,8 @@ empty_line = _{ WHITESPACE* ~ NEWLINE }
 command = { include | timezone | task | note }
 
 file = ${ SOI ~ (empty_line* ~ command)* ~ empty_line* ~ WHITESPACE* ~ EOI }
+
+today = { "today" }
+range_start = { (datum | today) ~ delta? }
+range_end = { (datum | today) ~ delta? | delta }
+range = { range_start ~ ("--" ~ range_end)? }
diff --git a/src/files/parse.rs b/src/files/parse.rs
index a1f5eef..e7a4590 100644
--- a/src/files/parse.rs
+++ b/src/files/parse.rs
@@ -15,7 +15,7 @@ use super::primitives::{Spanned, Time, Weekday};
 
 #[derive(pest_derive::Parser)]
 #[grammar = "files/grammar.pest"]
-struct TodayfileParser;
+pub struct TodayfileParser;
 
 pub type Error = pest::error::Error<Rule>;
 pub type Result<T> = result::Result<T, Error>;
@@ -55,7 +55,7 @@ fn parse_title(p: Pair<'_, Rule>) -> String {
     p.as_str().trim().to_string()
 }
 
-fn parse_datum(p: Pair<'_, Rule>) -> Result<Spanned<NaiveDate>> {
+pub fn parse_datum(p: Pair<'_, Rule>) -> Result<Spanned<NaiveDate>> {
     assert_eq!(p.as_rule(), Rule::datum);
     let pspan = p.as_span();
     let span = (&pspan).into();
@@ -203,7 +203,7 @@ fn parse_delta_step(
     Ok(Spanned::new(span, f(value)))
 }
 
-fn parse_delta(p: Pair<'_, Rule>) -> Result<Spanned<Delta>> {
+pub fn parse_delta(p: Pair<'_, Rule>) -> Result<Spanned<Delta>> {
     assert_eq!(p.as_rule(), Rule::delta);
     let span = (&p.as_span()).into();