// Copyright (c) 2013 Adobe Systems Incorporated. All rights reserved.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
import eve from './eve.js'
import { Snap, SnapElement, Paper, Fragment } from './svg.js'
import { $ } from './utils.js'
import { parseColor } from './lib/color.js'

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

Snap.filter = {}

eve.on('snap.util.getattr.filter', function () {
  eve.stop()
  let p = $(this.node, 'filter')
  if (p) {
    let match = Str(p).match(rgurl)
    return match && Snap.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
    }
    $(this.node, {
      filter: Snap.url(id)
    })
  }
  if (!value || value == 'none') {
    eve.stop()
    this.node.removeAttribute('filter')
  }
})
/*\
     * Snap.filter.blur
     [ method ]
     **
     * Returns an SVG markup string for the blur filter
     **
     - x (number) amount of horizontal blur, in pixels
     - y (number) #optional amount of vertical blur, in pixels
     = (string) filter representation
     > Usage
     | let f = paper.filter(Snap.filter.blur(5, 10)),
     |     c = paper.circle(10, 10, 10).attr({
     |         filter: f
     |     });
    \*/
Snap.filter.blur = function (x, y) {
  if (x == null) {
    x = 2
  }
  let def = y == null ? x : [x, y]
  return `<feGaussianBlur stdDeviation="${def}"/>`
}
Snap.filter.blur.toString = function () {
  return this()
}
/*\
     * Snap.filter.shadow
     [ method ]
     **
     * 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(Snap.filter.shadow(0, 2, .3)),
     |     c = paper.circle(10, 10, 10).attr({
     |         filter: f
     |     });
    \*/
Snap.filter.shadow = function (dx, dy, blur, color, opacity) {
  if (opacity == null) {
    if (color == null) {
      opacity = blur
      blur = 4
      color = '#000'
    } else {
      opacity = color
      color = blur
      blur = 4
    }
  }
  if (blur == null) {
    blur = 4
  }
  if (opacity == null) {
    opacity = 1
  }
  if (dx == null) {
    dx = 0
    dy = 2
  }
  if (dy == null) {
    dy = dx
  }
  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>`
}
Snap.filter.shadow.toString = function () {
  return this()
}
/*\
     * Snap.filter.grayscale
     [ method ]
     **
     * Returns an SVG markup string for the grayscale filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.grayscale = function (amount) {
  if (amount == null) {
    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"/>`
}
Snap.filter.grayscale.toString = function () {
  return this()
}
/*\
     * Snap.filter.sepia
     [ method ]
     **
     * Returns an SVG markup string for the sepia filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.sepia = function (amount) {
  if (amount == null) {
    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} ${i} 0 0 0 0 0 1 0"/>`
}
Snap.filter.sepia.toString = function () {
  return this()
}
/*\
     * Snap.filter.saturate
     [ method ]
     **
     * Returns an SVG markup string for the saturate filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.saturate = function (amount) {
  if (amount == null) {
    amount = 1
  }
  return `<feColorMatrix type="saturate" values="${1 - amount}"/>`
}
Snap.filter.saturate.toString = function () {
  return this()
}
/*\
     * Snap.filter.hueRotate
     [ method ]
     **
     * Returns an SVG markup string for the hue-rotate filter
     **
     - angle (number) angle of rotation
     = (string) filter representation
    \*/
Snap.filter.hueRotate = function (angle) {
  angle = angle || 0
  return `<feColorMatrix type="hueRotate" values="${angle}"/>`
}
Snap.filter.hueRotate.toString = function () {
  return this()
}
/*\
     * Snap.filter.invert
     [ method ]
     **
     * Returns an SVG markup string for the invert filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.invert = function (amount) {
  if (amount == null) {
    amount = 1
  }
  //        <feColorMatrix type="matrix" values="-1 0 0 0 1  0 -1 0 0 1  0 0 -1 0 1  0 0 0 1 0" color-interpolation-filters="sRGB"/>
  return `<feComponentTransfer><feFuncR type="table" tableValues="${amount} ${
    1 - amount
  }"/><feFuncG type="table" tableValues="${amount} ${
    1 - amount
  }"/><feFuncB type="table" tableValues="${amount} ${
    1 - amount
  }"/></feComponentTransfer>`
}
Snap.filter.invert.toString = function () {
  return this()
}
/*\
     * Snap.filter.brightness
     [ method ]
     **
     * Returns an SVG markup string for the brightness filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.brightness = function (amount) {
  if (amount == null) {
    amount = 1
  }
  return `<feComponentTransfer><feFuncR type="linear" slope="${amount}"/><feFuncG type="linear" slope="${amount}"/><feFuncB type="linear" slope="${amount}"/></feComponentTransfer>`
}
Snap.filter.brightness.toString = function () {
  return this()
}
/*\
     * Snap.filter.contrast
     [ method ]
     **
     * Returns an SVG markup string for the contrast filter
     **
     - amount (number) amount of filter (`0..1`)
     = (string) filter representation
    \*/
Snap.filter.contrast = function (amount) {
  if (amount == null) {
    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>`
}

Snap.filter.contrast.toString = function () {
  return this()
}