From cbe7aead32ea241b69870625fb6ec70fb32e145e Mon Sep 17 00:00:00 2001
From: Max Fierke <max@maxfierke.com>
Date: Mon, 7 Aug 2017 00:25:01 -0500
Subject: [PATCH] Add keymap replacement strategy

Adds a replacement strategy which uses knowledge of a particular keyboard
layout to create typos which would be easy mistakes on the configured
layout.

Seems to be pivoting off the wrong character in the source text right now,
but is otherwise working.
---
 data/keymaps/en-US_qwerty.yml               | 146 ++++++++++++++++++++
 src/typhar.cr                               |   1 +
 src/typhar/cli.cr                           |   3 +
 src/typhar/exceptions.cr                    |   3 +
 src/typhar/strategies/replacement/keymap.cr |  30 ++++
 src/typhar/transformer.cr                   |   1 +
 src/typhar/types/keymap.cr                  |  39 ++++++
 src/typhar/types/keymap_entry.cr            |  10 ++
 8 files changed, 233 insertions(+)
 create mode 100644 data/keymaps/en-US_qwerty.yml
 create mode 100644 src/typhar/strategies/replacement/keymap.cr
 create mode 100644 src/typhar/types/keymap.cr
 create mode 100644 src/typhar/types/keymap_entry.cr

diff --git a/data/keymaps/en-US_qwerty.yml b/data/keymaps/en-US_qwerty.yml
new file mode 100644
index 0000000..41213ec
--- /dev/null
+++ b/data/keymaps/en-US_qwerty.yml
@@ -0,0 +1,146 @@
+---
+data:
+  '`':
+    shift: '~'
+    neighbors: ['1']
+  '1':
+    shift: '!'
+    neighbors: ['`', 'q']
+  '2':
+    shift: '@'
+    neighbors: ['1', 'q', '3']
+  '3':
+    shift: '#'
+    neighbors: ['2', 'w', 'e', '4']
+  '4':
+    shift: '$'
+    neighbors: ['3', 'e', 'r', '5']
+  '5':
+    shift: '%'
+    neighbors: ['4', 'r', 't', '6']
+  '6':
+    shift: '^'
+    neighbors: ['5', 't', 'y', '7']
+  '7':
+    shift: '&'
+    neighbors: ['6', 'y', 'u', '8']
+  '8':
+    shift: '*'
+    neighbors: ['7', 'u', 'i', '9']
+  '9':
+    shift: '('
+    neighbors: ['8', 'i', 'o', '0']
+  '0':
+    shift: ')'
+    neighbors: ['9', 'o', 'p', '-']
+  '-':
+    shift: '_'
+    neighbors: ['0', 'p', '[', '=']
+  '=':
+    shift: '+'
+    neighbors: ['-', '[', ']']
+  q:
+    shift: 'Q'
+    neighbors: ['1', '2', 'w', 'a']
+  w:
+    shift: 'W'
+    neighbors: ['q', '2', '3', 'e', 'a', 's']
+  e:
+    shift: 'E'
+    neighbors: ['w', '3', '4', 'r', 'd', 's']
+  r:
+    shift: 'R'
+    neighbors: ['e', '4', '5', 't', 'f', 'd']
+  t:
+    shift: 'T'
+    neighbors: ['r', '5', '6', 'y', 'g', 'f']
+  y:
+    shift: 'Y'
+    neighbors: ['t', '6', '7', 'u', 'h', 'g']
+  u:
+    shift: 'U'
+    neighbors: ['y', '7', '8', 'i', 'j', 'h']
+  i:
+    shift: 'I'
+    neighbors: ['u', '8', '9', 'o', 'k', 'j']
+  o:
+    shift: 'O'
+    neighbors: ['i', '9', '0', 'p', 'l', 'k']
+  p:
+    shift: 'P'
+    neighbors: ['o', '0', '-', '[', ';', 'l']
+  '[':
+    shift: '{'
+    neighbors: ['p', '-', '=', ']', "'", ';']
+  ']':
+    shift: '}'
+    neighbors: ['[', '=', '\', "'"]
+  '\':
+    shift: '|'
+    neighbors: [']']
+  a:
+    shift: 'A'
+    neighbors: ['q', 'w', 's', 'z']
+  s:
+    shift: 'S'
+    neighbors: ['a', 'w', 'e', 'd', 'x', 'z']
+  d:
+    shift: 'D'
+    neighbors: ['s', 'e', 'r', 'f', 'c', 'x']
+  f:
+    shift: 'F'
+    neighbors: ['d', 'r', 't', 'g', 'v', 'c']
+  g:
+    shift: 'G'
+    neighbors: ['f', 't', 'y', 'h', 'b', 'v']
+  h:
+    shift: 'H'
+    neighbors: ['g', 'y', 'u', 'j', 'n', 'b']
+  j:
+    shift: 'J'
+    neighbors: ['h', 'u', 'i', 'k', 'm', 'n']
+  k:
+    shift: 'K'
+    neighbors: ['j', 'i', 'o', 'l', ',', 'm']
+  l:
+    shift: 'L'
+    neighbors: ['k', 'o', 'p', ';', '.', ',']
+  ';':
+    shift: ':'
+    neighbors: ['l', 'p', '[', "'", '/', '.']
+  "'":
+    shift: '"'
+    neighbors: [';', '[', ']', '/']
+  z:
+    shift: 'Z'
+    neighbors: ['a', 's', 'x']
+  x:
+    shift: 'X'
+    neighbors: ['z', 's', 'd', 'c']
+  c:
+    shift: 'C'
+    neighbors: ['x', 'd', 'f', 'v']
+  v:
+    shift: 'V'
+    neighbors: ['c', 'f', 'g', 'b']
+  b:
+    shift: 'B'
+    neighbors: ['v', 'g', 'h', 'n']
+  n:
+    shift: 'N'
+    neighbors: ['b', 'h', 'j', 'm']
+  m:
+    shift: 'M'
+    neighbors: ['n', 'j', 'k', ',']
+  ',':
+    shift: '<'
+    neighbors: ['m', 'k', 'l', '.']
+  '.':
+    shift: '>'
+    neighbors: [',', 'l', ';', '/']
+  '/':
+    shift: '?'
+    neighbors: ['.', ';', "'"]
+  ' ':
+    shift: ' '
+    neighbors: ['x', 'c', 'v', 'b', 'n', 'm', ',']
diff --git a/src/typhar.cr b/src/typhar.cr
index 1749e37..c80c78d 100644
--- a/src/typhar.cr
+++ b/src/typhar.cr
@@ -1,5 +1,6 @@
 require "cli"
 require "secure_random"
+require "yaml"
 require "./typhar/*"
 
 module Typhar
diff --git a/src/typhar/cli.cr b/src/typhar/cli.cr
index 2f811d3..a51acb0 100644
--- a/src/typhar/cli.cr
+++ b/src/typhar/cli.cr
@@ -83,6 +83,9 @@ module Typhar
         when "n-shifter"
           codepoint_shift = options.codepoint_shift.to_i
           Typhar::ReplacementStrategies::NShifter.new(seed, codepoint_shift)
+        when "keymap"
+          keymap_name = "en-US_qwerty"
+          Typhar::ReplacementStrategies::Keymap.new(seed, keymap_name)
         else
           raise StrategyDoesNotExistException.new("'#{strategy}' does not exist.")
         end
diff --git a/src/typhar/exceptions.cr b/src/typhar/exceptions.cr
index a1ec217..876499a 100644
--- a/src/typhar/exceptions.cr
+++ b/src/typhar/exceptions.cr
@@ -4,4 +4,7 @@ module Typhar
 
   class StrategyDoesNotExistException < Exception
   end
+
+  class UnknownKeyError < Exception
+  end
 end
\ No newline at end of file
diff --git a/src/typhar/strategies/replacement/keymap.cr b/src/typhar/strategies/replacement/keymap.cr
new file mode 100644
index 0000000..d45b152
--- /dev/null
+++ b/src/typhar/strategies/replacement/keymap.cr
@@ -0,0 +1,30 @@
+module Typhar
+  module ReplacementStrategies
+    class Keymap < Base
+      @keymap : Typhar::Types::Keymap
+
+      getter keymap_name
+      getter keymap
+
+      def initialize(@seed : UInt32, @keymap_name : String)
+        keymap_yml = File.read("./data/keymaps/#{keymap_name}.yml")
+        @keymap = Typhar::Types::Keymap.from_yaml(keymap_yml).not_nil!
+        @keymap.dereference!
+      end
+
+      def replace(to_replace : String | Char) : String | Char
+        keymap_entry = keymap[to_replace]?
+
+        if keymap_entry
+          keymap_entry.neighbors.sample(sampler)
+        else
+          raise UnknownKeyError.new("Unknown key '#{to_replace}' in keymap")
+        end
+      end
+
+      private def sampler
+        @sampler ||= Random.new(seed)
+      end
+    end
+  end
+end
diff --git a/src/typhar/transformer.cr b/src/typhar/transformer.cr
index f5602b2..3602ba8 100644
--- a/src/typhar/transformer.cr
+++ b/src/typhar/transformer.cr
@@ -1,3 +1,4 @@
+require "./types/*"
 require "./strategies/*"
 
 module Typhar
diff --git a/src/typhar/types/keymap.cr b/src/typhar/types/keymap.cr
new file mode 100644
index 0000000..226329c
--- /dev/null
+++ b/src/typhar/types/keymap.cr
@@ -0,0 +1,39 @@
+module Typhar
+  module Types
+    class Keymap
+      YAML.mapping(
+        data: {
+          type: Hash(String, KeymapEntry)
+        }
+      )
+
+      def [](key)
+        data[key]?.not_nil!
+      end
+
+      def []?(key)
+        data.fetch(key.to_s) do |key|
+          result = data.find { |k, v| v.shift == key }
+          if result
+            result[1]
+          else
+            nil
+          end
+        end
+      end
+
+      def dereference!
+        data.map do |key, value|
+          value.neighbors = value.neighbors.flat_map do |neighbor|
+            if data[neighbor]?
+              neighbor_entry = data[neighbor]
+              [neighbor, neighbor_entry.shift]
+            else
+              raise UnknownKeyError.new("Unknown key '#{neighbor}' in keymap")
+            end
+          end
+        end
+      end
+    end
+  end
+end
diff --git a/src/typhar/types/keymap_entry.cr b/src/typhar/types/keymap_entry.cr
new file mode 100644
index 0000000..bc66b32
--- /dev/null
+++ b/src/typhar/types/keymap_entry.cr
@@ -0,0 +1,10 @@
+module Typhar
+  module Types
+    class KeymapEntry
+      YAML.mapping(
+        shift: String,
+        neighbors: Array(String)
+      )
+    end
+  end
+end