import re
import unittest

from mako.template import Template
from mako.codegen import (
        _FOR_LOOP, mangle_mako_loop, LoopVariable
    )
from mako.runtime import LoopStack, LoopContext
from mako import exceptions
from test import assert_raises_message

class TestLoop(unittest.TestCase):

    def test__FOR_LOOP(self):
        for statement, target_list, expression_list in (
                ('for x in y:', 'x', 'y'),
                ('for x, y in z:', 'x, y', 'z'),
                ('for (x,y) in z:', '(x,y)', 'z'),
                ('for ( x, y, z) in a:', '( x, y, z)', 'a'),
                ('for x in [1, 2, 3]:', 'x', '[1, 2, 3]'),
                ('for x in "spam":', 'x', '"spam"'),
                ('for k,v in dict(a=1,b=2).items():', 'k,v',
                    'dict(a=1,b=2).items()'),
                ('for x in [y+1 for y in [1, 2, 3]]:', 'x',
                    '[y+1 for y in [1, 2, 3]]')
                ):
            match = _FOR_LOOP.match(statement)
            assert match and match.groups() == (target_list, expression_list)

    def test_no_loop(self):
        template = Template("""% for x in 'spam':
${x}
% endfor""")
        code = template.code
        assert not re.match(r"loop = __M_loop._enter\(:", code), "No need to "\
                "generate a loop context if the loop variable wasn't accessed"
        print template.render()

    def test_loop_demo(self):
        template = Template("""x|index|reverse_index|first|last|cycle|even|odd
% for x in 'ham':
${x}|${loop.index}|${loop.reverse_index}|${loop.first}|${loop.last}|${loop.cycle('even', 'odd')}|${loop.even}|${loop.odd}
% endfor""")
        expected = [
                "x|index|reverse_index|first|last|cycle|even|odd",
                "h|0|2|True|False|even|True|False",
                "a|1|1|False|False|odd|False|True",
                "m|2|0|False|True|even|True|False"
            ]
        code = template.code
        assert "loop = __M_loop._enter(" in code, "Generated a loop context since "\
                "the loop variable was accessed"
        rendered = template.render()
        print rendered
        for line in expected:
            assert line in rendered, "Loop variables give information about "\
                    "the progress of the loop"

    def test_nested_loops(self):
        template = Template("""% for x in 'ab':
${x} ${loop.index} <- start in outer loop
% for y in [0, 1]:
${y} ${loop.index} <- go to inner loop
% endfor
${x} ${loop.index} <- back to outer loop
% endfor""")
        code = template.code
        rendered = template.render()
        expected = [
                "a 0 <- start in outer loop",
                "0 0 <- go to inner loop",
                "1 1 <- go to inner loop",
                "a 0 <- back to outer loop",
                "b 1 <- start in outer loop",
                "0 0 <- go to inner loop",
                "1 1 <- go to inner loop",
                "b 1 <- back to outer loop",
            ]
        for line in expected:
            assert line in rendered, "The LoopStack allows you to take "\
                    "advantage of the loop variable even in embedded loops"

    def test_parent_loops(self):
        template = Template("""% for x in 'ab':
${x} ${loop.index} <- outer loop
% for y in [0, 1]:
${y} ${loop.index} <- inner loop
${x} ${loop.parent.index} <- parent loop
% endfor
${x} ${loop.index} <- outer loop
% endfor""")
        code = template.code
        rendered = template.render()
        expected = [
                "a 0 <- outer loop",
                "a 0 <- parent loop",
                "b 1 <- outer loop",
                "b 1 <- parent loop"
            ]
        for line in expected:
            print code
            assert line in rendered, "The parent attribute of a loop gives "\
                    "you the previous loop context in the stack"

    def test_out_of_context_access(self):
        template = Template("""${loop.index}""")
        assert_raises_message(
            exceptions.RuntimeException,
            "No loop context is established",
            template.render
        )

class TestLoopStack(unittest.TestCase):

    def setUp(self):
        self.stack = LoopStack()
        self.bottom = 'spam'
        self.stack.stack = [self.bottom]

    def test_enter(self):
        iterable = 'ham'
        s = self.stack._enter(iterable)
        assert s is self.stack.stack[-1], "Calling the stack with an iterable returns "\
                "the stack"
        assert iterable == self.stack.stack[-1]._iterable, "and pushes the "\
                "iterable on the top of the stack"

    def test__top(self):
        assert self.bottom == self.stack._top, "_top returns the last item "\
                "on the stack"

    def test__pop(self):
        assert len(self.stack.stack) == 1
        top = self.stack._pop()
        assert top == self.bottom
        assert len(self.stack.stack) == 0

    def test__push(self):
        assert len(self.stack.stack) == 1
        iterable = 'ham'
        self.stack._push(iterable)
        assert len(self.stack.stack) == 2
        assert iterable is self.stack._top._iterable

    def test_exit(self):
        iterable = 'ham'
        self.stack._enter(iterable)
        before = len(self.stack.stack)
        self.stack._exit()
        after = len(self.stack.stack)
        assert before == (after + 1), "Exiting a context pops the stack"


class TestLoopContext(unittest.TestCase):

    def setUp(self):
        self.iterable = [1, 2, 3]
        self.ctx = LoopContext(self.iterable)

    def test___len__(self):
        assert len(self.iterable) == len(self.ctx), "The LoopContext is the "\
                "same length as the iterable"

    def test_index(self):
        expected = tuple(range(len(self.iterable)))
        actual = tuple(self.ctx.index for i in self.ctx)
        assert expected == actual, "The index is consistent with the current "\
                "iteration count"

    def test_reverse_index(self):
        length = len(self.iterable)
        expected = tuple([length-i-1 for i in range(length)])
        actual = tuple(self.ctx.reverse_index for i in self.ctx)
        print expected, actual
        assert expected == actual, "The reverse_index is the number of "\
                "iterations until the end"

    def test_first(self):
        expected = (True, False, False)
        actual = tuple(self.ctx.first for i in self.ctx)
        assert expected == actual, "first is only true on the first iteration"

    def test_last(self):
        expected = (False, False, True)
        actual = tuple(self.ctx.last for i in self.ctx)
        assert expected == actual, "last is only true on the last iteration"

    def test_even(self):
        expected = (True, False, True)
        actual = tuple(self.ctx.even for i in self.ctx)
        assert expected == actual, "even is true on even iterations"

    def test_odd(self):
        expected = (False, True, False)
        actual = tuple(self.ctx.odd for i in self.ctx)
        assert expected == actual, "odd is true on odd iterations"

    def test_cycle(self):
        expected = ('a', 'b', 'a')
        actual = tuple(self.ctx.cycle('a', 'b') for i in self.ctx)
        assert expected == actual, "cycle endlessly cycles through the values"