"""
银行流水等场景的水印去除预设（页级 / 单元格级）。

对外 YAML 只需 method、enabled、contrast_enhancement 等少量键；
mask / hough / adaptive 细参由此模块提供，避免配置漂移。
"""
from __future__ import annotations

import copy
from typing import Any, Dict, Literal, Optional

Scope = Literal["page", "cell"]
Method = Literal["threshold", "masked", "masked_adaptive"]

_DETECT_DEFAULT: Dict[str, Any] = {
    "ratio_threshold": 0.025,
    "midtone_low": 100,
    "midtone_high": 220,
    "check_diagonal": True,
    "diagonal_angle_range": (30, 60),
}

_MASK_PAGE: Dict[str, Any] = {
    "mask_mode": "light_on_white",
    "text_protect_gray_max": 130,
    "light_gray_low": 236,
    "light_gray_high": 253,
    "whiten_gray_low": 200,
    "direction_filter": "hough",
    "morph_close_kernel": 0,
    "morph_dilate_kernel": 0,
    "min_component_area": 200,
    "debug_block_maps": False,
    "debug_block_size": 48,
    "hough_midtone_low": 200,
    "hough_midtone_high": 254,
    "hough_canny_low": 30,
    "hough_canny_high": 100,
    "hough_threshold": 25,
    "hough_min_line_length": 35,
    "hough_max_line_gap": 18,
    "hough_line_thickness": 12,
    "hough_band_dilate_radius": 16,
    "hough_use_angle_statistics": True,
    "hough_angle_tolerance": 5.0,
    "hough_secondary_peak_ratio": 0.35,
    "hough_min_length_percentile": 25.0,
    "midtone_low": 95,
    "midtone_high": 235,
    "remove_horizontal_vertical": True,
    "diagonal_enhance": True,
    "diagonal_kernel_length": 25,
    "horizontal_kernel_length": 35,
    "vertical_kernel_length": 35,
    "morph_open_kernel": 2,
    "dmorph_close_kernel": 3,
    "text_protect_percentile": 10.0,
    "background_threshold": 248,
    "seal_protect": True,
}

_MASK_CELL: Dict[str, Any] = {
    **_MASK_PAGE,
    "min_component_area": 60,
    "hough_min_line_length": 18,
    "hough_max_line_gap": 12,
    "hough_line_thickness": 8,
    "hough_band_dilate_radius": 10,
    "hough_threshold": 20,
    "text_protect_gray_max": 125,
}

_ADAPTIVE_PAGE: Dict[str, Any] = {
    "whiten_mode": "mask_fill",
    "text_percentile": 10.0,
    "watermark_percentile": 70.0,
    "background_percentile": 95.0,
    "background_threshold": 248,
    "wm_margin": 12,
    "text_protect_max": 120,
}

_ADAPTIVE_CELL: Dict[str, Any] = {
    **_ADAPTIVE_PAGE,
    "text_protect_max": 110,
    "wm_margin": 10,
}

_CONTRAST_PAGE_DEFAULT: Dict[str, Any] = {
    "enabled": True,
    "method": "text_restore",
    "text_black_target": 85,
    "background_threshold": 248,
    "text_lo_percentile": 1.0,
    "text_hi_percentile": 99.0,
}

_CONTRAST_CELL_DEFAULT: Dict[str, Any] = {
    "enabled": False,
    "method": "text_restore",
    "text_black_target": 88,
    "background_threshold": 248,
    "text_lo_percentile": 1.0,
    "text_hi_percentile": 99.0,
}


def _base_preset(scope: Scope, method: Method) -> Dict[str, Any]:
    mask = _MASK_CELL if scope == "cell" else _MASK_PAGE
    adaptive = _ADAPTIVE_CELL if scope == "cell" else _ADAPTIVE_PAGE
    contrast = (
        copy.deepcopy(_CONTRAST_CELL_DEFAULT)
        if scope == "cell"
        else copy.deepcopy(_CONTRAST_PAGE_DEFAULT)
    )
    threshold = 175 if scope == "page" else 155
    cfg: Dict[str, Any] = {
        "enabled": True,
        "detect_before_remove": scope == "page",
        "detect": copy.deepcopy(_DETECT_DEFAULT),
        "method": method,
        "threshold": threshold,
        "morph_close_kernel": 0,
        "contrast_enhancement": contrast,
        "debug_options": {
            "enabled": False,
            "save_compare": True,
            "image_format": "png",
            "subdir": "watermark_removal",
        },
    }
    if method in ("masked", "masked_adaptive"):
        cfg["mask"] = copy.deepcopy(mask)
    if method == "masked_adaptive":
        cfg["adaptive"] = copy.deepcopy(adaptive)
    return cfg


PAGE_WATERMARK_PRESETS: Dict[str, Dict[str, Any]] = {
    "threshold": _base_preset("page", "threshold"),
    "masked": _base_preset("page", "masked"),
    "masked_adaptive": _base_preset("page", "masked_adaptive"),
}

CELL_WATERMARK_PRESETS: Dict[str, Dict[str, Any]] = {
    "threshold": _base_preset("cell", "threshold"),
    "masked": _base_preset("cell", "masked"),
    "masked_adaptive": _base_preset("cell", "masked_adaptive"),
}


def get_preset(scope: Scope, method: str) -> Dict[str, Any]:
    method = method or "masked_adaptive"
    presets = CELL_WATERMARK_PRESETS if scope == "cell" else PAGE_WATERMARK_PRESETS
    if method not in presets:
        method = "masked_adaptive"
    return copy.deepcopy(presets[method])


def _deep_merge(base: Dict[str, Any], override: Dict[str, Any]) -> Dict[str, Any]:
    out = copy.deepcopy(base)
    for k, v in override.items():
        if k in out and isinstance(out[k], dict) and isinstance(v, dict):
            out[k] = _deep_merge(out[k], v)
        else:
            out[k] = copy.deepcopy(v)
    return out


def merge_watermark_config(
    scope: Scope,
    user_cfg: Optional[Dict[str, Any]] = None,
    *,
    method: Optional[str] = None,
) -> Dict[str, Any]:
    """将用户 YAML 片段与 scope 预设合并；保留旧版 mask/adaptive 全量覆盖能力。"""
    user_cfg = user_cfg or {}
    m = method or user_cfg.get("method") or "masked_adaptive"
    merged = get_preset(scope, str(m))

    for key in (
        "enabled",
        "detect_before_remove",
        "method",
        "threshold",
        "morph_close_kernel",
    ):
        if key in user_cfg:
            merged[key] = user_cfg[key]

    for nested in ("detect", "mask", "adaptive", "contrast_enhancement", "debug_options"):
        if nested in user_cfg and isinstance(user_cfg[nested], dict):
            merged[nested] = _deep_merge(merged.get(nested) or {}, user_cfg[nested])

    if method:
        merged["method"] = method
    return merged