module Csvlint

  class Schema

    include Csvlint::ErrorCollector

    attr_reader :uri, :fields, :title, :description

    def initialize(uri, fields=[], title=nil, description=nil)
      @uri = uri
      @fields = fields
      @title = title
      @description = description
      reset
    end

    class << self

      def from_json_table(uri, json)
        fields = []
        json["fields"].each do |field_desc|
          fields << Csvlint::Field.new( field_desc["name"] , field_desc["constraints"],
            field_desc["title"], field_desc["description"] )
        end if json["fields"]
        return Schema.new( uri , fields, json["title"], json["description"] )
      end

      def from_csvw_metadata(uri, json)
        return Csvlint::Csvw::TableGroup.from_json(uri, json)
      end

      def load_from_json(uri, output_errors = true)
        begin
          json = JSON.parse( open(uri).read )
          if json["@context"]
            uri = "file:#{File.expand_path(uri)}" unless uri.to_s =~ /^http(s)?/
            return Schema.from_csvw_metadata(uri,json)
          else
            return Schema.from_json_table(uri,json)
          end
        rescue Csvlint::Csvw::MetadataError => e
          raise e
        rescue OpenURI::HTTPError, Errno::ENOENT => e
          raise e
        rescue => e
          if output_errors === true
            STDERR.puts e.class
            STDERR.puts e.message
            STDERR.puts e.backtrace
          end
          return Schema.new(nil, [], "malformed", "malformed")
        end
      end

    end

    def validate_header(header, source_url=nil)
      reset

      found_header = header.to_csv(:row_sep => '')
      expected_header = @fields.map{ |f| f.name }.to_csv(:row_sep => '')
      if found_header != expected_header
        build_warnings(:malformed_header, :schema, 1, nil, found_header, "expectedHeader" => expected_header)
      end
      return valid?
    end

    def validate_row(values, row=nil, all_errors=[], source_url=nil)
      reset
      if values.length < fields.length
        fields[values.size..-1].each_with_index do |field, i|
          build_warnings(:missing_column, :schema, row, values.size+i+1)
        end
      end
      if values.length > fields.length
        values[fields.size..-1].each_with_index do |data_column, i|
          build_warnings(:extra_column, :schema, row, fields.size+i+1)
        end
      end

      fields.each_with_index do |field,i|
        value = values[i] || ""
        result = field.validate_column(value, row, i+1, all_errors)
        @errors += fields[i].errors
        @warnings += fields[i].warnings
      end

      return valid?
    end

  end
end