name: PR → Issue Linker (smart)

on:
  workflow_call:
    secrets:
      ACTION_PAT:
        required: true

permissions:
  contents: read
  issues: write
  pull-requests: read

env:
  LOG_PREFIX: "[PR-Linker]"

jobs:
  link:
    runs-on: ubuntu-latest
    timeout-minutes: 10

    steps:
      - name: Validate inputs
        id: validate
        env:
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_BODY: ${{ github.event.pull_request.body }}
        run: |
          echo "${{ env.LOG_PREFIX }} Starting validation..."

          BODY="${PR_TITLE} ${PR_BODY}"

          if [ -z "$BODY" ] || [ "$BODY" == "null" ]; then
            echo "${{ env.LOG_PREFIX }} ℹ️ No PR content found"
            echo "has_issues=false" >> $GITHUB_OUTPUT
            exit 0
          fi

          echo "has_issues=true" >> $GITHUB_OUTPUT

      - name: Extract issue references
        id: extract
        if: steps.validate.outputs.has_issues == 'true'
        env:
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_BODY: ${{ github.event.pull_request.body }}
        run: |
          echo "${{ env.LOG_PREFIX }} Extracting issue references..."

          BODY="${PR_TITLE} ${PR_BODY}"

          ISSUES=$(echo "$BODY" | \
            grep -Eo '([a-zA-Z0-9_.-]+\/[a-zA-Z0-9_.-]+)?#[0-9]+' | \
            sort -u)

          if [ -z "$ISSUES" ]; then
            echo "${{ env.LOG_PREFIX }} No issues found"
            echo "count=0" >> $GITHUB_OUTPUT
            exit 0
          fi

          ISSUE_COUNT=$(echo "$ISSUES" | wc -l)

          echo "${{ env.LOG_PREFIX }} Found $ISSUE_COUNT issue(s)"

          echo "count=$ISSUE_COUNT" >> $GITHUB_OUTPUT

          echo "issues<<EOF" >> $GITHUB_OUTPUT
          echo "$ISSUES" >> $GITHUB_OUTPUT
          echo "EOF" >> $GITHUB_OUTPUT

      - name: Cleanup stale issue links
        if: github.event.action == 'edited'
        env:
          GH_TOKEN: ${{ secrets.ACTION_PAT }}
          PR_URL: ${{ github.event.pull_request.html_url }}
          PR_TITLE: ${{ github.event.pull_request.title }}
          PR_BODY: ${{ github.event.pull_request.body }}
        run: |
          set +e
          set +o pipefail

          echo "${{ env.LOG_PREFIX }} Cleaning stale issue links..."

          CURRENT_BODY="${PR_TITLE} ${PR_BODY}"

          CURRENT_ISSUES=$(echo "$CURRENT_BODY" | \
            grep -Eo '([a-zA-Z0-9_.-]+\/[a-zA-Z0-9_.-]+)?#[0-9]+' | \
            sort -u || true)

          MARKER="pr-linker:${PR_URL}"

          SEARCH_RESPONSE=$(curl -s \
            -H "Authorization: Bearer $GH_TOKEN" \
            -H "Accept: application/vnd.github+json" \
            "https://api.github.com/search/issues?q=${MARKER}+in:comments")

          COMMENT_URLS=$(echo "$SEARCH_RESPONSE" | \
            jq -r '.items[].comments_url' 2>/dev/null || true)

          while IFS= read -r COMMENTS_URL; do
            [ -z "$COMMENTS_URL" ] && continue

            ISSUE_API=$(echo "$COMMENTS_URL" | sed 's|/comments||')

            ISSUE_DATA=$(curl -s \
              -H "Authorization: Bearer $GH_TOKEN" \
              -H "Accept: application/vnd.github+json" \
              "$ISSUE_API")

            ISSUE_NUMBER=$(echo "$ISSUE_DATA" | jq -r '.number')

            ISSUE_REPO=$(echo "$ISSUE_DATA" | \
              jq -r '.repository_url' | \
              sed 's|https://api.github.com/repos/||')

            ISSUE_REF="${ISSUE_REPO}#${ISSUE_NUMBER}"

            if ! echo "$CURRENT_ISSUES" | grep -q "$ISSUE_REF"; then

              echo "${{ env.LOG_PREFIX }} Removing stale link from $ISSUE_REF"

              COMMENT_ID=""
              CLEANUP_PAGE=1

              while :; do
                COMMENTS_DATA=$(curl -s \
                  -H "Authorization: Bearer $GH_TOKEN" \
                  -H "Accept: application/vnd.github+json" \
                  "${COMMENTS_URL}?per_page=100&page=$CLEANUP_PAGE")

                COMMENT_ID=$(echo "$COMMENTS_DATA" | jq -r \
                  --arg marker "$MARKER" \
                  '.[] | select(.body | contains($marker)) | .id' \
                  2>/dev/null | head -n1 || true)

                [ -n "$COMMENT_ID" ] && break

                CLEANUP_PAGE_SIZE=$(echo "$COMMENTS_DATA" | jq 'length')

                [ "$CLEANUP_PAGE_SIZE" -lt 100 ] && break

                CLEANUP_PAGE=$((CLEANUP_PAGE + 1))
              done

              if [ -n "$COMMENT_ID" ] && [ "$COMMENT_ID" != "null" ]; then

                curl -s -X DELETE \
                  -H "Authorization: Bearer $GH_TOKEN" \
                  -H "Accept: application/vnd.github+json" \
                  "https://api.github.com/repos/$ISSUE_REPO/issues/comments/$COMMENT_ID"

                echo "${{ env.LOG_PREFIX }} Deleted stale comment from $ISSUE_REF"
              fi
            fi

          done <<< "$COMMENT_URLS"

      - name: Process issue links
        if: steps.extract.outputs.count > 0
        env:
          GH_TOKEN: ${{ secrets.ACTION_PAT }}
          PR_URL: ${{ github.event.pull_request.html_url }}
          SOURCE_REPO: ${{ github.repository }}
          PR_ACTION: ${{ github.event.action }}
          PR_MERGED: ${{ github.event.pull_request.merged }}
        run: |
          set +e
          set +o pipefail

          ISSUES="${{ steps.extract.outputs.issues }}"
          MARKER="<!-- pr-linker:${PR_URL} -->"

          PROCESSED=0
          FAILED=0

          echo "${{ env.LOG_PREFIX }} Processing issues..."

          if [[ "$PR_ACTION" == "closed" && "$PR_MERGED" == "true" ]]; then
            STATUS="MERGED ✅"
          elif [[ "$PR_ACTION" == "closed" && "$PR_MERGED" == "false" ]]; then
            STATUS="CLOSED ❌"
          else
            STATUS="OPEN 🔄"
          fi

          while IFS= read -r ISSUE; do
            [ -z "$ISSUE" ] && continue

            if [[ "$ISSUE" == *"/"* ]]; then
              REPO=$(echo "$ISSUE" | cut -d'#' -f1)
              NUMBER=$(echo "$ISSUE" | cut -d'#' -f2)
            else
              REPO="$SOURCE_REPO"
              NUMBER=$(echo "$ISSUE" | cut -d'#' -f2)
            fi

            if ! [[ "$NUMBER" =~ ^[0-9]+$ ]]; then
              echo "${{ env.LOG_PREFIX }} Invalid issue number: $NUMBER"
              ((FAILED++))
              continue
            fi

            echo "${{ env.LOG_PREFIX }} → Processing $REPO#$NUMBER"

            COMMENT_ID=""
            PAGE=1

            while :; do
              COMMENTS_RESPONSE=$(curl -s -w "\n%{http_code}" \
                -H "Authorization: Bearer $GH_TOKEN" \
                -H "Accept: application/vnd.github+json" \
                "https://api.github.com/repos/$REPO/issues/$NUMBER/comments?per_page=100&page=$PAGE")

              HTTP_CODE=$(echo "$COMMENTS_RESPONSE" | tail -n1)
              COMMENTS_BODY=$(echo "$COMMENTS_RESPONSE" | head -n-1)

              if [ "$HTTP_CODE" != "200" ]; then
                echo "${{ env.LOG_PREFIX }} Failed to fetch comments (HTTP $HTTP_CODE)"
                ((FAILED++))
                continue 2
              fi

              COMMENT_ID=$(echo "$COMMENTS_BODY" | jq -r \
                --arg marker "$MARKER" \
                '.[] | select(.body | contains($marker)) | .id' \
                2>/dev/null | head -n1 || true)

              [ -n "$COMMENT_ID" ] && break

              PAGE_SIZE=$(echo "$COMMENTS_BODY" | jq 'length')

              [ "$PAGE_SIZE" -lt 100 ] && break

              PAGE=$((PAGE + 1))
            done

            BODY_TEXT="🔗 Linked PR

            - PR: ${PR_URL}
            - Source: ${SOURCE_REPO}
            - Status: ${STATUS}
            - Updated: $(date -u +"%Y-%m-%d %H:%M:%S UTC")

            ${MARKER}"

            if [ -n "$COMMENT_ID" ] && [ "$COMMENT_ID" != "null" ]; then

              echo "${{ env.LOG_PREFIX }} Updating comment $COMMENT_ID"

              UPDATE_RESPONSE=$(curl -s -w "\n%{http_code}" -X PATCH \
                -H "Authorization: Bearer $GH_TOKEN" \
                -H "Accept: application/vnd.github+json" \
                -H "Content-Type: application/json" \
                "https://api.github.com/repos/$REPO/issues/comments/$COMMENT_ID" \
                -d "$(jq -n --arg body "$BODY_TEXT" '{body: $body}')")

              UPDATE_CODE=$(echo "$UPDATE_RESPONSE" | tail -n1)

              if [[ "$UPDATE_CODE" =~ ^(200|201)$ ]]; then
                ((PROCESSED++))
              else
                echo "${{ env.LOG_PREFIX }} Update failed (HTTP $UPDATE_CODE)"
                ((FAILED++))
              fi

            else

              echo "${{ env.LOG_PREFIX }} Creating new comment"

              CREATE_RESPONSE=$(curl -s -w "\n%{http_code}" -X POST \
                -H "Authorization: Bearer $GH_TOKEN" \
                -H "Accept: application/vnd.github+json" \
                -H "Content-Type: application/json" \
                "https://api.github.com/repos/$REPO/issues/$NUMBER/comments" \
                -d "$(jq -n --arg body "$BODY_TEXT" '{body: $body}')")

              CREATE_CODE=$(echo "$CREATE_RESPONSE" | tail -n1)

              if [[ "$CREATE_CODE" =~ ^(200|201)$ ]]; then
                ((PROCESSED++))
              else
                echo "${{ env.LOG_PREFIX }} Create failed (HTTP $CREATE_CODE)"
                ((FAILED++))
              fi
            fi

          done <<< "$ISSUES"

          echo "${{ env.LOG_PREFIX }} Done. Processed: $PROCESSED | Failed: $FAILED"

          exit 0

      - name: Success summary
        if: success()
        run: |
          echo "${{ env.LOG_PREFIX }} ✅ Workflow completed successfully"