3 files changed, 91 insertions, 7 deletions

diff --git a/apps/cassiopeia/src/format/ir.rs b/apps/cassiopeia/src/format/ir.rs
new file mode 100644
index 000000000000..32922ec079e7
--- /dev/null
+++ b/apps/cassiopeia/src/format/ir.rs
@@ -0,0 +1,63 @@
+use crate::{format::LineCfg, Date, Time, TimeFile};
+use std::collections::BTreeMap;
+
+/// A set of IR parsed items that makes up a whole cass file
+pub(crate) type IrStream = Vec<IrItem>;
+
+/// Intermediate representation for parsing and generating files
+///
+/// The CASS IR is largely based on the output of the parser's
+/// [`LineCfg`](crate::format::LineCfg), but with concrete types used
+/// in the data layer (namely [`Date`][date] and [`Time`][time]),
+/// while also keeping track of the line numbers to allow idempotent
+/// file changes.
+///
+/// Something not yet implemented is comment pass-through (this needs
+/// to happen in the parser first), but will likely be implemented in
+/// a future version.
+///
+/// [date]: crate::Date
+/// [time]: crate::Time
+#[derive(Debug, Clone)]
+pub(crate) struct IrItem {
+    pub(crate) tt: IrType,
+    pub(crate) lo: usize,
+}
+
+/// Disambiguate between different IR line types with their payload
+#[derive(Debug, Clone)]
+pub(crate) enum IrType {
+    /// A line with parsed header information
+    Header(BTreeMap<String, String>),
+    /// Start a session at a given timestapm
+    Start(Time),
+    /// Stop a session at a given timestamp
+    Stop(Time),
+    /// Invoice a block of previous work
+    Invoice(Date),
+    /// An item that gets ignored
+    Ignore,
+}
+
+/// Generate a stream of IR items from the raw parser output
+pub(crate) fn generate_ir(buf: impl Iterator<Item = LineCfg>) -> IrStream {
+    buf.enumerate().fold(vec![], |mut buf, (lo, item)| {
+        #[cfg_attr(rustfmt, rustfmt_skip)]
+        buf.push(match item {
+            LineCfg::Header(map) => IrItem { tt: IrType::Header(map), lo },
+            LineCfg::Start(Some(time)) => IrItem { tt: IrType::Start(time.into()), lo },
+            LineCfg::Stop(Some(time)) => IrItem { tt: IrType::Stop(time.into()), lo },
+            LineCfg::Invoice(Some(date)) => IrItem { tt: IrType::Invoice(date.into()), lo },
+            LineCfg::Ignore => IrItem { tt: IrType::Ignore, lo },
+            _ => IrItem { tt: IrType::Ignore, lo },
+        });
+
+        buf
+    })
+}
+
+
+pub(crate) trait MakeIr {
+    /// Make a new IR line from an object
+    fn make_ir(&self) -> IrType;
+}
diff --git a/apps/cassiopeia/src/format/mod.rs b/apps/cassiopeia/src/format/mod.rs
index e55658d515ff..814c08656dbe 100644
--- a/apps/cassiopeia/src/format/mod.rs
+++ b/apps/cassiopeia/src/format/mod.rs
@@ -1,17 +1,33 @@
 //! cassiopeia file format
 
+mod ir;
 mod lexer;
 mod parser;
 
+pub(crate) use ir::{IrItem, IrStream, IrType, MakeIr};
 pub(crate) use lexer::{LineLexer, LineToken, Token};
 pub(crate) use parser::LineCfg;
 
 use crate::TimeFile;
 use std::{fs::File, io::Read};
 
+#[derive(Default)]
+pub struct ParseOutput {
+    pub(crate) ir: IrStream,
+    pub(crate) tf: TimeFile,
+}
+
+impl ParseOutput {
+    fn append(mut self, ir: IrItem) -> Self {
+        self.tf.append(ir.clone());
+        self.ir.push(ir);
+        self
+    }
+}
+
 /// Load a file from disk and parse it into a
 /// [`TimeFile`](crate::TimeFile)
-pub fn load_file(path: &str) -> Option<TimeFile> {
+pub fn load_file(path: &str) -> Option<ParseOutput> {
     let mut f = File::open(path).ok()?;
     let mut content = String::new();
     f.read_to_string(&mut content).ok()?;
@@ -19,11 +35,13 @@ pub fn load_file(path: &str) -> Option<TimeFile> {
     let mut lines: Vec<String> = content.split("\n").map(|l| l.to_owned()).collect();
 
     Some(
-        lines
-            .iter_mut()
-            .map(|line| lexer::lex(line))
-            .map(|lex| parser::parse(lex))
-            .filter(|line| line.valid())
-            .fold(TimeFile::default(), |file, line| file.append(line)),
+        ir::generate_ir(
+            lines
+                .iter_mut()
+                .map(|line| lexer::lex(line))
+                .map(|lex| parser::parse(lex)),
+        )
+        .into_iter()
+        .fold(ParseOutput::default(), |output, ir| output.append(ir)),
     )
 }
diff --git a/apps/cassiopeia/src/format/parser.rs b/apps/cassiopeia/src/format/parser.rs
index 430fee6332a7..d1f0bcdebc68 100644
--- a/apps/cassiopeia/src/format/parser.rs
+++ b/apps/cassiopeia/src/format/parser.rs
@@ -53,6 +53,9 @@ pub(crate) fn parse<'l>(lex: LineLexer<'l>) -> LineCfg {
         (Stop(_), LineToken { tt: T::Date, slice }) => Stop(parse_datetime(slice)),
         (Invoice(_), LineToken { tt: T::Date, slice }) => Invoice(parse_date(slice)),
 
+        // Pass empty lines through,
+        (Empty, _) => Empty,
+
         // Ignore everything else (which will be filtered)
         _ => Ignore,
     })