module RaspbergFilenamer

# File lib/raspberg_filenamer.rb, line 10
def parse(args_text)
  text = args_text.to_s.strip
  return { error: "Usage: !raspberg filenamer <prefix> <start> <ext> -- <file> [file...]" } if text.empty?

  head, sources_text = text.split(/\s+--\s+/, 2)
  parts = head.to_s.split(/\s+/)
  return { error: "Usage: !raspberg filenamer <prefix> <start> <ext> -- <file> [file...]" } if parts.length < 3

  prefix = parts[0]
  start = parts[1].to_i
  ext = parts[2]
  sources = sources_text.to_s.split(/\s+/).reject(&:empty?)

  return { error: "prefix cannot exceed #{MAX_PREFIX} characters." } if prefix.length > MAX_PREFIX
  return { error: "extension cannot exceed #{MAX_EXT} characters." } if ext.length > MAX_EXT

  { prefix: prefix, start: start, ext: ext, sources: sources }
end

# File lib/raspberg_filenamer.rb, line 29
def preview(prefix:, start:, ext:, sources:)
  return { error: "Please select a nonzero starting value." } if start.to_i.zero?
  return { error: "Please select the files you wish to have converted." } if sources.nil? || sources.empty?

  filenumber = start.to_i - 1
  names = sources.map do |_source|
    filenumber += 1
    "#{prefix}#{filenumber}.#{ext}"
  end

  { names: names, prefix: prefix, start: start, ext: ext, sources: sources }
end