///|
/// A tour through the built-ins, grouped by what they work on. Each block is
/// rendered on its own so the output reads top to bottom; the point is to show
/// the shape of the language and the breadth of what ships, not to build
/// anything in particular. Redundancy here is on purpose.
let text_src =
  #|
{{ "hello WORLD"|capitalize }}

  #|
{{ "a-b-c"|replace("-", " ") }}

  #|
{{ "  spaced  "|trim }}

  #|
{{ "a long sentence about the weather"|truncate(20) }}

  #|
{{ "one two three four five"|wordwrap(10) }}

  #|
{{ "hi"|center(10) }}

  #|
{{ "hi"|striptags }}

  #|
{{ "link"|urlize }}

  #|
{{ "a"|e }}


///|
let numbers_src =
  #|
{{ 3.14159|round(2) }}

  #|
{{ "3.14"|float }}

  #|
{{ 1234567|filesizeformat }}

  #|
{{ [3, 1, 2]|sort|list }}

  #|
{{ [1, 2, 3, 4]|sum }}

  #|
{{ [1, 2, 3, 4, 5]|batch(2)|list }}

  #|
{{ [1, 2, 3, 4, 5]|slice(2)|list }}

  #|
{{ [1, 2, 2, 3]|unique|list }}

  #|
{{ [1, 2, 3]|random }}

  #|
{{ {"b": 2, "a": 1}|dictsort|list }}


///|
let lists_src =
  #|
{{ users|map(attribute="name")|join(", ") }}

  #|
{{ items|selectattr("shown")|list }}

  #|
{{ users|groupby("kind")|map(attribute="grouper")|join(", ") }}

  #|
{{ [1, 2, 3, 4]|reject("odd")|list }}

  #|
{{ [1, 2, 3, 4]|first }} {{ [1, 2, 3, 4]|last }} {{ [1, 2, 3, 4]|length }}

  #|
{{ [1, 2, 3]|reverse|list }}

  #|
{{ {"a": 1}|tojson }}

  #|
{{ {"q": "a b"}|urlencode }}

  #|
{{ {"class": "x", "id": 5}|xmlattr }}


///|
let choose_src =
  #|
{{ missing|default("none") }}

  #|
{% set ns = namespace(total=0) %}{% for i in [1, 2, 3] %}{% set ns.total = ns.total + i %}{% endfor %}{{ ns.total }}

  #|
{% if 9 is divisibleby(3) %}yes{% else %}no{% endif %}

  #|
{% set c = cycler("odd", "even") %}{{ c.next() }}{{ c.next() }}{{ c.next() }}

  #|
{% set j = joiner(", ") %}{% for x in ["a", "b", "c"] %}{{ j() }}{{ x }}{% endfor %}

  #|
{{ ok|yesno }} ยท {{ count|pluralize }}


///|
let dates_src =
  #|
{{ d|date("Y-m-d") }}

  #|
{{ d|timesince(now) }}


///|
let tests_src =
  #|
{{ 4 is even }} {{ 9 is divisibleby(3) }} {{ "ab" is iterable }}

  #|
{{ [1, 2] is sequence }} {{ range is callable }} {{ (""|safe) is escaped }}

  #|
{% set present = 1 %}{{ present is defined }} {{ missing is undefined }}

  #|
{{ 7 is number }} {{ "x" is string }} {{ {"a": 1} is mapping }}

  #|
{{ 3 is integer }} {{ 3.0 is float }} {{ none is none }} {{ true is boolean }}

  #|
{{ "abc" is lower }} {{ "ABC" is upper }} {{ a is sameas a }}


///|
let globals_src =
  #|
{{ range(1, 4)|list }} {{ range(0, 10, 2)|list }}

  #|
{{ dict(a=1, b=2)|items|list }}

  #|
{{ gettext("Hello") }} {{ _("World") }}

  #|
{{ lipsum(n=1, min=5, max=8) }}


///|
let statements_src =
  #|
{% for b in books|sort(attribute='year') %}{{ loop.index }}. {{ b.title }}{% if not loop.last %}; {% endif %}{% endfor %}

  #|
{% macro field(name, value='') %}{% endmacro %}{{ field('email') }}

  #|
{% filter upper %}shouted{% endfilter %}

  #|
{% with total = 3 %}{{ total }}{% endwith %}

  #|
{% set total = [1, 2, 3]|sum %}{{ total }}


///|
/// Render one section and print it under a heading.
fn show(title : String, source : String, data : Json) -> Unit {
  println("## " + title)
  println(@moonpug.render(source, data)) catch {
    e => println("refused: \{e}")
  }
  println("")
}

///|
fn main {
  try {
    show("Text", text_src, @json.parse("{}"))
    show("Numbers", numbers_src, @json.parse("{}"))
    show(
      "Lists and maps",
      lists_src,
      @json.parse(
        "{\"users\":[{\"name\":\"Ada\",\"kind\":\"a\"},{\"name\":\"Grace\",\"kind\":\"b\"},{\"name\":\"Alan\",\"kind\":\"a\"}],\"items\":[{\"shown\":true},{\"shown\":false}]}",
      ),
    )
    show(
      "Choosing a value",
      choose_src,
      @json.parse("{\"ok\":true,\"count\":3}"),
    )
    show(
      "Dates",
      dates_src,
      @json.parse("{\"d\":\"2026-01-01\",\"now\":\"2026-05-04\"}"),
    )
    show("Tests", tests_src, @json.parse("{}"))
    show("Globals", globals_src, @json.parse("{}"))
    show(
      "Statements",
      statements_src,
      @json.parse(
        "{\"books\":[{\"title\":\"Dune\",\"year\":1965},{\"title\":\"The Hobbit\",\"year\":1937}]}",
      ),
    )
  } catch {
    e => println("refused: \{e}")
  }
}