permissions:
  contents: read
  pull-requests: write
name: PR Linter

# This workflow runs on pull requests that are opened, edited, or have new commits pushed.
on:
  pull_request:
    types: [opened, edited, synchronize]


concurrency:
  group: ${{ github.workflow }}-${{ github.event.pull_request.number || github.ref }}
  cancel-in-progress: true
jobs:
  lint-pr:
    runs-on: ubuntu-latest
    steps:
      - name: Checkout Code
        uses: actions/checkout@v6

      - name: Validate PR Title, Description, and Commits
        uses: actions/github-script@v7
        with:
          script: |
            // Get the PR context
            const pr = context.payload.pull_request;
            if (!pr) {
              core.setFailed("Could not get PR from context.");
              return;
            }
            const owner = context.repo.owner;
            const repo = context.repo.repo;
            
            let errors = [];

            // 1. Validate PR Title
            const title = pr.title;
            const titleRegex = /^\[(OPIK-\d+|DND-\d+|DEV-\d+|CUST-\d+|issue-\d+|NA)\](\s*\[(BE|FE|DOCS|SDK|GHA|CI|HELM)\])*\s*.+$/;
            if (!titleRegex.test(title)) {
              errors.push(
                "❌ **Invalid Title Format.** Your PR title must include a ticket/issue number and may optionally include component tags (`[FE]`, `[BE]`, etc.).\n\n" +
                "  - **Internal contributors: Open a JIRA ticket and link to it:** `[OPIK-xxxx]` or `[CUST-xxxx]` or `[DND-xxxx]` or `[DEV-xxxx] [COMPONENT] Your change`\n" +
                "  - **External contributors: Open a Github Issue and link to it via its number:** `[issue-xxxx] [COMPONENT] Your change`\n" +
                "  - **No ticket:** Use `[NA] [COMPONENT] Your change` (Issues section not required)\n\n" +
                "  *Example: `[issue-3108] [BE] [FE] Fix authentication bug` or `[OPIK-1234] Fix bug` or `[NA] Update README`*"
              );
            }

            // 2. Validate PR Description
            const body = pr.body || "";
            const requiredHeadings = ["## Details", "## Change checklist", "## Issues", "## Testing", "## Documentation"];
            if (body.length === 0) {
              errors.push("❌ **Missing Description.** The PR description cannot be empty.");
            } else {
              for (const heading of requiredHeadings) {
                if (!body.includes(heading)) {
                  errors.push(`❌ **Missing Section.** The description is missing the \`${heading}\` section.`);
                }
              }

              // Helper function to get content of a markdown section
              const getSectionContent = (sectionTitle) => {
                const startIndex = body.indexOf(sectionTitle);
                if (startIndex === -1) return null;
                const nextHeaderIndex = body.indexOf("## ", startIndex + sectionTitle.length);
                const endIndex = nextHeaderIndex !== -1 ? nextHeaderIndex : body.length;
                return body.substring(startIndex + sectionTitle.length, endIndex).trim();
              };
              
              const detailsContent = getSectionContent("## Details");
              if (detailsContent !== null && detailsContent.length === 0) {
                  errors.push("❌ **Incomplete Details Section.** The `## Details` section cannot be empty.");
              }

              const issuesContent = getSectionContent("## Issues");
              const issuesRegex = /(#\d+|OPIK-\d+|DND-\d+|DEV-\d+|CUST-\d+)/;
              const isNATicket = title.startsWith("[NA]");
              if (issuesContent !== null && !isNATicket && !issuesRegex.test(issuesContent)) {
                 errors.push(
                   "❌ **Incomplete Issues Section.** You must reference at least one GitHub issue (`#xxxx`), Jira ticket (`OPIK-xxxx`), CUST ticket (`CUST-xxxx`), DEV ticket (`DEV-xxxx`), or DND ticket (`DND-xxxx`) under the `## Issues` section."
                 );
              }
            }
            
            // 3. Find all existing linter comments across all pages
            const COMMENT_MARKER = "<!-- pr-linter-comment -->";
            const allComments = await github.paginate(github.rest.issues.listComments, { owner, repo, issue_number: pr.number });
            const markerComments = allComments.filter(c => c.body && c.body.includes(COMMENT_MARKER));

            // 4. Final step: upsert/delete comment and/or fail the job
            if (errors.length > 0) {
              const commentBody = COMMENT_MARKER + "\n### 📋 PR Linter Failed\n\n" + errors.join("\n\n---\n\n");

              const logMessage = "PR Linter Failed:\n\n" + errors.join("\n\n")
                  .replace(/❌ \*\*/g, '❌ ')
                  .replace(/\*\*`/g, '`')
                  .replace(/`\*\*/g, '`')
                  .replace(/###\s/g, '')
                  .replace(/---\n\n/g, '');

              if (markerComments.length > 0) {
                // Keep the newest, delete any duplicates
                const [keep, ...duplicates] = [...markerComments].sort((a, b) => b.id - a.id);
                await github.rest.issues.updateComment({ owner, repo, comment_id: keep.id, body: commentBody });
                await Promise.all(duplicates.map(c => github.rest.issues.deleteComment({ owner, repo, comment_id: c.id })));
              } else {
                await github.rest.issues.createComment({ owner, repo, issue_number: pr.number, body: commentBody });
              }

              core.setFailed(logMessage);
            } else {
              await Promise.all(markerComments.map(c => github.rest.issues.deleteComment({ owner, repo, comment_id: c.id })));
              console.log("✅ PR linting passed!");
            }