#434

frontend/src/lib/countsClipboard.ts

@@ -1,11 +1,67 @@
 export type CountsClipboard = { text: string; html: string }
+export type CountsClipboardColumn = { label: string; children?: CountsClipboardColumn[] }
+export type CountsClipboardCell = string | CountsClipboardTable
+export type CountsClipboardTable = {
+    columns: CountsClipboardColumn[]; rows: CountsClipboardCell[][] }
 
 
 const escapeHTML = (value: string): string => value.replace (/[&<>"']/g, character =>
     ({ '&': '&amp;', '<': '&lt;', '>': '&gt;', '"': '&quot;', "'": '&#39;' })[character]!)
 
 
-export const countsClipboard = (rows: string[][], headers = false): CountsClipboard => {
+const columnWidth = (column: CountsClipboardColumn): number =>
+    column.children?.reduce ((sum, child) => sum + columnWidth (child), 0) || 1
+
+
+const headerDepth = (columns: CountsClipboardColumn[]): number =>
+    columns.length === 0 ? 0 : 1 + Math.max (0, ...columns.map (column =>
+	headerDepth (column.children ?? [])))
+
+
+const headerRows = (columns: CountsClipboardColumn[]): string[][] => {
+  const width = columns.reduce ((sum, column) => sum + columnWidth (column), 0)
+  const rows = Array.from ({ length: headerDepth (columns) },
+      () => Array<string> (width).fill (''))
+  const place = (fields: CountsClipboardColumn[], row: number, offset: number) => {
+    for (const field of fields)
+    {
+      rows[row][offset] = field.label
+      if (field.children?.length) place (field.children, row + 1, offset)
+      offset += columnWidth (field)
+    }
+  }
+  if (columns.length) place (columns, 0, 0)
+  return rows
+}
+
+
+const dataRows = (
+    table: CountsClipboardTable,
+    columns = table.columns,
+): string[][] => {
+  if (columns.length === 0) return []
+  return table.rows.flatMap (record => {
+    const blocks = columns.map ((column, index) => {
+      const value = record[index] ?? ''
+      return typeof value === 'string' ? [[value]]
+	  : dataRows (value, column.children ?? value.columns)
+    })
+    const height = Math.max (1, ...blocks.map (block => block.length))
+    // Sibling arrays share the parent row's height; they never form a Cartesian product.
+    return Array.from ({ length: height }, (_, row) => columns.flatMap ((column, index) =>
+	Array.from ({ length: columnWidth (column) }, (_, offset) =>
+	    blocks[index][row]?.[offset] ?? '')))
+  })
+}
+
+
+export const countsClipboard = (
+    source: string[][] | CountsClipboardTable,
+    headers = false,
+): CountsClipboard => {
+  const headings = !Array.isArray (source) && headers ? headerRows (source.columns) : []
+  const rows = Array.isArray (source) ? source : [...headings, ...dataRows (source)]
+  const headingCount = Array.isArray (source) ? (headers ? 1 : 0) : headings.length
   // Excel accepts quoted TSV fields only when delimiters or quotes require them.
   // Prefix formula-like text in both representations, including leading whitespace.
   const safe = rows.map (row => row.map (value => /^\s*[=+@-]/.test (value)
@@ -13,7 +69,7 @@ export const countsClipboard = (rows: string[][], headers = false): CountsClipbo
   const text = safe.map (row => row.map (value => /[\t\r\n"]/.test (value)
       ? `"${value.replaceAll ('"', '""')}"` : value).join ('\t')).join ('\r\n')
   const html = '<html><body><table>' + safe.map ((row, index) => '<tr>' + row.map (value => {
-    const tag = headers && index === 0 ? 'th' : 'td'
+    const tag = index < headingCount ? 'th' : 'td'
     // Preserve time strings, leading zeroes, and user text instead of inferring dates/formulae.
     const numeric = value.length <= 15 && /^(?:0|[1-9]\d*)(?:\.\d+)?$/.test (value)
     const style = numeric ? 'white-space:pre-wrap' : 'white-space:pre-wrap;mso-number-format:"\\@"'