table_format - a ascii table formatter

require 'active_support/core_ext/object/blank'
# require "benchmark"

=begin benchmark setup
a = []

10000.times do
    a << "BlackRose@sakura.theta.cyberconnect.co.jp"
    a << "Azure!~azt@unaffiliated/azure"
end
=end

def 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 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
            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
        }
        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

=begin benchmark
Benchmark.bm(20) do |x|
  x.report("table_format (20000):")   { table_format a, splitchars: "!@", regexp: /(.+!)?(.+)@(.+)/, headers: ["nick","username","host"], gutter: 6, justify: :right, left_gutter: true; }
end

results: #######################################################################
                          user     system      total        real
table_format (20000):  0.593000   0.000000   0.593000 (  0.617036)

=end
=begin test cases:

Default (only array) ###########################################################
table_format a
> [NLR]Azuresocks!~azt@unaffiliated/azure
> Azure!~azt@unaffiliated/azure
> Azure|netbook!~blue@affiliated/azure

splitchars only ################################################################
table_format a, splitchars: "!@"
> [NLR]Azuresocks    ~azt     unaffiliated/azure
> Azure              ~azt     unaffiliated/azure
> Azure|netbook      ~blue    affiliated/azure

headers only ###################################################################
table_format a, headers: ["nick","username","host"]
> nick                                       username    host
> ---------------------------------------    --------    ----
> [NLR]Azuresocks!~azt@unaffiliated/azure
> Azure!~azt@unaffiliated/azure
> Azure|netbook!~blue@affiliated/azure

splitchars + headers ###########################################################
table_format a, splitchars: "!@", headers: ["nick","username","host"]
> nick               username    host
> ---------------    --------    ------------------
> [NLR]Azuresocks    ~azt        unaffiliated/azure
> Azure              ~azt        unaffiliated/azure
> Azure|netbook      ~blue       affiliated/azure

All options ####################################################################
table_format a, splitchars: "!@", headers: ["nick","username","host"], gutter: 20, justify: :right, left_gutter: true;
>                                nick                    username                                  host
>                     ---------------                    --------                    ------------------
>                     [NLR]Azuresocks                        ~azt                    unaffiliated/azure
>                               Azure                        ~azt                    unaffiliated/azure
>                       Azure|netbook                       ~blue                      affiliated/azure
=end