<template>
  <Teleport to="body">
    <Transition name="sheet">
      <div v-if="open" class="sheet-backdrop" @click.self="$emit('close')" @keydown.escape="$emit('close')">
        <div
          class="sheet"
          role="dialog"
          aria-modal="true"
          :aria-label="label"
          ref="sheetEl"
          tabindex="-1"
          :style="dragStyle"
          @touchstart="onTouchStart"
          @touchmove="onTouchMove"
          @touchend="onTouchEnd"
        >
          <div class="sheet__handle" aria-hidden="true" />
          <slot />
        </div>
      </div>
    </Transition>
  </Teleport>
</template>

<script setup lang="ts">
import { ref, computed, watch, nextTick } from 'vue'

defineProps<{
  open: boolean
  label: string
}>()

const emit = defineEmits<{
  close: []
}>()

const sheetEl = ref<HTMLElement | null>(null)

watch(
  () => sheetEl.value,
  async (el) => {
    if (el) {
      await nextTick()
      const firstInput = el.querySelector<HTMLElement>('input, textarea, button[type="submit"]')
      if (firstInput) {
        firstInput.focus()
      } else {
        el.focus()
      }
    }
  },
)

/* ── Drag-to-dismiss ── */
const DISMISS_THRESHOLD = 100
const dragY = ref(0)
const dragging = ref(false)
let startY = 0

const dragStyle = computed(() => {
  if (!dragging.value || dragY.value <= 0) return undefined
  return {
    transform: `translateY(${dragY.value}px)`,
    transition: 'none',
  }
})

function onTouchStart(e: TouchEvent) {
  const touch = e.touches[0]
  if (!touch) return
  startY = touch.clientY
  dragging.value = true
  dragY.value = 0
}

function onTouchMove(e: TouchEvent) {
  if (!dragging.value) return
  const touch = e.touches[0]
  if (!touch) return
  const delta = touch.clientY - startY
  if (delta > 0) e.preventDefault()
  dragY.value = Math.max(0, delta)
}

function onTouchEnd() {
  if (dragY.value >= DISMISS_THRESHOLD) {
    emit('close')
  }
  dragging.value = false
  dragY.value = 0
}
</script>

<style scoped>
.sheet-backdrop {
  position: fixed;
  inset: 0;
  background: var(--color-glass-overlay);
  display: flex;
  align-items: flex-end;
  justify-content: center;
  z-index: 100;
}

.sheet {
  background: linear-gradient(135deg, var(--color-glass-strong) 0%, var(--color-glass-subtle) 100%);
  border: 1px solid var(--color-glass-border);
  border-bottom: none;
  backdrop-filter: blur(24px);
  border-radius: 20px 20px 0 0;
  padding: var(--spacing-lg) var(--spacing-xl) var(--spacing-2xl);
  width: 100%;
  max-width: var(--content-max-width);
  display: flex;
  flex-direction: column;
  gap: var(--spacing-lg);
  outline: none;
}

.sheet__handle {
  width: 36px;
  height: 4px;
  background: var(--color-glass-border-hover);
  border-radius: 2px;
  align-self: center;
  flex-shrink: 0;
}

/* Transition */
.sheet-enter-active,
.sheet-leave-active {
  transition: opacity 0.25s ease;
}

.sheet-enter-active .sheet,
.sheet-leave-active .sheet {
  transition: transform 0.25s ease;
}

.sheet-enter-from,
.sheet-leave-to {
  opacity: 0;
}

.sheet-enter-from .sheet,
.sheet-leave-to .sheet {
  transform: translateY(100%);
}
</style>
