#!/usr/bin/ruby

require 'selsurf'

class GradsWX < SelSurf

  WXMAP = {
  # 0: EMPTY
  0 => 0,	1 => 0,		2 => 0,		3 => 0,		4 => 39,
  # 39: SMOKE - no good for haze but GrADS don't have it
  # 36: SAND RAISED BY WIND
  5 => 39,	6 => 36,	7 => 36,	8 => 36,	9 => 36,
  # 34: LIGHT FOG - we really need normal FOG
  # 38: LIGHTNING BUT NO THUNDER
  10 => 34,	11 => 34,	12 => 34,	13 => 38,	14 => 16,
  # 2: THUNDER BUT NO LIGHTNING
  # 1: FUNNEL CLOUD
  15 => 16,	16 => 16,	17 => 2,	18 => 15,	19 => 1,
  20 => 28,	21 => 16,	22 => 21,	23 => 37,	24 => 13,
  25 => 15,	26 => 19,	27 => 31,	28 => 34,	29 => 2,
  30 => 36,	31 => 36,	32 => 36,	33 => 36,	34 => 36,
  35 => 36,	36 => 35,	37 => 35,	38 => 35,	39 => 35,
  40 => 34,	41 => 34,	42 => 34,	43 => 34,	44 => 34,
  45 => 34,	46 => 34,	47 => 34,	48 => 34,	49 => 34,
  50 => 28,	51 => 28,	52 => 29,	53 => 29,	54 => 30,
  55 => 30,	56 => 27,	57 => 26,	58 => 28,	59 => 29,
  60 => 16,	61 => 16,	62 => 17,	63 => 17,	64 => 18,
  65 => 19,	66 => 13,	67 => 12,	68 => 37,	69 => 37,
  70 => 21,	71 => 21,	72 => 22,	73 => 22,	74 => 23,
  75 => 23,	76 => 33,	77 => 25,	78 => 33,	79 => 24,
  80 => 15,	81 => 14,	82 => 14,	83 => 19,	84 => 20,
  85 => 19,	86 => 20,	87 => 31,	88 => 32,	89 => 31,
  90 => 32,	91 => 3,	92 => 8,	93 => 4,	94 => 9,
  95 => 3,	96 => 6,	97 => 8,	98 => 5,	99 => 11,
  }

  MISS = -999.0 

  def initialize
    super
    @seq = "A000"
  end

  def ddff2uv dd, ff, iw
    return [MISS, MISS] unless (Numeric === dd and Numeric === ff)
    return [0.0, 0.0] if (dd.zero? or ff.zero?)
    ff *= 1.94384 unless 3..4 === iw
    drad = dd / 18.0 * Math::PI
    u = -ff * Math::sin(drad)
    v = -ff * Math::cos(drad)
    [u, v]
  end

  def convert ent, dcd
    ent[:id] = dcd['@ID']
    ent[:mimj] = dcd['@MiMj']
    ent[:t] = if Numeric === dcd['TTT'] then dcd['TTT'] * 0.1 else MISS end
    ent[:d] = if Numeric === dcd['Td.3'] then dcd['Td.3'] * 0.1 else MISS end
    ent[:slp] = if Numeric === dcd['P.4'] then dcd['P.4'] else MISS end
    ent[:dp] = if Numeric === dcd['ppp'] then dcd['ppp'] else MISS end
    ent[:cld] = case dcd['N']
      when 0..1 then 20 # clear
      when 2..6 then 21 # scattered (METAR's SCT is 3 to 4 oktas)
      when 7 then 22 # BKN
      when 8 then 23 # OVC
      when 9 then 24 # obscured
      else
        if 'BOGUS' === dcd['@ID'] then 6 # X mark
	elsif 4..7 === dcd['ix'] then 8 # triangle
	else 25 # 'M' for real missing
	end
      end
    ww = dcd['ww']
    if ww.nil? and [8, 24].include?(ent[:cld]) and ((1..989) === dcd['RRR'])
      if ent[:t] > 5 then ww = 60
      elsif ent[:t] > 0 then ww = 68
      else ww = 70
      end
    end
    ent[:wx] = (WXMAP[ww] || MISS)
    u, v = ddff2uv(dcd['dd'], dcd['ff'], dcd['iw'])
    ent[:u] = u
    ent[:v] = v
    ent[:VV] = case dcd['VV']
      when 0..2 then dcd['VV'] * 0.1
      when 0..55 then (dcd['VV'] * 0.4).floor * 0.25
      when 56..80 then dcd['VV'] - 50
      when 81..89 then dcd['VV'] * 5 - 370
      when 90 then 0.02
      when 91 then 0.05
      when 92 then 0.2
      when 93 then 0.5
      when 94 then 1.0
      when 95 then 2.0
      when 96 then 4.0
      when 97 then 10.0
      when 98 then 20.0
      when 99 then 50.0
      else MISS
      end
    unless ent.values_at(:slp, :t, :u) == [MISS, MISS, MISS]
      ent[:miss] = false
    end
  end

  def saveent dfp, ent = nil
    if ent.nil? then
      dfp.write ['', 0.0, 0.0, 0.0, 0, 0].pack('a8fffLL')
      return
    end
    #STDERR.puts ent.inspect if ent[:id] == '57687'
    return if ent[:miss]
    unless ent[:flalo]
      STDERR.puts "#{ent[:id]}: missing coords"
      return
    end
    ids = case ent[:id]
      when /^\d\d\d\d\d$/ then [ent[:id][1,4], '-', ent[:id][0,1]].join
      when /^SHIP$/ then 'SHIP' + @seq
      when /^BOGUS$/ then 'GUES' + @seq
      when /^\w+$/ then 
        case ent[:mimj]
	when /BBXX/ then 'SHIP' + ent[:id]
	when /ZZYY/ then 'BUOY' + ent[:id]
	end
      else 'XXXX' + @seq
      end
    @seq = @seq.succ
    lat = ent[:flalo][0]
    lon = ent[:flalo][1]
    dfp.write [ids, lat, lon, 0.0, 1, 1].pack('a8fffLL')
    rec = [ent[:slp], ent[:dp], ent[:t], ent[:d],
      ent[:u], ent[:v], ent[:cld], ent[:wx], ent[:VV]]
    if $VERBOSE
      printf("%-8.8s|%+5.1f|%+6.1f|%5.0f|%+5.0f|%+6.1f|%+6.1f|%+6.1f|%+6.1f|%5d|%5d|%02d\n",
        ids, lat, lon,*rec)
    end
    dfp.write rec.pack('f9')
  end

  def report
    gt = Time.gm(@year, @mon, @yy, @gg).strftime('%Hz%d%b%Y')
    File.open("zgrads.ctl", "w") {|cfp|
      cfp.write <<-ENDCTL
      DSET ^zgrads.dat
      DTYPE station
      STNMAP zgrads.map
      UNDEF #{MISS}
      TITLE station report #{gt}
      TDEF 1 linear #{gt} 6hr
      VARS 9
      ps    0 99 Surface Pressure [10 Pa]
      pdel  0 99 Surface Pressure Change [10 Pa]
      ts    0 99 Surface Temperature [C]
      ds    0 99 Surface Dewpoint T [C]
      us    0 99 Surface U-Wind [knot]
      vs    0 99 Surface V-Wind [knot]
      cld   0 99 Cloudiness [GrADS code]
      wx    0 99 Significant Weather [GrADS code]
      vis   0 99 Visibility [Code Table 4377]
      ENDVARS
      ENDCTL
    }
    File.open('zgrads.dat', 'w') {|dfp|
      dfp.binmode
      @dcd[:fixed].each {|ent| saveent dfp, ent }
      @dcd[:mobile].each {|ent| saveent dfp, ent }
      saveent dfp
    }
  end

end

GradsWX.new.run(ARGV) if $0 == __FILE__