from __future__ import annotations

import json
from pathlib import Path

from fastapi import HTTPException, Request
from pydantic import ValidationError

from .config import ACCOUNTS_PATH, CLASSNOTES_PATH, TEACHERS_PATH
from .data import Account, Payment, Teacher, read_accounts, read_classnotes, read_teachers
from .schemas import AccountPayload, RegisterLinesPayload, TeacherPayload


async def read_register_payload(request: Request) -> RegisterLinesPayload:
    body = await request.body()
    if not body.strip():
        return RegisterLinesPayload()

    content_type = request.headers.get("content-type", "").lower()
    if "application/json" in content_type:
        try:
            data = json.loads(body)
            if isinstance(data, str):
                return RegisterLinesPayload(line=data)
            if isinstance(data, list):
                return RegisterLinesPayload(lines=data)
            if isinstance(data, dict):
                return RegisterLinesPayload(**data)
        except (json.JSONDecodeError, ValidationError) as exc:
            raise ValueError("登记 JSON 格式错误") from exc
        raise ValueError("登记 JSON 必须是字符串、字符串数组，或包含 line/lines 的对象")

    try:
        text = body.decode("utf-8")
    except UnicodeDecodeError as exc:
        raise ValueError("登记内容必须使用 UTF-8 编码") from exc
    return RegisterLinesPayload(lines=text.splitlines())


def load_records():
    if not CLASSNOTES_PATH.exists():
        raise HTTPException(status_code=503, detail=f"课程记录文件不存在: {CLASSNOTES_PATH}")
    return read_classnotes(CLASSNOTES_PATH)


def load_accounts():
    if not ACCOUNTS_PATH.exists():
        raise HTTPException(status_code=503, detail=f"课时账户文件不存在: {ACCOUNTS_PATH}")
    return read_accounts(ACCOUNTS_PATH)


def load_teachers():
    if not TEACHERS_PATH.exists():
        return []
    return read_teachers(TEACHERS_PATH)


def file_meta(path: Path) -> dict:
    if not path.exists():
        return {"exists": False, "path": str(path)}
    stat = path.stat()
    return {
        "exists": True,
        "path": str(path),
        "size": stat.st_size,
        "mtime": stat.st_mtime,
    }


def payload_to_account(payload: AccountPayload, student_id: str | None = None) -> Account:
    return Account(
        student_id=student_id if student_id is not None else payload.student_id,
        student=payload.student,
        payments=[Payment(date=item.date, hours=item.hours) for item in payload.payments],
        remaining=payload.remaining,
        account_status=payload.account_status,
        note=payload.note,
    )


def payload_to_teacher(payload: TeacherPayload, teacher_id: str | None = None) -> Teacher:
    return Teacher(
        teacher_id=teacher_id if teacher_id is not None else payload.teacher_id,
        name=payload.name,
        alias=payload.alias,
        subjects=payload.subjects,
        status=payload.status,
        note=payload.note,
    )