Automate Your Week: Build an AI-Powered Calendar Briefing

// --- START OF CODE ---

// -----------------------------------------------------------------
// 1. CONFIGURATION
// -----------------------------------------------------------------
const API_KEY = "PASTE_YOUR_API_KEY_HERE"; // Your Gemini API Key
// Add the exact names of the calendars you want to scan below.
const CALENDAR_NAMES_TO_READ = ["your.email@company.com", "Project Calendar"];
const TIMEZONE = Session.getScriptTimeZone();
const EMAIL_SUBJECT = "Weekly Briefing: AI Summary";
const AI_MODEL = "gemini-2.5-flash"; // Stable, efficient model for summarization

/**
 * Primary function executed by the weekly trigger.
 */
function runWeeklySummary() {
  try {
    const userEmail = Session.getActiveUser().getEmail();
    if (!userEmail) return;

    const eventsString = getUpcomingWeekEvents(userEmail);
    const tasksString = getUpcomingWeekTasks();
    
    if (eventsString.includes("No upcoming events") && tasksString.includes("No upcoming Tasks")) {
      Logger.log("Schedule clear. No summary needed.");
      return;
    }

    const combinedData = eventsString + "\n\n" + tasksString;
    const summary = generateAISummary(combinedData, userEmail);
    sendSummaryEmail(userEmail, summary);

  } catch (e) {
    Logger.log("Error in runWeeklySummary: " + e.toString());
    MailApp.sendEmail(Session.getActiveUser().getEmail(), "Weekly Script Error", e.toString());
  }
}

/**
 * Aggregates events from all specified calendars.
 */
function getUpcomingWeekEvents(userEmail) {
  const today = new Date();
  const nextWeek = new Date();
  nextWeek.setDate(today.getDate() + 7);
  let allEvents = [];

  CALENDAR_NAMES_TO_READ.forEach(calName => {
    const calendars = CalendarApp.getCalendarsByName(calName);
    calendars.forEach(cal => {
      allEvents = allEvents.concat(cal.getEvents(today, nextWeek).map(event => ({
        event: event,
        calendarName: cal.getName()
      })));
    });
  });

  if (allEvents.length === 0) return "No upcoming events found.";

  allEvents.sort((a, b) => a.event.getStartTime() - b.event.getStartTime());

  let eventList = "Upcoming Calendar Events:\n\n";
  const userLower = userEmail.toLowerCase();

  allEvents.forEach(item => {
    const { event, calendarName } = item;
    const start = Utilities.formatDate(event.getStartTime(), TIMEZONE, "EEE, MMM d 'at' h:mm a");
    let details = `- [${calendarName}] ${event.getTitle()} (${start})`;

    const creators = event.getCreators();
    if (creators.length > 0 && creators[0].toLowerCase() !== userLower) {
      details += ` (Created by: ${creators[0]})`;
    }
    eventList += details + "\n";
  });

  return eventList;
}

/**
 * Aggregates tasks due in the next 7 days.
 */
function getUpcomingWeekTasks() {
  try {
    const taskLists = Tasks.Tasklists.list().items;
    if (!taskLists) return "No task lists found.";

    const today = new Date();
    today.setHours(0,0,0,0);
    const nextWeek = new Date();
    nextWeek.setDate(today.getDate() + 7);
    
    let taskOutput = "Upcoming Tasks:\n\n";
    let hasTasks = false;

    taskLists.forEach(list => {
      const tasks = Tasks.Tasks.list(list.id, { showCompleted: false }).items;
      if (tasks) {
        tasks.filter(t => t.due).forEach(task => {
          const dueDate = new Date(task.due);
          dueDate.setHours(0,0,0,0);
          if (dueDate >= today && dueDate <= nextWeek) {
             taskOutput += `- [Task] ${task.title} (Due: ${Utilities.formatDate(dueDate, TIMEZONE, "EEE, MMM d")})\n`;
             hasTasks = true;
          }
        });
      }
    });

    return hasTasks ? taskOutput : "No upcoming Tasks found.";
  } catch (e) {
    return "Error fetching tasks. Ensure Tasks API is enabled.";
  }
}

/**
 * Sends data to Gemini API for summarization.
 */
function generateAISummary(data, userEmail) {
  const url = `https://generativelanguage.googleapis.com/v1beta/models/${AI_MODEL}:generateContent?key=${API_KEY}`;
  const prompt = `
    Summarize the following schedule for ${userEmail} for the upcoming week.
    Data sources: 
    - [Calendar Name]: Events from specific calendars.
    - [Task]: To-do items with due dates.
    - (Created by: email): Events owned by others; phrase these as that person's activity, not the user's.
    
    Provide a high-level executive overview first. Then group by day (e.g., ### Monday, November 3rd).
    Keep the tone professional and actionable.
    
    Schedule Data:
    ${data}`;

  const options = {
    'method': 'post',
    'contentType': 'application/json',
    'payload': JSON.stringify({
      contents: [{ parts: [{ text: prompt }] }],
      generationConfig: { temperature: 0.5, maxOutputTokens: 8192 }
    }),
    'muteHttpExceptions': true
  };

  const response = UrlFetchApp.fetch(url, options);
  const json = JSON.parse(response.getContentText());
  
  if (json.candidates && json.candidates[0].content.parts[0].text) {
    return json.candidates[0].content.parts[0].text;
  } else {
    throw new Error("Gemini API failure: " + response.getContentText());
  }
}

/**
 * Formats Markdown to HTML and sends the email.
 */
function sendSummaryEmail(to, markdownSummary) {
  let html = markdownSummary
    .replace(/^### (.*?)$/gm, '<h3 style="margin-top:15px;font-weight:600;">$1</h3>')
    .replace(/\*\*(.*?)\*\*/g, '<strong>$1</strong>')
    .replace(/^\* (.*?)$/gm, '<li style="margin-left:20px;">$1</li>')
    .replace(/\n/g, '<br>');

  GmailApp.sendEmail(to, EMAIL_SUBJECT, "", {
    htmlBody: `<div style="font-family:sans-serif;line-height:1.5;color:#333;">
                 <h2>Weekly Briefing</h2>
                 <div style="background:#f9f9f9;padding:20px;border-left:4px solid #4285f4;">${html}</div>
               </div>`
  });
}

/**
 * One-time setup for the weekly automation trigger.
 */
function setupWeeklyTrigger() {
  const triggers = ScriptApp.getProjectTriggers();
  triggers.forEach(t => ScriptApp.deleteTrigger(t));

  ScriptApp.newTrigger("runWeeklySummary")
    .timeBased().onWeekDay(ScriptApp.WeekDay.SUNDAY).atHour(8).create();
  Logger.log("Weekly Sunday trigger active.");
}

/**
 * Utility to list exact calendar names for configuration.
 */
function logAllCalendarNames() {
  CalendarApp.getAllCalendars().forEach(c => Logger.log(c.getName()));
}
// --- END OF CODE ---