module Fontist::Indexes::IncrementalScanner

# File lib/fontist/indexes/incremental_scanner.rb, line 67
def self.compute_signature(path)
  return nil unless File.exist?(path)

  # Read first 1KB for fast signature
  header = File.read(path, 1024)
  Digest::SHA256.hexdigest(header)
end

# File lib/fontist/indexes/incremental_scanner.rb, line 76
def self.detect_format(path)
  return :unknown unless File.exist?(path)

  header = File.read(path, 4)

  # Debug output
  # puts "detect_format: path=#{path}, header=#{header.bytes.inspect}"

  case header
  when /^\x00\x01\x00\x00/
    :truetype
  when /^OTTO/
    :opentype
  when /^wOFF/
    :woff
  when /^wOF2/
    :woff2
  else
    :unknown
  end
end

# File lib/fontist/indexes/incremental_scanner.rb, line 55
def self.scan_batch(paths, cache: {})
  paths.map do |path|
    cached = cache[path]
    if cached
      scan_with_cache(path, cached)
    else
      scan_font_file(path)
    end
  end.compact
end

# File lib/fontist/indexes/incremental_scanner.rb, line 8
def self.scan_directory(directory)
  return [] unless Dir.exist?(directory)

  PathScanning.list_font_directory(directory).map do |path|
    scan_font_file(path)
  end
end

# File lib/fontist/indexes/incremental_scanner.rb, line 18
def self.scan_font_file(path)
  return nil unless File.exist?(path)

  stat = File.stat(path)

  {
    path: path,
    filename: File.basename(path),
    file_size: stat.size,
    file_mtime: stat.mtime.to_i,
    signature: compute_signature(path),
    format: detect_format(path),
  }
end

# File lib/fontist/indexes/incremental_scanner.rb, line 35
def self.scan_with_cache(path, cached_version)
  return nil unless File.exist?(path)

  current_stat = File.stat(path)

  # Check if file changed
  if cached_version &&
      cached_version[:file_size] == current_stat.size &&
      cached_version[:file_mtime] == current_stat.mtime.to_i
    # Could also check signature here for extra certainty
    return cached_version
  end

  # File changed or no cache - rescan
  scan_font_file(path)
end