"""
Regression tests for form field label geometry (spec S15).

Text renders with a baseline anchor, so drawing the label at the field's origin
put its glyphs above that origin - outside the box the field claims through size
and in_object. Stacked fields therefore had each label overprinting the input box
of the field before it.
"""

import numpy as np
import pytest
from PIL import Image, ImageDraw

from pyWebLayout.abstract.functional import Form, FormField, FormFieldType
from pyWebLayout.concrete.functional import FormFieldText
from pyWebLayout.concrete.page import Page
from pyWebLayout.layout.document_layouter import form_layouter
from pyWebLayout.style import Font
from pyWebLayout.style.page_style import PageStyle


ORIGIN = (10, 40)
FIELD_HEIGHT = 24


@pytest.fixture
def font():
    return Font(font_size=12, colour=(0, 0, 0))


@pytest.fixture
def canvas():
    image = Image.new("RGB", (300, 200), (255, 255, 255))
    return image, ImageDraw.Draw(image)


def make_field(font, draw, label="Email Address"):
    field = FormField(name="email", field_type=FormFieldType.TEXT, label=label)
    renderable = FormFieldText(field, font, draw, field_height=FIELD_HEIGHT)
    renderable.set_origin(np.array(list(ORIGIN)))
    return renderable


def ink_rows(image, x_range, y_range):
    pixels = image.convert("RGB").load()
    return [y for y in y_range
            if any(sum(pixels[x, y]) < 400 for x in x_range)]


class TestLabelStaysInsideTheFieldBox:

    def test_label_ink_is_below_the_origin(self, font, canvas):
        image, draw = canvas
        renderable = make_field(font, draw)
        renderable.render()

        rows = ink_rows(image, range(ORIGIN[0], ORIGIN[0] + 140),
                        range(0, ORIGIN[1]))
        assert not rows, \
            f"label drew above its own origin, at rows {rows}"

    def test_label_and_box_do_not_overlap(self, font, canvas):
        image, draw = canvas
        renderable = make_field(font, draw)
        renderable.render()

        ascent, descent = font.font.getmetrics()
        label_bottom = ORIGIN[1] + ascent + descent
        box_top = renderable.field_area_offset + ORIGIN[1]

        assert box_top >= label_bottom, \
            "the input box must start below the label's descenders"

    def test_reported_height_covers_everything_drawn(self, font, canvas):
        image, draw = canvas
        renderable = make_field(font, draw)
        renderable.render()

        top, bottom = ORIGIN[1], ORIGIN[1] + int(renderable.size[1])
        rows = ink_rows(image, range(ORIGIN[0], ORIGIN[0] + 200), range(0, 200))
        assert min(rows) >= top, "ink above the field's declared box"
        assert max(rows) < bottom, "ink below the field's declared box"


class TestStackedFieldsDoNotCollide:

    def test_form_layout_leaves_labels_clear(self, font):
        page = Page(size=(300, 400), style=PageStyle())
        form = Form("signup")
        for name in ["Username", "Email Address", "Password"]:
            form.add_field(FormField(name=name.lower().replace(" ", "_"),
                                     field_type=FormFieldType.TEXT, label=name))

        ok, ids = form_layouter(form, page, font)
        assert ok and len(ids) == 3

        fields = [c for c in page.children if isinstance(c, FormFieldText)]
        assert len(fields) == 3

        for earlier, later in zip(fields, fields[1:]):
            earlier_bottom = earlier.origin[1] + earlier.size[1]
            assert later.origin[1] >= earlier_bottom, \
                "fields overlap: a label would print over the preceding input box"

    def test_rendered_form_has_no_ink_collisions(self, font):
        """Every field's ink stays within its own declared bounds."""
        page = Page(size=(300, 400), style=PageStyle())
        form = Form("signup")
        for name in ["Username", "Email Address"]:
            form.add_field(FormField(name=name.lower(), field_type=FormFieldType.TEXT,
                                     label=name))
        form_layouter(form, page, font)
        image = page.render()

        fields = [c for c in page.children if isinstance(c, FormFieldText)]
        for field in fields:
            top = int(field.origin[1])
            bottom = top + int(field.size[1])
            rows = ink_rows(image, range(int(field.origin[0]),
                                         int(field.origin[0] + field.size[0])),
                            range(max(0, top - 6), top))
            assert not rows, f"ink found just above a field at y={top}"


class TestClickTargetsFollowTheLayout:

    def test_click_in_the_input_area_focuses(self, font, canvas):
        _, draw = canvas
        renderable = make_field(font, draw)

        inside = (5, renderable.field_area_offset + FIELD_HEIGHT // 2)
        assert renderable.handle_click(inside) is True
        assert renderable._focused is True

    def test_click_on_the_label_does_not_focus(self, font, canvas):
        _, draw = canvas
        renderable = make_field(font, draw)

        on_label = (5, 2)
        assert renderable.handle_click(on_label) is False