name: Add External Component Comment

on:
  pull_request_target:
    types: [opened, synchronize]

permissions:
  contents: read       #  Needed to fetch PR details
  issues: write        #  Needed to create and update comments (PR comments are managed via the issues REST API)
  pull-requests: write  # also needed?

jobs:
  external-comment:
    name: External component comment
    runs-on: ubuntu-latest
    steps:
      - name: Add external component comment
        uses: actions/github-script@v7.0.1
        with:
          github-token: ${{ secrets.GITHUB_TOKEN }}
          script: |
            // Generate external component usage instructions
            function generateExternalComponentInstructions(prNumber, componentNames, owner, repo) {
                let source;
                if (owner === 'esphome' && repo === 'esphome')
                    source = `github://pr#${prNumber}`;
                else
                    source = `github://${owner}/${repo}@pull/${prNumber}/head`;
                return `To use the changes from this PR as an external component, add the following to your ESPHome configuration YAML file:

            \`\`\`yaml
            external_components:
              - source: ${source}
                components: [${componentNames.join(', ')}]
                refresh: 1h
            \`\`\``;
            }

            // Generate repo clone instructions
            function generateRepoInstructions(prNumber, owner, repo, branch) {
                return `To use the changes in this PR:

            \`\`\`bash
            # Clone the repository:
            git clone https://github.com/${owner}/${repo}
            cd ${repo}

            # Checkout the PR branch:
            git fetch origin pull/${prNumber}/head:${branch}
            git checkout ${branch}

            # Install the development version:
            script/setup

            # Activate the development version:
            source venv/bin/activate
            \`\`\`

            Now you can run \`esphome\` as usual to test the changes in this PR.
            `;
            }

            async function createComment(octokit, owner, repo, prNumber, esphomeChanges, componentChanges) {
                const commentMarker = "<!-- This comment was generated automatically by the external-component-bot workflow. -->";
                const legacyCommentMarker = "<!-- This comment was generated automatically by a GitHub workflow. -->";
                let commentBody;
                if (esphomeChanges.length === 1) {
                    commentBody = generateExternalComponentInstructions(prNumber, componentChanges, owner, repo);
                } else {
                    commentBody = generateRepoInstructions(prNumber, owner, repo, context.payload.pull_request.head.ref);
                }
                commentBody += `\n\n---\n(Added by the PR bot)\n\n${commentMarker}`;

                // Check for existing bot comment
                const comments = await github.paginate(
                    github.rest.issues.listComments,
                    {
                        owner: owner,
                        repo: repo,
                        issue_number: prNumber,
                        per_page: 100,
                    }
                );

                const sorted = comments.sort((a, b) => new Date(b.updated_at) - new Date(a.updated_at));

                const botComment = sorted.find(comment =>
                    (
                      comment.body.includes(commentMarker) ||
                      comment.body.includes(legacyCommentMarker)
                    ) && comment.user.type === "Bot"
                );

                if (botComment && botComment.body === commentBody) {
                    // No changes in the comment, do nothing
                    return;
                }

                if (botComment) {
                    // Update existing comment
                    await github.rest.issues.updateComment({
                        owner: owner,
                        repo: repo,
                        comment_id: botComment.id,
                        body: commentBody,
                    });
                } else {
                    // Create new comment
                    await github.rest.issues.createComment({
                        owner: owner,
                        repo: repo,
                        issue_number: prNumber,
                        body: commentBody,
                    });
                }
            }

            async function getEsphomeAndComponentChanges(github, owner, repo, prNumber) {
                const changedFiles = await github.rest.pulls.listFiles({
                    owner: owner,
                    repo: repo,
                    pull_number: prNumber,
                });

                const esphomeChanges = changedFiles.data
                    .filter(file => file.filename !== "esphome/core/defines.h" && file.filename.startsWith('esphome/'))
                    .map(file => {
                        const match = file.filename.match(/esphome\/([^/]+)/);
                        return match ? match[1] : null;
                    })
                    .filter(it => it !== null);

                if (esphomeChanges.length === 0) {
                    return {esphomeChanges: [], componentChanges: []};
                }

                const uniqueEsphomeChanges = [...new Set(esphomeChanges)];
                const componentChanges = changedFiles.data
                    .filter(file => file.filename.startsWith('esphome/components/'))
                    .map(file => {
                        const match = file.filename.match(/esphome\/components\/([^/]+)\//);
                        return match ? match[1] : null;
                    })
                    .filter(it => it !== null);

                return {esphomeChanges: uniqueEsphomeChanges, componentChanges: [...new Set(componentChanges)]};
            }

            // Start of main code.

            const prNumber = context.payload.pull_request.number;
            const {owner, repo} = context.repo;

            const {esphomeChanges, componentChanges} = await getEsphomeAndComponentChanges(github, owner, repo, prNumber);
            if (componentChanges.length !== 0) {
                await createComment(github, owner, repo, prNumber, esphomeChanges, componentChanges);
            }