local hb = require("luaharfbuzz")

-- special tags
hb.Tag.NONE = hb.Tag.new()

-- special script codes (ISO 15924)
hb.Script.COMMON    = hb.Script.new("Zyyy")
hb.Script.INHERITED = hb.Script.new("Zinh")
hb.Script.UNKNOWN   = hb.Script.new("Zzzz")
hb.Script.INVALID   = hb.Script.from_iso15924_tag(hb.Tag.NONE)

-- directions
hb.Direction.INVALID = hb.Direction.new("invalid")
hb.Direction.LTR = hb.Direction.new("ltr")
hb.Direction.RTL = hb.Direction.new("rtl")
hb.Direction.TTB = hb.Direction.new("ttb")
hb.Direction.BTT = hb.Direction.new("btt")

-- special languages
hb.Language.INVALID = hb.Language.new()

hb.shape = function(font, buf, options)
  options = options or { }

  -- Apply options to buffer if they are set.
  if options.language then buf:set_language(options.language) end
  if options.script then buf:set_script(options.script) end
  if options.direction then buf:set_direction(options.direction) end

  -- Guess segment properties, in case all steps above have failed
  -- to set the right properties.
  buf:guess_segment_properties()

  local features = {}

  -- Parse features
  if type(options.features) == "string" then
    for fs in string.gmatch(options.features, '([^,]+)') do
      local feature = hb.Feature.new(fs)
      if feature then
        table.insert(features, hb.Feature.new(fs))
      else
        error(string.format("Invalid feature string: '%s'", fs))
      end
    end
  elseif type(options.features) == "table" then
    features = options.features
  elseif options.features then -- non-nil but not a string or table
    error("Invalid features option")
  end

  return hb.shape_full(font,buf,features,options.shapers or {})
end

-- For backward compatibility
hb.Buffer.HB_BUFFER_CLUSTER_LEVEL_MONOTONE_GRAPHEMES  = hb.Buffer.CLUSTER_LEVEL_MONOTONE_GRAPHEMES
hb.Buffer.HB_BUFFER_CLUSTER_LEVEL_MONOTONE_CHARACTERS = hb.Buffer.CLUSTER_LEVEL_MONOTONE_CHARACTERS
hb.Buffer.HB_BUFFER_CLUSTER_LEVEL_CHARACTERS          = hb.Buffer.CLUSTER_LEVEL_CHARACTERS
hb.Buffer.HB_BUFFER_CLUSTER_LEVEL_DEFAULT             = hb.Buffer.CLUSTER_LEVEL_DEFAULT

hb.Tag.HB_TAG_NONE = hb.Tag.NONE

hb.Script.HB_SCRIPT_COMMON    = hb.Script.COMMON
hb.Script.HB_SCRIPT_INHERITED = hb.Script.INHERITED
hb.Script.HB_SCRIPT_UNKNOWN   = hb.Script.UNKNOWN
hb.Script.HB_SCRIPT_INVALID   = hb.Script.INVALID

hb.Language.HB_LANGUAGE_INVALID = hb.Language.INVALID

hb.Direction.HB_DIRECTION_INVALID = hb.Direction.INVALID
hb.Direction.HB_DIRECTION_LTR = hb.Direction.LTR
hb.Direction.HB_DIRECTION_RTL = hb.Direction.RTL
hb.Direction.HB_DIRECTION_TTB = hb.Direction.TTB
hb.Direction.HB_DIRECTION_BTT = hb.Direction.BTT

hb.Direction.HB_DIRECTION_IS_VALID = hb.Direction.is_valid
hb.Direction.HB_DIRECTION_IS_HORIZONTAL = hb.Direction.is_horizontal
hb.Direction.HB_DIRECTION_IS_VERTICAL = hb.Direction.is_vertical
hb.Direction.HB_DIRECTION_IS_FORWARD = hb.Direction.is_forward
hb.Direction.HB_DIRECTION_IS_BACKWARD = hb.Direction.is_backward

hb.Buffer.get_glyph_infos_and_positions = hb.Buffer.get_glyphs

return hb