class Danger::DSLError

def contents
  @contents ||= dsl_path && File.exist?(dsl_path) && File.read(dsl_path)
end

def initialize(description, dsl_path, backtrace, contents = nil)
  @description = description
  @dsl_path    = dsl_path
  @backtrace   = backtrace
  @contents    = contents
end

def message
  @message ||= begin
    description, stacktrace = parse.values_at(:description, :stacktrace)
    msg = description
    msg = msg.red if msg.respond_to?(:red)
    msg << stacktrace if stacktrace
    msg
  end
end

def parse
  result = {}
  trace_line, description = parse_line_number_from_description
  latest_version = Danger.danger_outdated?
  result[:description] = "\n[!] #{description}"
  result[:description] << upgrade_message(latest_version) if latest_version
  return result unless backtrace && dsl_path && contents
  trace_line = backtrace.find { |l| l.include?(dsl_path.to_s) } || trace_line
  return result unless trace_line
  line_numer = trace_line.split(":")[1].to_i - 1
  return result unless line_numer
  lines      = contents.lines
  indent     = " #  "
  indicator  = indent.tr("#", ">")
  first_line = line_numer.zero?
  last_line  = (line_numer == (lines.count - 1))
  result[:stacktrace] = "\n"
  result[:stacktrace] << "#{indent}from #{trace_line.gsub(/:in.*$/, '')}\n"
  result[:stacktrace] << "#{indent}-------------------------------------------\n"
  result[:stacktrace] << "#{indent}#{lines[line_numer - 1]}" unless first_line
  result[:stacktrace] << "#{indicator}#{lines[line_numer]}"
  result[:stacktrace] << "#{indent}#{lines[line_numer + 1]}" unless last_line
  result[:stacktrace] << "\n" unless result[:stacktrace].end_with?("\n")
  result[:stacktrace] << "#{indent}-------------------------------------------\n"
  result
end

def parse_line_number_from_description
  description = self.description
  if dsl_path && description =~ /((#{Regexp.quote File.expand_path(dsl_path)}|#{Regexp.quote dsl_path.to_s}):\d+)/
    trace_line = Regexp.last_match[1]
    description = description.sub(/#{Regexp.quote trace_line}:\s*/, "")
  end
  [trace_line, description]
end

def to_markdown
  @markdown ||= begin
    description, stacktrace = parse.values_at(:description, :stacktrace)
    # Highlight failed method in markdown
    description = description.tr("'", "`")
    # Escape markdown brackets
    description = description.gsub(/<|>/) { |bracket| "\\#{bracket}" }
    md = "## Danger has errored"
    md << "#{description}\n"
    md << "```#{stacktrace}```" if stacktrace
    Markdown.new(md, nil, nil)
  end
end

def upgrade_message(latest_version)
  ". Updating the Danger gem might fix the issue. "\
  "Your Danger version: #{Danger::VERSION}, "\
  "latest Danger version: #{latest_version}\n"
end