import csv
import math
import random
from datetime import datetime, timedelta, timezone
from pathlib import Path

import pytest

from src.accuracy_report import (
    Options, evaluate_trial, load_face_series, load_trials, main, percentile, run_report,
)
from src.accuracy_session import SessionRunner, build_plan

TZ = timezone(timedelta(hours=9))
FPS = 30.0


class FakeTime:
    def __init__(self) -> None:
        self.now = datetime(2026, 10, 4, 12, 0, 0, tzinfo=TZ)

    def sleep(self, seconds: float) -> None:
        self.now += timedelta(seconds=seconds)

    def clock(self) -> str:
        return self.now.isoformat(timespec="milliseconds")


def _simulate(tmp_path: Path, scale: float = 0.95, offset: float = -19.0, noise: float = 0.5, face_dropout: float = 0.0):
    """Run a fake session and write a matching face_frames CSV (30 fps, yaw ramps after each cue)."""
    plan = build_plan([1, 3], [0, 5, -5, 10, -10], 3, seed=3)
    fake, trials = FakeTime(), tmp_path / "trials.csv"
    start = fake.now

    def operator_pause(_prompt: str) -> str:
        fake.sleep(4.0)  # time the subject needs to return and the operator needs to press Enter
        return ""

    SessionRunner(plan, trials, "S", input_fn=operator_pause, out=lambda _m: None, sleep=fake.sleep, clock=fake.clock,
                  beep=lambda _k: None).run()
    end = fake.now + timedelta(seconds=2)
    rng = random.Random(0)
    marks = [(datetime.fromisoformat(r["t_turn_cue"]), float(r["true_yaw_deg"]), datetime.fromisoformat(r["t_hold_end"]))
             for r in csv.DictReader(trials.open(encoding="utf-8-sig"))]
    path = tmp_path / "20261004_120000_exp_face_frames.csv"
    with path.open("w", encoding="utf-8-sig", newline="") as stream:
        writer = csv.writer(stream)
        writer.writerow(["frame_number", "timestamp", "track_id", "pose_estimated", "yaw", "raw_yaw"])
        t, frame = start - timedelta(seconds=1), 0
        while t < end:
            frame += 1
            true = 0.0
            for cue, angle, stop in marks:
                if cue <= t <= stop:
                    true = angle * min(1.0, (t - cue).total_seconds() / 0.8)
            yaw = offset + scale * true + rng.gauss(0, noise)
            ok = rng.random() >= face_dropout
            writer.writerow([frame, t.isoformat(timespec="milliseconds"), 1, ok, f"{yaw:.4f}" if ok else "", f"{yaw:.4f}" if ok else ""])
            t += timedelta(seconds=1 / FPS)
    return trials, path


def test_percentile() -> None:
    assert percentile([0.0, 10.0], 50) == 5.0 and math.isnan(percentile([], 50))


def test_full_pipeline_recovers_scale_bias_and_threshold(tmp_path: Path) -> None:
    trials, face = _simulate(tmp_path)
    result = run_report([trials], [face], tmp_path / "out", Options(), plots=False)
    records = result["records"]
    assert len(records) == 30 and all(r["status"] == "ok" for r in records)
    # a constant -19 deg offset must cancel; 0.95 scale makes +10 read about 9.5 -> bias about -0.5
    cond = {(c["distance_m"], c["true_yaw_deg"]): c for c in result["conditions"]}
    assert abs(cond[(1.0, 0.0)]["bias_deg"]) < 0.3
    assert abs(cond[(3.0, 10.0)]["bias_deg"] + 0.5) < 0.3
    th = result["thresholds"][1.0]
    assert 0.95 - 0.05 < th["slope"] < 0.95 + 0.05 and th["r2"] > 0.99
    assert 1.0 < th["theta_th_deg"] < 3.5
    assert th["theta_worst_deg"] >= th["theta_pooled_deg"] - 1e-9
    assert th["min_detectable_deg"] == 5.0           # 5 deg turns exceed theta_th in >= 95 % of frames
    assert cond[(1.0, 0.0)]["exceed_rate"] < 0.05    # false-positive rate at 0 deg
    assert cond[(1.0, 10.0)]["mean_detection_rate"] > 0.95
    for name in ("accuracy_trials.csv", "accuracy_conditions.csv", "accuracy_thresholds.csv", "accuracy_report.md"):
        assert (tmp_path / "out" / name).is_file()
    assert "θ_th" in result["markdown"]


def test_flip_sign_is_flagged_by_negative_slope(tmp_path: Path) -> None:
    trials, face = _simulate(tmp_path, scale=-1.0)
    result = run_report([trials], [face], tmp_path / "out", Options(), plots=False)
    assert result["thresholds"][1.0]["slope"] < 0 and "--flip-sign" in result["markdown"]
    fixed = run_report([trials], [face], tmp_path / "out2", Options(flip_sign=True), plots=False)
    assert fixed["thresholds"][1.0]["slope"] > 0.9


def test_dropout_lowers_detection_rate_and_missing_data_is_excluded(tmp_path: Path) -> None:
    trials, face = _simulate(tmp_path, face_dropout=0.3)
    result = run_report([trials], [face], tmp_path / "out", Options(), plots=False)
    rates = [r["detection_rate"] for r in result["records"] if r["status"] == "ok"]
    assert 0.55 < sum(rates) / len(rates) < 0.85
    # a face log that ends early leaves later trials without any track
    series = load_face_series([face])
    cut = series.times[len(series.times) // 2]
    short = tmp_path / "short_face_frames.csv"
    with face.open(encoding="utf-8-sig", newline="") as src, short.open("w", encoding="utf-8-sig", newline="") as dst:
        reader, writer = csv.reader(src), csv.writer(dst)
        for index, row in enumerate(reader):
            if index == 0 or datetime.fromisoformat(row[1]).timestamp() <= cut:
                writer.writerow(row)
    partial = run_report([trials], [short], tmp_path / "out3", Options(), plots=False)
    statuses = {r["status"] for r in partial["records"]}
    assert "no_track" in statuses and "ok" in statuses


def test_last_row_wins_and_exclude_seq(tmp_path: Path) -> None:
    path = tmp_path / "t.csv"
    header = "session_id,seq,block,condition_id,distance_m,true_yaw_deg,pitch_deg,repeat,subject,status,t_baseline_start,t_turn_cue,t_hold_end\n"
    path.write_text(header + "S,1,1,c,1,10,0,1,,ok,a,b,c\nS,1,1,c,1,10,0,1,,discarded,,,\nS,2,1,c,1,10,0,2,,ok,a,b,c\n"
                    "S,3,1,c,1,10,0,3,,ok,a,b,c\n", encoding="utf-8-sig")
    assert [r["seq"] for r in load_trials([path])] == ["2", "3"]
    assert [r["seq"] for r in load_trials([path], exclude_seqs=[3])] == ["2"]


def test_bad_timestamps_do_not_crash(tmp_path: Path) -> None:
    trials, face = _simulate(tmp_path)
    series = load_face_series([face])
    record, deltas = evaluate_trial({"seq": "1", "condition_id": "x", "distance_m": "1", "true_yaw_deg": "5",
                                     "pitch_deg": "0", "t_baseline_start": "", "t_turn_cue": "", "t_hold_end": ""},
                                    series, Options())
    assert record["status"] == "bad_timestamps" and deltas == []


def test_cli_end_to_end_with_glob_and_plots(tmp_path: Path, capsys: pytest.CaptureFixture[str]) -> None:
    trials, face = _simulate(tmp_path)
    out = tmp_path / "report"
    assert main(["--trials", str(trials), "--face-csv", str(tmp_path / "*_face_frames.csv"), "--out", str(out)]) == 0
    assert "しきい値" in capsys.readouterr().out
    assert (out / "plots" / "accuracy_scatter.png").is_file()  # matplotlib is in requirements.txt
    assert main(["--trials", str(trials), "--face-csv", str(tmp_path / "missing.csv")]) == 2