Update compression file

src/state/queries/nudges/compression.ts

@@ -1,26 +1,55 @@
+/*
+ * This module provides functions to pack and unpack flags into a compact
+ * binary format for storage in our NUX system. Given the max length of 300
+ * characters, and a 6-bit encoding scheme, we can store up to 1800 flags in a
+ * single string.
+ */
+
+const TRUTHY = '1'
+const FALSY = '0'
+
+/**
+ * Total number of characters that flags can be packed. This corresponds to the
+ * max-length of a NUX.
+ */
 const MAX_FLAGS = 300
-const FLAGS_PER_CHAR = 6
+
+/**
+ * Length of binary string chunks used to encode flags.
+ */
+const CHAR_CODE_LENGTH = 6
 
 export function pack(flags: Record<string, boolean>) {
   const values = Object.values(flags)
+
   if (values.length > MAX_FLAGS) {
     throw new Error(`Too many flags. Maximum supported is ${MAX_FLAGS}`)
   }
-  const compacted = values.map(value => value ? '1' : '0').join('')
-  // split into chunks of 6 values
-  const encoded = (compacted.match(/.{1,6}/g) || [])
-    .map(chunk => String.fromCharCode(parseInt(chunk.padEnd(6, '0'), 2)))
+
+  /*
+   * Splits `compactBinaryNotation` string into 6 char chunks of 0s and 1s.
+   */
+  const compactBinaryNotation = values
+    .map(value => (value ? TRUTHY : FALSY))
     .join('')
+  const matcher = new RegExp(`.{1,${CHAR_CODE_LENGTH}}`, 'g')
+  const encoded = (compactBinaryNotation.match(matcher) || [])
+    .map(chunk =>
+      String.fromCharCode(parseInt(chunk.padEnd(CHAR_CODE_LENGTH, '0'), 2)),
+    )
+    .join('')
+
   return encoded
 }
 
 export function unpack<K extends string>(encoded: string, keys: K[]) {
-  const binary = encoded.split('')
-    .map(char => char.charCodeAt(0).toString(2).padEnd(6, '0'))
+  const compactBinaryNotation = encoded
+    .split('')
+    .map(char => char.charCodeAt(0).toString(2).padEnd(CHAR_CODE_LENGTH, '0'))
     .join('')
+
   return keys.reduce((obj, key, i) => {
-    obj[key] = binary[i] === '1'
+    obj[key] = compactBinaryNotation[i] === TRUTHY
     return obj
   }, {} as Record<K, boolean>)
 }
-