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 }}
      pr_number: ${{ steps.check-pr.outputs.pr_number }}
    steps:
      - name: Check for existing PR
        id: check-pr
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
        run: |
          existing_pr=$(gh pr list --repo ${{ github.repository }} --head "auto-update-flake-" --state open --json number --jq '.[0].number')
          if [ -n "$existing_pr" ]; then
            echo "pr_exists=true" >> $GITHUB_OUTPUT
            echo "pr_number=$existing_pr" >> $GITHUB_OUTPUT
          else
            echo "pr_exists=false" >> $GITHUB_OUTPUT
          fi

  update-flake:
    needs: check-existing-pr
    if: needs.check-existing-pr.outputs.pr_exists == 'false'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

      - 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
          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 -u origin ${{ env.BRANCH_NAME }}

      - name: Create Pull Request
        if: steps.update-flake.outputs.CHANGED == 'true'
        id: create-pr
        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: Trigger Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        uses: ./.github/actions/trigger-hydra-build
        with:
          hydra_instance: ${{ env.HYDRA_INSTANCE }}
          hydra_project: ${{ env.HYDRA_PROJECT }}
          hydra_jobset: ${{ env.HYDRA_JOBSET }}
          hydra_username: ${{ secrets.HYDRA_USERNAME }}
          hydra_password: ${{ secrets.HYDRA_PASSWORD }}

      - name: Wait for Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        id: wait-for-build
        uses: ./.github/actions/wait-for-hydra-build
        with:
          hydra_instance: ${{ env.HYDRA_INSTANCE }}
          hydra_project: ${{ env.HYDRA_PROJECT }}
          hydra_jobset: ${{ env.HYDRA_JOBSET }}
          hydra_username: ${{ secrets.HYDRA_USERNAME }}
          hydra_password: ${{ secrets.HYDRA_PASSWORD }}

      - 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: |
          gh pr merge ${{ steps.create-pr.outputs.pr_number }} --merge

      - name: Exit if build fails
        if: steps.update-flake.outputs.CHANGED == 'true' && steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        run: exit 1

  retry-update:
    needs: check-existing-pr
    if: needs.check-existing-pr.outputs.pr_exists == 'true'
    runs-on: ubuntu-latest
    steps:
      - name: Checkout repository
        uses: actions/checkout@v3
        with:
          fetch-depth: 0

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

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

      - name: Update flake dependencies
        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
            git add .
            git commit -m "Auto-update flake dependencies (retry)"
            git push origin HEAD
          else
            echo "CHANGED=false" >> $GITHUB_OUTPUT
            echo "No changes detected."
          fi

      - name: Trigger Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        uses: ./.github/actions/trigger-hydra-build
        with:
          hydra_instance: ${{ env.HYDRA_INSTANCE }}
          hydra_project: ${{ env.HYDRA_PROJECT }}
          hydra_jobset: ${{ env.HYDRA_JOBSET }}
          hydra_username: ${{ secrets.HYDRA_USERNAME }}
          hydra_password: ${{ secrets.HYDRA_PASSWORD }}

      - name: Wait for Hydra build
        if: steps.update-flake.outputs.CHANGED == 'true'
        id: wait-for-build
        uses: ./.github/actions/wait-for-hydra-build
        with:
          hydra_instance: ${{ env.HYDRA_INSTANCE }}
          hydra_project: ${{ env.HYDRA_PROJECT }}
          hydra_jobset: ${{ env.HYDRA_JOBSET }}
          hydra_username: ${{ secrets.HYDRA_USERNAME }}
          hydra_password: ${{ secrets.HYDRA_PASSWORD }}

      - 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: |
          gh pr merge ${{ needs.check-existing-pr.outputs.pr_number }} --merge

      - name: Exit if build fails
        if: steps.update-flake.outputs.CHANGED == 'true' && steps.wait-for-build.outputs.BUILD_SUCCESS != 'true'
        run: exit 1