import itertools

from jinja2 import Template
from jinja2.runtime import LoopContext


TEST_IDX_TEMPLATE_STR_1 = (
    "[{% for i in lst|reverse %}"
    + "(len={{ loop.length }}, revindex={{ loop.revindex }}, index={{ loop.index }}, val={{ i }})"
    + "{% endfor %}]"
)


TEST_IDX0_TEMPLATE_STR_1 = (
    "[{% for i in lst|reverse %}"
    + "(len={{ loop.length }}, revindex0={{ loop.revindex0 }}, index0={{ loop.index0 }}, val={{ i }})"
    + "{% endfor %}]"
)


def test_loop_idx():
    t = Template(TEST_IDX_TEMPLATE_STR_1)
    lst = [10]
    excepted_render = "[(len=1, revindex=1, index=1, val=10)]"
    assert excepted_render == t.render(lst=lst)


def test_loop_idx0():
    t = Template(TEST_IDX0_TEMPLATE_STR_1)
    lst = [10]
    excepted_render = "[(len=1, revindex0=0, index0=0, val=10)]"
    assert excepted_render == t.render(lst=lst)


def test_loopcontext0():
    in_lst = []
    l = LoopContext(reversed(in_lst), None)
    assert l.length == len(in_lst)


def test_loopcontext1():
    in_lst = [10]
    l = LoopContext(reversed(in_lst), None)
    assert l.length == len(in_lst)


def test_loopcontext2():
    in_lst = [10, 11]
    l = LoopContext(reversed(in_lst), None)
    assert l.length == len(in_lst)


def test_iterator_not_advanced_early():
    t = Template("{% for _, g in gs %}{{ loop.index }} {{ g|list }}\n{% endfor %}")
    out = t.render(gs=itertools.groupby(
        [(1, "a"), (1, "b"), (2, "c"), (3, "d")], lambda x: x[0]
    ))
    # groupby groups depend on the current position of the iterator. If
    # it was advanced early, the lists would appear empty.
    assert out == "1 [(1, 'a'), (1, 'b')]\n2 [(2, 'c')]\n3 [(3, 'd')]\n"