"""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
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_and_tasks():
    tasks = [{"summary": "Buy milk", "completed": False}, {"summary": "Walk the dog", "completed": True}]
    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", tasks=tasks)
    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


# --- 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