initial design

[plastikfan]

Change the README to contain information about the parameter list. This issue will allow the effective design of the UI and from this we can derive how the CLI will work.

[plastikfan]

here is an example yaml config:

# ==========================
# Actions
# ==========================
actions:

  # Transcode video with medium quality
  komp-2:
    cmd: "ffmpeg -i {{.path}} -q:v 2 {{.dir}}/{{.stem}}.mp4"
    # Only apply to large video files
    when: "isVideo && isLarge && !isHidden"

  # Transcode video with lower quality
  komp-18:
    cmd: "ffmpeg -i {{.path}} -q:v 18 {{.dir}}/{{.stem}}.mp4"
    when: "isVideo && size > 50MB"

  # Upload to S3 bucket if transcoded file exists
  upload-s3:
    cmd: "aws s3 cp {{.dir}}/{{.stem}}.mp4 s3://mybucket/"
    when: "exists({{.dir}}/{{.stem}}.mp4)"

  # Generate a thumbnail for video
  thumbnail:
    cmd: "ffmpeg -i {{.path}} -vf 'thumbnail' -frames:v 1 {{.dir}}/{{.stem}}.jpg"
    when: "isVideo"

# ==========================
# Pipelines
# ==========================
pipelines:

  # Full video workflow: transcode + thumbnail + upload
  video-workflow:
    steps:
      - komp-2
      - thumbnail
      - upload-s3

  # Quick low-quality workflow
  quick-transcode:
    steps:
      - komp-18
      - upload-s3

Other place-holders:

{{.path}}, {{.name}}, {{.dir}}, {{.stem}}, etc.

Conditional actions:

when: "isVideo && isLarge && !isHidden"

goo exposes filters:

var GooFilters = map[string]func(*core.Node) bool{
    "isLarge": func(n *core.Node) bool { return n.Size() > 100*1024*1024 },
    "isVideo": func(n *core.Node) bool { return n.Ext() == ".mp4" || n.Ext() == ".mov" },
    "isHidden": func(n *core.Node) bool { return strings.HasPrefix(n.Name(), ".") },
}

Use a simple embedded DSL

• github.com/antonmedv/expr

Example Execution

goo walk --pipeline video-workflow --workers 8

•	/media/movie.mp4 → passes all filters → video-workflow
•	Step 1: komp-2 → executed (isVideo && isLarge)
•	Step 2: thumbnail → executed (isVideo)
•	Step 3: upload-s3 → executed only if komp-2 created the file
•	/media/file.txt → filtered out (not video) → no actions run
•	/media/clip.mov → passes → processed in parallel with other nodes

Benefits
• Fully declarative multi-step pipelines
• Conditional actions per node, leveraging agenor filters
• Concurrency safe via worker pool
• Easy for users to configure without scripting
• YAML format is user-friendly and extensible
• Can later support JSON as an alternative config format

1️⃣ Core Path / File Placeholders

Placeholder	Description
{{.path}}	Full absolute path to the node (file or directory).
{{.dir}}	Directory containing the node. Example: /home/user/videos
{{.name}}	Filename including extension. Example: movie.mp4
{{.stem}}	Filename without extension. Example: movie from movie.mp4
{{.ext}}	File extension including the dot. Example: .mp4
{{.basename}}	Alias for {{.name}}.
{{.parent}}	Name of the immediate parent directory. Example: videos in /home/user/videos/movie.mp4
{{.relpath}}	Relative path from the root of the walk. Example: videos/movie.mp4 if root is /home/user

---

2️⃣ File Metadata Placeholders

Placeholder	Description
{{.size}}	File size in bytes.
{{.sizeKB}}	File size in kilobytes.
{{.sizeMB}}	File size in megabytes.
{{.mtime}}	Last modified time (ISO8601 format).
{{.ctime}}	Creation time (if supported by OS).
{{.atime}}	Last access time.
{{.mode}}	File permissions (Unix style, e.g., -rw-r--r--).
{{.isDir}}	Boolean true if node is a directory.
{{.isFile}}	Boolean true if node is a regular file.
{{.isSymlink}}	Boolean true if node is a symbolic link.

---

3️⃣ Derived / Custom Placeholders

Placeholder	Description
{{.hash}}	Optional: full file hash (SHA256, MD5, etc.)
{{.hashShort}}	Short hash (first 8–12 characters).
{{.mime}}	MIME type (requires file sniffing).
{{.extLower}}	File extension in lowercase (e.g., .mp4).
{{.stemSlug}}	Filename sanitized for URLs or filesystem-safe naming.
{{.parentSlug}}	Parent directory sanitized similarly.
{{.depth}}	Depth of the node relative to root (integer).
{{.index}}	Sequential index of nodes emitted so far.