Metacat

# Copyright: 2006 Regents of the University of California,

# Santa Barbara Coastal LTER

# http://sbcdata.lternet.edu/

#

# This program is free software; you can redistribute it and/or modify

# it under the terms of the GNU General Public License as published by

# the Free Software Foundation; either version 2 of the License, or

# (at your option) any later version.

# 

# This program is distributed in the hope that it will be useful,

# but WITHOUT ANY WARRANTY; without even the implied warranty of

# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

# GNU General Public License for more details.

# 

# You should have received a copy of the GNU General Public License

# along with this program; if not, write to the Free Software

# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA

# 02111-1307  USA

$:.unshift File.join(File.dirname(__FILE__), "..", "lib")

require "date"

require "rexml/document"

require "data_table.rb"

# == What is it

# The goal of this object is to encapsulate a dom representation of

# an EML(http://knb.ecoinformatics.org/software/eml) document and provide

# quick helper methods to access commonly needed attributes. These methods

# will return a more "ruby friendly" representation of this metadata.

# 

# At their core Eml objects contain a REXML::Document in the instance variable @doc.

# Until this object is feature-complete, this dom document can be used when this

# object is returned from this module's Metacat client.

# 

# ==   Examples

# ===  Get temporal coverage

#

#   metacat = Metacat.new('http://data.piscoweb.org/catalog/metacat')

#   eml_object = metacat.find(:docid => 'HMS001_020ADCP019R00_20060612.50.1')

#   geographic_coverage = eml_object.geographic_coverage

#   => [{ "latitude"=>-121.8996,

#         "longitude"=>36.6214,

#         "id"=>"HMS001",

#         "description"=>

#         "Hopkins Marine Station: HMS001: This inner-shelf mooring is located offshore 

#         of the city of Monterey, California, USA, near Hopkins Marine Station.  The 

#         mooring is located in an overall water depth of 020 meters (referenced to Mean 

#         Sea Level, MSL).  The altitudeMinimum and altitudeMaximum tags in this initial 

#         coverage section refer to the ADCP measurement range and are also referenced to 

#         MSL.  They do not represent the overall water depth.  Note the nominal range of 

#         the ADCP may extend from near-bottom (a depth expressed as a negative altitude) 

#         to slightly above MSL (a height expressed as a positive altitude)."}]

#

# ===  Get associated data table(DataTable) and write it to disk

#   eml_object.data_tables.each do |data_table|

#     file = File.new("./store/#{data_table.id}")

#     # data_table is an object, with method read

#     data_table.read do |buffer|

#       file.write(buffer)

#     end

#     file.close()

#   end

class Eml

  attr_reader :docid, :doc

  # Accepts an EML REXML::Document

  def initialize(metadata)

    if(metadata.class != REXML::Document || metadata.root.name != 'eml')

      raise ArgumentError, 'Must initialize with REXML::Document representation of EML metadata'

    else

      @doc = metadata

      @docid = @doc.root.attributes['packageId']

    end

  end

  def to_s

    @doc.to_s

  end

  def data_tables

    tables = []

    @doc.root.elements.each("dataset/dataTable") { |element|  

      tables.push(DataTable.new(element, self))

    }

    return tables

  end

  def largest_data_table

    if(data_tables.length == 1)

      return data_tables[0]

    else

      size = 0

      largest = nil

      data_tables.each do |data_table|

        if(data_table.size > size)

          size = data_table.size

          largest = data_table

        end

      end

      largest

    end

  end

  # Pulls a date range from the temporalCoverage element

  #

  # Note : EML supports multiple date ranges to account for gaps

  # this code just lumps them into one

  # Also, it does not support cases of singleDateTime

  def temporal_coverage

    beginDates = endDates = Array.new()

    path = "dataset/coverage/temporalCoverage/rangeOfDates"

    @doc.root.elements.each(path){ |range|  

      beginDates.push(

        Date.strptime(range.elements["beginDate"].elements[1].text)

      )

      endDates.push(

        Date.strptime(range.elements["endDate"].elements[1].text)

      )

    }

    return beginDates.min, endDates.max

  end

  def geographic_coverage

    sites = Array.new

    coverage.elements.each('geographicCoverage') do |g|

      site = {

        'id'          =>  g.attributes['id'],

        'description' =>  g.elements['geographicDescription'].text,

        'latitude'    =>  g.elements['boundingCoordinates/westBoundingCoordinate'].text.to_f,

        'longitude'   =>  g.elements['boundingCoordinates/northBoundingCoordinate'].text.to_f

      }

      sites << site

    end

    return sites

  end

  def coverage

    @doc.root.elements["dataset/coverage"]

  end

  def title

    @doc.root.elements["dataset/title"].text

  end

  def short_name

    @doc.root.elements["dataset/shortName"].text

  end

end