display what accouting would create

web/src/pages/add_table/state.rs

@@ -13,7 +13,7 @@
 
 use crate::schema::{ColumnCatalog, ColumnDraft, columns_from_rows};
 
-use super::draft::TableDraft;
+use super::draft::{ACCOUNTING_FIELD_TYPE, TableDraft};
 
 /// The `profile_name` option meaning "create a new profile too".
 pub(crate) const NEW_PROFILE: &str = "__new__";
@@ -172,6 +172,75 @@ impl AddTablePageState {
         }
     }
 
+    /// The "Columns" list: every declared column, each followed by the columns
+    /// it expands into.
+    ///
+    /// The expansion is flattened here rather than nested in the template so
+    /// the markup stays one loop over one list, and so what a definition row
+    /// brings is decided in one place.
+    pub(crate) fn column_rows(&self) -> Vec<ColumnRow> {
+        let columns = &self.draft.columns;
+        let last_index = columns.added.len().saturating_sub(1);
+        let mut rows = Vec::new();
+
+        for (index, column) in columns.added.iter().enumerate() {
+            let mut tags = Vec::new();
+            if column.quantity_ledger {
+                tags.push("quantity ledger".to_string());
+            }
+            if !column.option_label().is_empty() {
+                tags.push(column.option_label());
+            }
+            rows.push(ColumnRow {
+                index: Some(index),
+                first: index == 0,
+                last: index == last_index,
+                name: column.name.clone(),
+                data_type: column.data_type.clone(),
+                indexable: columns.is_indexable(index),
+                indexed: column.indexed,
+                tags,
+            });
+
+            for generated in columns.generated_columns_of(index) {
+                let mut tags = vec![format!("generated by {}", column.data_type)];
+                if generated.inherits_currency {
+                    tags.push(format!("{}, {}", column.currency, column.money_mode.label()));
+                }
+                rows.push(ColumnRow {
+                    index: None,
+                    first: false,
+                    last: false,
+                    name: generated.name.clone(),
+                    data_type: generated.data_type.clone(),
+                    indexable: false,
+                    indexed: false,
+                    tags,
+                });
+            }
+
+            // The account foreign key is a system column rather than a
+            // generated user column, so the catalog does not report it; the
+            // same explanation as in `TableDraft::preview_rows`.
+            if column.data_type == ACCOUNTING_FIELD_TYPE {
+                rows.push(ColumnRow {
+                    index: None,
+                    first: false,
+                    last: false,
+                    name: "account_id".to_string(),
+                    data_type: "BIGINT".to_string(),
+                    indexable: false,
+                    indexed: true,
+                    tags: vec![
+                        "system column".to_string(),
+                        "written as account".to_string(),
+                    ],
+                });
+            }
+        }
+        rows
+    }
+
     /// Row-display candidates: `id` first, then every column, matching the
     /// client's candidate list.
     pub(crate) fn row_display_candidates(&self) -> Vec<RowDisplayCandidate> {
@@ -203,6 +272,23 @@ impl AddTablePageState {
     }
 }
 
+/// One line of the "Columns" list: either a column the user declared, or one
+/// the server will generate from the definition row above it.
+pub(crate) struct ColumnRow {
+    /// Where the column sits in the draft, for the buttons that act on it.
+    /// `None` for a generated column, which is not the user's to act on: it
+    /// moves and is removed with the definition row it came from.
+    pub index: Option<usize>,
+    /// Whether it can move any further up, and any further down.
+    pub first: bool,
+    pub last: bool,
+    pub name: String,
+    pub data_type: String,
+    pub indexable: bool,
+    pub indexed: bool,
+    pub tags: Vec<String>,
+}
+
 pub(crate) struct RowDisplayCandidate {
     pub index: usize,
     pub name: String,
@@ -288,6 +374,57 @@ mod tests {
         assert_eq!(form.to_draft().row_display_columns, vec!["number"]);
     }
 
+    /// The column list shows a definition row with the columns it expands
+    /// into. Only the definition row is the user's to act on: the generated
+    /// ones carry no index, so they get no buttons.
+    #[test]
+    fn the_column_list_shows_what_a_definition_row_expands_into() {
+        let mut page = AddTablePageState {
+            nav: crate::ui::Nav::default(),
+            profiles: Vec::new(),
+            draft: posted_form().to_draft(),
+            status: None,
+            error: None,
+        };
+        page.draft.columns.catalog = crate::schema::tests::catalog();
+        page.draft.columns.added.push(crate::schema::ColumnDefinition {
+            name: "accounting".to_string(),
+            data_type: "accounting".to_string(),
+            indexed: false,
+            quantity_ledger: false,
+            money_mode: MoneyMode::Exact,
+            currency: "EUR".to_string(),
+        });
+
+        let rows = page.column_rows();
+        assert_eq!(
+            rows.iter().map(|row| row.name.as_str()).collect::<Vec<_>>(),
+            [
+                "number",
+                "total",
+                "accounting",
+                "name",
+                "tax_point_date",
+                "debit",
+                "credit",
+                "account_id",
+            ]
+        );
+
+        let row = |name: &str| rows.iter().find(|row| row.name == name).unwrap();
+        // Only the three declared columns can be moved, indexed or removed.
+        assert_eq!(
+            rows.iter().filter(|row| row.index.is_some()).count(),
+            3,
+            "only declared columns carry an index"
+        );
+        assert!(row("number").first);
+        assert!(row("accounting").last);
+        assert!(!row("accounting").indexable, "a definition row is no column");
+        assert!(row("debit").tags.contains(&"EUR, exact".to_string()));
+        assert!(row("name").tags.contains(&"generated by accounting".to_string()));
+    }
+
     #[test]
     fn the_draft_never_trusts_the_posted_table_list() {
         // `existing_profile_tables` is what duplicate-name checks read, so it