"""Acceptance for the single 2D image backend.

The point of this module is that live, recomputed, replayed and previewed frames go
through *one* renderer and that the view modes come from what the frame carries. These
tests pin both halves: a plan derived from fields (not from a view preset), and
pixel-for-pixel agreement with the primitives the application used before.
"""

from __future__ import annotations

import numpy as np
import pytest

from orisys_app_shared.acquisition import image_backend as backend
from orisys_app_shared.acquisition.arrows import (
    depth_map_to_bgr,
    draw_arrow_display,
    flow_colormap,
)


def _image(h: int = 12, w: int = 16) -> np.ndarray:
    return np.arange(h * w * 3, dtype=np.uint8).reshape(h, w, 3)


def _flow(h: int = 12, w: int = 16) -> np.ndarray:
    flow = np.zeros((h, w, 2), dtype=np.float32)
    flow[..., 0] = 3.0
    flow[..., 1] = -1.5
    return flow


# ------------------------------------------------------------------------- plans
def test_a_live_frame_offers_the_derived_modes_and_needs_no_note():
    plan = backend.plan_image(
        backend.ImageFrame(_image(), flow=_flow(), depth=np.ones((12, 16)))
    )
    assert plan.available_modes == ("arrows_pure", "arrows_stitched", "depth")
    assert plan.default_mode == "arrows_pure"
    assert plan.missing == ()
    assert plan.note_key == ""


def test_a_recorded_frame_is_raw_and_says_so():
    """No flow and no depth: the frame *is* the picture, and the note explains it."""
    plan = backend.plan_image(backend.ImageFrame(_image(), source=backend.SOURCE_REPLAY))
    assert plan.available_modes == ("recorded",)
    assert plan.default_mode == "recorded"
    assert plan.missing == ("flow", "depth")
    assert plan.note_key == backend.RAW_NOTE_KEY
    assert plan.source == "replay"


def test_a_derived_source_keeps_every_mode_and_reports_what_is_missing():
    """A dropped frame must not silently switch the operator's view.

    Live and recomputed frames may be missing a field for one frame; the mode stays
    selectable and ``missing`` says which field is absent, so the panel can state it
    instead of the view looking broken.
    """
    flow_only = backend.plan_image(backend.ImageFrame(_image(), flow=_flow()))
    assert flow_only.available_modes == backend.DERIVED_MODES
    assert flow_only.missing == ("depth",)
    assert flow_only.default_mode == "arrows_pure"
    assert flow_only.note_key == backend.MISSING_NOTE_KEY
    assert flow_only.note_fields == ("depth",)
    assert flow_only.needs("depth") == "depth"
    assert flow_only.needs("arrows_pure") is None

    depth_only = backend.plan_image(backend.ImageFrame(_image(), depth=np.ones((12, 16))))
    assert depth_only.available_modes == backend.DERIVED_MODES
    assert depth_only.missing == ("flow",)
    assert depth_only.default_mode == "depth"
    assert depth_only.needs("arrows_pure") == "flow"

    complete = backend.plan_image(
        backend.ImageFrame(_image(), flow=_flow(), depth=np.ones((12, 16)))
    )
    assert complete.missing == ()
    assert complete.note_key == ""


def test_a_raw_source_cannot_offer_a_derived_view_at_all():
    """A recording and a camera preview have no derived field, ever."""
    for source in (backend.SOURCE_REPLAY, backend.SOURCE_PREVIEW):
        plan = backend.plan_image(backend.ImageFrame(_image(), source=source))
        assert plan.available_modes == ("recorded",)
        assert plan.note_key == backend.RAW_NOTE_KEY
        assert plan.note_fields == ()


def test_the_plan_carries_the_frame_identity_for_the_panel():
    plan = backend.plan_image(
        backend.ImageFrame(
            _image(), source=backend.SOURCE_RECOMPUTE, frame_id=42, t_rel_s=1.25, stale=True
        )
    )
    assert (plan.source, plan.frame_id, plan.t_rel_s, plan.stale) == ("recompute", 42, 1.25, True)


def test_a_mode_the_plan_does_not_offer_falls_back_to_the_default():
    """Never draw a view the source cannot have at all."""
    recorded = backend.plan_image(
        backend.ImageFrame(_image(), source=backend.SOURCE_REPLAY)
    )
    assert recorded.resolve("arrows_pure") == "recorded"
    assert recorded.resolve("nonsense") == "recorded"
    live = backend.plan_image(backend.ImageFrame(_image(), flow=_flow()))
    assert live.resolve("recorded") == "arrows_pure", "a derived source has no raw mode"
    assert live.resolve("arrows_stitched") == "arrows_stitched"


# --------------------------------------------------------------- one renderer
def test_the_backend_renders_what_the_primitives_rendered_before():
    """Live went through these two calls; the backend must not change a pixel."""
    image = _image()
    flow = _flow()
    mask = np.ones((12, 16), dtype=bool)
    mask[0, 0] = False

    frame = backend.ImageFrame(image, flow=flow, valid_mask=mask)
    plan = backend.plan_image(frame)
    for mode in ("arrows_pure", "arrows_stitched"):
        expected = draw_arrow_display(
            image,
            flow,
            background="captured" if mode == "arrows_stitched" else "pure_color",
            draw_style="finger",
            valid_mask=mask,
            colormap=flow_colormap("dark"),
        )
        got = backend.render_image(frame, plan, mode=mode, draw_style="finger")
        assert np.array_equal(got, expected), mode

    depth = np.linspace(0.0, 1.0, 12 * 16, dtype=np.float32).reshape(12, 16)
    depth_frame = backend.ImageFrame(image, depth=depth, valid_mask=mask)
    # The depth picture uses the *theme's* ramp — the same table the panel's colour bar
    # paints. The window used to leave this argument out, so the map was drawn with
    # OpenCV's JET while the legend under it showed the brand ramp: two colour tables
    # for one picture, and the legend claiming they were the same.
    expected_depth = depth_map_to_bgr(
        depth, flow_colormap("dark"), value_range=(0.0, 1.0), invalid_mask=mask
    )
    got_depth = backend.render_image(
        depth_frame, mode="depth", depth_range=(0.0, 1.0)
    )
    assert np.array_equal(got_depth, expected_depth)


def test_a_recorded_frame_is_passed_through_and_never_resized_to_fit():
    image = _image(9, 7)
    got = backend.render_image(
        backend.ImageFrame(image, source=backend.SOURCE_REPLAY), mode="recorded"
    )
    assert got is not None and got.shape == image.shape
    assert np.array_equal(got, image)


def test_nothing_to_draw_is_none_not_a_blank_picture():
    assert backend.render_image(backend.ImageFrame(), mode="recorded") is None
    assert backend.render_image(
        backend.ImageFrame(None, flow=_flow()), mode="arrows_pure"
    ) is None
    assert backend.render_image(backend.ImageFrame(None, depth=None), mode="depth") is None


def test_a_grey_base_frame_is_widened_once_by_the_backend():
    """A 2-D frame must reach the shader as BGR, and only one place may do it."""
    grey = np.zeros((8, 6), dtype=np.uint8)
    got = backend.render_image(backend.ImageFrame(grey), mode="recorded")
    assert got is not None and got.shape == (8, 6, 3)
    assert np.array_equal(got, np.stack([grey] * 3, axis=-1))


@pytest.mark.parametrize("mode", list(backend.ALL_MODES))
def test_every_offered_mode_renders_something_or_says_it_cannot(mode):
    """A mode the plan offers must never come back empty."""
    frame = backend.ImageFrame(_image(), flow=_flow(), depth=np.ones((12, 16)))
    plan = backend.plan_image(frame)
    if not plan.accepts(mode):
        assert plan.resolve(mode) in plan.available_modes
        return
    assert backend.render_image(frame, plan, mode=mode) is not None


def test_a_missing_field_is_reported_not_invented():
    """Depth with no depth says so; arrows with no flow show the base picture."""
    no_depth = backend.ImageFrame(_image(), flow=_flow())
    assert backend.render_image(no_depth, mode="depth") is None
    no_flow = backend.ImageFrame(_image(), depth=np.ones((12, 16)))
    base = backend.render_image(no_flow, mode="arrows_pure")
    assert base is not None
    assert np.array_equal(base, _image()), "the base picture must not be redrawn"