From 42088e06d54b782581439a5dd44c06aa56e3e7f9 Mon Sep 17 00:00:00 2001
From: Stephen Waits <1+swaits@noreply.git.swaits.com>
Date: Sun, 11 Oct 2026 03:02:24 +0000
Subject: [PATCH] Next steps 5-10: resources, cash flow, QB interop, backfill,
 HTTP, parallel-run plan

---
 crates/ledger-import/src/iif.rs | 139 ++++++++++++++++++++++++++++++++
 1 file changed, 139 insertions(+)
 create mode 100644 crates/ledger-import/src/iif.rs

diff --git a/crates/ledger-import/src/iif.rs b/crates/ledger-import/src/iif.rs
new file mode 100644
index 0000000..f1d7275
--- /dev/null
+++ b/crates/ledger-import/src/iif.rs
@@ -0,0 +1,139 @@
+//! Generate Intuit Interchange Format (IIF) journal entries for QuickBooks
+//! Desktop, which many CPAs still run.
+//!
+//! Layout per entry:
+//!
+//! ```text
+//! !TRNS	TRNSTYPE	DATE	ACCNT	NAME	AMOUNT	DOCNUM	MEMO
+//! !SPL	TRNSTYPE	DATE	ACCNT	AMOUNT	DOCNUM	MEMO
+//! !ENDTRNS
+//! TRNS	GENERAL JOURNAL	01/15/2026	Cash		1000.00	1	Memo
+//! SPL	GENERAL JOURNAL	01/15/2026	Revenue	-1000.00	1	Memo
+//! ENDTRNS
+//! ```
+//!
+//! Amounts are signed from the entry's perspective: debits positive,
+//! credits negative. Dates are `MM/DD/YYYY`. Accounts are referenced by
+//! name (QuickBooks matches on name).
+
+use ledger_core::{JournalEntry, Side};
+use rust_decimal::Decimal;
+
+/// One entry's data for IIF export.
+pub struct IifEntry<'a> {
+    /// The journal entry.
+    pub entry: &'a JournalEntry,
+    /// Account id → account name, for resolving line accounts.
+    pub account_names: &'a dyn Fn(ledger_core::AccountId) -> String,
+}
+
+/// Render posted entries as IIF text. `docnum` numbers entries sequentially
+/// from 1 in the order given.
+pub fn journal_to_iif(entries: &[IifEntry<'_>]) -> String {
+    let mut out = String::new();
+    out.push_str("!TRNS\tTRNSTYPE\tDATE\tACCNT\tNAME\tAMOUNT\tDOCNUM\tMEMO\n");
+    out.push_str("!SPL\tTRNSTYPE\tDATE\tACCNT\tAMOUNT\tDOCNUM\tMEMO\n");
+    out.push_str("!ENDTRNS\n");
+    for (idx, item) in entries.iter().enumerate() {
+        let docnum = idx + 1;
+        let date = item.entry.date().format("%m/%d/%Y").to_string();
+        let memo = sanitize(&item.entry.description().replace('\t', " "));
+        let mut lines: Vec<_> = item.entry.lines().iter().collect();
+        // TRNS carries the first debit (or first line); the rest are SPLs.
+        lines.sort_by_key(|l| match l.side {
+            Side::Debit => 0,
+            Side::Credit => 1,
+        });
+        let (first, rest) = lines.split_first().expect("entry has lines");
+        let first_acct = sanitize(&(item.account_names)(first.account));
+        let first_amount = signed(first.side, first.amount.amount);
+        out.push_str(&format!(
+            "TRNS\tGENERAL JOURNAL\t{date}\t{first_acct}\t\t{}\t{docnum}\t{memo}\n",
+            format_amount(first_amount),
+        ));
+        for line in rest {
+            let acct = sanitize(&(item.account_names)(line.account));
+            let amount = signed(line.side, line.amount.amount);
+            out.push_str(&format!(
+                "SPL\tGENERAL JOURNAL\t{date}\t{acct}\t{}\t{docnum}\t{memo}\n",
+                format_amount(amount),
+            ));
+        }
+        out.push_str("ENDTRNS\n");
+    }
+    out
+}
+
+/// Debit positive, credit negative.
+fn signed(side: Side, amount: Decimal) -> Decimal {
+    match side {
+        Side::Debit => amount,
+        Side::Credit => -amount,
+    }
+}
+
+fn format_amount(d: Decimal) -> String {
+    // Two decimal places, no thousands separators.
+    format!("{d:.2}")
+}
+
+/// Strip tabs/newlines that would corrupt the tab-delimited format.
+fn sanitize(s: &str) -> String {
+    s.replace(['\t', '\n', '\r'], " ")
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use ledger_core::{AccountType, Currency, Ledger, Money};
+    use rust_decimal::Decimal;
+
+    #[test]
+    fn iif_round_trip_shape() {
+        let mut ledger = Ledger::new(Currency::USD);
+        let cash = ledger
+            .add_account("1000", "Cash", AccountType::Asset, None, false)
+            .unwrap();
+        let rev = ledger
+            .add_account("4000", "Revenue", AccountType::Revenue, None, false)
+            .unwrap();
+        let id = ledger.create_entry(
+            chrono::NaiveDate::from_ymd_opt(2026, 1, 15).unwrap(),
+            "Sale",
+        );
+        ledger
+            .add_line(
+                id,
+                cash,
+                Side::Debit,
+                Money::new(Decimal::new(100000, 2), Currency::USD),
+            )
+            .unwrap();
+        ledger
+            .add_line(
+                id,
+                rev,
+                Side::Credit,
+                Money::new(Decimal::new(100000, 2), Currency::USD),
+            )
+            .unwrap();
+        ledger.post_entry(id).unwrap();
+        let entry = ledger.get_entry(id).unwrap();
+        let names = |a: ledger_core::AccountId| {
+            ledger
+                .chart()
+                .get(a)
+                .map(|ac| ac.name.clone())
+                .unwrap_or_default()
+        };
+        let text = journal_to_iif(&[IifEntry {
+            entry,
+            account_names: &names,
+        }]);
+        assert!(text.contains("!TRNS\tTRNSTYPE\tDATE\tACCNT\tNAME\tAMOUNT\tDOCNUM\tMEMO"));
+        assert!(text.contains("TRNS\tGENERAL JOURNAL\t01/15/2026\tCash"));
+        assert!(text.contains("\t1000.00\t"));
+        assert!(text.contains("SPL\tGENERAL JOURNAL\t01/15/2026\tRevenue\t-1000.00"));
+        assert!(text.contains("ENDTRNS"));
+    }
+}