'use strict';

const API_BASE = `https://jessemcdonald.info/pacosako/api`;

const SHORT_TIMEOUT = 5000/*ms*/;
const LONG_TIMEOUT = 90000/*ms*/;

const RETRIES = 3;
const RETRY_DELAY = 1000/*ms*/;

const games = {};

const meta = {
   games: {},
   lastModified: 0,
   listeners: {},
   nextId: 1,
   currentRequest: null,
};

/* One-time request, no caching or polling */
function getGameState(gameId, retries) {
   if (arguments.length < 2) {
      retries = RETRIES;
   }
   return new Promise((resolve, reject) => {
      $.ajax({
         dataType: 'json',
         contentType: 'application/json',
         url: `${API_BASE}/game/${gameId}`,
         cache: false,
         timeout: SHORT_TIMEOUT,
      }).done((data, textStatus, jqXHR) => {
         resolve(data);
      }).fail((jqXHR, textStatus, errorThrown) => {
         if ((!jqXHR.status || jqXHR.status < 400 || jqXHR.status > 499) && retries > 0) {
            setTimeout(() => {
               getGameState(gameId, retries - 1).then(resolve, reject);
            }, RETRY_DELAY);
         } else {
            reject({ status: jqXHR.status, data: jqXHR.responseJSON, textStatus, errorThrown });
         }
      });
   });
}

/* One-time request, no caching or polling */
function getGameMeta(gameId, retries) {
   if (arguments.length < 2) {
      retries = RETRIES;
   }
   return new Promise((resolve, reject) => {
      $.ajax({
         dataType: 'json',
         contentType: 'application/json',
         url: `${API_BASE}/meta/${gameId}`,
         cache: false,
         timeout: SHORT_TIMEOUT,
      }).done((data, textStatus, jqXHR) => {
         resolve(data);
      }).fail((jqXHR, textStatus, errorThrown) => {
         if ((!jqXHR.status || jqXHR.status < 400 || jqXHR.status > 499) && retries > 0) {
            setTimeout(() => {
               getGameMeta(gameId, retries - 1).then(resolve, reject);
            }, RETRY_DELAY);
         } else {
            reject({ status: jqXHR.status, data: jqXHR.responseJSON, textStatus, errorThrown });
         }
      });
   });
}

function onGameUpdate(gameId, callback) {
   const game = gamePollState(gameId);

   if (Object.keys(game.listeners).length === 0) {
      startGamePoll(gameId, game.data.modified);
   }

   const cbId = game.nextId;
   game.nextId += 1;
   game.listeners[cbId] = callback;

   /* delay the initial run of the callback to the microtask queue */
   (Promise.resolve()).then(() => {
      if (cbId in game.listeners) {
         try {
            callback(game.data, gameId);
         } catch(err) {
            console.error('uncaught exception in callback', err);
         }
      }
   });

   return function clearGameUpdate(keepPolling) {
      if (cbId in game.listeners) {
         delete game.listeners[cbId];
         if (!keepPolling && Object.keys(game.listeners).length === 0) {
            stopGamePoll(gameId);
         }
      }
   }
}

function onMetaUpdate(callback) {
   if (Object.keys(meta.listeners).length === 0) {
      startMetaPoll(meta.lastModified);
   }

   const cbId = meta.nextId;
   meta.nextId += 1;
   meta.listeners[cbId] = callback;

   /* delay the initial run of the callback to the microtask queue */
   (Promise.resolve()).then(() => {
      if (cbId in meta.listeners) {
         for (const gameId in meta.games) {
            try {
               callback(meta.games[gameId], gameId);
            } catch(err) {
               console.error('uncaught exception in callback', err);
            }
         }
      }
   });

   return function clearMetaUpdate(keepPolling) {
      if (cbId in meta.listeners) {
         delete meta.listeners[cbId];
         if (!keepPolling && Object.keys(meta.listeners).length === 0) {
            stopMetaPoll();
         }
      }
   }
}

function sendUpdate(gameId, data, retries) {
   if (arguments.length < 3) {
      retries = RETRIES;
   }
   return new Promise((resolve, reject) => {
      $.ajax({
         dataType: 'json',
         contentType: 'application/json',
         url: `${API_BASE}/game/${gameId}`,
         method: 'POST',
         cache: false,
         data: JSON.stringify(data),
         timeout: SHORT_TIMEOUT,
      }).done((responseData, textStatus, jqXHR) => {
         resolve({ status: jqXHR.status, data: responseData });
      }).fail((jqXHR, textStatus, errorThrown) => {
         if ((!jqXHR.status || jqXHR.status < 400 || jqXHR.status > 499) && retries > 0) {
            setTimeout(() => {
               sendUpdate(gameId, data, retries - 1).then(resolve, reject);
            }, RETRY_DELAY);
         } else {
            reject({ status: jqXHR.status, data: jqXHR.responseJSON, textStatus, errorThrown });
         }
      });
   });
}

function gamePollState(gameId) {
   if (gameId in games === false) {
      games[gameId] = {
         currentRequest: null,
         data: { gameId, modified: 0 },
         listeners: [],
         nextId: 1,
      };
   }

   return games[gameId];
}

function processGame(gameId, data) {
   const game = gamePollState(gameId);

   if (data && data.modified > game.data.modified) {
      game.data = data;
      for (const cbId in game.listeners) {
         try {
            game.listeners[cbId](data, gameId);
         } catch(err) {
            console.error('uncaught exception in callback', err);
         }
      }
   }
}

function startGamePoll(gameId, afterTime) {
   const game = gamePollState(gameId);

   if (game.currentRequest === null) {
      if (afterTime === undefined) {
         afterTime = game.data.modified;
      }

      const thisRequest = game.currentRequest = $.ajax({
         dataType: 'json',
         contentType: 'application/json',
         url: `${API_BASE}/game/${gameId}/poll/${afterTime}`,
         cache: false,
         timeout: LONG_TIMEOUT,
      }).done((data, textStatus, jqXHR) => {
         if (game.currentRequest === thisRequest) {
            game.currentRequest = null;
            if (jqXHR.status == 204) {
               startGamePoll(gameId, afterTime);
            } else {
               processGame(gameId, data);
               startGamePoll(gameId, data.modified);
            }
         }
      }).fail((jqXHR, textStatus, errorThrown) => {
         if (game.currentRequest === thisRequest) {
            setTimeout(() => {
               if (game.currentRequest === thisRequest) {
                  game.currentRequest = null;
                  startGamePoll(gameId, 0);
               }
            }, RETRY_DELAY);
         }
      });
   }
}

function stopGamePoll(gameId) {
   if (gameId in games === false) {
      return;
   }

   const game = games[gameId];
   const request = game.currentRequest;
   if (request !== null) {
      game.currentRequest = null;
      request.abort();
   }
}

function processMeta(data) {
   meta.lastModified = data.modified;

   for (const game of data.games) {
      if (game.gameId in meta.games === false || game.modified > meta.games[game.gameId].modified) {
         meta.games[game.gameId] = game;
         for (const cbId in meta.listeners) {
            try {
               meta.listeners[cbId](game, game.gameId);
            } catch(err) {
               console.error('uncaught exception in callback', err);
            }
         }
      }
   }
}

function startMetaPoll(afterTime) {
   if (meta.currentRequest === null) {
      if (afterTime === undefined) {
         afterTime = meta.lastModified;
      }

      const thisRequest = meta.currentRequest = $.ajax({
         dataType: 'json',
         contentType: 'application/json',
         url: `https://jessemcdonald.info/pacosako/api/games/poll/${afterTime}`,
         cache: false,
         timeout: LONG_TIMEOUT,
      }).done((data, textStatus, jqXHR) => {
         if (meta.currentRequest === thisRequest) {
            meta.currentRequest = null;
            if (jqXHR.status == 204) {
               startMetaPoll(afterTime);
            } else {
               processMeta(data);
               startMetaPoll(data.modified);
            }
         }
      }).fail((jqXHR, textStatus, errorThrown) => {
         if (meta.currentRequest === thisRequest) {
            setTimeout(() => {
               if (meta.currentRequest === thisRequest) {
                  meta.currentRequest = null;
                  startMetaPoll(0);
               }
            }, RETRY_DELAY);
         }
      });
   }
}

function stopMetaPoll() {
   const request = meta.currentRequest;
   if (request !== null) {
      meta.currentRequest = null;
      request.abort();
   }
}

module.exports = {
   getGameState,
   getGameMeta,
   onGameUpdate,
   onMetaUpdate,
   sendUpdate,
};

/* vim:set expandtab sw=3 ts=8: */