# -*- coding: utf-8 -*-
"""Shared market symbol normalization helpers."""

from dataclasses import dataclass


@dataclass(frozen=True)
class MarketSymbol:
    """Normalized symbol metadata."""

    raw: str
    canonical: str
    market: str


def canonical_symbol(symbol: str) -> str:
    """Return canonical uppercase symbol for storage and routing."""
    return (symbol or "").strip().upper()


def normalize_symbol(symbol: str) -> str:
    """
    Normalize symbols across US and exchange-prefixed formats.

    Examples:
    - sh600519 -> 600519
    - 600519.SH -> 600519
    - aapl -> AAPL
    - hk00700 -> HK00700
    """
    canonical = canonical_symbol(symbol)

    if canonical.startswith(("SH", "SZ", "BJ")) and len(canonical) > 2:
        candidate = canonical[2:]
        if candidate.isdigit() and len(candidate) in (5, 6):
            return candidate

    if "." in canonical:
        base, suffix = canonical.rsplit(".", 1)
        if suffix in {"SH", "SZ", "SS", "BJ"} and base.isdigit():
            return base

    return canonical


def detect_market(symbol: str) -> str:
    """Infer market tag from normalized symbol."""
    normalized = normalize_symbol(symbol)
    if normalized.startswith("HK") or (
        normalized.isdigit() and len(normalized) == 5
    ):
        return "hk"
    if normalized.isalpha() or (
        "/" not in normalized and not normalized.isdigit()
    ):
        return "us"
    return "cn"


def describe_symbol(symbol: str) -> MarketSymbol:
    """Return normalized symbol metadata."""
    normalized = normalize_symbol(symbol)
    return MarketSymbol(
        raw=symbol,
        canonical=normalized,
        market=detect_market(normalized),
    )