--- font
-- @module SILE.font
local icu = require("justenoughicu")

local lastshaper

SILE.registerCommand("font", function (options, content)
   if SU.ast.hasContent(content) then
      SILE.settings:pushState()
   end
   if options.filename then
      SILE.settings:set("font.filename", options.filename)
   end
   if options.family then
      SILE.settings:set("font.family", options.family)
      SILE.settings:set("font.filename", "")
   end
   if options.size then
      local size = SU.cast("measurement", options.size)
      if not size then
         SU.error("Couldn't parse font size " .. options.size)
      end
      SILE.settings:set("font.size", size:absolute())
   end
   if options.weight then
      SILE.settings:set("font.weight", 0 + options.weight)
   end
   if options.style then
      SILE.settings:set("font.style", options.style)
   end
   if options.variant then
      SILE.settings:set("font.variant", options.variant)
   end
   if options.features then
      SILE.settings:set("font.features", options.features)
   end
   if options.variations then
      SILE.settings:set("font.variations", options.variations)
   end
   if options.direction then
      SILE.settings:set("font.direction", options.direction)
   end
   if options.language then
      if options.language ~= "und" and icu and icu.canonicalize_language then
         local newlang = icu.canonicalize_language(options.language)
         -- if newlang ~= options.language then
         -- SU.warn("Language '"..options.language.."' not canonical, '"..newlang.."' will be used instead")
         -- end
         options.language = newlang
      end
      SILE.languageSupport.loadLanguage(options.language)
      SILE.settings:set("document.language", options.language)
   end
   if options.script then
      SILE.settings:set("font.script", options.script)
   elseif SILE.settings:get("document.language") then
      local lang = SILE.languageSupport.languages[SILE.settings:get("document.language")]
      if lang and lang.defaultScript then
         SILE.settings:set("font.script", lang.defaultScript)
      end
   end
   if options.hyphenchar then
      -- must be in the form of, for example, "-" or "U+2010" or "0x2010" (Unicode hex codepoint)
      SILE.settings:set("font.hyphenchar", SU.utf8charfromcodepoint(options.hyphenchar))
   end

   -- We must *actually* load the font here, because by the time we're inside
   -- SILE.shaper.shapeToken, it's too late to respond appropriately to things
   -- that the post-load hook might want to do.
   SILE.font.cache(SILE.font.loadDefaults({}), SILE.shaper.getFace)

   if SU.ast.hasContent(content) then
      SILE.process(content)
      SILE.settings:popState()
      if SILE.shaper._name == "harfbuzzWithColor" and lastshaper then
         SU.debug("color-fonts", "Switching from color fonts shaper back to previous shaper")
         SILE.typesetter:leaveHmode(true)
         lastshaper, SILE.shaper = nil, lastshaper
      end
   end
end, "Set current font family, size, weight, style, variant, script, direction and language", nil, true)

SILE.settings:declare({ parameter = "font.family", type = "string or nil", default = "Gentium Plus" })
SILE.settings:declare({ parameter = "font.size", type = "number or integer", default = 10 })
SILE.settings:declare({ parameter = "font.weight", type = "integer", default = 400 })
SILE.settings:declare({ parameter = "font.variant", type = "string", default = "normal" })
SILE.settings:declare({ parameter = "font.script", type = "string", default = "" })
SILE.settings:declare({ parameter = "font.style", type = "string", default = "" })
SILE.settings:declare({ parameter = "font.direction", type = "string", default = "" })
SILE.settings:declare({ parameter = "font.filename", type = "string or nil", default = "" })
SILE.settings:declare({ parameter = "font.features", type = "string", default = "" })
SILE.settings:declare({ parameter = "font.variations", type = "string", default = "" })
SILE.settings:declare({ parameter = "font.hyphenchar", type = "string", default = "-" })

SILE.fontCache = {}

local _key = function (options)
   return table.concat({
      options.family,
      ("%g"):format(SILE.types.measurement(options.size):tonumber()),
      ("%d"):format(options.weight or 0),
      options.style,
      options.variant,
      options.features,
      options.variations,
      options.direction,
      options.filename,
   }, ";")
end

local font = {

   loadDefaults = function (options)
      if not options.family then
         options.family = SILE.settings:get("font.family")
      end
      if not options.size then
         options.size = SILE.settings:get("font.size")
      end
      if not options.weight then
         options.weight = SILE.settings:get("font.weight")
      end
      if not options.style then
         options.style = SILE.settings:get("font.style")
      end
      if not options.variant then
         options.variant = SILE.settings:get("font.variant")
      end
      if SILE.settings:get("font.filename") ~= "" then
         options.filename = SILE.settings:get("font.filename")
         options.family = ""
      end
      if not options.language then
         options.language = SILE.settings:get("document.language")
      end
      if not options.script then
         options.script = SILE.settings:get("font.script")
      end
      if not options.direction then
         options.direction = SILE.settings:get("font.direction")
         if not options.direction or options.direction == "" then
            options.direction = SILE.typesetter and SILE.typesetter.frame and SILE.typesetter.frame:writingDirection()
               or "LTR"
         end
      end
      if not options.features then
         options.features = SILE.settings:get("font.features")
      end
      if not options.variations then
         options.variations = SILE.settings:get("font.variations")
      end
      if not options.hyphenchar then
         options.hyphenchar = SILE.settings:get("font.hyphenchar")
      end
      return options
   end,

   cache = function (options, callback)
      local key = _key(options)
      if not SILE.fontCache[key] then
         SU.debug("fonts", "Looking for", key)
         local face = callback(options)
         SILE.fontCache[key] = face
      end
      local cached = SILE.fontCache[key]
      SILE.font.postLoadHook(cached)
      return cached
   end,

   finish = function ()
      for key, font in pairs(SILE.fontCache) do
         if font.tempfilename ~= font.filename then
            SU.debug("fonts", "Removing temporary file of", key, ":", font.tempfilename)
            os.remove(font.tempfilename)
         end
      end
   end,

   postLoadHook = function (face)
      local ot = require("core.opentype-parser")
      local font = ot.parseFont(face)
      if font.cpal then
         SILE.require("packages.color-fonts")
         if SILE.shaper._name ~= "harfbuzzWithColor" then
            SU.debug("color-fonts", "Switching to color font Shaper")
            SILE.typesetter:leaveHmode(true)
            lastshaper, SILE.shaper = SILE.shaper, SILE.shapers.harfbuzzWithColor()
         end
      end
   end,

   _key = _key,
}

return font
