import * as iter from './iterator.js';

const RUN_COALESCE_MAX_INTERVAL = 10 /* min */ * 60 /* sec */ * 1000; /* ms */

export function runs(messages, self) {
  const bareRuns = iter.chunkBy(messages, runKey, continueRun);
  return iter.map(bareRuns, (run) => summarizeRun(self, run));
}

function summarizeRun(self, { key, chunk }) {
  const [sender, at] = key;
  return {
    sender: sender.name,
    ownMessage: sender.id === self.id,
    messages: chunk
  };
}

function runKey(message) {
  return [message.sender, message.at];
}

function continueRun([lastSender, lastAt], [newSender, newAt]) {
  const { id: lastId, name: lastName } = lastSender;
  const { id: newId, name: newName } = newSender;
  if (lastId !== newId) {
    return false;
  }
  if (lastName !== newName) {
    return false;
  }
  return newAt - lastAt < RUN_COALESCE_MAX_INTERVAL;
}