/**
 * {}
 * @author yutent<yutent.io@gmail.com>
 * @date 2024/03/07 16:04:23
 */

import eve from './eve.js'
import { select, SnapElement } from './svg.js'
import { $, url } from './utils.js'
import { parseColor } from './lib/color.js'

let rgurl = /^\s*url\((.+)\)/,
  Str = String

eve.on('snap.util.getattr.filter', function () {
  eve.stop()
  let p = $(this.node, 'filter')
  if (p) {
    let match = Str(p).match(rgurl)
    return match && select(match[1])
  }
})
eve.on('snap.util.attr.filter', function (value) {
  if (value instanceof SnapElement && value.type == 'filter') {
    eve.stop()
    let id = value.node.id
    if (!id) {
      $(value.node, { id: value.id })
      id = value.id
    }
    $(this.node, {
      filter: url(id)
    })
  }
  if (!value || value == 'none') {
    eve.stop()
    this.node.removeAttribute('filter')
  }
})

export const filter = {
  /**
   * Returns an SVG markup string for the blur filter
   **
    - x (number) amount of horizontal blur, in pixels
    - y (number) #optional amount of vertical blur, in pixels
    = (string) filter representation
    > Usage
    | let f = paper.filter(filter.blur(5, 10)),
    |     c = paper.circle(10, 10, 10).attr({
    |         filter: f
    |     });
  */
  blur(x, y) {
    if (x == null) {
      x = 2
    }
    let def = y == null ? x : [x, y]
    return `<feGaussianBlur stdDeviation="${def}"/>`
  },

  /**
   * Returns an SVG markup string for the shadow filter
   **
    - dx (number) #optional horizontal shift of the shadow, in pixels
    - dy (number) #optional vertical shift of the shadow, in pixels
    - blur (number) #optional amount of blur
    - color (string) #optional color of the shadow
    - opacity (number) #optional `0..1` opacity of the shadow
    * or
    - dx (number) #optional horizontal shift of the shadow, in pixels
    - dy (number) #optional vertical shift of the shadow, in pixels
    - color (string) #optional color of the shadow
    - opacity (number) #optional `0..1` opacity of the shadow
    * which makes blur default to `4`. Or
    - dx (number) #optional horizontal shift of the shadow, in pixels
    - dy (number) #optional vertical shift of the shadow, in pixels
    - opacity (number) #optional `0..1` opacity of the shadow
    = (string) filter representation
    > Usage
    let f = paper.filter(filter.shadow(0, 2, .3)),
        c = paper.circle(10, 10, 10).attr({
            filter: f
        });
  */
  shadow(dx = 0, dy = 2, blur = 4, color = '#000', opacity = 1) {
    color = parseColor(color)
    return `<feGaussianBlur in="SourceAlpha" stdDeviation="${blur}"/><feOffset dx="${dx}" dy="${dy}" result="offsetblur"/><feFlood flood-color="${color}"/><feComposite in2="offsetblur" operator="in"/><feComponentTransfer><feFuncA type="linear" slope="${opacity}"/></feComponentTransfer><feMerge><feMergeNode/><feMergeNode in="SourceGraphic"/></feMerge>`
  },

  /**
     * Returns an SVG markup string for the grayscale filter
     **
      - amount (number) amount of filter (`0..1`)
      = (string) filter representation
    */
  grayscale(amount = 1) {
    let a = 0.2126 + 0.7874 * (1 - amount)
    let b = 0.7152 - 0.7152 * (1 - amount)
    let c = 0.0722 - 0.0722 * (1 - amount)
    let d = 0.2126 - 0.2126 * (1 - amount)
    let e = 0.7152 + 0.2848 * (1 - amount)
    let f = 0.0722 - 0.0722 * (1 - amount)
    let g = 0.2126 - 0.2126 * (1 - amount)
    let h = 0.0722 + 0.9278 * (1 - amount)

    return `<feColorMatrix type="matrix" values="${a} ${b} ${c} 0 0 ${d} ${e} ${f} 0 0 ${g} ${b} ${h} 0 0 0 0 0 1 0"/>`
  },

  /**
       * Returns an SVG markup string for the sepia filter
       **
       - amount (number) amount of filter (`0..1`)
       = (string) filter representation
      */
  sepia(amount = 1) {
    let a = 0.393 + 0.607 * (1 - amount)
    let b = 0.769 - 0.769 * (1 - amount)
    let c = 0.189 - 0.189 * (1 - amount)
    let d = 0.349 - 0.349 * (1 - amount)
    let e = 0.686 + 0.314 * (1 - amount)
    let f = 0.168 - 0.168 * (1 - amount)
    let g = 0.272 - 0.272 * (1 - amount)
    let h = 0.534 - 0.534 * (1 - amount)
    let i = 0.131 + 0.869 * (1 - amount)

    return `<feColorMatrix type="matrix" values="${a} ${b} ${c} 0 0 ${d} ${e} ${f} 0 0 ${g} ${h} ${i} 0 0 0 0 0 1 0"/>`
  },

  /**
       * Returns an SVG markup string for the saturate filter
       **
       - amount (number) amount of filter (`0..1`)
       = (string) filter representation
      */
  saturate(amount = 1) {
    return `<feColorMatrix type="saturate" values="${1 - amount}"/>`
  },

  /**
       * Returns an SVG markup string for the hue-rotate filter
       **
       - angle (number) angle of rotation
       = (string) filter representation
      */
  hueRotate(angle) {
    angle = angle || 0
    return `<feColorMatrix type="hueRotate" values="${angle}"/>`
  },

  /**
   * Returns an SVG markup string for the invert filter
   **
    - amount (number) amount of filter (`0..1`)
    = (string) filter representation
  */
  invert(amount = 1) {
    //        <feColorMatrix type="matrix" values="-1 0 0 0 1  0 -1 0 0 1  0 0 -1 0 1  0 0 0 1 0" color-interpolation-filters="sRGB"/>
    return `<feComponentTransfer><feFuncR type="table" tableValues="${amount} ${
      1 - amount
    }"/><feFuncG type="table" tableValues="${amount} ${
      1 - amount
    }"/><feFuncB type="table" tableValues="${amount} ${
      1 - amount
    }"/></feComponentTransfer>`
  },

  /**
   * Returns an SVG markup string for the brightness filter
   **
    - amount (number) amount of filter (`0..1`)
    = (string) filter representation
  */
  brightness(amount = 1) {
    return `<feComponentTransfer><feFuncR type="linear" slope="${amount}"/><feFuncG type="linear" slope="${amount}"/><feFuncB type="linear" slope="${amount}"/></feComponentTransfer>`
  },

  /**
   * Returns an SVG markup string for the contrast filter
   **
    - amount (number) amount of filter (`0..1`)
    = (string) filter representation
  */
  contrast(amount = 1) {
    let amount2 = 0.5 - amount / 2
    return `<feComponentTransfer><feFuncR type="linear" slope="${amount}" intercept="${amount2}"/><feFuncG type="linear" slope="${amount}" intercept="${amount2}"/><feFuncB type="linear" slope="${amount}" intercept="${amount2}"/></feComponentTransfer>`
  }
}