background.js

let lastTabId = -1
let confettiShown = false

const requiredFiles = [
  'lib/confetti.browser.js',
  'src/main/utils.js',
  'src/main/canvas.js',
  'src/main/confetti.js',
  'src/main/main.js'
]

function pageIsAllowed(url) {
  return !url.startsWith('chrome://') && !url.startsWith('chrome-extension://')
}

// On first install, set confettiEveryPage to true
chrome.runtime.onInstalled.addListener(() => {
  chrome.storage.sync.set({ confettiEveryPage: true }, () => {})
})

// On new tab created, reset confettiShown
chrome.tabs.onCreated.addListener((tab) => {
  confettiShown = false
  lastTabId = tab.id
})

// On tab update, show confetti if required
chrome.tabs.onUpdated.addListener((tabId, changeInfo, tab) => {
  chrome.storage.sync.get('confettiEveryPage', ({ confettiEveryPage }) => {
    if (confettiEveryPage && pageIsAllowed(tab.url) && tabId === lastTabId && !confettiShown) {
      chrome.scripting.executeScript({
        target: {
          tabId: tab.id,
        },
        files: requiredFiles,
      })
      confettiShown = true
    }
  })
})

// Show confetti when extension icon clicked
chrome.action.onClicked.addListener(() => {
  chrome.tabs.query({ active: true, currentWindow: true }, (tabs) => {
    const tab = tabs[0]
    if (pageIsAllowed(tab.url)) {
      chrome.scripting.executeScript({
        target: {
          tabId: tab.id,
        },
        files: requiredFiles,
      })
    }
  })
})