# encoding: utf-8
# copyright: 2015, Dominik Richter
# license: All rights reserved

class SimpleConfig
  attr_reader :params
  def initialize(raw_data, opts = {})
    parse(raw_data, opts)
  end

  # Parse some data
  # quotes: quoting characters, which are parsed, so everything inside
  # it will be part of a string
  # multiline: allow quoted text to span multiple lines
  # comment_char: char which identifies comments
  # standalone_comments: comments must appear alone in a line; if set to true,
  # no comments can be added to the end of an assignment/statement line
  def parse(raw_data, opts = {})
    @params = {}
    options = default_options.merge(opts)
    rest = raw_data
    rest = parse_rest(rest, options) while rest.length > 0
  end

  private

  def parse_values(match, values)
    start_idx = 2
    i = 0
    count = values - 1
    return match[start_idx] if (values == 1)

    # iterate over expected parameters
    values = []
    loop do
      values.push(match[start_idx + i])
      i += 1
      break if i > count
    end
    values
  end

  def parse_comment_line(rest, opts)
    idx_nl = rest.index("\n")
    idx_comment = rest.index(opts[:comment_char])
    idx_nl = rest.length if idx_nl.nil?
    idx_comment = idx_nl + 1 if idx_comment.nil?
    line = ''

    # is a comment inside this line
    if idx_comment < idx_nl && idx_comment != 0
      line = rest[0..(idx_comment - 1)]
      # in case we don't allow comments at the end
      # of an assignment/statement, ignore it and fall
      # back to treating this as a regular line
      if opts[:standalone_comments] && !is_empty_line(line)
        line = rest[0..(idx_nl - 1)]
      end
    # if there is no comment in this line
    elsif idx_comment > idx_nl && idx_nl != 0
      line = rest[0..(idx_nl - 1)]
    end
    [line, idx_nl]
  end

  def parse_line_params(line, opts)
    # now line contains what we are interested in parsing
    # check if it is an assignment
    m = opts[:assignment_re].match(line)
    if !m.nil?
      if opts[:multiple_values]
        @params[m[1]] ||= []
        @params[m[1]].push(parse_values(m, opts[:key_vals]))
      else
        @params[m[1]] = parse_values(m, opts[:key_vals])
      end
    elsif !is_empty_line(line)
      if opts[:multiple_values]
        @params[line.strip] ||= []
      else
        @params[line.strip] = ''
      end
    end
  end

  def parse_rest(rest, opts)
    line, idx_nl = parse_comment_line(rest, opts)
    parse_line_params(line, opts)

    # return whatever is left
    rest[(idx_nl + 1)..-1] || ''
  end

  def is_empty_line(l)
    l =~ /^\s*$/
  end

  def default_options
    {
      quotes: '',
      multiline: false,
      comment_char: '#',
      assignment_re: /^\s*([^=]*?)\s*=\s*(.*?)\s*$/,
      key_vals: 1, # default for key=value, may require for 'key val1 val2 val3'
      standalone_comments: false,
      multiple_values: false,
    }
  end
end