import csv
import re
import time
from typing import List

import requests


def fetch_html(url: str, timeout: int = 15) -> str:
    """
    获取目标页面 HTML 内容（带 UA 与重试）

    参数:
        url: 目标页面地址
        timeout: 请求超时时间（秒）

    返回值:
        页面 HTML 字符串，若失败则抛出异常
    """
    headers = {
        "User-Agent": (
            "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) "
            "AppleWebKit/537.36 (KHTML, like Gecko) "
            "Chrome/120.0.0.0 Safari/537.36"
        ),
        "Accept-Language": "zh-CN,zh;q=0.9,en;q=0.8",
        "Accept": "text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8",
        "Cache-Control": "no-cache",
        "Pragma": "no-cache",
    }
    last_exc = None
    for _ in range(3):
        try:
            resp = requests.get(url, headers=headers, timeout=timeout)
            if resp.status_code == 200:
                return resp.text
            last_exc = Exception(f"HTTP {resp.status_code}")
        except Exception as e:
            last_exc = e
        time.sleep(1.0)
    raise last_exc if last_exc else Exception("未知的网络错误")


def parse_chain_names(html: str) -> List[str]:
    """
    从 CoinGecko 链页 HTML 中解析链名称（尽量兼容多种结构）

    参数:
        html: 页面 HTML 字符串

    返回值:
        链名称列表（按页面出现顺序）
    """
    names: List[str] = []

    # 方案1：匹配到指向链详情的链接文本
    # /zh/chains/<slug> 或 /en/chains/<slug>
    link_name_pattern = re.compile(
        r'<a[^>]+href="/(?:zh|en)/chains/[^"]+"[^>]*>(.*?)</a>',
        re.IGNORECASE | re.DOTALL,
    )
    for m in link_name_pattern.finditer(html):
        text = re.sub(r"<[^>]+>", "", m.group(1)).strip()
        if text:
            names.append(text)

    # 仅使用链接匹配，避免误采集页面其他导航/文案

    # 去重并裁剪可能的非链名称噪音
    cleaned: List[str] = []
    for n in names:
        # 过滤常见非名称文本
        if n.lower() in {"chains", "tvl", "volume", "market share"}:
            continue
        if len(n) > 100:
            continue
        cleaned.append(n)

    # 有些页面会包含额外的链接文本，尽量只保留前 100 条
    return cleaned[:100]


def read_current_max_index(csv_path: str) -> int:
    """
    读取当前 CSV 的最大排名（第一列）

    参数:
        csv_path: CSV 路径

    返回值:
        最大排名数字，若仅有表头则返回 0
    """
    try:
        with open(csv_path, "r", encoding="utf-8") as f:
            reader = csv.reader(f)
            rows = list(reader)
        max_idx = 0
        for row in rows[1:]:
            if not row:
                continue
            try:
                max_idx = max(max_idx, int(row[0]))
            except Exception:
                pass
        return max_idx
    except FileNotFoundError:
        return 0


def append_to_csv(csv_path: str, names: List[str], start_index: int) -> None:
    """
    将解析到的链名称追加写入 CSV（其余字段按未知/不适用填充）

    参数:
        csv_path: CSV 路径
        names: 链名称列表
        start_index: 起始排名序号（例如 101）
    """
    with open(csv_path, "a", encoding="utf-8", newline="") as f:
        writer = csv.writer(f)
        for i, name in enumerate(names, start=0):
            idx = start_index + i
            writer.writerow(
                [
                    idx,
                    name,
                    "未知",
                    "未知",
                    "待补充",
                    "否",
                    "不适用",
                    "不适用",
                ]
            )


def read_existing_names(csv_path: str) -> List[str]:
    """
    读取 CSV 已存在的链名称列表（第二列）

    参数:
        csv_path: CSV 路径

    返回值:
        名称列表
    """
    try:
        with open(csv_path, "r", encoding="utf-8") as f:
            reader = csv.reader(f)
            next(reader, None)  # 跳过表头
            return [row[1] for row in reader if row and len(row) >= 2]
    except FileNotFoundError:
        return []


def main() -> None:
    """
    抓取指定页的链信息并顺序追加到 CSV

    说明:
        - 默认抓取第 2 页；可通过命令行参数传入页码，例如: `python script.py 3`
        - 起始排名自动接续 CSV 当前最大排名，避免重复编号
    """
    import sys

    page = 2
    if len(sys.argv) >= 2:
        try:
            page = int(sys.argv[1])
        except Exception:
            pass

    url_zh = f"https://www.coingecko.com/zh/chains?page={page}"
    url_en = f"https://www.coingecko.com/en/chains?page={page}"
    csv_path = "chain/top_100_chains.csv"

    names: List[str] = []
    # 合并不同语言页的解析结果，提高覆盖率
    try:
        html_zh = fetch_html(url_zh)
        names.extend(parse_chain_names(html_zh))
    except Exception:
        pass
    try:
        html_en = fetch_html(url_en)
        names.extend(parse_chain_names(html_en))
    except Exception:
        pass
    # 去重保持顺序
    seen = set()
    names = [n for n in names if not (n in seen or seen.add(n))]

    if not names:
        raise RuntimeError("未解析到链名称，请稍后重试或更换解析策略")

    # 仅追加当前 CSV 尚不存在的名称，避免重复
    existing = set(read_existing_names(csv_path))
    names_to_append = [n for n in names if n not in existing]
    if not names_to_append:
        return

    start_index = read_current_max_index(csv_path) + 1
    append_to_csv(csv_path, names_to_append, start_index)


if __name__ == "__main__":
    main()