Feature 12: Regular dinners and onboarding (#94)

Co-authored-by: dev_agent <dev_agent@cubecraftlabs.com>

web/src/dinners/names.ts

@@ -0,0 +1,58 @@
+// The PWA's copy of the server's dinner-name rules (internal/ai/harness
+// Normalize and Similar), so a screen can tell beforehand that the dinners
+// API would refuse a name as a duplicate. The server still decides.
+// internal/ai/harness/testdata/dedupe_cases.json is run against both.
+
+import folds from './letterFolds.json'
+
+// SIMILAR_THRESHOLD is harness.SimilarThreshold.
+const SIMILAR_THRESHOLD = 0.85
+
+// fillerWords is harness's fillerWords.
+const fillerWords = new Set(['easy', 'best', 'homemade', 'quick', 'simple', 'the', 'a', 'recipe', 'classic'])
+
+// letterFolds is harness's letterFolds: gen_folds.py writes both tables,
+// and harness's TestLetterFoldsMatchPWA fails when they differ.
+const letterFolds: Record<string, string> = folds
+
+const combiningMark = /\p{Mn}/u
+const wordChar = /[\p{L}\p{Nd}]/u
+
+// normalizeName is harness.Normalize: lowercased, accents dropped, letters
+// folded, apostrophes removed, other punctuation turned into spaces and
+// filler words dropped. "Easy Chicken Tikka-Masala!" is
+// "chicken tikka masala".
+export function normalizeName(name: string): string {
+  let out = ''
+  // Lowercased letter by letter, as Go's strings.ToLower does, so no
+  // letter is lowered by its context (a final Σ is σ, not ς).
+  for (const letter of name) {
+    for (const ch of letter.toLowerCase()) {
+      if (combiningMark.test(ch) || ch === "'" || ch === '’') continue
+      const fold = letterFolds[ch]
+      if (fold !== undefined) out += fold
+      else if (wordChar.test(ch)) out += ch
+      else out += ' '
+    }
+  }
+  return out
+    .split(' ')
+    .filter((word) => word !== '' && !fillerWords.has(word))
+    .join(' ')
+}
+
+function words(name: string): Set<string> {
+  const normalized = normalizeName(name)
+  return new Set(normalized === '' ? [] : normalized.split(' '))
+}
+
+// similarNames is harness.Similar: whether a and b name the same dinner, by
+// the share of the words of their normalized forms they have in common.
+export function similarNames(a: string, b: string): boolean {
+  const left = words(a)
+  const right = words(b)
+  if (left.size === 0 || right.size === 0) return false
+  let shared = 0
+  for (const word of left) if (right.has(word)) shared++
+  return shared / (left.size + right.size - shared) >= SIMILAR_THRESHOLD
+}