Add Google Flights price tracking with SerpApi and GitHub Actions

.github/workflows/pr-preview.yml

@@ -12,7 +12,7 @@ jobs:
   preview-link:
     runs-on: ubuntu-latest
     steps:
-      - name: Post preview link
+      - name: Post preview links
         uses: actions/github-script@v7
         with:
           script: |
@@ -21,8 +21,8 @@ jobs:
             const repo = context.repo.repo;
             const pr = context.payload.pull_request;
             const sha = pr.head.sha;
-            const preview = `https://rawcdn.githack.com/${owner}/${repo}/${sha}/index.html`;
-            const body = `${marker}\n## 🌍 Web preview\n\n[Open this PR as a live website](${preview})\n\nPreview is pinned to commit \`${sha.slice(0, 7)}\` and updates automatically when the PR changes.`;
+            const root = `https://rawcdn.githack.com/${owner}/${repo}/${sha}`;
+            const body = `${marker}\n## 🌍 Web preview\n\n- [Open travel dashboard](${root}/index.html)\n- [Open live flight prices](${root}/flights.html)\n\nPreview is pinned to commit \`${sha.slice(0, 7)}\` and updates automatically when the PR changes.`;
 
             const comments = await github.paginate(github.rest.issues.listComments, {
               owner,
@@ -36,17 +36,7 @@ jobs:
             );
 
             if (existing) {
-              await github.rest.issues.updateComment({
-                owner,
-                repo,
-                comment_id: existing.id,
-                body,
-              });
+              await github.rest.issues.updateComment({ owner, repo, comment_id: existing.id, body });
             } else {
-              await github.rest.issues.createComment({
-                owner,
-                repo,
-                issue_number: pr.number,
-                body,
-              });
+              await github.rest.issues.createComment({ owner, repo, issue_number: pr.number, body });
             }

.github/workflows/update-flight-prices.yml

@@ -0,0 +1,147 @@
+name: Update live flight prices
+
+on:
+  workflow_dispatch:
+  schedule:
+    # 07:17 in Vietnam (UTC+7). One refresh uses 4 SerpApi searches.
+    # Daily schedule keeps the project comfortably inside the 250-search free tier.
+    - cron: '17 0 * * *'
+
+permissions:
+  contents: write
+  pages: write
+  issues: write
+
+concurrency:
+  group: live-flight-prices-${{ github.ref }}
+  cancel-in-progress: false
+
+jobs:
+  refresh:
+    runs-on: ubuntu-latest
+    steps:
+      - name: Checkout repository
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.ref_name }}
+          fetch-depth: 0
+
+      - name: Set up Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: '20'
+
+      - name: Check SerpApi secret
+        id: config
+        env:
+          SERPAPI_API_KEY: ${{ secrets.SERPAPI_API_KEY }}
+        run: |
+          if [ -z "$SERPAPI_API_KEY" ]; then
+            echo "enabled=false" >> "$GITHUB_OUTPUT"
+            echo "::warning::SERPAPI_API_KEY is not configured. Add it in Settings → Secrets and variables → Actions."
+          else
+            echo "enabled=true" >> "$GITHUB_OUTPUT"
+          fi
+
+      - name: Fetch Google Flights prices via SerpApi
+        if: steps.config.outputs.enabled == 'true'
+        env:
+          SERPAPI_API_KEY: ${{ secrets.SERPAPI_API_KEY }}
+        run: node scripts/fetch-flights.mjs
+
+      - name: Evaluate price alert
+        if: steps.config.outputs.enabled == 'true' && github.ref_name == 'main'
+        env:
+          GH_TOKEN: ${{ github.token }}
+          ALERT_AMOUNT: ${{ vars.FLIGHT_ALERT_AMOUNT }}
+          ALERT_CURRENCY: ${{ vars.FLIGHT_ALERT_CURRENCY }}
+        shell: bash
+        run: |
+          if [ -z "$ALERT_AMOUNT" ]; then
+            echo "No FLIGHT_ALERT_AMOUNT repository variable configured; skipping GitHub Issue alert."
+            exit 0
+          fi
+
+          CURRENT_AMOUNT=$(node -p "require('./data/flights.json').cheapest?.offer?.total_amount || ''")
+          CURRENT_CURRENCY=$(node -p "require('./data/flights.json').cheapest?.offer?.total_currency || ''")
+          CURRENT_AIRLINE=$(node -p "require('./data/flights.json').cheapest?.offer?.owner?.name || 'Unknown airline'")
+          CURRENT_SCENARIO=$(node -p "require('./data/flights.json').cheapest?.label || 'China trip'")
+          CHECKED_AT=$(node -p "require('./data/flights.json').generated_at || new Date().toISOString()")
+          ALERT_CURRENCY=${ALERT_CURRENCY:-$CURRENT_CURRENCY}
+
+          if [ -z "$CURRENT_AMOUNT" ] || [ -z "$CURRENT_CURRENCY" ]; then
+            echo "No cheapest live price found; skipping alert."
+            exit 0
+          fi
+
+          if [ "$CURRENT_CURRENCY" != "$ALERT_CURRENCY" ]; then
+            echo "::warning::Price alert currency is $ALERT_CURRENCY but Google Flights returned $CURRENT_CURRENCY. Alert comparison skipped."
+            exit 0
+          fi
+
+          TITLE="✈️ Flight price alert · China 2026"
+          ISSUE=$(gh issue list --state open --json number,title --jq '.[] | select(.title == "✈️ Flight price alert · China 2026") | .number' | head -n 1)
+
+          if node -e "process.exit(Number(process.argv[1]) <= Number(process.argv[2]) ? 0 : 1)" "$CURRENT_AMOUNT" "$ALERT_AMOUNT"; then
+            BODY=$(cat <<EOF
+          ## Price target reached 🎯
+
+          Latest Google Flights snapshot via SerpApi is at or below the configured target.
+
+          | | |
+          |---|---|
+          | **Current total** | ${CURRENT_AMOUNT} ${CURRENT_CURRENCY} |
+          | **Target** | ${ALERT_AMOUNT} ${ALERT_CURRENCY} |
+          | **Airline** | ${CURRENT_AIRLINE} |
+          | **Scenario** | ${CURRENT_SCENARIO} |
+          | **Checked** | ${CHECKED_AT} |
+          | **Travellers** | 6 adults + 1 infant under 2 on lap |
+
+          Open the live dashboard: https://trips.eplus.dev/flights.html
+
+          > Search prices can change. Verify the itinerary and final booking price before paying.
+          EOF
+          )
+
+            if [ -n "$ISSUE" ]; then
+              gh issue edit "$ISSUE" --body "$BODY"
+              echo "Updated existing price alert issue #$ISSUE."
+            else
+              gh issue create --title "$TITLE" --body "$BODY"
+              echo "Created a new price alert issue."
+            fi
+          else
+            echo "Current price ${CURRENT_AMOUNT} ${CURRENT_CURRENCY} is above target ${ALERT_AMOUNT} ${ALERT_CURRENCY}."
+            if [ -n "$ISSUE" ]; then
+              gh issue close "$ISSUE" --comment "Latest price moved back above the target: ${CURRENT_AMOUNT} ${CURRENT_CURRENCY} (target ${ALERT_AMOUNT} ${ALERT_CURRENCY}). The next target hit can create a fresh alert."
+            fi
+          fi
+
+      - name: Commit refreshed price snapshot
+        if: steps.config.outputs.enabled == 'true'
+        id: commit
+        run: |
+          if git diff --quiet -- data/flights.json data/flight-history.json; then
+            echo "changed=false" >> "$GITHUB_OUTPUT"
+            echo "No flight price changes to commit."
+            exit 0
+          fi
+
+          git config user.name "github-actions[bot]"
+          git config user.email "41898282+github-actions[bot]@users.noreply.github.com"
+          git add data/flights.json data/flight-history.json
+          git commit -m "chore: refresh Google Flights prices [skip ci]"
+          git push origin "HEAD:${GITHUB_REF_NAME}"
+          echo "changed=true" >> "$GITHUB_OUTPUT"
+
+      - name: Request GitHub Pages rebuild
+        if: steps.config.outputs.enabled == 'true' && steps.commit.outputs.changed == 'true' && github.ref_name == 'main'
+        env:
+          GH_TOKEN: ${{ github.token }}
+        run: |
+          curl --fail-with-body -L \
+            -X POST \
+            -H "Accept: application/vnd.github+json" \
+            -H "Authorization: Bearer $GH_TOKEN" \
+            -H "X-GitHub-Api-Version: 2022-11-28" \
+            "https://api.github.com/repos/${GITHUB_REPOSITORY}/pages/builds"

README.md

@@ -1,58 +1,145 @@
 # Personal Travel Log
 
-A lightweight personal travel dashboard built for GitHub Pages. It works as a static site, stores personal planning data locally in the browser, and can also behave like a small installable web app.
+A lightweight personal travel dashboard for GitHub Pages with itinerary, budget, notes, PWA support and automated Google Flights price tracking.
 
 ## Features
 
-- Responsive desktop and mobile layout
-- Live countdown to the next departure
-- Visual trip route and overview statistics
-- Trip essentials: flights, hotels, internet and map shortcuts
-- Expandable day-by-day itinerary
-- Upcoming destination cards
-- Pre-trip checklist with completion percentage
-- Budget tracker with planned / actual / remaining totals
-- Personal trip notes saved automatically in `localStorage`
-- Export / import local travel data as JSON
-- Native share button when supported
-- Light / dark mode
-- Mobile bottom navigation
-- PWA manifest + service worker for install/offline use
-- No framework, database or build process required
+- Responsive desktop/mobile travel dashboard
+- Countdown, route, itinerary and destination cards
+- Checklist, budget and notes saved in `localStorage`
+- Export/import local travel data
+- Light/dark mode and PWA/offline support
+- **Google Flights price snapshots through SerpApi + GitHub Actions**
+- Return-date comparison, airline/stops filters, price history and price alerts
+- No separate backend server
 
-## Files
+## Current China trip
+
+- Ho Chi Minh City → Shanghai → Beijing
+- Outbound: **20 October 2026**
+- Return options: **25 October evening** or **26 October morning**
+- **6 adults + 1 infant under 2 on lap**
+- Economy
+- Direct or maximum 1 stop per leg
+
+## Live flight prices
+
+The workflow `.github/workflows/update-flight-prices.yml` calls SerpApi's Google Flights engine. The API key remains in GitHub Actions Secrets and is never exposed in the browser.
+
+Google Flights multi-city selection is sequential. For each return-date scenario the fetcher performs:
+
+1. initial multi-city search to get the first-leg options and a `departure_token`,
+2. a second search with that token to get the next leg and complete itinerary prices.
+
+There are two scenarios, so one refresh uses **4 SerpApi searches**.
+
+### 1. Create a SerpApi key
+
+Create a SerpApi account and copy your private API key.
+
+### 2. Add the GitHub Actions secret
+
+Repository → **Settings → Secrets and variables → Actions → New repository secret**
 
 ```text
-trip/
-├── index.html
-├── manifest.webmanifest
-├── sw.js
-├── icon.svg
-├── .nojekyll
-└── README.md
+Name: SERPAPI_API_KEY
+Value: <your SerpApi API key>
 ```
 
-## Current trip
+Do not add the key to source code, repository variables, `flights.json`, issues or PR comments.
 
-The starter data is configured for the China trip in October 2026:
+### 3. Merge the PR and run the first check
 
-- Ho Chi Minh City → Shanghai → Beijing
-- 20–26 October 2026
-- Day-by-day itinerary included in `index.html`
+After the workflow exists on `main`:
+
+```text
+Actions
+→ Update live flight prices
+→ Run workflow
+```
+
+The workflow writes:
+
+```text
+data/flights.json
+data/flight-history.json
+```
+
+and commits refreshed snapshots back to `main`.
 
-The site intentionally keeps travel data in plain HTML/JavaScript so it is easy to edit directly from GitHub without a build pipeline.
+### Automatic refresh
 
-## Personal data
+The default schedule is:
 
-Checklist, budget and notes are stored in the browser using `localStorage` under:
+```text
+07:17 Asia/Ho_Chi_Minh
+```
+
+One refresh uses 4 API searches, so a 30-day month is roughly **120 searches**, leaving room for manual checks within SerpApi's free quota.
+
+### Price dashboard
+
+`flights.html` provides:
+
+- comparison of returning **25 vs 26 October**
+- Cheapest / Fastest sorting
+- Direct only / 1 stop filters
+- airline filter
+- total search price for the selected 7 travellers
+- rough total ÷ 7 reference value
+- price change from the previous check
+- lowest/highest saved prices
+- saved trend chart
+- Fresh / Aging / Stale indicator
+- browser-local target price
+- shortcut to run GitHub Actions manually
+
+## Optional GitHub Issue price alert
+
+Create repository Actions variables:
 
 ```text
-travel-log-v2
+FLIGHT_ALERT_AMOUNT=30000000
+FLIGHT_ALERT_CURRENCY=VND
 ```
 
-Use **Export data** before changing browsers/devices. The exported JSON file can later be restored with **Import data**.
+When the current cheapest total is at or below the threshold, the workflow opens or updates:
+
+```text
+✈️ Flight price alert · China 2026
+```
 
-## Run locally
+When the price moves above the target again, the issue is closed.
+
+## Price notes
+
+The results are Google Flights search snapshots, not locked fares. Google Flights may omit some carriers/options and final seller prices can change. Baggage, card and other optional fees may be additional. Always verify the itinerary and final amount on Google Flights or the airline/agency before paying.
+
+## Files
+
+```text
+trips/
+├── .github/workflows/
+│   ├── pr-preview.yml
+│   └── update-flight-prices.yml
+├── data/
+│   ├── flights.json
+│   └── flight-history.json
+├── scripts/
+│   └── fetch-flights.mjs
+├── flights/
+│   └── index.html
+├── flights.html
+├── index.html
+├── manifest.webmanifest
+├── sw.js
+├── icon.svg
+├── CNAME
+├── .nojekyll
+└── README.md
+```
+
+## Local development
 
 ```bash
 python3 -m http.server 8080
@@ -61,22 +148,19 @@ python3 -m http.server 8080
 Open:
 
 ```text
-http://localhost:8080
+http://localhost:8080/
+http://localhost:8080/flights.html
 ```
 
-Using a local server is recommended when testing the service worker and PWA behavior.
-
 ## GitHub Pages
 
-Repository Settings → Pages:
-
 ```text
 Source: Deploy from a branch
 Branch: main
 Folder: / (root)
 ```
 
-The `.nojekyll` file keeps GitHub Pages in simple static-site mode.
+The refresh workflow explicitly requests a Pages rebuild after committing price data because a commit pushed by a workflow `GITHUB_TOKEN` does not itself trigger another Pages build.
 
 ---
 

data/flight-history.json

@@ -0,0 +1 @@
+[]