#!/usr/bin/ruby -Ke

=begin
最寄の電子基準点を調べる
=end

$options = {
  :mode => :normal,
  :src_dir => File::join(File::dirname(__FILE__), 'data'),
  :rinex => false,
}
  
ARGV.reject!{|arg|
  if arg =~ /--([^=]+)=?/ then
    $options[$1.to_sym] = $'
    true
  else
    false
  end
}

$options[:mode] = $options[:mode].to_sym
$options[:rinex] = eval($options[:rinex].to_s)
position_data = nil
  
if $options[:mode] == :update then
  unless FileTest::directory?($options[:src_dir])
    Dir::mkdir($options[:src_dir])
  end

  require 'net/ftp'
  Net::FTP.open('terras.gsi.go.jp'){|ftp|
    ftp.login
    ftp.passive = true
    ftp.chdir("data/coordinates_F3/#{Time::now.year}")
    ftp.list('*.pos').each{|f|
      f =~ /\S+\.pos/
      fname = $&
      $stderr.puts "Getting #{fname} ..."
      ftp.gettextfile(fname, File::join($options[:src_dir], fname))
    }
  }

  position_data = {}
  
  require 'time'
  Dir::glob(File::join($options[:src_dir], '*.pos')){|f|
    next unless f =~ /(\d+)\.\d+\.pos/
    index = $1
    $stderr.puts "Parsing #{index} ..."
    latest_data = nil
    open(f).each{|line|
      if line =~ /^ +(\d{4}) (\d{2}) (\d{2}) (\d{2}:\d{2}:\d{2}) +/ then
        date = Time::parse("#{$1}-#{$2}-#{$3}T#{$4}UTC")
        analyzed = $'.split(/ +/)
        x, y, z, lat, lng, alt = analyzed.collect{|v| v.to_f}
        latest_data = {:x => x, :y => y, :z => z, :lat => lat.to_f / 180 * Math::PI, :lng => lng.to_f  / 180 * Math::PI, :alt => alt.to_f, :date => date}
      end
    }
    position_data[index] = latest_data if latest_data
  }
  
  File::open(File::join($options[:src_dir], 'cache.db'), 'w'){|io|
    io.write Marshal::dump(position_data)
  }
else
  File::open(File::join($options[:src_dir], 'cache.db'), 'r'){|io|
    position_data = Marshal::load(io.read)
  }
end

$stderr.puts "Usage #{__FILE__} lat_deg lng_deg [date] [--mode=normal|update|test] [--rinex]"
$stderr.puts $options.inspect

lat, lng = [35.681382, 139.766084] # 東京駅 => 最も近い基準点 93016(東京都足立区一ツ家３−１５−１)
if $options[:mode] != :test then
  exit(-1) if ARGV.size < 2
  lat = ARGV.shift.to_f
  lng = ARGV.shift.to_f
end
lat = lat / 180 * Math::PI
lng = lng / 180 * Math::PI

$: << File::join(File::dirname(__FILE__), '..', '..', 'common', 'ruby')
require 'WGS84.rb'

distance_list = {}
position_data.each{|k, v|
  distance_list[k] = WGS84.distance(lat, lng, v[:lat], v[:lng])
}

sorted = distance_list.to_a.sort{|a, b| a[1] <=> b[1]}

nearest_station_name, distance = sorted.first
nearest_station_info = position_data[nearest_station_name]
$stderr.puts "The nearest station is #{nearest_station_name} (lat, lng, alt) = (#{nearest_station_info[:lat] / Math::PI * 180}, #{nearest_station_info[:lng] / Math::PI * 180}, #{nearest_station_info[:alt]}), about #{distance} m."

exit(0) unless $options[:rinex]

# RINEX ファイルを取得する
# @see http://terras.gsi.go.jp/ja/ngs100.php#rinex
  
date = Time::now
unless ARGV.empty?
  require 'time'
  date = Time::parse(ARGV.join(' '))
end

require 'net/ftp'
Net::FTP.open('terras.gsi.go.jp'){|ftp|
  ftp.login
  ftp.passive = true
  yday_str = date.strftime('%j')
  ftp.chdir("data/GPS_products/#{date.year}/#{yday_str}")
  ['o', 'n'].each{|suffix|
    fname = "#{nearest_station_name[-4..-1]}#{yday_str}0.#{date.strftime('%y')}#{suffix}.gz"
    $stderr.puts "Getting #{fname} ..."
    ftp.getbinaryfile(fname)
  }
}