# Copyright 2025 Google LLC
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
name: Link Checker

on:
  pull_request:
permissions:
  contents: read

jobs:
  link-check:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Repository
        uses: actions/checkout@9c091bb21b7c1c1d1991bb908d89e4e9dddfe3e0 # v7
        with:
          ref: ${{ github.event.pull_request.head.sha }}
          fetch-depth: 0
          persist-credentials: false

      - name: Identify Changed Files
        id: changed-files
        shell: bash
        run: |
          git fetch origin main
          CHANGED_FILES=$(git diff --name-only --diff-filter=ACMRT origin/main...HEAD -- '*.md')

          if [ -z "$CHANGED_FILES" ]; then
            echo "No markdown files changed. Skipping checks."
            echo "HAS_CHANGES=false" >> "$GITHUB_OUTPUT"
          else
            echo "--- Changed Files to Scan ---"
            echo "$CHANGED_FILES"
            echo "-----------------------------"
            
            FILES_QUOTED=$(echo "$CHANGED_FILES" | sed 's/^/"/;s/$/"/' | tr '\n' ' ')
            
            # Use EOF to write multiline or long strings to GITHUB_OUTPUT
            echo "HAS_CHANGES=true" >> "$GITHUB_OUTPUT"
            echo "CHECK_FILES<<EOF" >> "$GITHUB_OUTPUT"
            echo "$FILES_QUOTED" >> "$GITHUB_OUTPUT"
            echo "EOF" >> "$GITHUB_OUTPUT"
          fi

      - name: Restore lychee cache
        if: steps.changed-files.outputs.HAS_CHANGES == 'true'
        uses: actions/cache@27d5ce7f107fe9357f9df03efb73ab90386fccae # v5.0.5
        with:
          path: .lycheecache
          key: cache-lychee-${{ github.sha }}
          restore-keys: cache-lychee-

      - name: Link Checker
        id: lychee-check       
        if: steps.changed-files.outputs.HAS_CHANGES == 'true'
        uses: lycheeverse/lychee-action@8646ba30535128ac92d33dfc9133794bfdd9b411 # v2
        continue-on-error: true 
        with:
          args: >
            --quiet
            --no-progress
            --cache
            --max-cache-age 1d
            --exclude '^neo4j\+.*' --exclude '^bolt://.*'
            --max-retries 10
            ${{ steps.changed-files.outputs.CHECK_FILES }}
          output: lychee-report.md
          format: markdown
          fail: true           
          jobSummary: false    
          debug: false
        env:
          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Prepare Report 
        if: steps.changed-files.outputs.HAS_CHANGES == 'true' && steps.lychee-check.outcome == 'failure'
        run: |
          echo "## Link Resolution Note" > full-report.md
          echo "Local links and directory changes work differently on GitHub than on the docsite. You must ensure fixes pass the **GitHub check** and also work with **\`hugo server\`**." >> full-report.md
          echo "See [Link Checking and Fixing with Lychee](https://github.com/googleapis/mcp-toolbox/blob/main/DEVELOPER.md#link-checking-and-fixing-with-lychee) for more details." >> full-report.md          
          echo "" >> full-report.md 
          sed -E '/(Redirect|Redirects per input)/d' lychee-report.md >> full-report.md


      - name: Display Failure Report
        # Run this ONLY if the link checker failed
        if: steps.lychee-check.outcome == 'failure'
        run: |
          # We can now simply output the prepared file to the job summary
          cat full-report.md >> $GITHUB_STEP_SUMMARY
          
          # Fail the job
          exit 1