/**
 * public/settings.ts — theme + font-size settings (M3).
 *
 * A ⚙ toolbar button opens a small panel; choices persist to localStorage and
 * apply to every terminal via the onChange callback.
 */

import type { ITheme } from '@xterm/xterm'

export interface Settings {
  theme: string
  fontSize: number
}

export const THEMES: Record<string, ITheme> = {
  dark: {
    background: '#0e0f13',
    foreground: '#e7e8ec',
    cursor: '#7c8cff',
    selectionBackground: 'rgba(124,140,255,0.28)',
  },
  light: {
    background: '#f6f7f9',
    foreground: '#1a1d24',
    cursor: '#5b6cff',
    selectionBackground: '#cdd6ff',
  },
  solarized: { background: '#002b36', foreground: '#93a1a1', cursor: '#268bd2' },
}

const KEY = 'web-terminal:settings'
export const DEFAULT_SETTINGS: Settings = { theme: 'dark', fontSize: 14 }

export function loadSettings(): Settings {
  try {
    const raw = localStorage.getItem(KEY)
    if (raw) {
      const s = JSON.parse(raw) as Partial<Settings>
      return {
        theme: typeof s.theme === 'string' && THEMES[s.theme] ? s.theme : DEFAULT_SETTINGS.theme,
        fontSize:
          typeof s.fontSize === 'number' && s.fontSize >= 10 && s.fontSize <= 24
            ? s.fontSize
            : DEFAULT_SETTINGS.fontSize,
      }
    }
  } catch {
    // ignore
  }
  return { ...DEFAULT_SETTINGS }
}

function saveSettings(s: Settings): void {
  try {
    localStorage.setItem(KEY, JSON.stringify(s))
  } catch {
    // ignore
  }
}

export function mountSettings(
  toolbar: HTMLElement,
  current: () => Settings,
  onChange: (s: Settings) => void,
): void {
  const panel = document.createElement('div')
  panel.id = 'settingspanel'
  panel.style.display = 'none'

  const apply = (next: Settings): void => {
    saveSettings(next)
    onChange(next)
    render()
  }

  function render(): void {
    const s = current()
    panel.replaceChildren()

    const themeRow = document.createElement('div')
    themeRow.className = 'settings-row'
    themeRow.append(label('Theme'))
    for (const key of Object.keys(THEMES)) {
      const b = document.createElement('button')
      b.textContent = key
      b.className = key === s.theme ? 'settings-opt active' : 'settings-opt'
      b.addEventListener('click', () => apply({ ...s, theme: key }))
      themeRow.appendChild(b)
    }

    const fontRow = document.createElement('div')
    fontRow.className = 'settings-row'
    fontRow.append(label('Font'))
    const minus = document.createElement('button')
    minus.className = 'settings-opt'
    minus.textContent = 'A−'
    minus.addEventListener('click', () => apply({ ...s, fontSize: Math.max(10, s.fontSize - 1) }))
    const size = document.createElement('span')
    size.className = 'settings-size'
    size.textContent = String(s.fontSize)
    const plus = document.createElement('button')
    plus.className = 'settings-opt'
    plus.textContent = 'A+'
    plus.addEventListener('click', () => apply({ ...s, fontSize: Math.min(24, s.fontSize + 1) }))
    fontRow.append(minus, size, plus)

    panel.append(themeRow, fontRow)
  }

  function label(text: string): HTMLElement {
    const el = document.createElement('span')
    el.className = 'settings-label'
    el.textContent = text
    return el
  }

  document.body.appendChild(panel)

  const toggle = document.createElement('button')
  toggle.className = 'toolbtn'
  toggle.textContent = '⚙'
  toggle.title = 'Settings (theme, font)'
  toggle.setAttribute('aria-label', 'Settings')
  toggle.addEventListener('click', () => {
    if (panel.style.display === 'none') {
      render()
      panel.style.display = 'block'
    } else {
      panel.style.display = 'none'
    }
  })
  toolbar.appendChild(toggle)
}