Properly separate ConvenienceFunctions out of PackageUtils and move additional functions into MiscFunctions, and document the various roles of each class (#10343)

lib/misc_functions.rb

@@ -0,0 +1,75 @@
+# lib/misc_functions.rb
+# Generic implementations of various functions/algorithms that are not crew-specific.
+require 'matrix'
+
+class MiscFunctions
+  def self.human_size(bytes)
+    kilobyte = 1024.0
+    megabyte = kilobyte * kilobyte
+    gigabyte = megabyte * kilobyte
+    if bytes < kilobyte
+      units = 'B'
+      size = bytes
+    end
+    if (bytes >= kilobyte) && (bytes < megabyte)
+      units = 'KB'
+      size = bytes / kilobyte
+    end
+    if (bytes >= megabyte) && (bytes < gigabyte)
+      units = 'MB'
+      size = bytes / megabyte
+    end
+    if bytes >= gigabyte
+      units = 'GB'
+      size = bytes / gigabyte
+    end
+    return format('%.2f %s', size, units)
+  end
+
+  # Returns the edit distance between strings string1 and string12
+  # https://en.wikipedia.org/wiki/Edit_distance
+  def self.edit_distance(string1, string2)
+    # memo is the matrix for dynamic programming
+    # memo[i, j] = the edit distance between the
+    # prefixes of string1 and string2 of size i and j.
+    memo = Matrix.zero(string1.size + 1, string2.size + 1)
+    string1.size.times { |i| memo[i + 1, 0] = i + 1 }
+    string2.size.times { |j| memo[0, j + 1] = j + 1 }
+    string1.size.times do |i|
+      string2.size.times do |j|
+        memo[i + 1, j + 1] = if string1[i] == string2[j]
+                               memo[i, j]
+                             else
+                               [
+                                 memo[i + 1, j],
+                                 memo[i, j + 1],
+                                 memo[i, j]
+                               ].min + 1
+                             end
+      end
+    end
+
+    return memo[string1.size, string2.size]
+  end
+
+  def self.time_difference(start_time = nil, end_time = nil)
+    return 'ERROR' if start_time.nil? || end_time.nil?
+
+    time_elapsed = end_time.to_i - start_time.to_i
+    time_hours = time_elapsed / 3600
+    time_minutes = time_elapsed / 60 % 60
+    time_seconds = time_elapsed % 60
+    time_hour_string = if time_hours.zero?
+                         ''
+                       else
+                         "#{time_hours} hr#{time_hours > 1 ? 's, ' : ', '}"
+                       end
+    time_minutes_string = if time_minutes.zero?
+                            time_hour_string.empty? ? '' : "#{time_minutes} min, "
+                          else
+                            "#{time_minutes} min, "
+                          end
+    time_seconds_string = "#{time_seconds} second#{time_seconds == 1 ? '' : 's'}"
+    return time_hour_string + time_minutes_string + time_seconds_string
+  end
+end