"""Every renderer that produces a device-facing frame must return
exactly EPD_WIDTH*EPD_HEIGHT/2 bytes (the panel's packed 2px/byte
format) -- firmware writes this straight to the display with no length
checking of its own, so a renderer that's off by even one byte is a
silent on-device corruption bug, not a clean error. This is a cheap,
high-value regression guard: pure PIL rendering, no DB/HTTP/Node."""

from __future__ import annotations

import pytest
from PIL import Image

from app.calendar_render import CALENDAR_VIEWS, render_calendar, render_tasks
from app.grid import cell_to_pixels, full_panel_rect, grid_dims
from app.image_pipeline import EPD_HEIGHT, EPD_WIDTH, render_panel, render_placeholder

EXPECTED_BYTES = EPD_WIDTH * EPD_HEIGHT // 2
ORIENTATIONS = ["landscape", "landscape_flipped", "portrait", "portrait_flipped"]

_SAMPLE_EVENTS = [
    {
        "summary": "Dentist", "start": "2026-08-01T14:00:00+00:00", "end": "2026-08-01T15:00:00+00:00",
        "all_day": False, "sources": [{"owner_display_name": "Alice", "color_index": None}],
    },
    {
        "summary": "Team Offsite", "start": "2026-08-03T00:00:00", "end": "2026-08-04T00:00:00",
        "all_day": True, "sources": [{"owner_display_name": "Bob", "color_index": 2}],
    },
]


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_placeholder_render_size(orientation):
    data = render_placeholder(["Not configured yet"], orientation=orientation)
    assert len(data) == EXPECTED_BYTES


@pytest.mark.parametrize("view", CALENDAR_VIEWS)
def test_calendar_render_size_across_views(view):
    data = render_calendar(_SAMPLE_EVENTS, view, browse_offset=0, orientation="landscape",
                           palette_rgb=None, timezone="UTC")
    assert len(data) == EXPECTED_BYTES


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_calendar_render_size_across_orientations(orientation):
    data = render_calendar(_SAMPLE_EVENTS, "agenda", browse_offset=0, orientation=orientation,
                           palette_rgb=None, timezone="UTC")
    assert len(data) == EXPECTED_BYTES


def test_calendar_render_size_empty_events():
    data = render_calendar([], "week", browse_offset=0, orientation="landscape",
                           palette_rgb=None, timezone="UTC")
    assert len(data) == EXPECTED_BYTES


def test_calendar_render_size_with_fetch_summary():
    data = render_calendar(_SAMPLE_EVENTS, "week", browse_offset=0, orientation="landscape",
                           palette_rgb=None, timezone="UTC", fetch_summary="1 of 2 calendars unavailable",
                           week_days=5, week_layout="vertical")
    assert len(data) == EXPECTED_BYTES


def test_calendar_render_size_with_week_start_offset():
    data = render_calendar(_SAMPLE_EVENTS, "week", browse_offset=0, orientation="landscape",
                           palette_rgb=None, timezone="UTC", week_days=3, week_start_offset=2)
    assert len(data) == EXPECTED_BYTES


# --- tasks widget (split out of the calendar widget's old week-view-only task list) ---

_SAMPLE_TASKS = [
    {"summary": "Buy milk", "due": "2026-08-02"},
    {"summary": "Walk the dog", "due": None},
]


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_tasks_render_size_across_orientations(orientation):
    data = render_tasks(_SAMPLE_TASKS, orientation=orientation, palette_rgb=None)
    assert len(data) == EXPECTED_BYTES


def test_tasks_render_size_empty():
    data = render_tasks([], orientation="landscape", palette_rgb=None)
    assert len(data) == EXPECTED_BYTES


# --- render_panel (the widget-system compositor) ---


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_render_panel_size_single_full_panel_region(orientation):
    from app.image_pipeline import logical_render_size

    w, h = logical_render_size(orientation)
    region = Image.new("RGB", (w, h), (200, 0, 0))
    data = render_panel([((0, 0, w, h), region)], orientation=orientation)
    assert len(data) == EXPECTED_BYTES


def test_render_panel_size_multiple_non_overlapping_regions():
    cols, rows = grid_dims("landscape")
    left_px = cell_to_pixels("landscape", EPD_WIDTH, EPD_HEIGHT, (0, 0, cols // 2, rows))
    right_px = cell_to_pixels("landscape", EPD_WIDTH, EPD_HEIGHT, (cols // 2, 0, cols - cols // 2, rows))
    regions = [
        (left_px, Image.new("RGB", left_px[2:], (200, 0, 0))),
        (right_px, Image.new("RGB", right_px[2:], (0, 0, 200))),
    ]
    data = render_panel(regions, orientation="landscape")
    assert len(data) == EXPECTED_BYTES


def test_render_panel_empty_region_list_is_blank_but_correctly_sized():
    """No widgets on a frame yet (or all somehow filtered out) shouldn't
    crash the compositor -- just a blank panel, same size invariant."""
    data = render_panel([], orientation="landscape")
    assert len(data) == EXPECTED_BYTES


def test_render_panel_pastes_regions_at_the_right_place():
    """Not just a size check -- confirms two regions actually land where
    their rects say, not just that *something* the right size comes out."""
    cols, rows = grid_dims("landscape")
    left_rect = (0, 0, cols // 2, rows)
    right_rect = (cols // 2, 0, cols - cols // 2, rows)
    left_px = cell_to_pixels("landscape", EPD_WIDTH, EPD_HEIGHT, left_rect)
    right_px = cell_to_pixels("landscape", EPD_WIDTH, EPD_HEIGHT, right_rect)
    # Pure red vs pure blue, both already-palette colors, dither_strength=0
    # so quantization can't introduce any blending/dithering noise --
    # every pixel on each side should land on exactly the color it started as.
    regions = [
        (left_px, Image.new("RGB", left_px[2:], (255, 0, 0))),
        (right_px, Image.new("RGB", right_px[2:], (0, 0, 255))),
    ]
    data = render_panel(regions, orientation="landscape", dither_strength=0.0)

    from app.image_pipeline import PANEL_CODES

    def code_at(x, y):
        i = (y * EPD_WIDTH + x) // 2
        byte = data[i]
        return (byte >> 4) if x % 2 == 0 else (byte & 0x0F)

    red_code = PANEL_CODES[3]  # DEFAULT_PALETTE_RGB index 3 = RED
    blue_code = PANEL_CODES[4]  # index 4 = BLUE
    # Sample well inside each half, away from the boundary, at a y
    # comfortably inside the panel.
    assert code_at(50, 240) == red_code
    assert code_at(750, 240) == blue_code


def test_render_panel_backfilled_full_panel_widget_matches_grid_full_panel_rect():
    """Sanity-links app.grid's full_panel_rect (what the migration backfill
    uses for the single auto-migrated widget) to render_panel's own size
    invariant, so a mismatch between the two would fail loudly here."""
    rect = full_panel_rect("landscape")
    px = cell_to_pixels("landscape", EPD_WIDTH, EPD_HEIGHT, rect)
    assert px == (0, 0, EPD_WIDTH, EPD_HEIGHT)
    region = Image.new("RGB", px[2:], (10, 20, 30))
    data = render_panel([(px, region)], orientation="landscape")
    assert len(data) == EXPECTED_BYTES


# --- a second, synthetic panel size (proves the packing path is genuinely
# resolution-agnostic, ahead of the real 13.3" panel's numbers existing --
# see image_pipeline._transpose_and_pack, which derives its output size
# from the quantized image itself rather than a hardcoded EPD_WIDTH/
# EPD_HEIGHT global) ---


@pytest.fixture
def synthetic_panel(monkeypatch):
    """Registers a second PANEL_SPECS entry, a different size than the
    real 7.3" panel, without needing the real 13.3" panel's confirmed
    resolution to exist yet."""
    from app import image_pipeline

    monkeypatch.setitem(image_pipeline.PANEL_SPECS, "test_panel", (600, 400))
    return "test_panel", 600, 400


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_render_panel_size_for_a_synthetic_second_panel_type(synthetic_panel, orientation):
    from app.image_pipeline import logical_render_size

    panel_type, panel_w, panel_h = synthetic_panel
    w, h = logical_render_size(orientation, panel_w, panel_h)
    region = Image.new("RGB", (w, h), (200, 0, 0))
    data = render_panel([((0, 0, w, h), region)], orientation=orientation, panel_type=panel_type)
    assert len(data) == panel_w * panel_h // 2


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_render_placeholder_size_for_a_synthetic_second_panel_type(synthetic_panel, orientation):
    panel_type, panel_w, panel_h = synthetic_panel
    data = render_placeholder(["Not configured yet"], orientation=orientation, panel_type=panel_type)
    assert len(data) == panel_w * panel_h // 2


def test_render_panel_default_panel_type_is_unaffected_by_a_new_registry_entry(synthetic_panel):
    """A second PANEL_SPECS entry existing must never change what an
    ordinary (no panel_type passed) render produces -- every existing
    7.3" frame's output stays byte-identical regardless of what other
    panels get registered."""
    data = render_placeholder(["Not configured yet"], orientation="landscape")
    assert len(data) == EXPECTED_BYTES


def test_panel_size_falls_back_to_the_original_panel_for_unknown_types():
    from app.image_pipeline import panel_size

    assert panel_size("nonexistent") == (EPD_WIDTH, EPD_HEIGHT)
    assert panel_size("") == (EPD_WIDTH, EPD_HEIGHT)


# --- the real (not synthetic) 13.3" Spectra 6 / EE02 panel geometry,
# confirmed from Waveshare's/Seeed's public product pages -- the vendor
# init/LUT/refresh sequence firmware-side is still unconfirmed (see
# image_pipeline.PANEL_SPECS's own comment), but the geometry itself is
# real, not a placeholder, so it gets the same coverage as the 7.3" panel
# rather than just the synthetic-panel tests above. ---


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_render_panel_size_for_the_real_13in3_panel(orientation):
    from app.image_pipeline import PANEL_SPECS, logical_render_size

    panel_w, panel_h = PANEL_SPECS["epd13in3e"]
    w, h = logical_render_size(orientation, panel_w, panel_h)
    region = Image.new("RGB", (w, h), (200, 0, 0))
    data = render_panel([((0, 0, w, h), region)], orientation=orientation, panel_type="epd13in3e")
    assert len(data) == panel_w * panel_h // 2


@pytest.mark.parametrize("orientation", ORIENTATIONS)
def test_render_placeholder_size_for_the_real_13in3_panel(orientation):
    from app.image_pipeline import PANEL_SPECS

    panel_w, panel_h = PANEL_SPECS["epd13in3e"]
    data = render_placeholder(["Not configured yet"], orientation=orientation, panel_type="epd13in3e")
    assert len(data) == panel_w * panel_h // 2