name: PR Bot

on:
  pull_request:
    types: [opened]

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

jobs:
  label-and-comment:
    runs-on: ubuntu-latest

    steps:
      - name: Checkout
        uses: actions/checkout@v3

      - name: Get PR Diff
        id: diff
        run: |
          curl -sSL -H "Accept: application/vnd.github.v3.diff" \
            "${{ github.event.pull_request.url }}" > pr.diff

      - name: Determine Labels and Comment
        id: label-and-comment
        uses: actions/github-script@v7
        with:
          script: |
            const fs = require('fs');
            const diff = fs.readFileSync('pr.diff', 'utf8');
            const user = context.payload.pull_request.user.login;
            const isBot = user.includes('bot');
            const labels = new Set();
            let changeCount = 0;

            // Simple diff parsing
            const files = diff.match(/^diff --git a\/(.+?) b\//gm)?.map(line => line.split(' ')[2]) || [];

            for (const file of files) {
              if (file.startsWith('src/')) labels.add('backend');
              if (file.startsWith('pyproject.toml')) labels.add('backend');
              if (file.startsWith('src-ui/')) labels.add('frontend');
              if (file.startsWith('docs/')) labels.add('documentation');
              if (file.startsWith('.github/')) labels.add('ci-cd');
            }

            // Change size estimate (added lines > 2 chars, non-docs)
            const addedLines = diff.match(/^\+[^+]/gm) || [];
            for (const line of addedLines) {
              const trimmed = line.slice(1).trim();
              if (trimmed.length > 2 && !/\.(md|rst|txt|lock)$/.test(line)) {
                changeCount++;
              }
            }

            if (changeCount < 10) labels.add('small-change');
            else labels.add('non-trivial');

            if (user.includes('dependabot')) {
              labels.clear();
              labels.add('dependencies');
            }

            if (user.includes('paperlessngx-bot')) {
              labels.add('skip-changelog');
              labels.add('translation');
            }

            core.setOutput('labels', JSON.stringify([...labels]));
            core.setOutput('should_comment', (!isBot).toString());
            core.setOutput('user', user);

      - name: Apply Labels
        if: steps.label-and-comment.outputs.labels != '[]'
        run: |
          gh pr edit ${{ github.event.pull_request.number }} \
            --add-label $(echo '${{ steps.label-and-comment.outputs.labels }}' | jq -r '. | join(",")')
        env:
          GH_TOKEN: ${{ secrets.GITHUB_TOKEN }}

      - name: Comment on PR
        if: steps.label-and-comment.outputs.should_comment == 'true'
        uses: actions/github-script@v7
        with:
          script: |
            const user = '${{ steps.label-and-comment.outputs.user }}';

            const body = `
            Hello @${user},

            Thank you very much for submitting this PR to us!

            This is what will happen next:

            1. CI tests will run against your PR to ensure quality and consistency.
            2. Next, human contributors from paperless-ngx review your changes. ${reviewNote}
            3. Please address any issues that come up during the review as soon as you are able to.
            4. If accepted, your pull request will be merged into the \`dev\` branch and changes there will be tested further.
            5. Eventually, changes from you and other contributors will be merged into \`main\` and a new release will be made.

            You'll be hearing from us soon, and thank you again for contributing to our project.
            `;

            await github.rest.issues.createComment({
              issue_number: context.issue.number,
              owner: context.repo.owner,
              repo: context.repo.repo,
              body,
            });