manage ssh config

shatter.rb

#!/bin/ruby

def parse_config(config)
  hash = {}
  results = config.scan(REGEXP)
  results.each do |subarray|
    hash[subarray[1]] = subarray[2].split("\n").map {|el|
      ar = el.split
      [ar.shift, ar.join(' ')]}.inject({}) {|h, a| h[a[0]] = a[1]; h}
  end
  hash
end

def replace(map, name, key, value)
  map[name][key] = value
end

def entry_template(name, values_hash)
  template = ""
  template << "Host #{name}\n"
  values_hash.each do |key, value|
    template << "  #{key} #{value}\n"
  end
  template << "\n"
  template
end

def output(map)
  string = ""
  map.each do |name, values_hash|
    string << entry_template(name, values_hash)
  end
  string
end

SSH_CONFIG_PATH = "~/.ssh/config"
REGEXP = /(Host)\s(\S*$)\s(.*?)(?=\1|\Z)/m
FILE_PATH = File.expand_path(SSH_CONFIG_PATH)

if ARGV.count != 3
  raise "Too few arguments"
else
  entry = ARGV[0]
  key = ARGV[1]
  value = ARGV[2]

  config = File.read(FILE_PATH)
  map = parse_config(config)
  replace(map, entry, key, value)
  File.open(FILE_PATH, 'w') do |f|
    f.write(output(map))
  end
end

# Usage: shatter.rb <entry-name> <key-name> <value-to-replace-with>