Improve strategy choice based on path (#27)

spec/server_spec.cr

@@ -1,26 +1,48 @@
 require "./spec_helper"
 
-describe "Crystal Snake Server" do
-  it "returns metadata on root path" do
-    get "/"
-    response.status_code.should eq 200
+request_headers = HTTP::Headers{"Content-Type" => "application/json"}
+SUPPORTED_STRATEGIES = [
+  "random",
+  "random_valid",
+  "blast_random_valid",
+  "chase_closest_food",
+  "chase_random_food",
+  "cautious_carol"
+]
+
+describe "Crystal Snake Battlesnake endpoints for all supported strategies" do
+  it "responds with metadata for all supported strategies" do
+    SUPPORTED_STRATEGIES.each do |strategy_name|
+      get "/#{strategy_name}"
+      response.status_code.should eq 200
+      res = Hash(String, String).from_json(response.body)
+      res.keys.should eq(["apiversion", "author", "color", "head", "tail", "version"])
+    end
   end
 
   it "returns 200 on /start" do
-    payload = File.read("./spec/fixtures/start.json")
-    post "/start", body: payload, headers: HTTP::Headers{"Content-Type" => "application/json"}
-    response.status_code.should eq 200
+    SUPPORTED_STRATEGIES.each do |strategy_name|
+      payload = File.read("./spec/fixtures/start.json")
+      post "/#{strategy_name}/start", body: payload, headers: request_headers
+      response.status_code.should eq 200
+    end
   end
 
-  it "returns 200 on /move" do
-    payload = File.read("./spec/fixtures/move.json")
-    post "/move", body: payload, headers: HTTP::Headers{"Content-Type" => "application/json"}
-    response.status_code.should eq 200
+  it "returns 200 and valid move on /move" do
+    SUPPORTED_STRATEGIES.each do |strategy_name|
+      payload = File.read("./spec/fixtures/move.json")
+      post "/#{strategy_name}/move", body: payload, headers: request_headers
+      response.status_code.should eq 200
+      selected_move = Hash(String, String).from_json(response.body)["move"]
+      (Strategy::VALID_MOVES.includes?(selected_move)).should be_true
+    end
   end
 
   it "returns 200 on /end" do
-    payload = File.read("./spec/fixtures/end.json")
-    post "/end", body: payload, headers: HTTP::Headers{"Content-Type" => "application/json"}
-    response.status_code.should eq 200
+    SUPPORTED_STRATEGIES.each do |strategy_name|
+      payload = File.read("./spec/fixtures/end.json")
+      post "/#{strategy_name}/end", body: payload, headers: HTTP::Headers{"Content-Type" => "application/json"}
+      response.status_code.should eq 200
+    end
   end
 end

src/app.cr

@@ -9,9 +9,17 @@ require "../config/**"
 require "./models/**"
 require "./jobs/**"
 
+add_context_storage_type(Strategy::Base)
 persist_to_db = ENV["DISABLE_DB_PERSIST"]?.nil?
-selected_strategy = ENV["STRATEGY"] ||= "RandomValid"
-Log.info { "Selected strategy: #{selected_strategy}" }
+not_found_response = "
+  <p style='margin-top: 100px;'>
+    <center>
+      Strategy Not Found.
+      <br><br>
+      <a href='https://github.com/fdocr/crystalsnake'>Read usage details</a>
+    </center>
+  </p>
+"
 
 macro persist_turn!
   PersistTurnJob.new(
@@ -25,10 +33,23 @@ def truncate_uuid(str)
 end
 
 before_all do |env|
-  env.response.content_type = "application/json" unless env.request.path =~ /\/games?/
+  next if env.request.path =~ /\/games?/
+
+  env.response.content_type = "application/json"
+  next if env.params.json.empty?
+
+  context = BattleSnake::Context.from_json(env.params.json.to_json)
+  strategy = Strategy.build(env.params.url["strategy"], context)
+  halt env, status_code: 404, response: not_found_response if strategy.nil?
+  env.set("strategy", strategy)
+end
+
+get "/strategy_not_found" do |env|
+  halt env, status_code: 404, response: not_found_response
 end
 
-get "/" do
+# Battlesnake API Endpoints
+get "/:strategy" do |env|
   {
     "apiversion": "1",
     "author": "fdocr",
@@ -39,39 +60,22 @@ get "/" do
   }.to_json
 end
 
-post "/start" do |env|
-  context = BattleSnake::Context.from_json(env.params.json.to_json)
+post "/:strategy/start" do |env|
   persist_turn!
 end
 
-post "/move" do |env|
-  context = BattleSnake::Context.from_json(env.params.json.to_json)
+post "/:strategy/move" do |env|
   persist_turn!
-
-  case selected_strategy
-  when "RandomValid"
-    move = Strategy::RandomValid.new(context).move
-  when "BlastRandomValid"
-    move = Strategy::BlastRandomValid.new(context).move
-  when "ChaseClosestFood"
-    move = Strategy::ChaseClosestFood.new(context).move
-  when "ChaseRandomFood"
-    move = Strategy::ChaseRandomFood.new(context).move
-  when "CautiousCarol"
-    move = Strategy::CautiousCarol.new(context).move
-  else
-    move = Strategy::RandomValid.new(context).move
-  end
-
+  move = env.get("strategy").as(Strategy::Base).move
   res = { "move": move, "shout": "Moving #{move}!" }
   res.to_json
 end
 
-post "/end" do |env|
-  context = BattleSnake::Context.from_json(env.params.json.to_json)
+post "/:strategy/end" do |env|
   persist_turn!
 end
 
+# DB-persisted games
 get "/games" do |env|
   offset = (env.params.query["page"]? || 0).to_i * 50
   count = Turn.where { _path == "/end" }.count

src/strategy/base.cr

@@ -1,11 +1,34 @@
 # Abstract class of all strategies. They're all initialized with a *@context*
 # and their entrypoint is the `#move` method
-abstract class Strategy::Base
-  def initialize(@context : BattleSnake::Context)
+module Strategy
+  VALID_MOVES = ["up", "left", "down", "right"]
+
+  def self.build(name, context)
+    case name
+    when "random"
+      Strategy::Random.new(context)
+    when "random_valid"
+      Strategy::RandomValid.new(context)
+    when "blast_random_valid"
+      Strategy::BlastRandomValid.new(context)
+    when "chase_closest_food"
+      Strategy::ChaseClosestFood.new(context)
+    when "chase_random_food"
+      Strategy::ChaseClosestFood.new(context)
+    when "cautious_carol"
+      Strategy::CautiousCarol.new(context)
+    else
+      nil
+    end
   end
 
-  # Returns the move (direction) to chose based on the *@context*
-  def move
-    "up"
+  abstract class Base
+    def initialize(@context : BattleSnake::Context)
+    end
+
+    # Returns the move (direction) to chose based on the *@context*
+    def move
+      "up"
+    end
   end
 end

src/strategy/random.cr

@@ -1,6 +1,6 @@
 # A strategy that chooses a random direction to move without any considerations
 class Strategy::Random < Strategy::Base
   def move
-    ["up", "left", "down", "right"].sample
+    VALID_MOVES.sample
   end
 end