name: Nix Flake Update

on:
  schedule:
    - cron: '0 0 * * *'  # Run daily at midnight UTC
  workflow_dispatch:  # Allow manual trigger

env:
  BRANCH_NAME: auto-update-flake-${{ github.run_number }}
  HYDRA_INSTANCE: https://hydra.zoeys.computer
  HYDRA_PROJECT: config
  HYDRA_JOBSET: pr-${{ github.run_number }}

jobs:
  check-existing-pr:
    runs-on: ubuntu-latest
    outputs:
      pr_exists: ${{ steps.check-pr.outputs.pr_exists }}
    steps:
      - name: Check for existing PR
        id: check-pr
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          existing_pr=$(gh pr list --repo ${{ github.repository }} --head "auto-update-flake-" --state open --json number --jq length)
          echo "pr_exists=$existing_pr" >> $GITHUB_OUTPUT

  update-flake:
    needs: check-existing-pr
    if: needs.check-existing-pr.outputs.pr_exists == '0'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          fetch-depth: 0  # Fetch all history for all branches and tags

      - name: Install Nix
        uses: cachix/install-nix-action@v30

      - name: Update flake dependencies
        id: update-flake
        run: |
          git config user.name github-actions
          git config user.email github-actions@github.com
          nix flake update --accept-flake-config
          git diff
          if [[ -n $(git status -s) ]]; then
            echo "CHANGED=true" >> $GITHUB_OUTPUT
            echo "Changes detected:"
            git status -s
          else
            echo "CHANGED=false" >> $GITHUB_OUTPUT
            echo "No changes detected."
          fi

      - name: Create branch and commit changes
        if: steps.update-flake.outputs.CHANGED == 'true'
        run: |
          git checkout -b ${{ env.BRANCH_NAME }}
          git add .
          git commit -m "chore: update flake dependencies"
          git push origin ${{ env.BRANCH_NAME }}

      - name: Create Pull Request
        if: steps.update-flake.outputs.CHANGED == 'true'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          gh pr create --title "Auto-update Nix flake dependencies" \
                       --body "This PR updates the Nix flake dependencies." \
                       --base main \
                       --head ${{ env.BRANCH_NAME }}

      - name: Create Hydra jobset
        if: steps.update-flake.outputs.CHANGED == 'true'
        run: |
          AUTH_HEADER="Authorization: Basic $(echo -n '${{ secrets.HYDRA_USERNAME }}:${{ secrets.HYDRA_PASSWORD }}' | base64)"
          curl -X PUT -H "Content-Type: application/json" \
            -H "$AUTH_HEADER" \
            -d '{
              "enabled": 1,
              "visible": true,
              "keepnr": 3,
              "schedulingshares": 100,
              "checkinterval": 60,
              "description": "PR #${{ github.event.pull_request.number }} - Auto-update flake dependencies",
              "flake": "github:${{ github.repository }}/${{ env.BRANCH_NAME }}",
              "type": 1
            }' \
            "${{ env.HYDRA_INSTANCE }}/jobset/${{ env.HYDRA_PROJECT }}/${{ env.HYDRA_JOBSET }}"

      - name: Trigger Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        run: |
          AUTH_HEADER="Authorization: Basic $(echo -n '${{ secrets.HYDRA_USERNAME }}:${{ secrets.HYDRA_PASSWORD }}' | base64)"
          curl -X POST -H "Content-Type: application/json" \
            -H "$AUTH_HEADER" \
            -H "Origin: ${{ env.HYDRA_INSTANCE }}" \
            -d '{"jobsets": ["${{ env.HYDRA_PROJECT }}:${{ env.HYDRA_JOBSET }}"]}' \
            "${{ env.HYDRA_INSTANCE }}/api/push"

      - name: Wait for Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        id: wait-for-build
        run: |
          AUTH_HEADER="Authorization: Basic $(echo -n '${{ secrets.HYDRA_USERNAME }}:${{ secrets.HYDRA_PASSWORD }}' | base64)"
          max_attempts=60  # 30 minutes (30 * 2 minutes)
          attempt=0
          while [ $attempt -lt $max_attempts ]; do
            response=$(curl -s -H "$AUTH_HEADER" \
              "${{ env.HYDRA_INSTANCE }}/api/jobsets?project=${{ env.HYDRA_PROJECT }}")
            status=$(echo "$response" | jq -r '.[] | select(.name == "${{ env.HYDRA_JOBSET }}") | .nrfailed')
            if [ "$status" = "0" ]; then
              echo "BUILD_SUCCESS=true" >> $GITHUB_OUTPUT
              exit 0
            elif [ "$status" != "null" ] && [ "$status" != "0" ]; then
              echo "BUILD_SUCCESS=false" >> $GITHUB_OUTPUT
              exit 0
            fi
            sleep 120  # Wait for 2 minutes before checking again
            ((attempt++))
          done
          echo "BUILD_SUCCESS=false" >> $GITHUB_OUTPUT  # Timeout, consider as failure

      - name: Merge PR if build succeeds
        if: steps.update-flake.outputs.CHANGED == 'true' && steps.wait-for-build.outputs.BUILD_SUCCESS == 'true'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          pr_number=$(gh pr list --head ${{ env.BRANCH_NAME }} --json number --jq '.[0].number')
          gh pr merge $pr_number --merge

      - name: Comment on PR if build fails
        if: steps.update-flake.outputs.CHANGED == 'true' && steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          pr_number=$(gh pr list --head ${{ env.BRANCH_NAME }} --json number --jq '.[0].number')
          gh pr comment $pr_number --body "The Hydra build failed. This PR will be updated and retried in 24 hours."

      - name: Schedule retry
        if: steps.update-flake.outputs.CHANGED == 'true' && steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        uses: peter-evans/repository-dispatch@v2
        with:
          event-type: retry-flake-update
          client-payload: '{"pr_number": "${{ steps.create-pr.outputs.pull-request-number }}"}'

  retry-update:
    runs-on: ubuntu-latest
    if: github.event.action == 'retry-flake-update'
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - name: Install Nix
        uses: cachix/install-nix-action@v22

      - name: Checkout PR branch
        run: |
          pr_number="${{ github.event.client_payload.pr_number }}"
          branch_name=$(gh pr view $pr_number --json headRefName -q .headRefName)
          git checkout $branch_name
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Update flake dependencies
        run: nix flake update

      - name: Commit and push changes
        run: |
          git config user.name github-actions
          git config user.email github-actions@github.com
          git add flake.lock
          git commit -m "Auto-update flake dependencies (retry)"
          git push origin HEAD

      - name: Trigger Hydra build
        run: |
          AUTH_HEADER="Authorization: Basic $(echo -n '${{ secrets.HYDRA_USERNAME }}:${{ secrets.HYDRA_PASSWORD }}' | base64)"
          curl -X POST -H "Content-Type: application/json" \
            -H "$AUTH_HEADER" \
            -H "Origin: ${{ env.HYDRA_INSTANCE }}" \
            -d '{"jobsets": ["${{ env.HYDRA_PROJECT }}:${{ env.HYDRA_JOBSET }}"]}' \
            "${{ env.HYDRA_INSTANCE }}/api/push"

      - name: Wait for Hydra build
        id: wait-for-build
        run: |
          AUTH_HEADER="Authorization: Basic $(echo -n '${{ secrets.HYDRA_USERNAME }}:${{ secrets.HYDRA_PASSWORD }}' | base64)"
          max_attempts=60  # 30 minutes (30 * 2 minutes)
          attempt=0
          while [ $attempt -lt $max_attempts ]; do
            response=$(curl -s -H "$AUTH_HEADER" \
              "${{ env.HYDRA_INSTANCE }}/api/jobsets?project=${{ env.HYDRA_PROJECT }}")
            status=$(echo "$response" | jq -r '.[] | select(.name == "${{ env.HYDRA_JOBSET }}") | .nrfailed')
            if [ "$status" = "0" ]; then
              echo "BUILD_SUCCESS=true" >> $GITHUB_OUTPUT
              exit 0
            elif [ "$status" != "null" ] && [ "$status" != "0" ]; then
              echo "BUILD_SUCCESS=false" >> $GITHUB_OUTPUT
              exit 0
            fi
            sleep 120  # Wait for 2 minutes before checking again
            ((attempt++))
          done
          echo "BUILD_SUCCESS=false" >> $GITHUB_OUTPUT  # Timeout, consider as failure

      - name: Merge PR if build succeeds
        if: steps.wait-for-build.outputs.BUILD_SUCCESS == 'true'
        run: |
          pr_number="${{ github.event.client_payload.pr_number }}"
          gh pr merge $pr_number --merge
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Schedule another retry if build fails
        if: steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        uses: peter-evans/create-or-update-comment@v3
        with:
          issue-number: ${{ github.event.client_payload.pr_number }}
          body: |
            The Hydra build failed again. This PR will be updated and retried in 24 hours.

      - name: Retry update after 24 hours
        if: steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        uses: peter-evans/repository-dispatch@v2
        with:
          event-type: retry-flake-update
          client-payload: '{"pr_number": "${{ github.event.client_payload.pr_number }}"}'