<template>
  <div
      ref="el"
      :style="style"
      class="fixed z-[999] w-72 bg-white dark:bg-gray-900 shadow-2xl rounded-xl border border-gray-200 dark:border-gray-800 p-4 select-none touch-none"
  >
    <div class="flex items-center justify-between mb-4 cursor-move border-b pb-2 dark:border-gray-800">
      <div class="flex items-center gap-2 text-gray-500">
        <UIcon name="i-heroicons-calculator" />
        <span class="text-xs font-bold uppercase tracking-wider">Kalkulator</span>
      </div>
      <div class="flex items-center gap-1">
        <UTooltip text="Verlauf">
          <UButton
              color="gray"
              variant="ghost"
              :icon="showHistory ? 'i-heroicons-clock-solid' : 'i-heroicons-clock'"
              size="xs"
              @click="showHistory = !showHistory"
          />
        </UTooltip>
        <UTooltip text="Schließen (Esc)">
          <UButton
              color="gray"
              variant="ghost"
              icon="i-heroicons-x-mark"
              size="xs"
              @click="store.isOpen = false"
          />
        </UTooltip>
      </div>
    </div>

    <div v-if="!showHistory">
      <div
          class="bg-gray-100 dark:bg-gray-800 p-3 rounded-lg mb-4 text-right border border-gray-200 dark:border-gray-700 cursor-pointer group relative"
          @click="copyDisplay"
      >
        <div class="text-[10px] text-gray-500 h-4 font-mono uppercase tracking-tighter">
          Speicher: {{ Number(store.memory).toFixed(2).replace('.', ',') }} €
        </div>
        <div class="text-2xl font-mono truncate tracking-tighter">{{ store.display }}</div>

        <div class="absolute inset-0 flex items-center justify-center bg-primary-500/10 opacity-0 group-hover:opacity-100 transition-opacity rounded-lg">
          <span class="text-[10px] font-bold text-primary-600 uppercase">
            {{ copied ? 'Kopiert!' : 'Klicken zum Kopieren' }}
          </span>
        </div>
      </div>

      <div class="grid grid-cols-4 gap-2">
        <UTooltip text="Brutto (+19%)"><UButton color="green" variant="soft" block size="xs" @click="applyTax(19)">+19%</UButton></UTooltip>
        <UTooltip text="Brutto (+7%)"><UButton color="green" variant="soft" block size="xs" @click="applyTax(7)">+7%</UButton></UTooltip>
        <UTooltip text="Netto (-19%)"><UButton color="rose" variant="soft" block size="xs" @click="removeTax(19)">-19%</UButton></UTooltip>
        <UTooltip text="Netto (-7%)"><UButton color="rose" variant="soft" block size="xs" @click="removeTax(7)">-7%</UButton></UTooltip>

        <UTooltip text="Löschen"><UButton color="gray" variant="ghost" block @click="clear">C</UButton></UTooltip>
        <UTooltip text="Speicher +"><UButton color="gray" variant="ghost" block @click="addToSum">M+</UButton></UTooltip>
        <UTooltip text="Speicher Reset"><UButton color="gray" variant="ghost" block @click="store.memory = 0">MC</UButton></UTooltip>
        <UButton color="primary" variant="soft" @click="setOperator('/')">/</UButton>

        <UButton v-for="n in [7, 8, 9]" :key="n" color="white" @click="appendNumber(n)">{{ n }}</UButton>
        <UButton color="primary" variant="soft" @click="setOperator('*')">×</UButton>

        <UButton v-for="n in [4, 5, 6]" :key="n" color="white" @click="appendNumber(n)">{{ n }}</UButton>
        <UButton color="primary" variant="soft" @click="setOperator('-')">-</UButton>

        <UButton v-for="n in [1, 2, 3]" :key="n" color="white" @click="appendNumber(n)">{{ n }}</UButton>
        <UButton color="primary" variant="soft" @click="setOperator('+')">+</UButton>

        <UButton color="white" class="col-span-2" @click="appendNumber(0)">0</UButton>
        <UButton color="white" @click="addComma">,</UButton>
        <UButton color="primary" block @click="calculate">=</UButton>
      </div>
    </div>

    <div v-else class="h-[270px] flex flex-col animate-in fade-in duration-200">
      <div class="flex-1 overflow-y-auto space-y-2 pr-1 custom-scrollbar">
        <div v-if="store.history.length === 0" class="text-center text-gray-400 text-xs mt-10 italic">
          Keine Berechnungen im Verlauf
        </div>
        <div
            v-for="(item, i) in store.history" :key="i"
            class="p-2 bg-gray-50 dark:bg-gray-800 rounded text-right border-l-2 border-primary-500 cursor-pointer hover:bg-primary-50 dark:hover:bg-primary-900/20 transition-colors"
            @click="useHistoryItem(item.result)"
        >
          <div class="text-[10px] text-gray-400">{{ item.expression }} =</div>
          <div class="text-sm font-bold">{{ item.result }}</div>
        </div>
      </div>
      <UButton
          color="gray"
          variant="ghost"
          size="xs"
          block
          class="mt-2"
          icon="i-heroicons-trash"
          @click="store.history = []"
      >
        Verlauf leeren
      </UButton>
    </div>
  </div>
</template>

<script setup>
import { useDraggable, useClipboard } from '@vueuse/core'
import { useCalculatorStore } from '~/stores/calculator'

const store = useCalculatorStore()
const { copy, copied } = useClipboard()

const el = ref(null)
const { style } = useDraggable(el, {
  initialValue: { x: window.innerWidth - 350, y: 150 },
})

const shouldResetDisplay = ref(false)
const showHistory = ref(false)
const previousValue = ref(null)
const lastOperator = ref(null)

// --- Logik ---
const appendNumber = (num) => {
  if (store.display === '0' || shouldResetDisplay.value) {
    store.display = String(num)
    shouldResetDisplay.value = false
  } else {
    store.display += String(num)
  }
}

const addComma = () => {
  if (!store.display.includes(',')) {
    store.display += ','
  }
}

const setOperator = (op) => {
  previousValue.value = parseFloat(store.display.replace(',', '.'))
  lastOperator.value = op
  shouldResetDisplay.value = true
}

const calculate = () => {
  if (lastOperator.value === null) return
  const currentVal = parseFloat(store.display.replace(',', '.'))
  const prevVal = previousValue.value
  let result = 0

  switch (lastOperator.value) {
    case '+': result = prevVal + currentVal; break
    case '-': result = prevVal - currentVal; break
    case '*': result = prevVal * currentVal; break
    case '/': result = currentVal !== 0 ? prevVal / currentVal : 0; break
  }

  const expression = `${prevVal} ${lastOperator.value} ${currentVal}`
  const resultString = String(Number(result.toFixed(4))).replace('.', ',')

  store.addHistory(expression, resultString)
  store.display = resultString
  lastOperator.value = null
  shouldResetDisplay.value = true
}

const clear = () => {
  store.display = '0'
  previousValue.value = null
  lastOperator.value = null
}

const applyTax = (percent) => {
  const current = parseFloat(store.display.replace(',', '.'))
  store.display = (current * (1 + percent / 100)).toFixed(2).replace('.', ',')
}

const removeTax = (percent) => {
  const current = parseFloat(store.display.replace(',', '.'))
  store.display = (current / (1 + percent / 100)).toFixed(2).replace('.', ',')
}

const addToSum = () => {
  store.memory += parseFloat(store.display.replace(',', '.'))
  shouldResetDisplay.value = true
}

const copyDisplay = () => {
  copy(store.display)
}

const useHistoryItem = (val) => {
  store.display = val
  showHistory.value = false
}

// --- Shortcuts ---
defineShortcuts({
  '0': () => appendNumber(0),
  '1': () => appendNumber(1),
  '2': () => appendNumber(2),
  '3': () => appendNumber(3),
  '4': () => appendNumber(4),
  '5': () => appendNumber(5),
  '6': () => appendNumber(6),
  '7': () => appendNumber(7),
  '8': () => appendNumber(8),
  '9': () => appendNumber(9),
  'comma': addComma,
  'plus': () => setOperator('+'),
  'minus': () => setOperator('-'),
  'enter': { usingInput: true, handler: calculate },
  'backspace': () => {
    store.display = store.display.length > 1 ? store.display.slice(0, -1) : '0'
  },
  // Escape schließt nun das Fenster via Store
  'escape': {
    usingInput: true,
    whenever: [computed(() => store.isOpen)],
    handler: () => { store.isOpen = false }
  }
})
</script>

<style scoped>
.custom-scrollbar::-webkit-scrollbar {
  width: 4px;
}
.custom-scrollbar::-webkit-scrollbar-track {
  @apply bg-transparent;
}
.custom-scrollbar::-webkit-scrollbar-thumb {
  @apply bg-gray-200 dark:bg-gray-700 rounded-full;
}
</style>