local utils = {}

utils.if_nil = function(x, was_nil, was_not_nil)
  if x == nil then
    return was_nil
  else
    return was_not_nil
  end
end

utils.get_default = function(x, default)
  return utils.if_nil(x, default, x)
end

utils.get_lazy_default = function(x, defaulter, ...)
  if x == nil then
    return defaulter(...)
  else
    return x
  end
end

local function reversedipairsiter(t, i)
  i = i - 1
  if i ~= 0 then
    return i, t[i]
  end
end

utils.reversed_ipairs = function(t)
  return reversedipairsiter, t, #t + 1
end

utils.default_table_mt = {
  __index = function(t, k)
    local obj = {}
    rawset(t, k, obj)
    return obj
  end
}

utils.repeated_table = function(n, val)
  local empty_lines = {}
  for _ = 1, n do
    table.insert(empty_lines, val)
  end
  return empty_lines
end

utils.quickfix_items_to_entries = function(locations)
  local results = {}

  for _, entry in ipairs(locations) do
    local vimgrep_str = entry.vimgrep_str or string.format(
      "%s:%s:%s: %s",
      vim.fn.fnamemodify(entry.display_filename or entry.filename, ":."),
      entry.lnum,
      entry.col,
      entry.text
    )

    table.insert(results, {
      valid = true,
      value = entry,
      ordinal = vimgrep_str,
      display = vimgrep_str,

      start = entry.start,
      finish = entry.finish,
    })
  end

  return results
end

utils.new_ngram = function()
  return require("telescope._private.NGram"):new()
end

-- TODO: Figure out how to do this... could include in plenary :)
-- NOTE: Don't use this yet. It will segfault sometimes.
--
-- opts.shorten_path and function(value)
--     local result = {
--       valid = true,
--       display = utils.path_shorten(value),
--       ordinal = value,
--       value = value
--     }

--     return result
--   end or nil)
utils.path_shorten = (function()
  if jit then
    local ffi = require('ffi')
    ffi.cdef [[
    typedef unsigned char char_u;
    char_u *shorten_dir(char_u *str);
    ]]

    return function(path)
      if not path then
        return path
      end

      local c_str = ffi.new("char[?]", #path + 1)
      ffi.copy(c_str, path)
      return ffi.string(ffi.C.shorten_dir(c_str))
    end
  else
    return function(path)
      return path
    end
  end
end)()

-- local x = utils.make_default_callable(function(opts)
--   return function()
--     print(opts.example, opts.another)
--   end
-- end, { example = 7, another = 5 })

-- x()
-- x.new { example = 3 }()
function utils.make_default_callable(f, default_opts)
  return setmetatable({
    new = function(opts)
      opts = vim.tbl_extend("keep", opts, default_opts)
      return f(opts)
    end,
  }, {
    __call = function()
      local ok, err = pcall(f(default_opts))
      if not ok then
        error(debug.traceback(err))
      end
    end
  })
end

return utils