Next steps 5-10: resources, cash flow, QB interop, backfill, HTTP, parallel-run plan

crates/ledger-import/src/chart_csv.rs

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+//! Parse chart-of-accounts CSVs.
+//!
+//! Expected layout (header row required):
+//!
+//! ```csv
+//! code,name,type,parent_code
+//! 1000,Cash,asset,
+//! 1010,Checking,asset,1000
+//! ```
+//!
+//! `type` is one of `asset`, `liability`, `equity`, `revenue`, `expense`
+//! (case-insensitive). `parent_code` is optional; empty means top-level.
+
+use thiserror::Error;
+
+/// One chart row.
+#[derive(Clone, Debug, PartialEq)]
+pub struct ChartRow {
+    /// Account code.
+    pub code: String,
+    /// Account name.
+    pub name: String,
+    /// Account type, lowercase: asset, liability, equity, revenue, expense.
+    pub account_type: String,
+    /// Parent account code, if any.
+    pub parent_code: Option<String>,
+}
+
+/// Parse errors.
+#[derive(Debug, Error, PartialEq)]
+pub enum ChartCsvError {
+    /// Wrong column count.
+    #[error("expected 4 columns (code,name,type,parent_code), found {0}")]
+    BadColumnCount(usize),
+    /// Missing or bad header.
+    #[error("bad header: expected code,name,type,parent_code")]
+    BadHeader,
+    /// Unknown account type.
+    #[error("bad account type {0:?}: expected asset, liability, equity, revenue, or expense")]
+    BadType(String),
+    /// Malformed CSV.
+    #[error("csv error: {0}")]
+    Csv(String),
+}
+
+/// Parse a chart CSV. Returns rows in file order (parents should come first,
+/// but order is not validated here).
+pub fn parse_chart_csv(text: &str) -> Result<Vec<ChartRow>, ChartCsvError> {
+    let mut reader = csv::ReaderBuilder::new()
+        .has_headers(false)
+        .trim(csv::Trim::All)
+        .from_reader(text.as_bytes());
+    let mut out = Vec::new();
+    for (idx, record) in reader.records().enumerate() {
+        let record = record.map_err(|e| ChartCsvError::Csv(e.to_string()))?;
+        let fields: Vec<&str> = record.iter().collect();
+        if fields.iter().all(|f| f.is_empty()) {
+            continue;
+        }
+        if idx == 0 {
+            let lower: Vec<String> = fields.iter().map(|f| f.to_lowercase()).collect();
+            if lower != ["code", "name", "type", "parent_code"] {
+                return Err(ChartCsvError::BadHeader);
+            }
+            continue;
+        }
+        if fields.len() != 4 {
+            return Err(ChartCsvError::BadColumnCount(fields.len()));
+        }
+        let account_type = fields[2].to_lowercase();
+        match account_type.as_str() {
+            "asset" | "liability" | "equity" | "revenue" | "expense" => {}
+            _ => return Err(ChartCsvError::BadType(fields[2].to_string())),
+        }
+        let parent_code = fields[3].trim();
+        out.push(ChartRow {
+            code: fields[0].to_string(),
+            name: fields[1].to_string(),
+            account_type,
+            parent_code: if parent_code.is_empty() {
+                None
+            } else {
+                Some(parent_code.to_string())
+            },
+        });
+    }
+    Ok(out)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn parses_chart() {
+        let csv = "code,name,type,parent_code\n1000,Cash,asset,\n1010,Checking,asset,1000\n4000,Revenue,revenue,\n";
+        let rows = parse_chart_csv(csv).unwrap();
+        assert_eq!(rows.len(), 3);
+        assert_eq!(rows[0].parent_code, None);
+        assert_eq!(rows[1].parent_code, Some("1000".to_string()));
+        assert_eq!(rows[2].account_type, "revenue");
+    }
+
+    #[test]
+    fn bad_type_rejected() {
+        let csv = "code,name,type,parent_code\n1000,Cash,money,\n";
+        assert!(matches!(
+            parse_chart_csv(csv),
+            Err(ChartCsvError::BadType(_))
+        ));
+    }
+}