require 'csv'

class GeoliteAsnImporter
  BATCH_SIZE = 1000

  def initialize(file_path, data_import:)
    @file_path = file_path
    @data_import = data_import
    @total_records = 0
    @processed_records = 0
    @failed_records = 0
    @errors = []
  end

  def import
    Rails.logger.info "Starting import for file: #{@file_path}"
    Rails.logger.info "File exists: #{File.exist?(@file_path)}"
    Rails.logger.info "File size: #{File.size(@file_path)} bytes" if File.exist?(@file_path)

    # Check if file is actually a zip by reading the magic bytes
    is_zip_file = check_if_zip_file
    Rails.logger.info "File is zip: #{is_zip_file}"

    if is_zip_file
      import_from_zip
    else
      import_csv_file(@file_path)
    end

    {
      total_records: @total_records,
      processed_records: @processed_records,
      failed_records: @failed_records,
      errors: @errors
    }
  end

  private

  def check_if_zip_file
    # Check if the file starts with ZIP magic bytes (PK\x03\x04)
    File.open(@file_path, 'rb') do |file|
      header = file.read(4)
      return header == "PK\x03\x04"
    end
  rescue => e
    Rails.logger.error "Error checking if file is zip: #{e.message}"
    false
  end

  def import_from_zip
    require 'zip'
    require 'stringio'

    Rails.logger.info "Processing zip file directly: #{@file_path}"

    # Read the entire ZIP file content into memory first
    zip_content = File.binread(@file_path)

    Zip::File.open_buffer(StringIO.new(zip_content)) do |zip_file|
      zip_file.each do |entry|
        if entry.name.include?('Blocks') && entry.name.end_with?('.csv')
          Rails.logger.info "Processing ASN block file from zip: #{entry.name}"
          process_csv_from_zip(zip_file, entry)
        end
      end
    end
  rescue => e
    Rails.logger.error "Error processing ZIP file: #{e.message}"
    Rails.logger.error e.backtrace.join("\n")
    raise
  end

  def process_csv_from_zip(zip_file, entry)
    zip_file.get_input_stream(entry) do |io|
      # Read the entire content from the stream
      content = io.read

      CSV.parse(content, headers: true, header_converters: :symbol, encoding: 'UTF-8') do |row|
        @total_records += 1

        begin
          import_record(row)
          @processed_records += 1
        rescue => e
          @failed_records += 1
          @errors << "Row #{@total_records}: #{e.message} - Data: #{row.to_h}"
        end

        update_progress_if_needed
      end
    end
  end

  def csv_files
    if @file_path.end_with?('.zip')
      # Look for extracted CSV files in the same directory
      base_dir = File.dirname(@file_path)
      base_name = File.basename(@file_path, '.zip')

      [
        File.join(base_dir, "#{base_name}-Blocks-IPv4.csv"),
        File.join(base_dir, "#{base_name}-Blocks-IPv6.csv")
      ].select { |file| File.exist?(file) }
    else
      [@file_path]
    end
  end

  def import_csv_file(csv_file)
    CSV.foreach(csv_file, headers: true, header_converters: :symbol, encoding: 'UTF-8') do |row|
      @total_records += 1

      begin
        import_record(row)
        @processed_records += 1
      rescue => e
        @failed_records += 1
        @errors << "Row #{@total_records}: #{e.message} - Data: #{row.to_h}"

        # Update progress every 100 records or on error
        update_progress_if_needed
      end

      update_progress_if_needed
    end
  end

  def import_record(row)
    network = row[:network]
    asn = row[:autonomous_system_number]&.to_i
    asn_org = row[:autonomous_system_organization]&.strip

    unless network && asn && asn_org
      raise "Missing required fields: network=#{network}, asn=#{asn}, asn_org=#{asn_org}"
    end

    # Validate network format
    IPAddr.new(network) # This will raise if invalid

    NetworkRange.upsert(
      {
        network: network,
        asn: asn,
        asn_org: asn_org,
        source: 'geolite_asn',
        updated_at: Time.current
      },
      unique_by: :index_network_ranges_on_network_unique
    )
  end

  def update_progress_if_needed
    if (@processed_records + @failed_records) % 100 == 0
      @data_import.update_progress(
        processed: @processed_records,
        failed: @failed_records,
        total_records: @total_records,
        stats: {
          total_records: @total_records,
          current_file: File.basename(@file_path),
          recent_errors: @errors.last(5)
        }
      )
    end
  end

  def extract_if_zipfile
    return unless @file_path.end_with?('.zip')

    require 'zip'

    Zip::File.open(@file_path) do |zip_file|
      zip_file.each do |entry|
        if entry.name.end_with?('.csv')
          extract_path = File.join(File.dirname(@file_path), entry.name)
          entry.extract(extract_path)
        end
      end
    end
  end
end