table_format - a ascii table formatter (nc)

# -*- coding: utf-8 -*-
require 'active_support/core_ext/object/blank'

module Helpers
    # Formats a supplied array into a list or table.
    # @author Mark Seymour ('Azure') (mark.seymour.ns@gmail.com)
    #
    # @param [Array] The source array.
    # @param [Hash] params Options for generating the table.
    # @option params [String] :splitchars ('\t') Characters to split each individual item on.
    # @option params [Regexp] :regexp (nil) A Regexp to split each individual item on. If one is supplied, then :splitchars is ignored.
    # @option params [Symbol] :justify (:left) Changes the justification of table items., `:left` or `:right`
    # @option params [Array] :headers ([]) Sets the names for the table column headers. If left unset, no headers will be generated.
    # @option params [Integer] :gutter (4) Sets the gutter size between columns and optionally the left gutter.
    # @option params [Boolean] :left_gutter (false) Generates a gutter on the left side of the generated table, equal to the same length as column gutters.
    # @todo Have :justify be set on individual columns.
    # @todo Have the ability to output either an array or string (params[:array]?)
    # @return [String] The formatted string with line endings.
    def Helpers.table_format array, params={}
        params = {
            splitchars: "\t",
            regexp: nil,
            justify: :left, # :left, :right
            headers: [], # ary (ex: ["a","b","c"])
            gutter: 4,
            left_gutter: false
        }.merge!(params)

        source = array.dup # We cannot be altering our original object now, can we?

        # We use the str.tr method if our regexp param is nil.
        # Otherwise, we just use regexp.
        source.map! {|e| params[:regexp].nil? ? e.tr(params[:splitchars], "\t").split("\t") : e.match(params[:regexp])[1..-1].map {|e| e.nil? ? "" : e; } }

        # calculating the maximum length of each column
        column_lengths = []
        source.dup.unshift(params[:headers]).each {|e|
            e.each_with_index {|item,index|
                column_lengths[index] = [] if column_lengths[index].blank?
                column_lengths[index] << item.size
            }
        }
        column_lengths.map! {|e| e.sort.last }

        data = []

        # Generating table headers
        if !params[:headers].blank?
            # Generating the headers, separators, etc.
            s_header = []
            s_separator = s_header.dup
            params[:headers].each_with_index {|e,i|
                s_header << "%#{"-" if params[:justify] == :left}#{column_lengths[i]}s" % e.to_s
                s_separator << "-"*column_lengths[i]
            }
            data << s_header.join(" "*params[:gutter]) << s_separator.join(" "*params[:gutter])
        end

        # Generating formatted table rows
        source.each {|e|
            line = []
            e.each_with_index {|item,index|
                line << "%#{"-" if params[:justify] == :left}#{column_lengths[index]}s" % item.to_s
            }
            data << line.join(" "*params[:gutter])
        }

        # Adding a gutter to the left side
        if params[:left_gutter] === true then data.map! {|e| " "*params[:gutter] + e } end

        data.join("\n")
    end
end