Fix what the last round of device fixes broke, and two dips it missed

plugins/tools/frontend/labelPages.js

@@ -0,0 +1,150 @@
+// Rows in, printed pages out.
+//
+// This is the half of the generator a preview cannot check. Two things live
+// here for that reason: the CSV columns, which are a contract with whoever
+// builds the file, and the PAGE ORDER of a two-sided card, which decides
+// whether card 3's back lands on card 3 or on card 4. Both are the kind of
+// wrong you only find once the stock is used up.
+//
+// Nothing here knows how a code is drawn or how big a label is. That is
+// utils/codes.js and the component's CSS respectively.
+
+// Rendering thousands of codes locks the tab, so stop at a number a person
+// would actually feed a label printer in one run. The cap counts CARDS, not
+// pages - a two-sided run of 500 is 1000 pages and that is fine.
+export const MAX_LABELS = 500
+export const MAX_COPIES = 1000
+
+const CONTENT_HEADERS = ['content', 'text', 'data', 'value', 'url', 'qr']
+const LABEL_HEADERS = ['label', 'name', 'caption', 'description']
+const COPIES_HEADERS = ['copies', 'qty', 'quantity', 'count']
+const BACK_HEADERS = ['back', 'backcontent', 'reverse']
+const BACKLABEL_HEADERS = ['backlabel', 'backcaption', 'backname']
+
+/** Split one CSV line, honoring quoted fields and "" escapes. */
+export function splitCsvLine(line) {
+  const fields = []
+  let current = ''
+  let inQuotes = false
+  for (let i = 0; i < line.length; i++) {
+    const char = line[i]
+    if (inQuotes) {
+      if (char === '"' && line[i + 1] === '"') { current += '"'; i++ }
+      else if (char === '"') { inQuotes = false }
+      else { current += char }
+    } else if (char === '"') {
+      inQuotes = true
+    } else if (char === ',') {
+      fields.push(current); current = ''
+    } else {
+      current += char
+    }
+  }
+  fields.push(current)
+  return fields.map(field => field.trim())
+}
+
+/**
+ * Parse the label CSV into rows.
+ *
+ * Columns: content (required), label, copies, back, backlabel. A header row is
+ * optional; without one the order is the order above. back/backlabel are only
+ * read when the back side is set to take its own content per row.
+ */
+export function parseCsv(text) {
+  const lines = String(text || '').split(/\r?\n/).filter(line => line.trim() !== '')
+  if (!lines.length) return []
+
+  let columns = { content: 0, label: 1, copies: 2, back: 3, backlabel: 4 }
+  let start = 0
+  const first = splitCsvLine(lines[0]).map(field => field.toLowerCase())
+  if (first.some(field => CONTENT_HEADERS.includes(field))) {
+    // Named header: map by name so column order does not matter.
+    const indexOf = names => first.findIndex(field => names.includes(field))
+    columns = {
+      content: indexOf(CONTENT_HEADERS),
+      label: indexOf(LABEL_HEADERS),
+      copies: indexOf(COPIES_HEADERS),
+      back: indexOf(BACK_HEADERS),
+      backlabel: indexOf(BACKLABEL_HEADERS),
+    }
+    start = 1
+  }
+
+  const at = (fields, index) => (index >= 0 ? (fields[index] || '') : '')
+
+  const rows = []
+  for (let i = start; i < lines.length; i++) {
+    const fields = splitCsvLine(lines[i])
+    const content = at(fields, columns.content)
+    if (!content) continue
+    const copies = columns.copies >= 0 ? parseInt(fields[columns.copies], 10) : 1
+    rows.push({
+      content,
+      label: at(fields, columns.label),
+      copies: Number.isFinite(copies) && copies > 0 ? Math.min(copies, MAX_COPIES) : 1,
+      back: at(fields, columns.back),
+      backlabel: at(fields, columns.backlabel),
+    })
+  }
+  return rows
+}
+
+/** The back page belonging to one row, per the chosen back source. */
+function backPageFor(row, back) {
+  const fallback = back.text || ''
+  switch (back.source) {
+    // The same payload again, so either face of a card scans. Worth it on a
+    // badge that can end up in a holder either way round.
+    case 'code':
+      return { content: row.content, label: row.label || '', side: 'back' }
+    // Per-row back: the CSV carries it. A row that left it empty still gets a
+    // page, because a card printer counts pages and a missing one shifts every
+    // back after it onto the wrong front.
+    case 'column':
+      return { content: row.back || '', label: row.backlabel || fallback, side: 'back' }
+    case 'blank':
+      return { content: '', label: '', side: 'back' }
+    case 'text':
+    default:
+      return { content: '', label: fallback, side: 'back' }
+  }
+}
+
+/**
+ * Expand rows by their copies count and, when a back side is enabled, pair
+ * each card with its back page.
+ *
+ * `back.order` is the one that matters on the floor:
+ *   interleave - front, back, front, back. What a duplex card printer's driver
+ *                expects: it takes pages two at a time.
+ *   grouped    - every front, then every back. For a single-sided printer,
+ *                where the stack comes out, gets flipped and goes back in.
+ * Getting this backwards prints readable cards with the wrong names on the
+ * back, which is worse than a jam because nothing looks broken.
+ */
+export function buildPages(rows, options = {}) {
+  const { back = {}, max = MAX_LABELS } = options
+  const fronts = []
+  const backs = []
+  let dropped = 0
+
+  for (const row of rows || []) {
+    const wanted = Number.isFinite(row.copies) && row.copies > 0
+      ? Math.min(row.copies, MAX_COPIES) : 1
+    for (let i = 0; i < wanted; i++) {
+      if (fronts.length >= max) { dropped += 1; continue }
+      fronts.push({ content: row.content, label: row.label || '', side: 'front' })
+      if (back.enabled) backs.push(backPageFor(row, back))
+    }
+  }
+
+  let pages = fronts
+  if (back.enabled) {
+    pages = back.order === 'grouped'
+      ? [...fronts, ...backs]
+      : fronts.flatMap((front, index) => [front, backs[index]])
+  }
+
+  return { pages, fronts, backs, dropped }
+}