From 780f85fc9d729735b192db866ad9a19484dc5743 Mon Sep 17 00:00:00 2001
From: a14m <a14m@pm.me>
Date: Thu, 10 Dec 2020 21:14:19 +0100
Subject: Add the stable seed generator implementation

---
 CLI/ruby/lib/game_of_life/generators/seed.rb | 37 +++++++++++++++++++++++++++-
 1 file changed, 36 insertions(+), 1 deletion(-)

diff --git a/CLI/ruby/lib/game_of_life/generators/seed.rb b/CLI/ruby/lib/game_of_life/generators/seed.rb
index e64a28f..917c9af 100644
--- a/CLI/ruby/lib/game_of_life/generators/seed.rb
+++ b/CLI/ruby/lib/game_of_life/generators/seed.rb
@@ -12,7 +12,42 @@ module GameOfLife
         # @option options [Numeric] "height" (floored) and used as the height of the universe
         # @return [GameOfLife::Universe] populated with the parsed input
         def new(options)
-          fail ::NotImplementedError, "Seed option isn't implemented yet, please use --input option"
+          width  = options["width"].to_i
+          height = options["height"].to_i
+          seed   = options["seed"].to_i
+          input = generate_seed_data(seed: seed, width: width, height: height)
+          populate(input: input, width: width, height: height)
+        end
+
+        # Generate the seeding data for populating the {GameOfLife::Universe}
+        # @param seed [Integer] used to generate {Array<"0"|"1">} using Std ruby {Random}
+        # @param width [Integer] width of the generated cyclic universe
+        # @param height [Integer] height of the generated cyclic universe
+        # @return [Array<Array<True|False>>] covering the defined size of universe
+        # @see ::GameOfLife::Generators::Seed.populate
+        private def generate_seed_data(seed:, width:, height:)
+          # Create a pseudo(stable) random generator from the seed
+          # Generate a sequence of bytes to cover the Game of Life Universe plane
+          # each byte can be unpacked into 8 cells of binary data (ex. "01101011")
+          raw = Random.new(seed).bytes(width * height / 2).unpack1("B*").split("").each_slice(width)
+          raw.map { |row| row.map { |char| char.eql?("1") } }
+        end
+
+        # Populate the {GameOfLife::Universe} with reference to the parsed input 2D array (True/False)
+        # @param input [Array<Array<True|False>>]
+        # @param width [Integer] width of the generated cyclic universe
+        # @param height [Integer] height of the generated cyclic universe
+        # @return [GameOfLife::Universe] populated with the parsed input
+        private def populate(input:, width:, height:)
+          # Generate a universe based on the parsed raw file and fill it with the cells
+          universe = GameOfLife::Universe.new(height: height, width: width)
+          (0...height).each do |i|
+            (0...width).each do |j|
+              cell = { x: j, y: i, alive: input.fetch(i, nil)&.fetch(j, nil) }
+              universe[i][j] = ::GameOfLife::Cell.new(cell)
+            end
+          end
+          universe
         end
       end
     end
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