from io import BytesIO
from pathlib import Path

from openpyxl import Workbook, load_workbook

QUESTION_COLUMNS = [
    ("chapter", "章节"),
    ("primary_knowledge", "一级知识点"),
    ("secondary_knowledge", "二级知识点"),
    ("question_type", "题目类型"),
    ("difficulty", "难度"),
    ("stem", "题干"),
    ("option_a", "选项A"),
    ("option_b", "选项B"),
    ("option_c", "选项C"),
    ("option_d", "选项D"),
    ("answer", "正确答案"),
    ("explanation", "解析"),
    ("notes", "备注"),
    ("source_file", "来源文件"),
]


def create_template_bytes() -> bytes:
    wb = Workbook()
    ws = wb.active
    ws.title = "questions"
    ws.append([col[1] for col in QUESTION_COLUMNS])
    ws.append(["函数", "", "函数性质", "单选", "中", "示例题干", "A", "B", "C", "D", "A", "示例解析", "", "template.xlsx"])
    buf = BytesIO()
    wb.save(buf)
    return buf.getvalue()


def parse_excel_file(path: Path) -> list[dict]:
    wb = load_workbook(path, read_only=True)
    ws = wb.active
    rows = list(ws.iter_rows(values_only=True))
    if not rows:
        return []
    headers = [str(v).strip() if v is not None else "" for v in rows[0]]
    key_map = {label: key for key, label in QUESTION_COLUMNS}
    result: list[dict] = []
    for row in rows[1:]:
        if not row or all(v is None or str(v).strip() == "" for v in row):
            continue
        item = {key: "" for key, _ in QUESTION_COLUMNS}
        for idx, val in enumerate(row):
            if idx >= len(headers):
                continue
            label = headers[idx]
            key = key_map.get(label)
            if not key:
                continue
            item[key] = "" if val is None else str(val)
        if item["stem"]:
            result.append(item)
    return result


def export_excel_bytes(items: list[dict]) -> bytes:
    wb = Workbook()
    ws = wb.active
    ws.title = "questions"
    ws.append([label for _, label in QUESTION_COLUMNS])
    for item in items:
        ws.append([item.get(key, "") for key, _ in QUESTION_COLUMNS])
    buf = BytesIO()
    wb.save(buf)
    return buf.getvalue()