From 87376decd1ca693d16e779269f30fc094351c6e7 Mon Sep 17 00:00:00 2001
From: Garrett Bjerkhoel <me@garrettbjerkhoel.com>
Date: Tue, 5 Dec 2023 00:51:50 -0800
Subject: [PATCH 1/2] Start tracking amazon products

---
 build.js                       |  2 +-
 chrome/manifest.json           |  8 ++++-
 firefox/manifest.json          | 12 +++++++
 src/content_scripts/amazon.tsx | 61 ++++++++++++++++++++++++++++++++++
 4 files changed, 81 insertions(+), 2 deletions(-)
 create mode 100644 src/content_scripts/amazon.tsx

diff --git a/build.js b/build.js
index 15a1e98..53adbe3 100755
--- a/build.js
+++ b/build.js
@@ -60,7 +60,7 @@ const cssAsStringPlugin = {
 
 const config = {
   logLevel: 'info',
-  entryPoints: ['./src/background.ts', './src/content_scripts/content_script.tsx'],
+  entryPoints: ['./src/background.ts', './src/content_scripts/content_script.tsx', './src/content_scripts/amazon.tsx'],
   bundle: true,
   sourcemap: !isProduction,
   watch,
diff --git a/chrome/manifest.json b/chrome/manifest.json
index 3d64213..f4821d9 100644
--- a/chrome/manifest.json
+++ b/chrome/manifest.json
@@ -80,7 +80,13 @@
   "content_scripts": [
     {
       "js": ["content_scripts/content_script.js"],
-      "matches": ["<all_urls>"],
+      "matches": ["*://*/*"],
+      "exclude_matches": ["*://*.amazon.com/*"],
+      "run_at": "document_start"
+    },
+    {
+      "js": ["content_scripts/amazon.js"],
+      "matches": ["*://*.amazon.com/*"],
       "run_at": "document_start"
     }
   ]
diff --git a/firefox/manifest.json b/firefox/manifest.json
index 3b34b91..d3dea1f 100644
--- a/firefox/manifest.json
+++ b/firefox/manifest.json
@@ -25,10 +25,22 @@
       "run_at": "document_start",
       "match_about_blank": false,
       "all_frames": false,
+      "exclude_matches": ["*://*.amazon.com/*"],
       "matches": [
         "http://*/*",
         "https://*/*"
       ]
+    },
+    {
+      "js": [
+        "content_scripts/amazon.js"
+      ],
+      "run_at": "document_start",
+      "match_about_blank": false,
+      "all_frames": false,
+      "matches": [
+        "*://*.amazon.com/*"
+      ]
     }
   ],
   "icons": {
diff --git a/src/content_scripts/amazon.tsx b/src/content_scripts/amazon.tsx
new file mode 100644
index 0000000..2866b42
--- /dev/null
+++ b/src/content_scripts/amazon.tsx
@@ -0,0 +1,61 @@
+import browser from 'webextension-polyfill'
+
+import {MessageAction} from '../@types/messages'
+import {ObservableElement} from '../@types/observables'
+import {insertIsInStockButton, removeIsInStockButton} from '../elements/isinstock-button'
+import ExclusiveValidationRequestCache from '../utils/exclusive-validation-request-cache'
+import {observeSelector} from '../utils/observers'
+import {notFoundCallback} from '../utils/products'
+
+const validationRequests = new ExclusiveValidationRequestCache()
+
+// We're observing changes to the DOM to know when to insert the button.
+//
+// link[rel="canonical"] - The canonical link element. This is the link that points to the canonical URL of the page, which contains the URL.
+// #ppd - The product details div. This is the div that contains the product title and price.
+const {search, observe, disconnect} = observeSelector(
+  `link[rel="canonical"], #ppd`,
+  async (observedElements: ObservableElement[], containsProductCandidates: boolean) => {
+    if (/\/dp\//.test(window.location.href)) {
+      console.debug('observeSelector.callback: Product found in link', window.location.href)
+      validationRequests.fetchWithLock(window.location.href, productValidation => {
+        insertIsInStockButton({productValidation})
+      })
+    } else if (!containsProductCandidates) {
+      // Because we don't fire the MutationObserver twice on the same <script>, it's possible there are products on the
+      // page and we should not have any side effects that clear state in this callback.
+      console.debug('observeSelector.callback: No product candidates found in DOM.')
+      removeIsInStockButton()
+      notFoundCallback()
+    }
+  },
+)
+
+window.addEventListener('beforeunload', () => validationRequests.cancelAllRequests())
+window.addEventListener('focus', observe)
+window.addEventListener('blur', disconnect)
+window.addEventListener('pageshow', async event => {
+  // If persisted then it's in the bfcache, meaning the page was restored from the bfcache.
+  if (event.persisted) {
+    console.debug('pageshow: Page was restored from cache.')
+    search({event})
+  } else {
+    console.debug('pageshow: Page was loaded without cache.')
+    observe()
+    search({event})
+  }
+})
+
+window.addEventListener('popstate', event => {
+  console.debug('popstate: The popstate event is fired when the active history entry changes.')
+  search({event})
+})
+
+browser.runtime.onMessage.addListener(async (request, _sender, _sendResponse) => {
+  if (request.action === MessageAction.URLChanged) {
+    const event = new CustomEvent('urlChanged', {detail: {request}})
+    search({event, filterFired: false})
+  } else {
+    console.debug('Unknown action', request.action)
+  }
+})

From 822dedccf87604e50075ca4b3c052eaf225803b2 Mon Sep 17 00:00:00 2001
From: Garrett Bjerkhoel <me@garrettbjerkhoel.com>
Date: Tue, 5 Dec 2023 19:42:25 -0800
Subject: [PATCH 2/2] Add tests for Amazon

---
 src/__tests__/amazon.test.ts | 176 +++++++++++++++++++++++++++++++++++
 1 file changed, 176 insertions(+)
 create mode 100644 src/__tests__/amazon.test.ts

diff --git a/src/__tests__/amazon.test.ts b/src/__tests__/amazon.test.ts
new file mode 100644
index 0000000..66e692f
--- /dev/null
+++ b/src/__tests__/amazon.test.ts
@@ -0,0 +1,176 @@
+import {Browser, HTTPRequest, Page} from 'puppeteer'
+
+import {createBrowser} from '../utils/browser'
+
+const isValidationRequest = (request: HTTPRequest) => {
+  return request.url() === 'https://isinstock.com/api/products/validations' && request.method() === 'POST'
+}
+
+describe('Browser Extension Test', () => {
+  let browser: Browser
+  let page: Page
+
+  beforeAll(async () => {
+    browser = await createBrowser()
+  })
+
+  beforeEach(async () => {
+    page = await browser.newPage()
+  })
+
+  afterEach(async () => {
+    await page.close()
+  })
+
+  afterAll(async () => {
+    if (process.env.CHROME_DEVTOOLS_ID === undefined || process.env.CHROME_DEVTOOLS_ID === '') {
+      await browser.close()
+    }
+  })
+
+  test('extension is installable and renders correctly', async () => {
+    await page.goto('https://www.amazon.com/dp/B08G58D42M/')
+
+    expect(await page.waitForSelector('#isinstock-button')).not.toBe(null)
+  })
+
+  test('available product renders available button', async () => {
+    await page.goto('https://www.amazon.com/dp/B08G58D42M/')
+    await page.waitForSelector('#isinstock-button')
+    const result = await page.evaluate(() => {
+      const button = document.querySelector('#isinstock-button')
+      if (!button) return null
+
+      const shadowRoot = button.shadowRoot
+      if (!shadowRoot) return null
+
+      const element = shadowRoot.querySelector('a[data-inventory-state-normalized]') as HTMLLinkElement
+      return {
+        inventoryState: element?.dataset.inventoryState,
+        inventoryStateNormalized: element?.dataset.inventoryStateNormalized,
+        textContent: element?.textContent,
+        target: element?.target,
+        rel: element?.rel,
+        href: element?.href,
+      }
+    })
+
+    const href = new URL(result?.href ?? '')
+
+    expect(result?.inventoryState).toBe('InStock')
+    expect(result?.inventoryStateNormalized).toBe('available')
+    expect(result?.textContent).toBe('In Stock')
+    expect(result?.target).toBe('_blank')
+    expect(result?.rel).toBe('noreferrer')
+    expect(href.protocol).toBe('https:')
+    expect(href.hostname).toBe('isinstock.com')
+    expect(href.pathname).toBe('/track')
+    expect(href.searchParams.get('url')).toBe('https://www.amazon.com/dp/B08G58D42M/')
+    expect(href.searchParams.get('utm_campaign')).toBe('web_extension')
+  })
+
+  test('does not perform validation request on non-product pages', async () => {
+    await page.setRequestInterception(true)
+    let interceptedValidationsRequest: HTTPRequest | undefined
+    page.on('request', (interceptedRequest: HTTPRequest) => {
+      if (isValidationRequest(interceptedRequest)) {
+        interceptedValidationsRequest = interceptedRequest
+      }
+      interceptedRequest.continue()
+    })
+
+    await page.goto('https://www.amazon.com/')
+
+    expect(interceptedValidationsRequest).toBeUndefined()
+  })
+
+  test.skip('unavailable product renders unavailable button', async () => {
+    await page.goto('https://isinstock.com/store/products/unavailable')
+    await page.waitForSelector('#isinstock-button')
+    const result = await page.evaluate(() => {
+      const button = document.querySelector('#isinstock-button')
+      if (!button) return null
+
+      const shadowRoot = button.shadowRoot
+      if (!shadowRoot) return null
+
+      const element = shadowRoot.querySelector('a[data-inventory-state-normalized]') as HTMLLinkElement
+      return {
+        inventoryState: element?.dataset.inventoryState,
+        inventoryStateNormalized: element?.dataset.inventoryStateNormalized,
+        textContent: element?.textContent,
+        target: element?.target,
+        rel: element?.rel,
+        href: element?.href,
+      }
+    })
+
+    const href = new URL(result?.href ?? '')
+
+    expect(result?.inventoryState).toBe('OutOfStock')
+    expect(result?.inventoryStateNormalized).toBe('unavailable')
+    expect(result?.textContent).toBe('Notify Me When Available')
+    expect(result?.target).toBe('_blank')
+    expect(result?.rel).toBe('noreferrer')
+    expect(href.protocol).toBe('https:')
+    expect(href.hostname).toBe('isinstock.com')
+    expect(href.pathname).toBe('/track')
+    expect(href.searchParams.get('url')).toBe('https://isinstock.com/store/products/unavailable')
+    expect(href.searchParams.get('utm_campaign')).toBe('web_extension')
+  })
+
+  test('extension makes validation request to isinstock', async () => {
+    await page.setRequestInterception(true)
+    let interceptedValidationsRequest: HTTPRequest | undefined
+    page.on('request', (interceptedRequest: HTTPRequest) => {
+      if (isValidationRequest(interceptedRequest)) {
+        interceptedValidationsRequest = interceptedRequest
+      }
+      interceptedRequest.continue()
+    })
+
+    await page.goto('https://www.amazon.com/dp/B08G58D42M/', {waitUntil: 'networkidle2'})
+
+    expect(interceptedValidationsRequest).toBeDefined()
+    expect(interceptedValidationsRequest?.method()).toBe('POST')
+    expect(interceptedValidationsRequest?.postData()).toBe(`{"url":"https://www.amazon.com/dp/B08G58D42M/"}`)
+  })
+
+  test('popstate to restore page searches for products', async () => {
+    await page.goto('https://www.amazon.com/dp/B08G58D42M/')
+    await page.waitForSelector('#isinstock-button')
+
+    await page.goto('https://www.amazon.com/')
+    await page.goBack()
+    const element = await page.waitForSelector('#isinstock-button')
+
+    expect(element).not.toBe(null)
+  })
+
+  test('monitors URL changes when no other events are fired', async () => {
+    await page.setRequestInterception(true)
+    const interceptedValidationsRequests: HTTPRequest[] = []
+    page.on('request', (interceptedRequest: HTTPRequest) => {
+      if (interceptedRequest.isInterceptResolutionHandled()) {
+        return
+      }
+
+      if (isValidationRequest(interceptedRequest)) {
+        const postData = JSON.parse(interceptedRequest.postData() ?? '{}')
+        interceptedValidationsRequests.push(postData.url)
+      }
+
+      interceptedRequest.continue()
+    })
+
+    await page.goto('https://www.amazon.com/dp/B088HH6LW5/')
+    await page.click('[data-dp-url] button')
+
+    await page.waitForRequest(request => isValidationRequest(request))
+
+    expect(interceptedValidationsRequests).toStrictEqual([
+      'https://www.amazon.com/dp/B088HH6LW5/',
+      'https://www.amazon.com/dp/B0BLF2RWNV/?th=1',
+    ])
+  })
+})