from __future__ import annotations

import calendar
import os
import re
from datetime import date, datetime, timedelta, timezone
from pathlib import Path
from typing import Any


APP_DIR = Path(__file__).resolve().parent
STATIC_DIR = APP_DIR / "static"
DATA_DIR = APP_DIR / "data"
ENV_FILE = APP_DIR / ".env"
MENTOR_SKILLS_DIR = APP_DIR / "游资skills"
PRIVATE_MENTOR_SKILLS_DIR = DATA_DIR / "private-mentor-skills"
TOKEN_PATTERN = re.compile(r"^[A-Za-z0-9_-]{20,128}$")
USERNAME_PATTERN = re.compile(r"^[A-Za-z0-9_\-\u4e00-\u9fff]{3,30}$")
SESSION_COOKIE = "xiaobai_session"
SESSION_MAX_AGE = 30 * 24 * 60 * 60


def load_local_env() -> None:
    if not ENV_FILE.exists():
        return
    for raw_line in ENV_FILE.read_text(encoding="utf-8").splitlines():
        line = raw_line.strip()
        if not line or line.startswith("#") or "=" not in line:
            continue
        key, value = line.split("=", 1)
        os.environ.setdefault(key.strip(), value.strip().strip('"').strip("'"))


def save_local_env(updates: dict[str, str]) -> None:
    values: dict[str, str] = {}
    if ENV_FILE.exists():
        for raw_line in ENV_FILE.read_text(encoding="utf-8").splitlines():
            if "=" in raw_line and not raw_line.lstrip().startswith("#"):
                key, value = raw_line.split("=", 1)
                values[key.strip()] = value.strip().strip('"').strip("'")
    values.update(updates)
    ENV_FILE.write_text(
        "".join(f"{key}={value}\n" for key, value in values.items()),
        encoding="utf-8",
    )


def remove_local_env(keys: set[str]) -> None:
    if not ENV_FILE.exists():
        return
    kept = []
    for raw_line in ENV_FILE.read_text(encoding="utf-8").splitlines():
        if "=" in raw_line and not raw_line.lstrip().startswith("#"):
            key = raw_line.split("=", 1)[0].strip()
            if key in keys:
                continue
        kept.append(raw_line)
    ENV_FILE.write_text("".join(f"{line}\n" for line in kept), encoding="utf-8")
    for key in keys:
        os.environ.pop(key, None)


def normalize_date(value: str) -> str:
    compact = value.replace("-", "").strip()
    try:
        parsed = datetime.strptime(compact, "%Y%m%d")
    except ValueError as exc:
        raise ValueError("日期格式应为 YYYY-MM-DD。") from exc
    if parsed.date() > date.today():
        raise ValueError("不能查询未来日期。")
    return parsed.strftime("%Y%m%d")


def validate_stock_code(value: str) -> str:
    code = value.strip()
    if not re.fullmatch(r"\d{6}", code):
        raise ValueError("股票代码应为 6 位数字。")
    return code


def tushare_code(code: str) -> str:
    if code.startswith(("4", "8", "9")):
        suffix = "BJ"
    elif code.startswith("6"):
        suffix = "SH"
    else:
        suffix = "SZ"
    return f"{code}.{suffix}"


def validate_text(value: Any, label: str, maximum: int, required: bool = False) -> str:
    text = str(value or "").strip()
    if required and not text:
        raise ValueError(f"{label}不能为空。")
    if len(text) > maximum:
        raise ValueError(f"{label}不能超过 {maximum} 个字符。")
    return text


def parse_iso_datetime(value: Any) -> datetime | None:
    text = str(value or "").strip()
    if not text:
        return None
    try:
        parsed = datetime.fromisoformat(text)
    except ValueError:
        return None
    return parsed.replace(tzinfo=timezone.utc) if parsed.tzinfo is None else parsed.astimezone(timezone.utc)


def membership_boundary(value: Any, end: bool) -> str | None:
    text = str(value or "").strip()
    if not text:
        return None
    try:
        day = datetime.strptime(text, "%Y-%m-%d").replace(tzinfo=timezone.utc)
    except ValueError as exc:
        raise ValueError("会员日期格式应为 YYYY-MM-DD。") from exc
    if end:
        day += timedelta(days=1)
    return day.isoformat(timespec="seconds")


def add_months(value: datetime, months: int) -> datetime:
    month_index = value.year * 12 + value.month - 1 + months
    year, zero_based_month = divmod(month_index, 12)
    month = zero_based_month + 1
    day = min(value.day, calendar.monthrange(year, month)[1])
    return value.replace(year=year, month=month, day=day)