Ruby method to format a text table that resizes to the screen width

gistfile1.rb

require "set"
require "highline"

#
# Prints a 2-d array as a table formatted to terminal size
#
def print_table(table, format = true, cols = nil)
    
    # Apply column filter
    unless cols.nil?
        
        headings = cols.split(",").to_set
        
        cols_to_delete = [ ]
        i = 0
        table[0].each do |col|
            cols_to_delete << i unless headings.include?(col)
            i = i + 1
        end
        
        table.each do |row|
            cols_to_delete.reverse_each { |j| row.delete_at(j) }
        end
    end
    
    if format
        
        # Calculate widths
        widths = []
        table.each do |line|
            c = 0
            line.each do |col|
                
                len = col.length
                widths[c] = (widths[c] && widths[c] > len) ? widths[c] : len
                c += 1
            end
        end
        
        max_scr_cols = HighLine::SystemExtensions.terminal_size[0] - (widths.length * 3) - 1
        max_tbl_cols = 0
        width_map = {}
        
        c = 0
        widths.each do |n| 
            max_tbl_cols += n
            width_map[c] = n
            c += 1
        end
        c = nil

        # Shrink columns that have too much space to try and fit table into visible console
        if max_tbl_cols > max_scr_cols
            
            width_map = width_map.sort_by { |col,width| -width }
            
            last_col = widths.length - 1
            c = 0
            
            while max_tbl_cols > max_scr_cols && c < last_col
                
                while width_map[c][1] > width_map[c + 1][1]
                    
                    i = c
                    while i >= 0
                        width_map[i][1] -= 1
                        widths[width_map[i][0]] -= 1
                        max_tbl_cols -= 1
                        i -= 1
                        
                        break if max_tbl_cols == max_scr_cols
                    end
                    break if max_tbl_cols == max_scr_cols
                end
                c += 1
            end
        end
        
        border1 = ""
        border2 = ""
        format = ""
        widths.each do |n|
            
            border1 += "+#{'-' * (n + 2)}"
            border2 += "+#{'=' * (n + 2)}"
            format += "| %#{n}s "
        end
        border1 += "+\n"
        border2 += "+\n"
        format += "|\n"
        
    else
        c = nil
        border1 = nil
        border2 = nil
        
        format = Array.new(table[0].size, "%s,").join.chop! + "\n"
        
        # Delete column headings for unformatted output
        table.delete_at(0)
    end
    
    # Print each line.
    write_header_border = !border2.nil?
    printf border1 if border1
    table.each do |line|
        
        if c
            # Check if cell needs to be truncated
            i = 0
            while i < c
                
                j = width_map[i][0]
                width = width_map[i][1]
                
                cell = line[j]
                len = cell.length
                if len > width
                    line[j] = cell[0, width - 2] + ".."
                end
                i += 1
            end
        end
        
        printf format, *line
        if write_header_border
            printf border2
            write_header_border = false
        end
    end
    printf border1 if border1

end