feat: make gradient colours configurable (#133)

[linkzera]

Add configurable gradient support for progress bar

This PR introduces a new --gradient (-g) flag that allows users to customize the progress bar gradient. Users can now select from predefined presets (default, sunset, aqua, forest, fire) or specify two custom hex colors separated by a comma (e.g., --gradient=#00FF00,#0000FF). If the flag is not set or an invalid value is provided, the default gradient is used.

Features:

New --gradient flag for selecting gradient style.
Support for both presets and custom color pairs.
Updated help text to document the new flag.

[Copilot]

Pull Request Overview

Adds a new --gradient flag to customize the progress bar gradient via presets or custom hex pairs.

• Introduce gradientFlag and register the --gradient CLI option with help text.
• Define gradientPresets map and select the appropriate gradient at runtime.
• Replace the hardcoded default gradient with dynamic gradient handling in main.go.

Comments suppressed due to low confidence (1)

main.go:162

• The new gradient parsing logic lacks unit tests. Add tests covering preset selection, custom hex parsing, and invalid-input fallback to ensure expected behavior.

var progressBar progress.Model

[caarlos0]

hey, thanks for the pr

have a couple of comments

[Copilot]

Pull Request Overview

This PR adds a new --gradient flag to allow users to customize the progress bar gradient using predefined presets or two custom hex colors.

• Introduced gradient flag and gradientPresets map.
• Implemented logic to select a preset or parse custom hex colors.
• Updated the Cobra command initialization to register and document the new flag.

Comments suppressed due to low confidence (2)

main.go:170

• [nitpick] Enhance this error message by listing valid presets or the expected format to guide users (e.g. "invalid gradient %q; valid presets are %v or two hex colors separated by a comma").

return fmt.Errorf("invalid gradient %q", gradient)

main.go:218

• Add unit tests for the new --gradient flag, covering valid presets, valid custom color pairs, and invalid inputs to ensure the parsing logic behaves as expected.

rootCmd.Flags().StringVarP(&gradient, "gradient", "g", "default", "Gradient preset (default, sunset, aqua, forest, fire) or two hex colors separated by comma (ex: --gradient=#00FF00,#0000FF)")