module Eviltransform

# File lib/eviltransform.rb, line 120
def self.bd2gcj(bdLat, bdLng)
  x = bdLng - 0.0065
  y = bdLat - 0.006
  z = Math.hypot(x, y) - 0.00002 * Math.sin(y * Math::PI)
  theta = Math.atan2(y, x) - 0.000003 * Math.cos(x * Math::PI)
  gcjLng = z * Math.cos(theta)
  gcjLat = z * Math.sin(theta)
  return [gcjLat, gcjLng]
end

# File lib/eviltransform.rb, line 136
def self.bd2wgs(bdLat, bdLng)
  return gcj2wgs(*bd2gcj(bdLat, bdLng))
end

# File lib/eviltransform.rb, line 140
def self.bd2wgs_exact(bdLat, bdLng)
  return gcj2wgs_exact(*bd2gcj(bdLat, bdLng))
end

# File lib/eviltransform.rb, line 37
def self.delta(lat, lng)
  earthR = 6378137.0
  ee = 0.00669342162296594323
  dLat, dLng = transform(lng - 105.0, lat - 35.0)
  radLat = lat / 180.0 * Math::PI
  magic = Math.sin(radLat)
  magic = 1.0 - ee * magic * magic
  sqrtMagic = Math.sqrt(magic)
  dLat = (dLat * 180.0) / ((earthR * (1.0 - ee)) / (magic * sqrtMagic) * Math::PI)
  dLng = (dLng * 180.0) / (earthR / sqrtMagic * Math.cos(radLat) * Math::PI)
  return [dLat, dLng]
end

# File lib/eviltransform.rb, line 91
def self.distance(latA, lngA, latB, lngB)
  earthR = 6378137.0
  pi180 = Math::PI / 180
  arcLatA = latA * pi180
  arcLatB = latB * pi180
  x = (Math.cos(arcLatA) * Math.cos(arcLatB) *
    Math.cos((lngA - lngB) * pi180))
  y = Math.sin(arcLatA) * Math.sin(arcLatB)
  s = x + y
  if s > 1
    s = 1
  elsif s < -1
    s = -1
  end
  alpha = Math.acos(s)
  distance = alpha * earthR
  return distance
end

# File lib/eviltransform.rb, line 110
def self.gcj2bd(gcjLat, gcjLng)
  x = gcjLng
  y = gcjLat
  z = Math.hypot(x, y) + 0.00002 * Math.sin(y * Math::PI)
  theta = Math.atan2(y, x) + 0.000003 * Math.cos(x * Math::PI)
  bdLng = z * Math.cos(theta) + 0.0065
  bdLat = z * Math.sin(theta) + 0.006
  return [bdLat, bdLng]
end

# File lib/eviltransform.rb, line 55
def self.gcj2wgs(gcjLat, gcjLng)
  dlat, dlng = delta(gcjLat, gcjLng)
  return [gcjLat - dlat, gcjLng - dlng]
end

# File lib/eviltransform.rb, line 60
def self.gcj2wgs_exact(gcjLat, gcjLng)
  initDelta = 0.01
  threshold = 0.000_001
  dLat = dLng = initDelta
  mLat = gcjLat - dLat
  mLng = gcjLng - dLng
  pLat = gcjLat + dLat
  pLng = gcjLng + dLng
  (0...30).each do |i|
    wgsLat = (mLat + pLat) / 2.0
    wgsLng = (mLng + pLng) / 2.0
    tmplat, tmplng = wgs2gcj(wgsLat, wgsLng)
    dLat = tmplat - gcjLat
    dLng = tmplng - gcjLng
    if dLat.abs < threshold and dLng.abs < threshold
      return wgsLat, wgsLng
    end
    if dLat > 0
      pLat = wgsLat
    else
      mLat = wgsLat
    end
    if dLng > 0
      pLng = wgsLng
    else
      mLng = wgsLng
    end
  end
  [wgsLat, wgsLng]
end

# File lib/eviltransform.rb, line 4
def self.outOfChina(lat, lng)
  if (lng >= 72.004 && lng <= 137.8347 && lat >= 0.8293 && lat <= 55.8271)
    return false
  else
    return true
  end
end

# File lib/eviltransform.rb, line 12
def self.transform(x, y)
  xy = x * y
  absX = Math.sqrt(x.abs)
  xPi = x * Math::PI
  yPi = y * Math::PI
  d = 20.0*Math.sin(6.0*xPi) + 20.0*Math.sin(2.0*xPi)

  lat = d
  lng = d

  lat += 20.0*Math.sin(yPi) + 40.0*Math.sin(yPi/3.0)
  lng += 20.0*Math.sin(xPi) + 40.0*Math.sin(xPi/3.0)

  lat += 160.0*Math.sin(yPi/12.0) + 320*Math.sin(yPi/30.0)
  lng += 150.0*Math.sin(xPi/12.0) + 300.0*Math.sin(xPi/30.0)

  lat *= 2.0 / 3.0
  lng *= 2.0 / 3.0

  lat += -100.0 + 2.0*x + 3.0*y + 0.2*y*y + 0.1*xy + 0.2*absX
  lng += 300.0 + x + 2.0*y + 0.1*x*x + 0.1*xy + 0.1*absX

  return [lat, lng]
end

# File lib/eviltransform.rb, line 130
def self.wgs2bd(wgsLat, wgsLng)
  lat, lng = wgs2gcj(wgsLat, wgsLng)
  clat, clng = gcj2bd(lat, lng)
  return [clat, clng]
end

# File lib/eviltransform.rb, line 50
def self.wgs2gcj(wgsLat, wgsLng)
  dlat, dlng = delta(wgsLat, wgsLng)
  return [wgsLat + dlat, wgsLng + dlng]
end