name: Cancel Unfinished PR Runs

on:
  workflow_dispatch:
    inputs:
      workflows:
        description: 'Space-separated list of workflow filenames to cancel'
        required: true
        type: string
        default: 'pr-test.yml pr-test-extra.yml'
      include_highest_priority:
        description: 'Also cancel runs from PRs labelled highest-priority'
        required: false
        type: boolean
        default: false
      include_rerun_test:
        description: 'Also cancel /rerun-test dispatched runs (rerun-test.yml)'
        required: false
        type: boolean
        default: false

permissions:
  actions: write   # Needed to cancel runs
  contents: read   # Needed to read repo info
  pull-requests: read  # needed for gh pr view (labels)

jobs:
  cancel-unfinished-pr-runs:
    runs-on: ubuntu-latest
    steps:
      - name: Install GitHub CLI
        run: sudo apt-get install -y gh jq

      - name: Cancel unfinished PR-associated runs
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}
          REPO: ${{ github.repository }}
          WORKFLOWS: ${{ github.event.inputs.workflows }}
          INCLUDE_HIGHEST_PRIORITY: ${{ github.event.inputs.include_highest_priority }}
          INCLUDE_RERUN_TEST: ${{ github.event.inputs.include_rerun_test }}
        shell: bash
        run: |
          set -euo pipefail

          # Read the space-separated string from the input into a bash array
          read -r -a WORKFLOW_FILES <<< "${WORKFLOWS}"
          if [ "$INCLUDE_RERUN_TEST" = "true" ]; then
            WORKFLOW_FILES+=("rerun-test.yml")
          fi

          echo "Targeting ${#WORKFLOW_FILES[@]} workflow(s): ${WORKFLOW_FILES[*]}"
          echo "include_highest_priority=$INCLUDE_HIGHEST_PRIORITY, include_rerun_test=$INCLUDE_RERUN_TEST"
          echo ""

          # Decide whether to cancel run_id given a PR-lookup endpoint.
          #   $1 = run_id
          #   $2 = gh api path returning a list of PR objects (head=... or commits/<sha>/pulls)
          #   $3 = short label for log messages
          maybe_cancel_for_pr() {
            local run_id="$1"
            local pr_query="$2"
            local pr_label="$3"

            local pr_info
            pr_info=$(gh api -H "Accept: application/vnd.github+json" "$pr_query" \
              --jq '.[0] | {number, state, merged_at}' 2>/dev/null || true)

            if [ -z "$pr_info" ] || [ "$pr_info" = "null" ]; then
              echo "  ⚠️  No PR found ($pr_label), skipping"
              return
            fi

            local pr_number pr_state
            pr_number=$(echo "$pr_info" | jq -r '.number // empty')
            pr_state=$(echo "$pr_info" | jq -r '.state // empty')

            if [ -z "$pr_number" ]; then
              echo "  ⚠️  PR lookup returned empty number, skipping"
              return
            fi

            local pr_url="https://github.com/$REPO/pull/$pr_number"
            echo "  PR: $pr_url ($pr_state)"

            # Closed PR (merged or not): always cancel, skip label checks.
            if [ "$pr_state" = "closed" ]; then
              echo "  🚫 Cancelling (PR closed)..."
              gh run cancel "$run_id" --repo "$REPO" || echo "  ⚠️  Cancellation failed"
              return
            fi

            # Open PR: apply label-based skip rules.
            local labels
            labels=$(gh pr view "$pr_number" --repo "$REPO" --json labels \
              | jq -r '.labels[].name' 2>/dev/null || true)

            if echo "$labels" | grep -Fxq "bypass-maintenance"; then
              echo "  🛑 Skipping (bypass-maintenance label, never cancelled)"
              return
            fi

            if echo "$labels" | grep -Fxq "highest-priority"; then
              if [ "$INCLUDE_HIGHEST_PRIORITY" != "true" ]; then
                echo "  🛑 Skipping (highest-priority label)"
                return
              fi
              echo "  ⚠️  highest-priority PR, but include_highest_priority is enabled"
            fi

            echo "  🚫 Cancelling..."
            gh run cancel "$run_id" --repo "$REPO" || echo "  ⚠️  Cancellation failed"
          }
          export -f maybe_cancel_for_pr

          for workflow_file in "${WORKFLOW_FILES[@]}"; do
            echo "========================================="
            echo "Workflow: $workflow_file"
            echo "========================================="

            # Get all unfinished runs.
            # Use server-side --status filter: without it, `gh run list --limit 1000`
            # only sees the most recent 1000 runs by createdAt, which on busy workflows
            # like pr-test.yml is < 3 days. Old stuck runs would be missed.
            all_runs=""
            for status in queued in_progress waiting; do
              batch=$(gh run list \
                --repo "$REPO" \
                --workflow "$workflow_file" \
                --status "$status" \
                --json databaseId,status,event,url,createdAt,displayTitle \
                --limit 1000 \
              | jq -c '.[]')
              if [ -n "$batch" ]; then
                if [ -n "$all_runs" ]; then
                  all_runs="$all_runs"$'\n'"$batch"
                else
                  all_runs="$batch"
                fi
              fi
            done

            if [ -z "$all_runs" ]; then
              echo "✅ No unfinished runs found"
              echo ""
              continue
            fi

            # Count runs by event type
            total_runs=$(echo "$all_runs" | wc -l)
            pr_runs=$(echo "$all_runs" | jq -s '[.[] | select(.event=="pull_request")] | length')
            dispatch_runs=$(echo "$all_runs" | jq -s '[.[] | select(.event=="workflow_dispatch")] | length')
            other_runs=$(echo "$all_runs" | jq -s '[.[] | select(.event!="pull_request" and .event!="workflow_dispatch")] | length')

            echo "📊 Summary: $total_runs unfinished ($pr_runs pull_request, $dispatch_runs workflow_dispatch, $other_runs other)"
            echo ""

            # Other runs: list only, do not cancel.
            if [ "$other_runs" -gt 0 ]; then
              echo "--- Other Runs (listed only, not cancelled) ---"
              echo "$all_runs" | jq -c 'select(.event!="pull_request" and .event!="workflow_dispatch")' | while read -r run; do
                run_url=$(echo "$run" | jq -r '.url')
                run_event=$(echo "$run" | jq -r '.event')
                run_status=$(echo "$run" | jq -r '.status')
                echo "  • $run_event ($run_status): $run_url"
              done
              echo ""
            fi

            # PR runs: resolve PR via head=owner:branch.
            if [ "$pr_runs" -gt 0 ]; then
              echo "--- PR Runs (resolving via head=owner:branch) ---"
              echo "$all_runs" | jq -c 'select(.event=="pull_request")' | while read -r run; do
                run_id=$(echo "$run" | jq -r '.databaseId')
                run_url=$(echo "$run" | jq -r '.url')
                run_status=$(echo "$run" | jq -r '.status')

                echo ""
                echo "Run ($run_status): $run_url"

                run_details=$(gh api -H "Accept: application/vnd.github+json" \
                  "repos/$REPO/actions/runs/$run_id" 2>/dev/null || true)
                if [ -z "$run_details" ]; then
                  echo "  ⚠️  Could not fetch run details, skipping"
                  continue
                fi

                head_owner=$(echo "$run_details" | jq -r '.head_repository.owner.login // empty')
                head_branch=$(echo "$run_details" | jq -r '.head_branch // empty')
                if [ -z "$head_owner" ] || [ -z "$head_branch" ]; then
                  echo "  ⚠️  Missing head info, skipping"
                  continue
                fi

                echo "  Branch: ${head_owner}:${head_branch}"
                maybe_cancel_for_pr "$run_id" \
                  "repos/$REPO/pulls?state=all&head=${head_owner}:${head_branch}" \
                  "head=${head_owner}:${head_branch}"
              done
              echo ""
            fi

            # workflow_dispatch runs (e.g. /rerun-test): resolve PR via pr_head_sha
            # parsed from run-name (`[rerun-test] <cmd> <sha>`).
            if [ "$dispatch_runs" -gt 0 ]; then
              echo "--- Dispatch Runs (resolving via pr_head_sha in display_title) ---"
              echo "$all_runs" | jq -c 'select(.event=="workflow_dispatch")' | while read -r run; do
                run_id=$(echo "$run" | jq -r '.databaseId')
                run_url=$(echo "$run" | jq -r '.url')
                run_status=$(echo "$run" | jq -r '.status')
                display_title=$(echo "$run" | jq -r '.displayTitle // empty')

                echo ""
                echo "Run ($run_status): $run_url"
                echo "  Title: $display_title"

                # Last whitespace-delimited token if it is a 40-hex SHA.
                last_token=$(echo "$display_title" | awk '{print $NF}')
                if ! [[ "$last_token" =~ ^[0-9a-f]{40}$ ]]; then
                  echo "  ⚠️  No pr_head_sha in title, skipping"
                  continue
                fi

                echo "  pr_head_sha: $last_token"
                maybe_cancel_for_pr "$run_id" \
                  "repos/$REPO/commits/$last_token/pulls" \
                  "sha=$last_token"
              done
              echo ""
            fi
          done

          echo "========================================="
          echo "✅ Processing complete"
          echo "========================================="