From e3afffc91d678301fcf7660db541cacc8b7a4e8d Mon Sep 17 00:00:00 2001
From: Marcin Chrzanowski <marcin.j.chrzanowski@gmail.com>
Date: Sat, 17 Aug 2019 23:31:13 -0700
Subject: Initial commit

---
 engine.rb | 51 +++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 51 insertions(+)
 create mode 100644 engine.rb

(limited to 'engine.rb')

diff --git a/engine.rb b/engine.rb
new file mode 100644
index 0000000..638a80e
--- /dev/null
+++ b/engine.rb
@@ -0,0 +1,51 @@
+class Engine
+  def initialize hash
+    validate_checksum hash
+    hash_to_state hash
+  end
+
+  def validate_checksum hash
+    if !checksum_valid? hash
+      throw 'Invalid state, checksum does not match!'
+    end
+  end
+
+  def checksum_valid? hash
+    if hash.empty?
+      return true
+    end
+
+    expected = checksum hash
+    expected == hash['checksum']
+  end
+
+  def checksum hash
+    string = hash
+      .keys
+      .filter { |k| k != 'checksum' }
+      .sort
+      .map { |k| "#{k}:#{hash[k]}" }
+      .append("secret:#{secret}")
+      .join '|'
+    Digest::SHA2.hexdigest string
+  end
+
+  def hash_to_state hash
+  end
+
+  def step command
+  end
+
+  def state_h
+    hash = state_to_hash
+    hash[:checksum] = checksum hash
+    hash
+  end
+
+  def state_to_hash
+    {}
+  end
+
+  def message
+  end
+end
-- 
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