obitools4/autodoc/docmd/pkg/obiutils/download.md

obiutils.DownloadFile — Semantic Feature Overview

• Core Functionality: Downloads a file from a given URL to a specified local path.

• HTTP Client Behavior:

  • Uses http.Get() for simple, synchronous GET requests.
  • Validates the HTTP status code; aborts on non-200 responses with a descriptive error.

• Resource Management:

  • Ensures proper cleanup via defer resp.Body.Close() and defer out.Close().

• Progress Tracking:

  • Integrates progressbar to display real-time download progress.
  • Uses DefaultBytes() for a human-readable, byte-based indicator (e.g., "downloading 12.3 MB / 45.6 MB").

• Efficient I/O:

  • Leverages io.Copy() with an io.MultiWriter to stream data directly from the HTTP response body into both:
    • The target file (out)
    • The progress bar (to update on each chunk written)

• Error Handling:

  • Returns early with wrapped errors for network failures, HTTP non-success codes, or file I/O issues.

• Simplicity & Usability:

  • Minimal API surface: only two arguments (url, filepath).
  • No external configuration needed — ideal for CLI tools or batch scripts.

• Assumptions:

  • No authentication, redirects, proxies, timeouts, or retries are implemented.
  • Designed for straightforward downloads where robustness is secondary to simplicity.

• Typical Use Cases:

  • CLI utilities, build scripts, CI/CD pipelines.
  • Prototyping or internal tools where advanced download features are unnecessary.

• Limitations:

  • Not suitable for large-scale or production-grade downloads without enhancements (e.g., retries, concurrency control).