import json
import os
import requests
import tempfile
import decimal
from datetime import datetime, date
from statistics import mean
from openpyxl import load_workbook
from frictionless import Resource, Detector
from frictionless.formats import ExcelControl
import logging

logger = logging.getLogger(__name__)

def main(file_info, detail_level="standard", sample_rows=5):
    """
    分析 Excel/CSV 文件并返回结构化画像。
    
    :param file_info: 包含 fileUrl 和 fileKey 的字典
    :param detail_level: 控制返回信息的详细程度
        - 'basic': 仅包含列名和数据类型。
        - 'standard': 包含 basic 内容 + 空值率 + 数值统计（最大/最小/平均）。
        - 'full': 包含 standard 内容 + 枚举值检测 + 自定义数量的数据样本。
    :param sample_rows: 当 detail_level 为 'full' 时，返回的样例行数。
    """
    src_tmp_name = None
    normalized_tmp_name = None

    try:
        file_url = file_info.get("fileUrl")
        file_key = file_info.get("fileKey", "file")

        logger.info(f"正在分析文件: {file_key}, 模式: {detail_level}")

        # 1. 下载文件到临时空间
        resp = requests.get(file_url, timeout=60)
        resp.raise_for_status()
        
        # 使用 .xlsx 后缀确保 openpyxl 和 frictionless 能正确识别格式
        with tempfile.NamedTemporaryFile(suffix=".xlsx", delete=False) as f_in:
            f_in.write(resp.content)
            src_tmp_name = f_in.name

        # 2. 规范化处理 (处理 Excel 公式、合并单元格)
        with tempfile.NamedTemporaryFile(suffix=".xlsx", delete=False) as f_out:
            normalized_tmp_name = f_out.name

        # data_only=True 确保读取的是计算后的值而非公式
        wb = load_workbook(src_tmp_name, data_only=True)
        wb.save(normalized_tmp_name)

        # 3. Frictionless 探测配置
        control = ExcelControl(fill_merged_cells=True)
        # 增加 header_rows 参数尝试自动探测表头
        detector = Detector(sample_size=1000, field_confidence=0.9)
        resource = Resource(path=normalized_tmp_name, control=control, detector=detector)
        resource.infer(stats=True)

        logger.info(f"Frictionless 推断的表头: {resource.schema.field_names}")
        # logger.info(f"Frictionless 样本行: {resource.read_rows(limit=2)}") # read_rows argument issue

        with resource:
            schema = resource.schema
            all_rows = resource.read_rows()
            total_rows = len(all_rows)
            
            fields_analysis = []
            for index, field in enumerate(schema.fields):
                # --- [Basic Level] 基础信息 ---
                analysis = {
                    "name": field.name,
                    "type": field.type
                }

                # 如果级别是 basic，直接跳过后续重型计算
                if detail_level == "basic":
                    fields_analysis.append(analysis)
                    continue

                # 提取非空数据用于后续分析
                col_data = []
                null_count = 0
                for row in all_rows:
                    # Frictionless Row object behaves like a dictionary for field access
                    val = row.get(field.name)
                    if val is not None:
                        col_data.append(val)
                    else:
                        null_count += 1

                # --- [Standard Level] 质量与数值统计 ---
                analysis["missing_rate"] = f"{(null_count / total_rows) * 100:.2f}%" if total_rows > 0 else "0%"
                
                if field.type in ['integer', 'number'] and col_data:
                    # 确保是可计算的数值
                    numeric_values = [
                        float(v) for v in col_data 
                        if isinstance(v, (int, float, decimal.Decimal))
                    ]
                    if numeric_values:
                        analysis["numeric_stats"] = {
                            "min": min(numeric_values),
                            "max": max(numeric_values),
                            "avg": round(mean(numeric_values), 2)
                        }

                # --- [Full Level] 枚举与样本 ---
                if detail_level == "full":
                    # 枚举检测：如果唯一值较少（<15）且有数据，则视为枚举
                    unique_vals = list(set(col_data))
                    if 0 < len(unique_vals) <= 15:
                        analysis["is_enumeration"] = True
                        analysis["enum_values"] = [str(v) for v in unique_vals]
                    else:
                        analysis["is_enumeration"] = False
                    
                    # 样本提取：转换日期等特殊对象为字符串
                    samples = []
                    for v in col_data[:sample_rows]:
                        if isinstance(v, (datetime, date)):
                            samples.append(v.isoformat())
                        else:
                            samples.append(str(v))
                    analysis["samples"] = samples

                fields_analysis.append(analysis)

            # 4. 组装最终报告
            report = {
                "file_summary": {
                    "key": file_key,
                    "total_rows": total_rows,
                    "total_fields": len(fields_analysis),
                    "detail_level_applied": detail_level
                },
                "schema_analysis": fields_analysis
            }

            logger.info(f"分析成功: 识别到 {len(fields_analysis)} 列")
            return report

    except Exception as e:
        logger.error(f"分析异常: {str(e)}")
        return {
            "status": "failed",
            "error_type": type(e).__name__,
            "message": str(e)
        }

    finally:
        # 5. 清理临时文件，防止磁盘溢出
        for path in (src_tmp_name, normalized_tmp_name):
            if path and os.path.exists(path):
                try:
                    os.unlink(path)
                except Exception as cleanup_err:
                    logger.warning(f"清理临时文件失败: {cleanup_err}")