<template>
  <SvgWrapper class="grid-lines">
    <path 
      :style="{
        transform: `scale(${canvasScale})`,
      }" 
      :d="path" 
      fill="none" 
      :stroke="gridColor" 
      stroke-width="0.3" 
      shape-rendering="crispEdges"
      stroke-dasharray="5"
    ></path>
  </SvgWrapper>
</template>

<script lang="ts">
import { defineComponent, computed } from 'vue'
import tinycolor from 'tinycolor2'
import { useStore } from '@/store'
import { VIEWPORT_SIZE, VIEWPORT_ASPECT_RATIO } from '@/configs/canvas'
import { SlideBackground } from '@/types/slides'

export default defineComponent({
  name: 'grid-lines',
  setup() {
    const store = useStore()
    const canvasScale = computed(() => store.state.canvasScale)
    const background = computed<SlideBackground | undefined>(() => store.getters.currentSlide.background)

    const gridColor = computed(() => {
      if(!background.value || background.value.type === 'image') return 'rgba(100, 100, 100, 0.5)'
      const color = background.value.color
      const rgba = tinycolor(color).toRgb()
      const newRgba = {
        r: rgba.r > 128 ? rgba.r - 128 : rgba.r + 127,
        g: rgba.g > 128 ? rgba.g - 128 : rgba.g + 127,
        b: rgba.b > 128 ? rgba.b - 128 : rgba.b + 127,
        a: 0.5
      }
      return `rgba(${[newRgba.r, newRgba.g, newRgba.b, newRgba.a].join(',')})`
    })

    const gridSize = 50

    const getPath = () => {
      const maxX = VIEWPORT_SIZE
      const maxY = VIEWPORT_SIZE * VIEWPORT_ASPECT_RATIO

      let path = ''
      for(let i = 0; i <= Math.floor(maxY / gridSize); i++) {
        path += `M0 ${i * gridSize}, L${maxX} ${i * gridSize}`
      }
      for(let i = 0; i <= Math.floor(maxX / gridSize); i++) {
        path += `M${i * gridSize} 0, L${i * gridSize} ${maxY}`
      }
      return path
    }

    return {
      canvasScale,
      gridColor,
      width: VIEWPORT_SIZE,
      height: VIEWPORT_SIZE * VIEWPORT_ASPECT_RATIO,
      path: getPath(),
    }
  },
})
</script>

<style lang="scss" scoped>
.grid-lines {
  width: 100%;
  height: 100%;
  position: absolute;
  top: 0;
  left: 0;
  bottom: 0;
  right: 0;
  overflow: visible;
}
</style>