#!/usr/bin/env ruby

#--
# Cloud Foundry
# Copyright (c) [2009-2014] Pivotal Software, Inc. All Rights Reserved.
#
# This product is licensed to you under the Apache License, Version 2.0 (the "License").
# You may not use this product except in compliance with the License.
#
# This product includes a number of subcomponents with
# separate copyright notices and license terms. Your use of these
# subcomponents is subject to the terms and conditions of the
# subcomponent's license, as noted in the LICENSE file.
#++

# given the indents, find sub-commands of a given command
def find_sub_commands (lines, indents, i)
  result = Array.new
  x = i+1
  while x < lines.size && indents[x] > indents[i]
    if indents[x] - indents[i] == 1
      result.push(x)
    end
    x = x+1
  end
  result
end

def find_sub_command_index (lines, sub_command_indices, sub_command)
  sub_command_indices.each do |i|
    if lines[i] == sub_command
      return i
    end
  end
  -1
end

# traverse sub-command tree with the given list of args
def traverse_command_tree(lines, sub_command_indices, args)
  #puts "traversing for #{args}"
  x = 0
  args.drop(1).each do |arg|
    next if arg.start_with? ("-")
    nx = find_sub_command_index(lines, sub_command_indices[x], arg)
    if nx != -1
      x = nx
    end
  end
  x
end

# use values in array1 as indices into array2 and find the subset from array2
def find_subset(values, indices)
  result = Array.new
  indices.each do |i|
    result.push(values[i])
  end
  result.join(' ')
end

def get_cache_filename(cmd)
  curr_user = `whoami`.chomp
  home_dir = `echo ~#{curr_user}`.chomp
  "#{home_dir}/.#{cmd}-commands"
end

indent_char = "\t"
command_file_name = get_cache_filename(ARGV[0])
if !FileTest.exists?(command_file_name)
  `#{ARGV[0]} help commands > #{command_file_name}`
end
lines = File.readlines(command_file_name)
children = Array.new
indents = Array.new

lines.each_with_index do |line, i|
  indents[i] = line.count(indent_char)
end

# now that we have computed the indent level for each line, remove new-lines and tabs
lines.collect! { |line| line.gsub(/[#{indent_char}]/, '') }
lines.collect! { |line| line.gsub(/[\n]/, '') }

# pre-processing: find the sub-commands for command (using indent levels)
lines.each_with_index do |line, i|
  children[i] = find_sub_commands(lines, indents, i)
end

# now that a sub-command tree is available, parse it using the input arguments to find the auto-completion options
x = traverse_command_tree(lines, children, ARGV.drop(1))
puts x == -1 ? "" : find_subset(lines, children[x])