<template>
  <div class="card p-4">
    <h3 class="text-sm font-semibold text-gray-900 dark:text-white mb-4">{{ t('admin.dashboard.tokenUsageTrend') }}</h3>
    <div v-if="loading" class="flex items-center justify-center h-48">
      <LoadingSpinner />
    </div>
    <div v-else-if="trendData.length > 0 && chartData" class="h-48">
      <Line :data="chartData" :options="lineOptions" />
    </div>
    <div v-else class="flex items-center justify-center h-48 text-gray-500 dark:text-gray-400 text-sm">
      {{ t('admin.dashboard.noDataAvailable') }}
    </div>
  </div>
</template>

<script setup lang="ts">
import { computed } from 'vue'
import { useI18n } from 'vue-i18n'
import {
  Chart as ChartJS,
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  Title,
  Tooltip,
  Legend,
  Filler
} from 'chart.js'
import { Line } from 'vue-chartjs'
import LoadingSpinner from '@/components/common/LoadingSpinner.vue'
import type { TrendDataPoint } from '@/types'

ChartJS.register(
  CategoryScale,
  LinearScale,
  PointElement,
  LineElement,
  Title,
  Tooltip,
  Legend,
  Filler
)

const { t } = useI18n()

const props = defineProps<{
  trendData: TrendDataPoint[]
  loading?: boolean
}>()

const isDarkMode = computed(() => {
  return document.documentElement.classList.contains('dark')
})

const chartColors = computed(() => ({
  text: isDarkMode.value ? '#e5e7eb' : '#374151',
  grid: isDarkMode.value ? '#374151' : '#e5e7eb',
  input: '#3b82f6',
  output: '#10b981',
  cache: '#f59e0b',
}))

const chartData = computed(() => {
  if (!props.trendData?.length) return null

  return {
    labels: props.trendData.map(d => d.date),
    datasets: [
      {
        label: 'Input',
        data: props.trendData.map(d => d.input_tokens),
        borderColor: chartColors.value.input,
        backgroundColor: `${chartColors.value.input}20`,
        fill: true,
        tension: 0.3,
      },
      {
        label: 'Output',
        data: props.trendData.map(d => d.output_tokens),
        borderColor: chartColors.value.output,
        backgroundColor: `${chartColors.value.output}20`,
        fill: true,
        tension: 0.3,
      },
      {
        label: 'Cache',
        data: props.trendData.map(d => d.cache_tokens),
        borderColor: chartColors.value.cache,
        backgroundColor: `${chartColors.value.cache}20`,
        fill: true,
        tension: 0.3,
      },
    ],
  }
})

const lineOptions = computed(() => ({
  responsive: true,
  maintainAspectRatio: false,
  interaction: {
    intersect: false,
    mode: 'index' as const,
  },
  plugins: {
    legend: {
      position: 'top' as const,
      labels: {
        color: chartColors.value.text,
        usePointStyle: true,
        pointStyle: 'circle',
        padding: 15,
        font: {
          size: 11,
        },
      },
    },
    tooltip: {
      callbacks: {
        label: (context: any) => {
          return `${context.dataset.label}: ${formatTokens(context.raw)}`
        },
        footer: (tooltipItems: any) => {
          const dataIndex = tooltipItems[0]?.dataIndex
          if (dataIndex !== undefined && props.trendData[dataIndex]) {
            const data = props.trendData[dataIndex]
            return `Actual: $${formatCost(data.actual_cost)} | Standard: $${formatCost(data.cost)}`
          }
          return ''
        },
      },
    },
  },
  scales: {
    x: {
      grid: {
        color: chartColors.value.grid,
      },
      ticks: {
        color: chartColors.value.text,
        font: {
          size: 10,
        },
      },
    },
    y: {
      grid: {
        color: chartColors.value.grid,
      },
      ticks: {
        color: chartColors.value.text,
        font: {
          size: 10,
        },
        callback: (value: string | number) => formatTokens(Number(value)),
      },
    },
  },
}))

const formatTokens = (value: number): string => {
  if (value >= 1_000_000_000) {
    return `${(value / 1_000_000_000).toFixed(2)}B`
  } else if (value >= 1_000_000) {
    return `${(value / 1_000_000).toFixed(2)}M`
  } else if (value >= 1_000) {
    return `${(value / 1_000).toFixed(2)}K`
  }
  return value.toLocaleString()
}

const formatCost = (value: number): string => {
  if (value >= 1000) {
    return (value / 1000).toFixed(2) + 'K'
  } else if (value >= 1) {
    return value.toFixed(2)
  } else if (value >= 0.01) {
    return value.toFixed(3)
  }
  return value.toFixed(4)
}
</script>
