"""
发票结构化解析器 — OFD / XML 零算力提取
OFD 文件本质是 ZIP 包含 XML，直接解包提取发票字段。
XML 电子发票（数电票）直接 XPath 提取。
"""
from __future__ import annotations

import io
import os
import re
import zipfile
from xml.etree import ElementTree as ET
from typing import Optional


def parse_ofd_invoice(file_bytes: bytes) -> dict:
    """
    解析 OFD 电子发票文件。
    OFD = ZIP 压缩包，内含 XML 描述文件。
    提取发票关键字段，返回结构化 dict。
    """
    result: dict = {}
    try:
        with zipfile.ZipFile(io.BytesIO(file_bytes)) as zf:
            # 收集所有 XML 内容
            all_text = ""
            for name in zf.namelist():
                if name.endswith(".xml"):
                    try:
                        xml_bytes = zf.read(name)
                        xml_text = xml_bytes.decode("utf-8", errors="replace")
                        all_text += xml_text + "\n"

                        # 尝试从 XML 标签中提取结构化数据
                        extracted = _extract_from_xml_text(xml_text)
                        if extracted:
                            result.update(extracted)
                    except Exception:
                        continue

            # 如果解析出了字段就直接返回
            if result.get("merchant") or result.get("amount"):
                return {"success": True, "data": result}

            # 降级：把所有 XML 文本当纯文本返回，交给 LLM 处理
            if all_text.strip():
                return {"success": True, "data": {"raw_text": all_text[:8000]}, "needs_llm": True}

            return {"success": False, "data": {}, "error": "OFD 文件中未找到有效 XML 内容"}

    except zipfile.BadZipFile:
        return {"success": False, "data": {}, "error": "OFD 文件格式损坏或不是有效的 OFD 文件"}
    except Exception as e:
        return {"success": False, "data": {}, "error": f"OFD 解析失败: {e}"}


def parse_xml_invoice(file_bytes: bytes) -> dict:
    """
    解析 XML 格式电子发票（数电票）。
    直接从 XML 标签提取所有发票字段。
    """
    try:
        xml_text = file_bytes.decode("utf-8", errors="replace")
        result = _extract_from_xml_text(xml_text)

        if result and (result.get("merchant") or result.get("amount")):
            return {"success": True, "data": result}

        # 降级：XML 结构未匹配预设标签，交给 LLM
        if xml_text.strip():
            return {"success": True, "data": {"raw_text": xml_text[:8000]}, "needs_llm": True}

        return {"success": False, "data": {}, "error": "XML 文件内容为空"}

    except Exception as e:
        return {"success": False, "data": {}, "error": f"XML 解析失败: {e}"}


def parse_zip_invoices(file_bytes: bytes) -> list[dict]:
    """
    解析 ZIP 压缩包中的所有 XML 发票文件。
    返回列表，每个元素 = {"filename": str, "success": bool, "data": dict, ...}
    支持系统导出的 ZIP 格式（内含多个 XML 发票）。
    """
    results: list[dict] = []
    try:
        with zipfile.ZipFile(io.BytesIO(file_bytes)) as zf:
            xml_names = [n for n in zf.namelist() if n.lower().endswith(".xml")]
            if not xml_names:
                return [{"filename": "(zip)", "success": False, "data": {}, "error": "ZIP 包中未找到 XML 文件"}]

            for name in xml_names:
                try:
                    xml_bytes = zf.read(name)
                    result = parse_xml_invoice(xml_bytes)
                    result["filename"] = os.path.basename(name)
                    results.append(result)
                except Exception as e:
                    results.append({"filename": os.path.basename(name), "success": False, "data": {}, "error": str(e)})

    except zipfile.BadZipFile:
        return [{"filename": "(zip)", "success": False, "data": {}, "error": "不是有效的 ZIP 文件"}]
    except Exception as e:
        return [{"filename": "(zip)", "success": False, "data": {}, "error": f"ZIP 解析失败: {e}"}]

    return results


# ── 内部工具函数 ──────────────────────────────────────

# 常见发票 XML 标签名映射（兼容多种数电票 XML 格式）
_FIELD_PATTERNS = {
    "merchant": [
        "SalesName", "SellerName", "销售方名称", "销方名称",
        "开票方", "Seller", "salername", "xfmc",
    ],
    "buyer": [
        "BuyerName", "PurchaserName", "购买方名称", "购方名称",
        "Buyer", "buyername", "gfmc",
    ],
    "amount": [
        "TotalAmount", "Amount", "InvoiceAmount", "金额",
        "合计金额", "价税合计", "jshj", "hjje",
    ],
    "tax_amount": [
        "TotalTax", "TaxAmount", "Tax", "税额",
        "合计税额", "hjse",
    ],
    "date": [
        "IssueDate", "InvoiceDate", "BillingDate", "开票日期",
        "kprq",
    ],
    "invoice_code": [
        "InvoiceCode", "发票代码", "fpdm",
    ],
    "invoice_number": [
        "InvoiceNumber", "InvoiceNo", "发票号码", "fphm",
    ],
    "items": [
        "GoodsName", "ItemName", "商品名称", "货物名称", "spmc",
    ],
    "tax_rate": [
        "TaxRate", "税率", "sl",
    ],
    "remark": [
        "Remark", "备注", "bz",
    ],
}


def _extract_from_xml_text(xml_text: str) -> Optional[dict]:
    """从 XML 文本中用多种策略提取发票字段。"""
    result: dict = {}

    # 策略 1: 正则匹配 <TagName>Value</TagName> 格式
    for field, tag_names in _FIELD_PATTERNS.items():
        for tag in tag_names:
            # 匹配 <Tag>value</Tag> 或 <ns:Tag>value</ns:Tag>
            pattern = rf'<(?:\w+:)?{re.escape(tag)}[^>]*>([^<]+)</(?:\w+:)?{re.escape(tag)}>'
            match = re.search(pattern, xml_text, re.IGNORECASE)
            if match:
                value = match.group(1).strip()
                if value:
                    # 数字字段转数值
                    if field in ("amount", "tax_amount"):
                        try:
                            result[field] = float(value)
                        except ValueError:
                            result[field] = value
                    else:
                        result[field] = value
                    break  # 找到一个就跳到下一个字段

    # 策略 2: 尝试 ElementTree 解析
    if not result:
        try:
            # 移除 XML 声明中可能的编码问题
            cleaned = re.sub(r'<\?xml[^?]*\?>', '', xml_text).strip()
            if cleaned:
                root = ET.fromstring(cleaned)
                _extract_from_element(root, result)
        except ET.ParseError:
            pass

    return result if result else None


def _extract_from_element(elem: ET.Element, result: dict, depth: int = 0):
    """递归遍历 XML 元素树提取字段。"""
    if depth > 10:
        return

    tag_local = elem.tag.split("}")[-1] if "}" in elem.tag else elem.tag

    for field, tag_names in _FIELD_PATTERNS.items():
        if field not in result:
            for tn in tag_names:
                if tag_local.lower() == tn.lower():
                    text = (elem.text or "").strip()
                    if text:
                        if field in ("amount", "tax_amount"):
                            try:
                                result[field] = float(text)
                            except ValueError:
                                result[field] = text
                        else:
                            result[field] = text
                        break

    for child in elem:
        _extract_from_element(child, result, depth + 1)