#!/usr/bin/env python3
# -*- coding: utf-8 -*-
"""
AT客户端模块
负责4G模块的AT命令通信和URC解析
"""
import _thread
from maix import time
import re
import threading

class ATClient:
    """
    单读者 AT/URC 客户端：唯一读取 uart4g，避免 tcp_main/at()/OTA 抢读导致 EOF / 丢包。
    - send(cmd, expect, timeout_ms) : 发送 AT 并等待 expect
    - pop_tcp_payload()            : 获取 +MIPURC:"rtcp" 的 payload（已按长度裁剪）
    - pop_http_event()             : 获取 +MHTTPURC 事件（header/content）
    """
    def __init__(self, uart_obj):
        self.uart = uart_obj
        self._cmd_lock = threading.Lock()
        self._q_lock = threading.Lock()
        self._rx = b""
        self._tcp_payloads = []
        self._http_events = []

        # 当前命令等待状态（仅允许单命令 in-flight）
        self._waiting = False
        self._expect = b"OK"
        self._resp = b""

        self._running = False

    def start(self):
        if self._running:
            return
        self._running = True
        _thread.start_new_thread(self._reader_loop, ())

    def stop(self):
        self._running = False

    def flush(self):
        """清空内部缓存与队列（用于 OTA/异常恢复）"""
        with self._q_lock:
            self._rx = b""
            self._tcp_payloads.clear()
            self._http_events.clear()
            self._resp = b""

    def pop_tcp_payload(self):
        with self._q_lock:
            if self._tcp_payloads:
                return self._tcp_payloads.pop(0)
        return None

    def pop_http_event(self):
        with self._q_lock:
            if self._http_events:
                return self._http_events.pop(0)
        return None

    def _push_tcp_payload(self, payload: bytes):
        # 注意：在 _reader_loop 内部解析 URC 时已经持有 _q_lock，
        # 这里不要再次 acquire（锁不可重入，会死锁）。
        self._tcp_payloads.append(payload)

    def _push_http_event(self, ev):
        # 同上：避免在 _reader_loop 持锁期间二次 acquire
        self._http_events.append(ev)

    def send(self, cmd: str, expect: str = "OK", timeout_ms: int = 2000):
        """
        发送 AT 命令并等待 expect（子串匹配）。
        注意：expect=">" 用于等待 prompt。
        """
        expect_b = expect.encode() if isinstance(expect, str) else expect
        with self._cmd_lock:
            # 初始化等待
            self._waiting = True
            self._expect = expect_b
            self._resp = b""

            # 发送
            if cmd:
                # 注意：这里不要再用 uart4g_lock（否则外层已经持锁时会死锁）。
                # 写入由 _cmd_lock 串行化即可。
                self.uart.write((cmd + "\r\n").encode())

            t0 = time.ticks_ms()
            while abs(time.ticks_diff(time.ticks_ms(), t0)) < timeout_ms:
                if (not self._waiting) or (self._expect in self._resp):
                    self._waiting = False
                    break
                time.sleep_ms(5)

            # 超时也返回已收集内容（便于诊断）
            self._waiting = False
            try:
                return self._resp.decode(errors="ignore")
            except:
                return str(self._resp)

    def _find_urc_tag(self, tag: bytes):
        """
        只在"真正的 URC 边界"查找 tag，避免误命中 HTTP payload 内容。
        规则：tag 必须出现在 buffer 开头，或紧跟在 b"\\r\\n" 后面。
        """
        try:
            i = 0
            rx = self._rx
            while True:
                j = rx.find(tag, i)
                if j < 0:
                    return -1
                if j == 0:
                    return 0
                if j >= 2 and rx[j - 2:j] == b"\r\n":
                    return j
                i = j + 1
        except:
            return -1

    def _parse_mipurc_rtcp(self):
        """
        解析：+MIPURC: "rtcp",<link_id>,<len>,<payload...>
        之前硬编码 link_id=0 会导致在多连接/重连场景下收不到数据。
        """
        prefix = b'+MIPURC: "rtcp",'
        i = self._find_urc_tag(prefix)
        if i < 0:
            return False
        # 丢掉前置噪声
        if i > 0:
            self._rx = self._rx[i:]
            i = 0

        j = len(prefix)
        # 解析 link_id
        k = j
        while k < len(self._rx) and 48 <= self._rx[k] <= 57:
            k += 1
        if k == j or k >= len(self._rx):
            return False
        if self._rx[k:k+1] != b",":
            self._rx = self._rx[1:]
            return True
        try:
            link_id = int(self._rx[j:k].decode())
        except:
            self._rx = self._rx[1:]
            return True

        # 解析 len
        j2 = k + 1
        k2 = j2
        while k2 < len(self._rx) and 48 <= self._rx[k2] <= 57:
            k2 += 1
        if k2 == j2 or k2 >= len(self._rx):
            return False
        if self._rx[k2:k2+1] != b",":
            self._rx = self._rx[1:]
            return True
        try:
            n = int(self._rx[j2:k2].decode())
        except:
            self._rx = self._rx[1:]
            return True

        payload_start = k2 + 1
        payload_end = payload_start + n
        if len(self._rx) < payload_end:
            return False  # payload 未收齐

        payload = self._rx[payload_start:payload_end]
        # 把 link_id 一起带上，便于上层过滤（如果需要）
        self._push_tcp_payload((link_id, payload))
        self._rx = self._rx[payload_end:]
        return True

    def _parse_mhttpurc_header(self):
        tag = b'+MHTTPURC: "header",'
        i = self._find_urc_tag(tag)
        if i < 0:
            return False
        if i > 0:
            self._rx = self._rx[i:]
            i = 0

        # header: +MHTTPURC: "header",<id>,<code>,<hdr_len>,<hdr_text...>
        j = len(tag)
        comma_count = 0
        k = j
        while k < len(self._rx) and comma_count < 3:
            if self._rx[k:k+1] == b",":
                comma_count += 1
            k += 1
        if comma_count < 3:
            return False

        prefix = self._rx[:k]
        m = re.search(rb'\+MHTTPURC: "header",\s*(\d+),\s*(\d+),\s*(\d+),', prefix)
        if not m:
            self._rx = self._rx[1:]
            return True
        urc_id = int(m.group(1))
        code = int(m.group(2))
        hdr_len = int(m.group(3))

        text_start = k
        text_end = text_start + hdr_len
        if len(self._rx) < text_end:
            return False

        hdr_text = self._rx[text_start:text_end].decode("utf-8", "ignore")
        self._push_http_event(("header", urc_id, code, hdr_text))
        self._rx = self._rx[text_end:]
        return True

    def _parse_mhttpurc_content(self):
        tag = b'+MHTTPURC: "content",'
        i = self._find_urc_tag(tag)
        if i < 0:
            return False
        if i > 0:
            self._rx = self._rx[i:]
            i = 0

        # content: +MHTTPURC: "content",<id>,<total>,<sum>,<cur>,<payload...>
        j = len(tag)
        comma_count = 0
        k = j
        while k < len(self._rx) and comma_count < 4:
            if self._rx[k:k+1] == b",":
                comma_count += 1
            k += 1
        if comma_count < 4:
            return False

        prefix = self._rx[:k]
        m = re.search(rb'\+MHTTPURC: "content",\s*(\d+),\s*(\d+),\s*(\d+),\s*(\d+),', prefix)
        if not m:
            self._rx = self._rx[1:]
            return True
        urc_id = int(m.group(1))
        total_len = int(m.group(2))
        sum_len = int(m.group(3))
        cur_len = int(m.group(4))

        payload_start = k
        payload_end = payload_start + cur_len
        if len(self._rx) < payload_end:
            return False

        payload = self._rx[payload_start:payload_end]
        self._push_http_event(("content", urc_id, total_len, sum_len, cur_len, payload))
        self._rx = self._rx[payload_end:]
        return True

    def _reader_loop(self):
        while self._running:
            # 关键：UART 驱动偶发 read failed，必须兜住，否则线程挂了 OTA/TCP 都会卡死
            try:
                d = self.uart.read(4096)  # 8192 在一些驱动上更容易触发 read failed
            except Exception as e:
                try:
                    print("[ATClient] uart read failed:", e)
                except:
                    pass
                time.sleep_ms(50)
                continue

            if not d:
                time.sleep_ms(1)
                continue

            with self._q_lock:
                self._rx += d
                if self._waiting:
                    self._resp += d

                while True:
                    progressed = (
                        self._parse_mipurc_rtcp()
                        or self._parse_mhttpurc_header()
                        or self._parse_mhttpurc_content()
                    )
                    if not progressed:
                        break

                # 使用 ota_manager 访问 ota_in_progress
                try:
                    from ota_manager import ota_manager
                    ota_flag = ota_manager.ota_in_progress
                except:
                    ota_flag = False

                has_http_hint = (b"+MHTTP" in self._rx) or (b"+MHTTPURC" in self._rx)
                if ota_flag or has_http_hint:
                    if len(self._rx) > 512 * 1024:
                        self._rx = self._rx[-256 * 1024:]
                else:
                    if len(self._rx) > 16384:
                        self._rx = self._rx[-4096:]