local exports = {}

-- Metafunctions
local function meta_size_function(task)
  local sizes = {
    100,
    200,
    500,
    1000,
    2000,
    4000,
    10000,
    20000,
    30000,
    100000,
    200000,
    400000,
    800000,
    1000000,
    2000000,
    8000000,
  }

  local size = task:get_size()
  for i = 1,#sizes do
    if sizes[i] >= size then
      return {(1.0 * i) / #sizes}
    end
  end

  return {0}
end

local function meta_images_function(task)
  local images = task:get_images()
  local ntotal = 0
  local njpg = 0
  local npng = 0
  local nlarge = 0
  local nsmall = 0

  if images then
    for _,img in ipairs(images) do
      if img:get_type() == 'png' then
        npng = npng + 1
      elseif img:get_type() == 'jpeg' then
        njpg = njpg + 1
      end

      local w = img:get_width()
      local h = img:get_height()

      if w > 0 and h > 0 then
        if w + h > 256 then
          nlarge = nlarge + 1
        else
          nsmall = nsmall + 1
        end
      end

      ntotal = ntotal + 1
    end
  end
  if ntotal > 0 then
    njpg = 1.0 * njpg / ntotal
    npng = 1.0 * npng / ntotal
    nlarge = 1.0 * nlarge / ntotal
    nsmall = 1.0 * nsmall / ntotal
  end
  return {ntotal,njpg,npng,nlarge,nsmall}
end

local function meta_nparts_function(task)
  local nattachments = 0
  local ntextparts = 0
  local totalparts = 1

  local tp = task:get_text_parts()
  if tp then
    ntextparts = #tp
  end

  local parts = task:get_parts()

  if parts then
    for _,p in ipairs(parts) do
      if p:get_filename() then
        nattachments = nattachments + 1
      end
      totalparts = totalparts + 1
    end
  end

  return {(1.0 * ntextparts)/totalparts, (1.0 * nattachments)/totalparts}
end

local function meta_encoding_function(task)
  local nutf = 0
  local nother = 0

  local tp = task:get_text_parts()
  if tp then
    for _,p in ipairs(tp) do
      if p:is_utf() then
        nutf = nutf + 1
      else
        nother = nother + 1
      end
    end
  end

  return {nutf, nother}
end

local function meta_recipients_function(task)
  local nmime = 0
  local nsmtp = 0

  if task:has_recipients('mime') then
    nmime = #(task:get_recipients('mime'))
  end
  if task:has_recipients('smtp') then
    nsmtp = #(task:get_recipients('smtp'))
  end

  if nmime > 0 then nmime = 1.0 / nmime end
  if nsmtp > 0 then nsmtp = 1.0 / nsmtp end

  return {nmime,nsmtp}
end

local function meta_received_function(task)
  local count_factor = 0
  local invalid_factor = 0
  local rh = task:get_received_headers()
  local time_factor = 0
  local secure_factor = 0
  local fun = require "fun"

  if rh and #rh > 0 then

    local ntotal = 0.0
    local init_time = 0

    fun.each(function(rc)
      ntotal = ntotal + 1.0

      if not rc.by_hostname then
        invalid_factor = invalid_factor + 1.0
      end
      if init_time == 0 and rc.timestamp then
        init_time = rc.timestamp
      elseif rc.timestamp then
        time_factor = time_factor + math.abs(init_time - rc.timestamp)
        init_time = rc.timestamp
      end
      if rc.flags and (rc.flags['ssl'] or rc.flags['authenticated']) then
        secure_factor = secure_factor + 1.0
      end
    end,
    fun.filter(function(rc) return not rc.flags or not rc.flags['artificial'] end, rh))

    invalid_factor = invalid_factor / ntotal
    secure_factor = secure_factor / ntotal
    count_factor = 1.0 / ntotal

    if time_factor ~= 0 then
      time_factor = 1.0 / time_factor
    end
  end

  return {count_factor, invalid_factor, time_factor, secure_factor}
end

local function meta_urls_function(task)
  if task:has_urls() then
    return {1.0 / #(task:get_urls())}
  end

  return {0}
end

local metafunctions = {
  {
    cb = meta_size_function,
    ninputs = 1,
  },
  {
    cb = meta_images_function,
    ninputs = 5,
    -- 1 - number of images,
    -- 2 - number of png images,
    -- 3 - number of jpeg images
    -- 4 - number of large images (> 128 x 128)
    -- 5 - number of small images (< 128 x 128)
  },
  {
    cb = meta_nparts_function,
    ninputs = 2,
    -- 1 - number of text parts
    -- 2 - number of attachments
  },
  {
    cb = meta_encoding_function,
    ninputs = 2,
    -- 1 - number of utf parts
    -- 2 - number of non-utf parts
  },
  {
    cb = meta_recipients_function,
    ninputs = 2,
    -- 1 - number of mime rcpt
    -- 2 - number of smtp rcpt
  },
  {
    cb = meta_received_function,
    ninputs = 4,
  },
  {
    cb = meta_urls_function,
    ninputs = 1,
  },
}

local function rspamd_gen_metatokens(task)
  local ipairs = ipairs
  local metatokens = {}
  local cached = task:cache_get('metatokens')

  if cached then
    return cached
  else
    for _,mt in ipairs(metafunctions) do
      local ct = mt.cb(task)

      for _,tok in ipairs(ct) do
        table.insert(metatokens, tok)
      end
    end

    task:cache_set('metatokens', metatokens)
  end

  return metatokens
end

exports.rspamd_gen_metatokens = rspamd_gen_metatokens

local function rspamd_count_metatokens()
  local ipairs = ipairs
  local total = 0
  for _,mt in ipairs(metafunctions) do
    total = total + mt.ninputs
  end

  return total
end

exports.rspamd_count_metatokens = rspamd_count_metatokens

return exports