"The backend for a platform-agnostic app using Google App Engine backed by Google Datastore."
This application is the backend for an implementation of the iterated prisoner's dilemma game.

####About the prisoner's dilemma The prisoner's dilemma is a common example in game theory, illustrating a situation in which by optimizing only their own outcomes, two parties cause a non-optimal outcome for both parties.

The situation is as follows:
Two prisoners, or suspects in a crime, are interrogated independently and cannot communicate with each other. They both have the following options; to stay silent, or to admit guilt by defecting and incriminating both themselves and the other party.
Their sentences are determined in the following manner:

(From wikipedia)

One can see from the table above that a party trying to optimize their own outcome (reduce their own sentence) will always choose to defect, as regardless of what the other party chooses, defecting will always reduce the defector's sentence. However, if both parties act in this way they will both receive a two year sentence, which is worse than the one year sentence that they both would have received if they had both stayed silent!

This is interesting in itself, however the iterated prisoner's dilemma is a more interesting game in which the above situation is repeated. In each round, the players (prisoners) decide whether to stay silent or to defect, and are then given the result (their sentence). This process is repeated a number of times until the game is terminated. The number of rounds is not known to the players beforehand. The final scores are determined by the total number of years to be served by each player, where less is better.

###Features

This backend for an online two player iterated prisoner's dilemma game has the following functionality.

• Create Users (players). Users' email addresses are sourced from their google login and are used for game notifications.
• Create Matches with multiple Games between Users. (A Game is a single round in the iterated prisoner's dilemma).
• Play Games with scores saved to User profiles
• Get history of Game results in a Match. (Results of rounds of the prisoner's dilemma).
• Get User rankings
• Notify Users of unfinished Matches by email (automatically every hour).

Python 2.7 (tested with version 2.7.6)
Google App Engine SDK (tested with version 1.9.28)

0. Clone this repository.
1. Create a new project in your Google Cloud Platform Console and copy your application ID to app.yaml in place of udacity-project-4-bryn.
2. Deploy your project. (See the docs for details).

Create Users:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/create_user?user_name=Alice
{ "message": "User Alice created!" }
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/create_user?user_name=Bob
{ "message": "User Bob created!" }

Create a Match between the two Users:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/create_match?player_1_name=Alice&player_2_name=Bob
{ "message": "Match created between Alice and Bob! (key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnISCxIFTWF0Y2gYgICAgICAgAsM)" }

Create a Game in the Match (one round in iterated prisoner's dilemma):
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/create_game?match_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnISCxIFTWF0Y2gYgICAgICAgAsM
{ "message": "Game created between Alice and Bob! (key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACAw)" }

Register the first player's move:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/play_game?game_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACAw&move=true&player_name=Alice
{ "message": "Registered player Alice's play of True in game ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACAw . Not all players have played yet. Match still in progress." }

Register the second player's move:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/play_game?game_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACAw&move=false&player_name=Bob
{ "message": "Registered player Bob's play of False in game ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACAw . Game result: Alice:0 years, Bob:3 years. Match still in progress." }

Repeat for the second (in this case final) Game in the Match:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/create_game?match_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnISCxIFTWF0Y2gYgICAgICAgAsM
{ "message": "Game created between Alice and Bob! (key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACgw)" }
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/play_game?game_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACgw&move=true&player_name=Alice
{ "message": "Registered player Alice's play of True in game ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACgw . Not all players have played yet. Match still in progress." }
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/play_game?game_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACgw&move=true&player_name=Bob
{ "message": "Registered player Bob's play of True in game ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnIjCxIFTWF0Y2gYgICAgICAgAsMCxIER2FtZRiAgICAgIDACgw . Game result: Alice:2 years, Bob:2 years. Match finished. Winner:Alice, Loser:Bob." }

Get the play history for the Match (a list of the Game results):
GET http://localhost:5000/_ah/api/prisonersDilemma/v1/get_match_history?match_key=ahpkZXZ-dWRhY2l0eS1wcm9qZWN0LTQtYnJ5bnISCxIFTWF0Y2gYgICAgICAgAsM
{ "message": [ "Alice:True, Bob:False. Game result: Alice:0 years, Bob:3 years.", "Alice:True, Bob:True. Game result: Alice:2 years, Bob:2 years.", ] }

Get the player rankings:
POST http://localhost:5000/_ah/api/prisonersDilemma/v1/get_user_rankings
{ "message": [ "Alice (score:1)", "Bob (score:-1)" ] }

• create_user

  • Path: 'create_user'
  • Method: POST
  • Parameters: user_name
  • Returns: StringMessage confirming creation of the User.
  • Description: Create a User. Requires a unique username. Gets email from oauth account

• create_match

  • Path: 'create_match'
  • Method: POST
  • Parameters: player_1_name, player_2_name
  • Returns: StringMessage confirming creation of the Match.
  • Description: Create a Match between two Users specified by their names

• create_game

  • Path: 'create_game'
  • Method: POST
  • Parameters: match_key
  • Returns: StringMessage confirming creation of the Game.
  • Description: Create a new Game in a current active Match (between the Users participating in the Match)

• get_game

  • Path: 'get_game'
  • Method: GET
  • Parameters: game_key
  • Returns: StringMessage listing players and game status/result if Game is found.
  • Description: Get a description of a Game from its websafe key

• play_game

  • Path: 'play_game'
  • Method: POST
  • Parameters: game_key, player_name, move
  • Returns: StringMessage listing move and result.
  • Description: Play a single player's move in a Game. A move of 'True' corresponds to defecting and 'False' corresponds to staying silent. If both player's have played, it scores the game and returns the result. It also automatically updates the Match and player User objects.

• get_user_matches

  • Path: 'get_user_matches'
  • Method: GET
  • Parameters: player_name
  • Returns: StringMessage containing list of active matches for the user specified by name
  • Description: Play move in a Game.

• cancel_match

  • Path: 'cancel_match'
  • Method: POST
  • Parameters: match_key
  • Returns: StringMessage containing confirmation message
  • Description: Cancel an active match

• get_user_rankings

  • Path: 'get_user_rankings'
  • Method: GET
  • Parameters: match_key
  • Returns: StringMessage containing list of Users in descending order of score
  • Description: Return list of Users in descending order of score

• get_match_history

  • Path: 'get_match_history'
  • Method: GET
  • Parameters: match_key
  • Returns: StringMessage containing list of Game plays in Match
  • Description: Return list of Game plays in Match

• get_active_users - Path: 'get_active_users' - Method: GET - Parameters: - Returns: StringMessage containing list of users with active matches - Description: Return list of users with active matches