/**
 * User confirmation utility
 * Non-blocking confirmation overlay to avoid `window.confirm()` (`no-alert`).
 * Used for critical confirmations (e.g. destructive actions) without requiring
 * a React modal or additional global state.
 */
export function userConfirm(message: string): Promise<boolean> {
  return confirmOverlay(message)
}

type ConfirmOverlayElements = {
  overlay: HTMLDivElement
  cancel: HTMLButtonElement
  confirm: HTMLButtonElement
}

type ConfirmOverlayHandlerParams = ConfirmOverlayElements & {
  resolve: (value: boolean) => void
}

function confirmOverlay(message: string): Promise<boolean> {
  const doc = globalThis.document
  if (!doc) {
    return Promise.resolve(false)
  }

  return new Promise((resolve) => {
    const { overlay, cancel, confirm } = buildConfirmOverlay(doc, message)
    doc.body.append(overlay)
    overlay.focus()
    attachConfirmOverlayHandlers({ overlay, cancel, confirm, resolve })
  })
}

function buildConfirmOverlay(doc: Document, message: string): ConfirmOverlayElements {
  const overlay = createOverlay(doc)
  const panel = createPanel(doc)
  const text = createText(doc, message)
  const buttons = createButtonsContainer(doc)
  const cancel = createCancelButton(doc)
  const confirm = createConfirmButton(doc)
  buttons.append(cancel, confirm)
  panel.append(text, buttons)
  overlay.append(panel)

  return { overlay, cancel, confirm }
}

function createOverlay(doc: Document): HTMLDivElement {
  const overlay = doc.createElement('div')
  overlay.setAttribute('role', 'dialog')
  overlay.setAttribute('aria-modal', 'true')
  overlay.tabIndex = -1
  overlay.style.position = 'fixed'
  overlay.style.inset = '0'
  overlay.style.background = 'rgba(0,0,0,0.6)'
  overlay.style.display = 'flex'
  overlay.style.alignItems = 'center'
  overlay.style.justifyContent = 'center'
  overlay.style.zIndex = '9999'
  return overlay
}

function createPanel(doc: Document): HTMLDivElement {
  const panel = doc.createElement('div')
  panel.style.background = '#fff'
  panel.style.borderRadius = '12px'
  panel.style.padding = '16px'
  panel.style.maxWidth = '520px'
  panel.style.width = 'calc(100% - 32px)'
  panel.style.boxShadow = '0 10px 30px rgba(0,0,0,0.35)'
  return panel
}

function createText(doc: Document, message: string): HTMLParagraphElement {
  const text = doc.createElement('p')
  text.textContent = message
  text.style.margin = '0 0 16px 0'
  text.style.color = '#111827'
  return text
}

function createButtonsContainer(doc: Document): HTMLDivElement {
  const buttons = doc.createElement('div')
  buttons.style.display = 'flex'
  buttons.style.gap = '12px'
  buttons.style.justifyContent = 'flex-end'
  return buttons
}

function createCancelButton(doc: Document): HTMLButtonElement {
  const cancel = doc.createElement('button')
  cancel.type = 'button'
  cancel.textContent = 'Cancel'
  cancel.style.padding = '8px 12px'
  cancel.style.borderRadius = '10px'
  cancel.style.border = '1px solid #e5e7eb'
  cancel.style.background = '#f3f4f6'
  return cancel
}

function createConfirmButton(doc: Document): HTMLButtonElement {
  const confirm = doc.createElement('button')
  confirm.type = 'button'
  confirm.textContent = 'Confirm'
  confirm.style.padding = '8px 12px'
  confirm.style.borderRadius = '10px'
  confirm.style.border = '1px solid #ef4444'
  confirm.style.background = '#fee2e2'
  confirm.style.color = '#991b1b'
  return confirm
}

function attachConfirmOverlayHandlers(params: ConfirmOverlayHandlerParams): void {
  const { overlay, cancel, confirm, resolve } = params
  let resolved = false

  function resolveOnce(next: boolean): void {
    if (resolved) {
      return
    }
    resolved = true
    cleanup()
    resolve(next)
  }

  function onCancel(): void {
    resolveOnce(false)
  }

  function onConfirm(): void {
    resolveOnce(true)
  }

  function onKeyDown(e: KeyboardEvent): void {
    if (e.key === 'Escape') {
      e.preventDefault()
      resolveOnce(false)
      return
    }
    if (e.key === 'Enter') {
      e.preventDefault()
      resolveOnce(true)
    }
  }

  function cleanup(): void {
    overlay.removeEventListener('keydown', onKeyDown)
    cancel.removeEventListener('click', onCancel)
    confirm.removeEventListener('click', onConfirm)
    overlay.remove()
  }

  cancel.addEventListener('click', onCancel)
  confirm.addEventListener('click', onConfirm)
  overlay.addEventListener('keydown', onKeyDown)
}