"""A4 图片模板布局分析器。

检测上传图片并逐行识别每个元素的：
- 位置 (x, y, w, h)
- 字体大小（基于 OCR 边界框高度估算）
- 文本内容

支持三种模式：
- 完整 A4 模板：比例匹配 + OCR 元素 ≥2 → 全量布局描述
- 行片段（非 A4 但有元素）：视为 A4 中的某几行 → 部分布局描述
- 修改匹配：将图片中的行与现有 JRXML 做匹配，定位修改位置

用法:
    from backend.layout_analyzer import analyze_layout, match_rows_to_jrxml
    result = analyze_layout("row_snippet.png")
    # result["template_type"] = "partial_rows"
    match = match_rows_to_jrxml(result, current_jrxml)
    # match["matched_rows"] = [{"row_index": 0, "jrxml_section": "detail_band", ...}]
"""

import re
import xml.etree.ElementTree as ET
from pathlib import Path
from typing import Optional

import PIL.Image

# A4 标准尺寸 (mm): 210 × 297, 比例 ≈ 0.707
A4_RATIO = 210 / 297
A4_RATIO_EXACT_MIN, A4_RATIO_EXACT_MAX = 0.686, 0.728
A4_RATIO_CLOSE_MIN, A4_RATIO_CLOSE_MAX = 0.650, 0.764


def analyze_layout(
    file_path: str,
    row_tolerance_ratio: float = 0.02,
) -> dict:
    """分析图片/PDF 的报表模板布局。

    返回:
    {
        "is_a4_template": bool,       # 完整 A4 模板
        "is_partial": bool,           # 行片段（非 A4 但有文字元素）
        "template_type": str,         # "full_a4" | "partial_rows" | "unknown"
        "image_size": (w, h),
        "aspect_ratio": float,
        "a4_confidence": str,
        "rows": [{y_center, elements: [{x, y, w, h, font_size, text}, ...]}, ...],
        "description": str,
        "total_rows": int,
        "total_elements": int,
    }
    """
    path = Path(file_path)
    if not path.exists():
        return _empty_result("文件不存在")

    img = _load_image(path)
    if img is None:
        return _empty_result("无法加载图片")

    w, h = img.size
    ratio = min(w, h) / max(w, h)

    # A4 比例判定
    if A4_RATIO_EXACT_MIN <= ratio <= A4_RATIO_EXACT_MAX:
        a4_confidence = "exact"
    elif A4_RATIO_CLOSE_MIN <= ratio <= A4_RATIO_CLOSE_MAX:
        a4_confidence = "close"
    else:
        a4_confidence = "not_a4"

    # OCR 提取
    elements = _ocr_elements(img, file_path)

    if not elements:
        return {
            "is_a4_template": False,
            "is_partial": False,
            "template_type": "unknown",
            "image_size": (w, h),
            "aspect_ratio": round(ratio, 3),
            "a4_confidence": a4_confidence,
            "rows": [],
            "description": _build_description([], w, h, a4_confidence, "unknown"),
            "total_rows": 0,
            "total_elements": 0,
        }

    # 行分组
    rows = _group_into_rows(elements, h, row_tolerance_ratio)

    total = sum(len(r["elements"]) for r in rows)

    # 模板类型判定
    is_full_a4 = a4_confidence != "not_a4" and total >= 2
    is_partial = not is_full_a4 and total >= 1  # 非 A4 但有文字 → 行片段

    if is_full_a4:
        template_type = "full_a4"
    elif is_partial:
        template_type = "partial_rows"
    else:
        template_type = "unknown"

    description = _build_description(rows, w, h, a4_confidence, template_type)

    return {
        "is_a4_template": is_full_a4,
        "is_partial": is_partial,
        "template_type": template_type,
        "image_size": (w, h),
        "aspect_ratio": round(ratio, 3),
        "a4_confidence": a4_confidence,
        "rows": rows,
        "description": description,
        "total_rows": len(rows),
        "total_elements": total,
    }


def match_rows_to_jrxml(
    layout_result: dict,
    current_jrxml: str,
) -> dict:
    """将图片中的行与现有 JRXML 中的 section/band 做匹配。

    匹配策略：
    1. 从图片 OCR 文本中提取关键词
    2. 在 JRXML 中搜索这些关键词出现在哪个 band
    3. 返回匹配结果，可用于定位修改位置

    返回:
    {
        "matched": bool,
        "matched_rows": [{row_index, row_y_center, jrxml_section, confidence}],
        "unmatched_rows": [...],
        "description": str,   # 人类可读的匹配结果
    }
    """
    rows = layout_result.get("rows", [])
    if not rows or not current_jrxml.strip():
        return {"matched": False, "matched_rows": [], "unmatched_rows": rows,
                "description": "无行数据或 JRXML 为空"}

    # 解析 JRXML 结构
    jrxml_sections = _parse_jrxml_sections(current_jrxml)

    matched_rows = []
    unmatched_rows = []

    for ri, row in enumerate(rows):
        ocr_texts = [e["text"] for e in row["elements"]]
        best_section = None
        best_score = 0

        for section in jrxml_sections:
            score = _text_similarity(ocr_texts, section["text_content"])
            if score > best_score:
                best_score = score
                best_section = section

        if best_score > 0.3 and best_section:  # 最低匹配阈值
            matched_rows.append({
                "row_index": ri,
                "row_y_center": row["y_center"],
                "jrxml_section": best_section["name"],
                "jrxml_section_type": best_section["type"],
                "confidence": round(best_score, 2),
                "matched_text": best_section["text_content"][:200],
            })
        else:
            unmatched_rows.append({
                "row_index": ri,
                "row_y_center": row["y_center"],
                "ocr_texts": ocr_texts,
            })

    # 生成描述
    desc_parts = []
    if matched_rows:
        desc_parts.append(f"图片中 {len(matched_rows)} 行匹配到当前 JRXML：")
        for m in matched_rows:
            desc_parts.append(
                f"  - 图片第 {m['row_index']+1} 行 → JRXML「{m['jrxml_section']}」"
                f"（{m['jrxml_section_type']}，置信度 {m['confidence']}）"
            )
    if unmatched_rows:
        desc_parts.append(f"图片中 {len(unmatched_rows)} 行未匹配到 JRXML 现有区域：")
        for u in unmatched_rows:
            texts = ", ".join(u["ocr_texts"][:3])
            desc_parts.append(f"  - 图片第 {u['row_index']+1} 行：{texts}")

    return {
        "matched": len(matched_rows) > 0,
        "matched_rows": matched_rows,
        "unmatched_rows": unmatched_rows,
        "description": "\n".join(desc_parts),
    }


def analyze_and_inject(file_path: str, base_prompt: str,
                       current_jrxml: str = "") -> str:
    """分析布局并增强 prompt。

    - 完整 A4 模板 → 全量布局描述
    - 行片段 + 有 JRXML → 行匹配 + 修改指引
    - 行片段 + 无 JRXML → 行片段描述（视为 A4 模板的一部分）
    """
    result = analyze_layout(file_path)
    tt = result.get("template_type", "unknown")

    if tt == "unknown":
        return base_prompt

    if tt == "full_a4":
        return f"[图片模板分析 — 完整 A4 报表]\n{result['description']}\n\n---\n原始需求:\n{base_prompt}"

    if tt == "partial_rows":
        if current_jrxml.strip():
            match = match_rows_to_jrxml(result, current_jrxml)
            if match["matched"]:
                return (
                    f"[图片模板分析 — 行片段修改]\n"
                    f"图片包含 {result['total_rows']} 行，视为 A4 模板的一部分。\n"
                    f"{match['description']}\n\n"
                    f"{result['description']}\n\n"
                    f"---\n请根据以上匹配结果，修改 JRXML 中对应区域的布局：\n{base_prompt}"
                )
            else:
                return (
                    f"[图片模板分析 — 行片段（未匹配到现有区域）]\n"
                    f"图片包含 {result['total_rows']} 行。\n"
                    f"{result['description']}\n\n"
                    f"---\n请根据以上行结构，在 JRXML 中找到合适位置进行修改：\n{base_prompt}"
                )
        else:
            return (
                f"[图片模板分析 — 行片段（无现有报表，按 A4 模板处理）]\n"
                f"图片包含 {result['total_rows']} 行，请按 A4 报表模板的需求输出整张报表。\n"
                f"{result['description']}\n\n"
                f"---\n原始需求:\n{base_prompt}"
            )

    return base_prompt


# ---------------------------------------------------------------------------
# JRXML 结构解析
# ---------------------------------------------------------------------------

def _parse_jrxml_sections(jrxml: str) -> list[dict]:
    """解析 JRXML 中的 section/band 结构。

    直接搜索所有 band 元素，通过上下文字符串推断其所属 section。
    """
    sections = []
    try:
        root = ET.fromstring(jrxml)
        section_tags = {
            "title", "pageHeader", "columnHeader", "detail",
            "columnFooter", "pageFooter", "summary", "background",
            "noData", "groupHeader", "groupFooter",
        }

        for section_elem in root.iter():
            stag = _tag(section_elem)
            if stag not in section_tags:
                continue

            for child in section_elem:
                if _tag(child) == "band":
                    name = child.get("name", "")
                    section_name = f"{stag}[{name}]" if name else stag
                    text_content = ET.tostring(child, encoding="unicode")
                    sections.append({
                        "name": section_name,
                        "type": stag,
                        "text_content": text_content,
                    })
    except Exception:
        pass

    # Fallback: 如果 structured parsing 失败，直接把整个 JRXML 按 band 分割
    if not sections:
        sections = _parse_jrxml_regex(jrxml)

    return sections


def _tag(elem) -> str:
    """去除命名空间前缀的标签名。"""
    return elem.tag.split("}")[-1] if "}" in elem.tag else elem.tag


def _parse_jrxml_regex(jrxml: str) -> list[dict]:
    """正则回退方案：直接在文本中搜索 band 块。"""
    sections = []
    band_pattern = re.compile(
        r'<(title|pageHeader|columnHeader|detail|columnFooter|pageFooter|summary|background|noData|groupHeader|groupFooter)>\s*'
        r'(<band[^>]*>.*?</band>)\s*'
        r'</\1>',
        re.DOTALL,
    )
    for m in band_pattern.finditer(jrxml):
        stag = m.group(1)
        band_xml = m.group(0)
        sections.append({
            "name": stag,
            "type": stag,
            "text_content": band_xml,
        })
    return sections


def _text_similarity(ocr_texts: list[str], jrxml_text: str) -> float:
    """计算 OCR 文本与 JRXML 文本的相似度（简单的词匹配）。"""
    if not ocr_texts or not jrxml_text:
        return 0.0

    jrxml_lower = jrxml_text.lower()
    score = 0.0
    for text in ocr_texts:
        # 精确匹配
        if text.lower() in jrxml_lower:
            score += 1.0
        else:
            # 部分词匹配
            words = re.findall(r"\w+", text)
            matched = sum(1 for w in words if w.lower() in jrxml_lower)
            if words:
                score += matched / len(words) * 0.5

    return min(score / len(ocr_texts), 1.0)


# ---------------------------------------------------------------------------
# 内部实现（不变）
# ---------------------------------------------------------------------------

def _load_image(path: Path) -> Optional[PIL.Image.Image]:
    suffix = path.suffix.lower()

    if suffix in (".png", ".jpg", ".jpeg", ".bmp", ".webp"):
        try:
            return PIL.Image.open(path).convert("RGB")
        except Exception:
            return None

    if suffix == ".pdf":
        try:
            import pdfplumber
            with pdfplumber.open(path) as pdf:
                if pdf.pages:
                    pil_img = pdf.pages[0].to_image(resolution=150)
                    return pil_img.original.convert("RGB")
        except Exception:
            pass

        try:
            import fitz
            doc = fitz.open(path)
            pix = doc[0].get_pixmap(dpi=150)
            img = PIL.Image.frombytes("RGB", [pix.width, pix.height], pix.samples)
            doc.close()
            return img
        except Exception:
            pass

    return None


def _ocr_elements(img: PIL.Image.Image, file_path: str) -> list[dict]:
    """OCR 提取图片中的文字元素（位置+内容）。优先 EasyOCR，回退 PaddleOCR。"""

    # 优先 EasyOCR
    try:
        import easyocr
        import numpy as np

        reader = easyocr.Reader(["ch_sim", "en"], gpu=False, verbose=False)
        result = reader.readtext(np.array(img))

        elements = []
        for (bbox, text, confidence) in result:
            if not text.strip():
                continue
            xs = [p[0] for p in bbox]
            ys = [p[1] for p in bbox]
            x_min, x_max = min(xs), max(xs)
            y_min, y_max = min(ys), max(ys)

            elements.append({
                "x": round(x_min, 1),
                "y": round(y_min, 1),
                "w": round(x_max - x_min, 1),
                "h": round(y_max - y_min, 1),
                "font_size": round(y_max - y_min, 1),
                "text": text.strip(),
            })

        elements.sort(key=lambda e: (e["y"], e["x"]))
        return elements
    except ImportError:
        pass
    except Exception:
        pass

    # 回退 PaddleOCR
    try:
        from paddleocr import PaddleOCR
        import numpy as np

        ocr = PaddleOCR(lang="ch")
        result = ocr.ocr(np.array(img))

        elements = []
        if result and result[0]:
            for line in result[0]:
                if len(line) < 2:
                    continue
                box = line[0]
                text_info = line[1]
                text = text_info[0] if isinstance(text_info, (list, tuple)) else str(text_info)
                if not text.strip():
                    continue

                xs = [p[0] for p in box]
                ys = [p[1] for p in box]
                x_min, x_max = min(xs), max(xs)
                y_min, y_max = min(ys), max(ys)

                elements.append({
                    "x": round(x_min, 1),
                    "y": round(y_min, 1),
                    "w": round(x_max - x_min, 1),
                    "h": round(y_max - y_min, 1),
                    "font_size": round(y_max - y_min, 1),
                    "text": text.strip(),
                })

        elements.sort(key=lambda e: (e["y"], e["x"]))
        return elements
    except ImportError:
        pass
    except Exception:
        pass

    return []


def _group_into_rows(elements: list[dict], img_height: int,
                     tolerance_ratio: float = 0.02) -> list[dict]:
    if not elements:
        return []

    tolerance = img_height * tolerance_ratio
    rows = []
    current_row = [elements[0]]

    for elem in elements[1:]:
        prev_cy = current_row[0]["y"] + current_row[0]["h"] / 2
        curr_cy = elem["y"] + elem["h"] / 2

        if abs(curr_cy - prev_cy) < tolerance:
            current_row.append(elem)
        else:
            rows.append(_build_row(current_row))
            current_row = [elem]

    if current_row:
        rows.append(_build_row(current_row))

    return rows


def _build_row(elements: list[dict]) -> dict:
    elements.sort(key=lambda e: e["x"])
    ys = [e["y"] for e in elements]
    return {"y_center": round(sum(ys) / len(ys), 1), "elements": elements}


def _build_description(rows: list[dict], img_w: int, img_h: int,
                       a4_confidence: str, template_type: str) -> str:
    if not rows:
        if template_type == "partial_rows":
            return f"图片 {img_w}x{img_h}（非 A4 比例），未检测到文字元素。"
        return f"图片共 {img_w}x{img_h} 像素，未检测到文字元素。"

    lines = []
    if template_type == "full_a4":
        lines.append(f"图片为完整 A4 报表模板，共 {len(rows)} 行，像素区域 {img_w}x{img_h}：")
    elif template_type == "partial_rows":
        lines.append(f"图片为报表模板行片段（非完整 A4），包含 {len(rows)} 行，"
                     f"像素区域 {img_w}x{img_h}，请按 A4 模板处理：")
    else:
        lines.append(f"图片共 {img_w}x{img_h} 像素，包含 {len(rows)} 行文字：")

    for i, row in enumerate(rows):
        elems = row["elements"]
        lines.append(f"\n第 {i+1} 行有 {len(elems)} 个元素：")
        for j, e in enumerate(elems):
            letter = chr(ord("a") + j)
            lines.append(
                f"  元素 {letter}：位置(x={e['x']}, y={e['y']})，"
                f"长 {e['w']}px，高 {e['h']}px，"
                f"字体 {e['font_size']}px，"
                f"内容「{e['text']}」"
            )

    if template_type == "full_a4":
        lines.append(f"\n请根据以上布局生成对应的 JRXML 报表模板。")
    elif template_type == "partial_rows":
        lines.append(f"\n请将以上 {len(rows)} 行作为 A4 模板的一部分，"
                     f"生成或修改对应的 JRXML 报表区域。")

    return "\n".join(lines)


def _empty_result(error: str = "") -> dict:
    return {
        "is_a4_template": False,
        "is_partial": False,
        "template_type": "unknown",
        "image_size": (0, 0),
        "aspect_ratio": 0,
        "a4_confidence": "not_a4",
        "rows": [],
        "description": error,
        "total_rows": 0,
        "total_elements": 0,
    }