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require "rails_helper"

RSpec.describe "Theme switching", type: :system do
  def current_theme
    page.evaluate_script("document.documentElement.getAttribute('data-theme')")
  end

  def toggle_button
    find("button[aria-label='Přepnout tmavý režim']")
  end

  it "defaults to light theme when no preference is saved" do
    visit root_path
    expect(current_theme).to eq("light")
    expect(toggle_button.text).to eq("🌙")
  end

  it "switches to dark when toggled and updates the icon" do
    visit root_path
    toggle_button.click
    expect(current_theme).to eq("dark")
    expect(toggle_button.text).to eq("🔅")
  end

  it "switches back to light on second toggle" do
    visit root_path
    toggle_button.click
    toggle_button.click
    expect(current_theme).to eq("light")
    expect(toggle_button.text).to eq("🌙")
  end

  it "persists preference across navigation" do
    visit root_path
    toggle_button.click
    expect(current_theme).to eq("dark")

    visit examples_path
    expect(current_theme).to eq("dark")
  end

  it "restores saved dark preference on a fresh page load" do
    visit root_path
    page.execute_script("localStorage.setItem('theme', 'dark')")

    visit root_path
    expect(current_theme).to eq("dark")
    expect(toggle_button.text).to eq("🔅")
  end
end