"""Debug overlay: what detection proposed, drawn on the page.

The fastest way to judge a detection change, and the tool for working out why
song #40 came out wrong. Kept after release for that reason.
"""

from __future__ import annotations

from pathlib import Path

import cv2
import numpy as np

from .detect import PageDetection

_SYSTEM = (0, 160, 0)
_CUT = (0, 0, 255)
_PROFILE = (220, 120, 0)
_PREVIEW_WIDTH = 1100


def draw(gray: np.ndarray, detection: PageDetection) -> np.ndarray:
    """Straightened page with systems boxed, cuts lined, row profile down the side."""
    from .detect import deskew, row_darkness

    straight = deskew(gray, detection.skew)
    vis = cv2.cvtColor(straight, cv2.COLOR_GRAY2BGR)
    h, w = straight.shape
    thickness = max(1, w // 700)

    profile = row_darkness(straight)
    if profile.max() > 0:
        scaled = (profile / profile.max() * (w * 0.08)).astype(int)
        for y in range(0, h, max(1, h // 900)):
            cv2.line(vis, (0, y), (int(scaled[y]), y), _PROFILE, 1)

    for i, system in enumerate(detection.systems):
        cv2.rectangle(vis, (2, system.top), (w - 3, system.bottom), _SYSTEM, thickness)
        label = f"{i + 1}"
        if system.staff_height:
            label += f"  staff {system.staff_height:.0f}px"
        cv2.putText(vis, label, (int(w * 0.10), system.top + int(h * 0.02)),
                    cv2.FONT_HERSHEY_SIMPLEX, w / 1400, _SYSTEM, thickness)

    for y in detection.cuts:
        cv2.line(vis, (0, y), (w, y), _CUT, thickness)

    return vis


def write(gray: np.ndarray, detection: PageDetection, path: Path) -> Path:
    vis = draw(gray, detection)
    height = int(vis.shape[0] * _PREVIEW_WIDTH / vis.shape[1])
    cv2.imwrite(str(path), cv2.resize(vis, (_PREVIEW_WIDTH, height), interpolation=cv2.INTER_AREA))
    return path