Demonstrates terminal color rendering and the Color module.

Terminal apps need vibrant colors. Specifying colors as symbols or calculated hex strings works but limits expressiveness.

This demo shows the Color module’s constructors for creating colors from HSL values or hex integers, producing a full-spectrum gradient.

Use it to understand color representation and the Color.hsl/Color.hex APIs.

Source Code

# frozen_string_literal: true

#--
# SPDX-FileCopyrightText: 2026 Kerrick Long <me@kerricklong.com>
# SPDX-License-Identifier: MIT-0
#++

$LOAD_PATH.unshift File.expand_path("../../lib", __dir__)
require "ratatui_ruby"

# Demonstrates terminal color rendering and the Color module.
#
# Terminal apps need vibrant colors. Specifying colors as symbols or
# calculated hex strings works but limits expressiveness.
#
# This demo shows the Color module's constructors for creating colors
# from HSL values or hex integers, producing a full-spectrum gradient.
#
# Use it to understand color representation and the Color.hsl/Color.hex APIs.
class WidgetStyleColors
  def initialize
    @width = 80
    @height = 24
  end

  def run
    RatatuiRuby.run do |tui|
      loop do
        tui.draw do |frame|
          frame.render_widget(render(tui), frame.area)
        end
        event = tui.poll_event
        break if event.key? && (event.ctrl_c? || event == :q)
      end
    end
  end

  private def render(tui)
    lines = []

    (0...@height).each do |row|
      spans = []
      (0...@width).each do |col|
        hue = (col.to_f / @width) * 360.0
        lightness = 50.0 - ((row.to_f / @height) * 50.0)

        # Use Color.hsl for top half, Color.hsluv for bottom half
        # HSLuv provides perceptually uniform colors (same visual brightness)
        hex = if row < @height / 2
          RatatuiRuby::Style::Color.hsl(hue, 100.0, lightness)
        else
          # HSLuv: perceptually uniform - all colors appear equal brightness
          RatatuiRuby::Style::Color.hsluv(hue, 100.0, lightness)
        end

        # Demonstrate Style.with for concise inline styling
        span = tui.text_span(
          content: " ",
          style: RatatuiRuby::Style::Style.with(bg: hex)
        )
        spans << span
      end

      lines << tui.text_line(spans:)
    end

    # Also demonstrate Color.hex for the border
    border_color = RatatuiRuby::Style::Color.hex(0xFFD700) # Gold

    tui.paragraph(
      text: lines,
      block: tui.block(
        title: "HSL (top) vs HSLuv (bottom) - Style.with demo (Press 'q' to exit)",
        borders: [:all],
        border_type: :rounded,
        # Using Style.with for concise border styling
        border_style: RatatuiRuby::Style::Style.with(fg: border_color)
      )
    )
  end
end

WidgetStyleColors.new.run if __FILE__ == $PROGRAM_NAME