from __future__ import annotations

from pathlib import Path

import pyarrow.parquet as pq

from kitti_c2l.kitti_calib import load_rig_chain
from kitti_c2l.schema import WINDOWS_COLUMN_NAMES, WINDOWS_SCHEMA
from kitti_c2l.sequence_mapping import SequenceInfo
from kitti_c2l.stages import STAGES
from kitti_c2l.windows import (
    derive_window_seed,
    generate_sequence_windows,
    generate_window_row,
    iter_windows,
)
from kitti_c2l.writer import write_windows


def _fake_seq_info(frame_count: int = 4) -> SequenceInfo:
    return SequenceInfo(sequence="04", date="2011_09_30", drive="0016", start=0, end=frame_count - 1, frame_count=frame_count, split="train")


def test_iter_windows_tiles_non_overlapping():
    windows = list(iter_windows(frame_count=10, window_length=3))
    assert windows == [(0, 3), (3, 3), (6, 3), (9, 1)]  # final tile shorter, no frames dropped
    assert sum(length for _, length in windows) == 10


def test_iter_windows_exact_multiple():
    windows = list(iter_windows(frame_count=9, window_length=3))
    assert windows == [(0, 3), (3, 3), (6, 3)]


def test_iter_windows_single_window_larger_than_sequence():
    windows = list(iter_windows(frame_count=4, window_length=30))
    assert windows == [(0, 4)]


def test_derive_window_seed_deterministic_and_distinct():
    a = derive_window_seed("00", 0, 1)
    b = derive_window_seed("00", 0, 1)
    c = derive_window_seed("00", 30, 1)
    d = derive_window_seed("00", 0, 2)
    assert a == b
    assert a != c
    assert a != d


def test_generate_sequence_windows_count(fake_kitti_root: Path):
    seq_info = _fake_seq_info(frame_count=4)
    rows = list(generate_sequence_windows(seq_info, fake_kitti_root, window_length=3, stages=STAGES))
    # frame_count=4, window_length=3 -> windows (0,3) and (3,1) -> 2 windows x 5 stages = 10 rows
    assert len(rows) == 2 * len(STAGES)
    starts = sorted({row.window_start_frame for row in rows})
    assert starts == [0, 3]


def test_generate_sequence_windows_max_windows(fake_kitti_root: Path):
    seq_info = _fake_seq_info(frame_count=4)
    rows = list(generate_sequence_windows(seq_info, fake_kitti_root, window_length=3, stages=STAGES, max_windows=1))
    assert len(rows) == 1 * len(STAGES)
    assert {row.window_start_frame for row in rows} == {0}


def test_window_frames_share_the_same_decalibration(fake_kitti_root: Path):
    """The whole point: every frame in a window uses the SAME miscal extrinsic (one row covers the window)."""
    seq_info = _fake_seq_info(frame_count=4)
    rig = load_rig_chain(fake_kitti_root / "2011_09_30", camera_id=2)
    row = generate_window_row(seq_info, rig, window_start_frame=0, window_length=4, stage=STAGES[0])
    # A single row's miscal extrinsic is what's applied to every frame_offset in [0, window_length) --
    # verify raw_frame_start_index + window_length correctly spans the intended frame range.
    assert row.raw_frame_start_index == 0
    assert row.window_length == 4
    assert row.window_start_frame == 0


def test_raw_frame_start_index_offset(fake_kitti_root: Path):
    seq_info = SequenceInfo(sequence="08", date="2011_09_30", drive="0016", start=1100, end=1103, frame_count=4, split="train")
    rig = load_rig_chain(fake_kitti_root / "2011_09_30", camera_id=2)
    row = generate_window_row(seq_info, rig, window_start_frame=2, window_length=2, stage=STAGES[0])
    assert row.raw_frame_start_index == 1100 + 2  # start offset carried through correctly


def test_windows_parquet_round_trip(fake_kitti_root: Path, tmp_path: Path):
    seq_info = _fake_seq_info(frame_count=4)
    rows = list(generate_sequence_windows(seq_info, fake_kitti_root, window_length=3, stages=STAGES))

    output_path = tmp_path / "windows_train.parquet"
    count = write_windows(rows, output_path)
    assert count == len(rows)

    table = pq.read_table(output_path)
    assert table.schema.equals(WINDOWS_SCHEMA)
    first = table.to_pylist()[0]
    assert set(first.keys()) == set(WINDOWS_COLUMN_NAMES)
    assert len(first["gt_R_cam_from_velo"]) == 9


def test_window_id_format(fake_kitti_root: Path):
    seq_info = _fake_seq_info(frame_count=4)
    rig = load_rig_chain(fake_kitti_root / "2011_09_30", camera_id=2)
    row = generate_window_row(seq_info, rig, window_start_frame=3, window_length=1, stage=STAGES[2])
    assert row.window_id == "04_000003_stage3"