require "yaml"
require "digest"

module Picop
  class SourceFile
    attr_reader :file_path, :content

    METADATA_PATTERN = /^\s*#\s*@META_START\n(.*?)^\s*#\s*@META_END/m

    def initialize(file_path)
      @file_path = file_path
      @content = File.read(file_path)
    end

    def metadata
      @metadata ||= begin
        return {} unless content =~ METADATA_PATTERN
    
        yaml_content = $1.lines.map do |line|
          line.sub(/^\s*#\s?/, '').rstrip
        end.join("\n")
    
        YAML.safe_load(yaml_content)
      end
    end

    def file_content = content.sub(/^\s*#\s*@META_START\n.*?^\s*#\s*@META_END\n*/m, '')

    def checksum = "sha256:#{Digest::SHA256.hexdigest(file_content)}"

    def show = puts(metadata.merge({checksum: checksum}))

    def save = File.write(file_path, content)

    def add_metadata(metadata_hash)
      yaml_content = metadata_hash.to_yaml.strip
      metadata_block = [
        "# @META_START",
        yaml_content.lines.map { |line| "# #{line}" }.join,
        "# @META_END"
      ].join("\n")

      if content =~ METADATA_PATTERN
        @content = content.sub(METADATA_PATTERN, metadata_block)
      else
        @content = [metadata_block, content].join("\n\n")
      end
    end
    
    def sign
      hash = checksum
      meta = metadata || {}
      return puts "File already signed" if meta['content_checksum'] == hash
    
      meta['content_checksum'] = "#{hash}"
      add_metadata(meta)
      save
    end

    def verify
      return false unless metadata.key? 'content_checksum'
      checksum == metadata['content_checksum']
    end
  end
end