import os
import time
from flask import render_template, request, send_from_directory
from werkzeug.utils import secure_filename

from common.logger import system_logger


# ==========================
# 路径配置
# ==========================

BASE_DIR = os.path.dirname(
    os.path.dirname(os.path.abspath(__file__))
)

TEMP_FOLDER = os.path.join(
    BASE_DIR,
    "uploads",
    "temp"
)

os.makedirs(TEMP_FOLDER, exist_ok=True)


# ==========================
# 限制配置
# ==========================

MAX_FILE_SIZE = 50 * 1024 * 1024  # 50MB

UPLOAD_LIMIT = 5          # 次数
LIMIT_WINDOW = 60 * 60    # 10分钟


UPLOAD_RECORD = {}  # IP限流记录


# ==========================
# 工具函数
# ==========================

def get_client_ip():
    forwarded = request.headers.get("X-Forwarded-For")
    if forwarded:
        return forwarded.split(",")[0].strip()
    return request.remote_addr


def check_rate_limit(ip):
    now = time.time()

    if ip not in UPLOAD_RECORD:
        UPLOAD_RECORD[ip] = []

    # 清理过期记录
    UPLOAD_RECORD[ip] = [
        t for t in UPLOAD_RECORD[ip]
        if now - t < LIMIT_WINDOW
    ]

    if len(UPLOAD_RECORD[ip]) >= UPLOAD_LIMIT:
        remain = int(LIMIT_WINDOW - (now - UPLOAD_RECORD[ip][0]))

        system_logger.info(
            f"[TempUpload] rate limited ip={ip} remain={remain}s"
        )

        raise Exception(f"上传过于频繁，请 {remain} 秒后重试")

    UPLOAD_RECORD[ip].append(now)


# ==========================
# 页面主逻辑
# ==========================

def temp_upload_page():

    message = None
    ip = get_client_ip()

    if request.method == "POST":

        try:

            file = request.files.get("file")

            if not file or not file.filename:

                system_logger.info(
                    f"[TempUpload] upload rejected (no file) ip={ip}"
                )

                raise Exception("请选择文件")

            # 文件大小检测
            file.seek(0, os.SEEK_END)
            file_size = file.tell()
            file.seek(0)

            if file_size > MAX_FILE_SIZE:

                system_logger.info(
                    f"[TempUpload] file too large ip={ip} size={file_size}"
                )

                raise Exception("文件超过50MB限制")

            # IP限流
            check_rate_limit(ip)

            filename = secure_filename(file.filename)

            save_path = os.path.join(
                TEMP_FOLDER,
                filename
            )

            file.save(save_path)

            message = f"上传成功：{filename}"

            system_logger.info(
                f"[TempUpload] upload success "
                f"file={filename} ip={ip} size={file_size}"
            )

        except Exception as e:

            message = str(e)

            system_logger.info(
                f"[TempUpload] upload failed ip={ip} err={e}"
            )

    # ==========================
    # 文件列表
    # ==========================

    files = []

    for filename in os.listdir(TEMP_FOLDER):

        file_path = os.path.join(TEMP_FOLDER, filename)

        if os.path.isfile(file_path):

            size = os.path.getsize(file_path)

            files.append({
                "name": filename,
                "size": round(size / 1024 / 1024, 2)
            })

    files.sort(key=lambda x: x["name"], reverse=True)

    system_logger.info(
        f"[TempUpload] list files ip={ip} count={len(files)}"
    )

    return render_template(
        "temp_upload.html",
        files=files,
        message=message
    )


# ==========================
# 下载
# ==========================

def download_temp_file(filename):

    ip = get_client_ip()

    system_logger.info(
        f"[TempUpload] download file={filename} ip={ip}"
    )

    return send_from_directory(
        TEMP_FOLDER,
        filename,
        as_attachment=True
    )