if Cldr.Code.ensure_compiled?(Cldr.Unit) do
defmodule Cldr.HTML.Unit do
@moduledoc """
Implements `Phoenix.HTML.Form.select/4` specifically for
localised unit display.
"""
@type select_options :: [
{:units, [atom() | binary(), ...]}
| {:locale, Cldr.Locale.locale_name() | Cldr.LanguageTag.t()}
| {:collator, function()}
| {:mapper, (Cldr.Unit.t() -> String.t())}
| {:backend, module()}
| {:selected, atom() | binary()}
]
@doc """
Generate an HTML select tag for a unit list
that can be used with a `Phoenix.HTML.Form.t`.
## Arguments
* A `t:Phoenix.HTML.Form` form
* A `t:Phoenix.HTML.Form.field` field
* A `t:Keyword` list of options
## Options
For select options see `Phoenix.HTML.Form.select/4`
* `:units` is a list of units to be displayed in the
select. See `Cldr.Unit.known_units/0` and
`Cldr.Unit.known_units_for_category/1`
* `:style` is the style of unit name to be displayed and
must be one of the styles returned by `Cldr.Unit.known_styles/0`.
The current styles are :long, :short and :narrow.
The default is style: :long.
* `:locale` defines the locale to be used to localise the
description of the units. The default is the locale
returned by `Cldr.get_locale/0`
* `:backend` is any backend module. The default is
`Cldr.default_backend!/0`
* `:collator` is a function used to sort the units
in the selection list. It is passed a list of tuples where
each tuple is in the form `{unit_display_name, unit}`.
The default collator sorts by `name_1 < name_2`.
As a result, default collation sorts by code point which
will not return expected results for scripts other than Latin.
* `:mapper` is a function that creates the text to be
displayed in the select tag for each unit. It is
passed the a tuple of the form `{unit_display_name, unit}`,
The default is the identity function `&(&1)`.
* `:selected` identifies the unit that is to be selected
by default in the `select` tag. The default is `nil`. This
is passed unmodified to `Phoenix.HTML.Form.select/4`
* `:prompt` is a prompt displayed at the top of the select
box. This is passed unmodified to `Phoenix.HTML.Form.select/4`
# Examples
=> Cldr.HTML.Unit.select(:my_form, :unit, selected: :foot)
=> Cldr.HTML.Unit.select(:my_form, :unit, units: [:foot, :inch])
"""
@spec select(
form :: Phoenix.HTML.Form.t(),
field :: Phoenix.HTML.Form.field(),
select_options
) ::
Phoenix.HTML.safe()
| {:error, {Cldr.UnknownUnitError, binary()}}
| {:error, {Cldr.UnknownLocaleError, binary()}}
def select(form, field, options \\ [])
def select(form, field, options) when is_list(options) do
select(form, field, validate_options(options), options[:selected])
end
# Invalid options
defp select(_form, _field, {:error, reason}, _selected) do
{:error, reason}
end
# Selected currency
@omit_from_select_options [:units, :locale, :mapper, :collator, :backend, :style]
defp select(form, field, options, _selected) do
select_options =
options
|> Map.drop(@omit_from_select_options)
|> Map.to_list()
options =
options
|> maybe_include_selected_unit
|> unit_options
Phoenix.HTML.Form.select(form, field, options, select_options)
end
defp validate_options(options) do
with options <- Map.merge(default_options(), Map.new(options)),
{:ok, options} <- validate_locale(options),
{:ok, options} <- validate_selected(options),
{:ok, options} <- validate_units(options),
{:ok, options} <- validate_style(options) do
options
end
end
defp default_options do
Map.new(
units: default_unit_list(),
backend: nil,
locale: Cldr.get_locale(),
collator: &default_collator/1,
mapper: & &1,
style: :long,
selected: nil
)
end
defp default_collator(units) do
Enum.sort(units, &default_comparator/2)
end
# Note that this is not a unicode aware comparison
# It sorts by the display name
defp default_comparator({_, unit_1}, {_, unit_2}) do
unit_1 < unit_2
end
defp validate_selected(%{selected: nil} = options) do
{:ok, options}
end
defp validate_selected(%{selected: selected} = options) do
with {:ok, unit, _conversion} <- Cldr.Unit.validate_unit(selected) do
{:ok, Map.put(options, :selected, unit)}
end
end
# Return a list of validated units or an error
defp validate_units(%{units: units} = options) do
validate_units(units, options)
end
defp validate_units(units) when is_list(units) do
Enum.reduce_while(units, [], fn unit, acc ->
case Cldr.Unit.validate_unit(unit) do
{:ok, unit, _conversion} -> {:cont, [unit | acc]}
{:error, reason} -> {:halt, {:error, reason}}
end
end)
end
defp validate_units(units, options) do
case validate_units(units) do
{:error, reason} -> {:error, reason}
units -> {:ok, Map.put(options, :units, Enum.reverse(units))}
end
end
defp validate_style(options) do
with {:ok, style} <- Cldr.Unit.validate_style(options[:style]) do
{:ok, Map.put(options, :style, style)}
end
end
defp validate_locale(options) do
{locale, backend} = Cldr.locale_and_backend_from(options[:locale], options[:backend])
with {:ok, locale} <- Cldr.validate_locale(locale, backend) do
options
|> Map.put(:locale, locale)
|> Map.put(:backend, locale.backend)
|> wrap(:ok)
end
end
defp wrap(term, atom) do
{atom, term}
end
defp maybe_include_selected_unit(%{selected: nil} = options) do
options
end
defp maybe_include_selected_unit(%{units: units, selected: selected} = options) do
if Enum.any?(units, &(&1 == selected)) do
options
else
Map.put(options, :units, [selected | units])
end
end
defp unit_options(options) do
units = Map.fetch!(options, :units)
collator = Map.fetch!(options, :collator)
mapper = Map.fetch!(options, :mapper)
options = Map.to_list(options)
units
|> Enum.map(&to_selection_tuple(&1, options))
|> collator.()
|> Enum.map(&mapper.(&1))
end
defp to_selection_tuple(unit, options) do
display_name = Cldr.Unit.display_name(unit, options)
unit_code = to_string(unit)
{display_name, unit_code}
end
defp default_unit_list() do
Cldr.Unit.known_units()
end
end
end
