From 8fbe3adc8b5254e553637add4679591782277164 Mon Sep 17 00:00:00 2001
From: Glenn Jackman <glenn.jackman@gmail.com>
Date: Wed, 18 Mar 2026 08:32:38 -0400
Subject: [PATCH] Add secret-handshake

---
 config.json                                   | 24 +++++---
 exercises/practice/secret-handshake/.busted   |  5 ++
 .../secret-handshake/.docs/instructions.md    | 48 ++++++++++++++++
 .../secret-handshake/.docs/introduction.md    |  7 +++
 .../secret-handshake/.meta/config.json        | 19 +++++++
 .../secret-handshake/.meta/example.moon       | 18 ++++++
 .../.meta/spec_generator.moon                 | 16 ++++++
 .../secret-handshake/.meta/tests.toml         | 43 ++++++++++++++
 .../secret-handshake/secret_handshake.moon    |  4 ++
 .../secret_handshake_spec.moon                | 57 +++++++++++++++++++
 10 files changed, 233 insertions(+), 8 deletions(-)
 create mode 100644 exercises/practice/secret-handshake/.busted
 create mode 100644 exercises/practice/secret-handshake/.docs/instructions.md
 create mode 100644 exercises/practice/secret-handshake/.docs/introduction.md
 create mode 100644 exercises/practice/secret-handshake/.meta/config.json
 create mode 100644 exercises/practice/secret-handshake/.meta/example.moon
 create mode 100644 exercises/practice/secret-handshake/.meta/spec_generator.moon
 create mode 100644 exercises/practice/secret-handshake/.meta/tests.toml
 create mode 100644 exercises/practice/secret-handshake/secret_handshake.moon
 create mode 100644 exercises/practice/secret-handshake/secret_handshake_spec.moon

diff --git a/config.json b/config.json
index 54eb20b..be183d8 100644
--- a/config.json
+++ b/config.json
@@ -178,14 +178,6 @@
         "prerequisites": [],
         "difficulty": 2
       },
-      {
-        "slug": "rotational-cipher",
-        "name": "Rotational Cipher",
-        "uuid": "365fb81f-c059-4231-954b-bac1878e2a0c",
-        "practices": [],
-        "prerequisites": [],
-        "difficulty": 3
-      },
       {
         "slug": "rna-transcription",
         "name": "RNA Transcription",
@@ -346,6 +338,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "rotational-cipher",
+        "name": "Rotational Cipher",
+        "uuid": "365fb81f-c059-4231-954b-bac1878e2a0c",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "scrabble-score",
         "name": "Scrabble Score",
@@ -354,6 +354,14 @@
         "prerequisites": [],
         "difficulty": 3
       },
+      {
+        "slug": "secret-handshake",
+        "name": "Secret Handshake",
+        "uuid": "cf4561c6-c986-4136-8247-b3318cb54cd2",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 3
+      },
       {
         "slug": "space-age",
         "name": "Space Age",
diff --git a/exercises/practice/secret-handshake/.busted b/exercises/practice/secret-handshake/.busted
new file mode 100644
index 0000000..86b84e7
--- /dev/null
+++ b/exercises/practice/secret-handshake/.busted
@@ -0,0 +1,5 @@
+return {
+  default = {
+    ROOT = { '.' }
+  }
+}
diff --git a/exercises/practice/secret-handshake/.docs/instructions.md b/exercises/practice/secret-handshake/.docs/instructions.md
new file mode 100644
index 0000000..d2120b9
--- /dev/null
+++ b/exercises/practice/secret-handshake/.docs/instructions.md
@@ -0,0 +1,48 @@
+# Instructions
+
+Your task is to convert a number between 1 and 31 to a sequence of actions in the secret handshake.
+
+The sequence of actions is chosen by looking at the rightmost five digits of the number once it's been converted to binary.
+Start at the right-most digit and move left.
+
+The actions for each number place are:
+
+```plaintext
+00001 = wink
+00010 = double blink
+00100 = close your eyes
+01000 = jump
+10000 = Reverse the order of the operations in the secret handshake.
+```
+
+Let's use the number `9` as an example:
+
+- 9 in binary is `1001`.
+- The digit that is farthest to the right is 1, so the first action is `wink`.
+- Going left, the next digit is 0, so there is no double-blink.
+- Going left again, the next digit is 0, so you leave your eyes open.
+- Going left again, the next digit is 1, so you jump.
+
+That was the last digit, so the final code is:
+
+```plaintext
+wink, jump
+```
+
+Given the number 26, which is `11010` in binary, we get the following actions:
+
+- double blink
+- jump
+- reverse actions
+
+The secret handshake for 26 is therefore:
+
+```plaintext
+jump, double blink
+```
+
+~~~~exercism/note
+If you aren't sure what binary is or how it works, check out [this binary tutorial][intro-to-binary].
+
+[intro-to-binary]: https://medium.com/basecs/bits-bytes-building-with-binary-13cb4289aafa
+~~~~
diff --git a/exercises/practice/secret-handshake/.docs/introduction.md b/exercises/practice/secret-handshake/.docs/introduction.md
new file mode 100644
index 0000000..176b92e
--- /dev/null
+++ b/exercises/practice/secret-handshake/.docs/introduction.md
@@ -0,0 +1,7 @@
+# Introduction
+
+You are starting a secret coding club with some friends and friends-of-friends.
+Not everyone knows each other, so you and your friends have decided to create a secret handshake that you can use to recognize that someone is a member.
+You don't want anyone who isn't in the know to be able to crack the code.
+
+You've designed the code so that one person says a number between 1 and 31, and the other person turns it into a series of actions.
diff --git a/exercises/practice/secret-handshake/.meta/config.json b/exercises/practice/secret-handshake/.meta/config.json
new file mode 100644
index 0000000..3ea1730
--- /dev/null
+++ b/exercises/practice/secret-handshake/.meta/config.json
@@ -0,0 +1,19 @@
+{
+  "authors": [
+    "glennj"
+  ],
+  "files": {
+    "solution": [
+      "secret_handshake.moon"
+    ],
+    "test": [
+      "secret_handshake_spec.moon"
+    ],
+    "example": [
+      ".meta/example.moon"
+    ]
+  },
+  "blurb": "Given a decimal number, convert it to the appropriate sequence of events for a secret handshake.",
+  "source": "Bert, in Mary Poppins",
+  "source_url": "https://www.imdb.com/title/tt0058331/quotes/?item=qt0437047"
+}
diff --git a/exercises/practice/secret-handshake/.meta/example.moon b/exercises/practice/secret-handshake/.meta/example.moon
new file mode 100644
index 0000000..605a06f
--- /dev/null
+++ b/exercises/practice/secret-handshake/.meta/example.moon
@@ -0,0 +1,18 @@
+actions = {'wink', 'double blink', 'close your eyes', 'jump'}
+      
+-- reverse a table _in-place_
+treverse = (t) ->
+  i, j = 1, #t
+  while i < j
+    t[i], t[j] = t[j], t[i]
+    i += 1
+    j -= 1
+
+{
+  commands: (value) ->
+    return {} unless value > 0
+    result = [a for i, a in ipairs actions when (value >> (i-1)) & 1 == 1]
+    treverse result if (value >> #actions) & 1 == 1
+    result
+}
+
diff --git a/exercises/practice/secret-handshake/.meta/spec_generator.moon b/exercises/practice/secret-handshake/.meta/spec_generator.moon
new file mode 100644
index 0000000..d33e9a0
--- /dev/null
+++ b/exercises/practice/secret-handshake/.meta/spec_generator.moon
@@ -0,0 +1,16 @@
+list_of_strings = (list) ->
+  "{#{table.concat [quote word for word in *list], ', '}}"
+
+{
+  module_name: 'SecretHandshake',
+
+  generate_test: (case, level) ->
+    local lines
+    -- you may want to "switch case.property" here
+    lines = {
+      "result = SecretHandshake.#{case.property} #{case.input.number}",
+      "expected = #{list_of_strings case.expected}",
+      "assert.are.same expected, result"
+    }
+    table.concat [indent line, level for line in *lines], '\n'
+}
diff --git a/exercises/practice/secret-handshake/.meta/tests.toml b/exercises/practice/secret-handshake/.meta/tests.toml
new file mode 100644
index 0000000..f318e52
--- /dev/null
+++ b/exercises/practice/secret-handshake/.meta/tests.toml
@@ -0,0 +1,43 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[b8496fbd-6778-468c-8054-648d03c4bb23]
+description = "wink for 1"
+
+[83ec6c58-81a9-4fd1-bfaf-0160514fc0e3]
+description = "double blink for 10"
+
+[0e20e466-3519-4134-8082-5639d85fef71]
+description = "close your eyes for 100"
+
+[b339ddbb-88b7-4b7d-9b19-4134030d9ac0]
+description = "jump for 1000"
+
+[40499fb4-e60c-43d7-8b98-0de3ca44e0eb]
+description = "combine two actions"
+
+[9730cdd5-ef27-494b-afd3-5c91ad6c3d9d]
+description = "reverse two actions"
+
+[0b828205-51ca-45cd-90d5-f2506013f25f]
+description = "reversing one action gives the same action"
+
+[9949e2ac-6c9c-4330-b685-2089ab28b05f]
+description = "reversing no actions still gives no actions"
+
+[23fdca98-676b-4848-970d-cfed7be39f81]
+description = "all possible actions"
+
+[ae8fe006-d910-4d6f-be00-54b7c3799e79]
+description = "reverse all possible actions"
+
+[3d36da37-b31f-4cdb-a396-d93a2ee1c4a5]
+description = "do nothing for zero"
diff --git a/exercises/practice/secret-handshake/secret_handshake.moon b/exercises/practice/secret-handshake/secret_handshake.moon
new file mode 100644
index 0000000..d38d5ac
--- /dev/null
+++ b/exercises/practice/secret-handshake/secret_handshake.moon
@@ -0,0 +1,4 @@
+{
+  commands: (value) ->
+    error 'Implement me'
+}
diff --git a/exercises/practice/secret-handshake/secret_handshake_spec.moon b/exercises/practice/secret-handshake/secret_handshake_spec.moon
new file mode 100644
index 0000000..9bd6d3b
--- /dev/null
+++ b/exercises/practice/secret-handshake/secret_handshake_spec.moon
@@ -0,0 +1,57 @@
+SecretHandshake = require 'secret_handshake'
+
+describe 'secret-handshake', ->
+  it 'wink for 1', ->
+    result = SecretHandshake.commands 1
+    expected = {'wink'}
+    assert.are.same expected, result
+
+  pending 'double blink for 10', ->
+    result = SecretHandshake.commands 2
+    expected = {'double blink'}
+    assert.are.same expected, result
+
+  pending 'close your eyes for 100', ->
+    result = SecretHandshake.commands 4
+    expected = {'close your eyes'}
+    assert.are.same expected, result
+
+  pending 'jump for 1000', ->
+    result = SecretHandshake.commands 8
+    expected = {'jump'}
+    assert.are.same expected, result
+
+  pending 'combine two actions', ->
+    result = SecretHandshake.commands 3
+    expected = {'wink', 'double blink'}
+    assert.are.same expected, result
+
+  pending 'reverse two actions', ->
+    result = SecretHandshake.commands 19
+    expected = {'double blink', 'wink'}
+    assert.are.same expected, result
+
+  pending 'reversing one action gives the same action', ->
+    result = SecretHandshake.commands 24
+    expected = {'jump'}
+    assert.are.same expected, result
+
+  pending 'reversing no actions still gives no actions', ->
+    result = SecretHandshake.commands 16
+    expected = {}
+    assert.are.same expected, result
+
+  pending 'all possible actions', ->
+    result = SecretHandshake.commands 15
+    expected = {'wink', 'double blink', 'close your eyes', 'jump'}
+    assert.are.same expected, result
+
+  pending 'reverse all possible actions', ->
+    result = SecretHandshake.commands 31
+    expected = {'jump', 'close your eyes', 'double blink', 'wink'}
+    assert.are.same expected, result
+
+  pending 'do nothing for zero', ->
+    result = SecretHandshake.commands 0
+    expected = {}
+    assert.are.same expected, result