Automatically Review GitHub Pull Requests with OpenAI GPT-4o and Post Comments

id: ai-github-pr-review
namespace: company.team

inputs:
  - id: repo_owner
    type: STRING
    displayName: Repository owner
    description: GitHub username or organization owning the repository
    defaults: "your-org"
  - id: repo_name
    type: STRING
    displayName: Repository name
    description: Name of the GitHub repository to monitor for new pull requests
    defaults: "your-repo"
  - id: pull_number
    type: INT
    displayName: Pull request number
    description: The PR number to review
    defaults: 1
  - id: review_guidelines
    type: STRING
    displayName: Code review guidelines
    description: Custom coding standards or best practices for the AI reviewer to apply
    defaults: |
      - Prefer clear variable names over abbreviations
      - Functions should have a single responsibility
      - Avoid deeply nested conditionals; prefer early returns
      - All public APIs must have docstrings
      - No hardcoded credentials or magic strings

tasks:
  - id: fetch_pr_diff
    type: io.kestra.plugin.core.http.Request
    uri: "https://api.github.com/repos/{{ inputs.repo_owner }}/{{ inputs.repo_name
      }}/pulls/{{ inputs.pull_number }}/files"
    method: GET
    headers:
      Authorization: "Bearer {{ secret('GITHUB_TOKEN') }}"
      Accept: "application/vnd.github.v3+json"
      X-GitHub-Api-Version: "2022-11-28"

  - id: fetch_pr_metadata
    type: io.kestra.plugin.core.http.Request
    uri: "https://api.github.com/repos/{{ inputs.repo_owner }}/{{ inputs.repo_name
      }}/pulls/{{ inputs.pull_number }}"
    method: GET
    headers:
      Authorization: "Bearer {{ secret('GITHUB_TOKEN') }}"
      Accept: "application/vnd.github.v3+json"
      X-GitHub-Api-Version: "2022-11-28"

  - id: generate_review
    type: io.kestra.plugin.openai.ChatCompletion
    apiKey: "{{ secret('OPENAI_API_KEY') }}"
    model: gpt-4o
    maxTokens: 2000
    messages:
      - role: system
        content: |
          You are a senior software engineer performing a thorough code review.
          Review the pull request diff below and provide actionable, constructive feedback.

          Apply these coding guidelines:
          {{ inputs.review_guidelines }}

          Structure your review as:
          ## Summary
          Brief description of what this PR does.

          ## Issues Found
          List specific problems with file path and line context. Rate each as [CRITICAL], [MAJOR], or [MINOR].

          ## Suggestions
          Improvement suggestions that are not blocking.

          ## Verdict
          One of: ✅ APPROVED | ⚠️ APPROVED WITH SUGGESTIONS | ❌ CHANGES REQUESTED
      - role: user
        content: |
          PR Title: {{ outputs.fetch_pr_metadata.body | json | jq('.title') | first }}
          PR Description: {{ outputs.fetch_pr_metadata.body | json | jq('.body') | first }}

          Changed files and diffs:
          {{ outputs.fetch_pr_diff.body }}

  - id: post_review_comment
    type: io.kestra.plugin.core.http.Request
    uri: "https://api.github.com/repos/{{ inputs.repo_owner }}/{{ inputs.repo_name
      }}/issues/{{ inputs.pull_number }}/comments"
    method: POST
    contentType: "application/json"
    headers:
      Authorization: "Bearer {{ secret('GITHUB_TOKEN') }}"
      Accept: "application/vnd.github.v3+json"
      X-GitHub-Api-Version: "2022-11-28"
    body: |
      {
        "body": "## 🤖 Automated AI Code Review\n\n{{ outputs.generate_review.choices[0].message.content | replace('\"', '\\\"') | replace('\n', '\\n') }}\n\n---\n_Reviewed by Kestra AI Code Review workflow_"
      }

triggers:
  - id: github_webhook
    type: io.kestra.plugin.core.trigger.Webhook
    key: "{{ secret('WEBHOOK_KEY') }}"