"""Modbus RTU T1.5/T3.5 test tool for the STM32 slave project."""

import argparse
import queue
import threading
import time
import tkinter as tk
from tkinter import messagebox, ttk

import serial
from serial.tools import list_ports


BAUD_RATES = (9600, 19200, 115200)
BITS_PER_CHARACTER = 11
NEW_FRAME_GAP_US = 5000


def calculate_timing(baud_rate):
    """Return character, T1.2, T1.5 and T3.5 times in microseconds."""
    character_us = round(BITS_PER_CHARACTER * 1_000_000 / baud_rate)
    t12_us = round(character_us * 1.2)

    if baud_rate > 19200:
        t15_us = 750
        t35_us = 1750
    else:
        t15_us = round(character_us * 1.5)
        t35_us = round(character_us * 3.5)

    invalid_gap_us = round((t15_us + t35_us) / 2)
    return character_us, t12_us, t15_us, t35_us, invalid_gap_us


def modbus_crc(data):
    """Return the Modbus RTU CRC-16 value."""
    crc = 0xFFFF

    for value in data:
        crc ^= value

        for _ in range(8):
            if crc & 1:
                crc = (crc >> 1) ^ 0xA001
            else:
                crc >>= 1

    return crc


def build_read_coils_request(slave, address, quantity):
    """Build an 0x01 Read Coils RTU request."""
    if not 1 <= slave <= 247:
        raise ValueError("从站地址必须为1～247")
    if not 0 <= address <= 0xFFFF:
        raise ValueError("线圈地址必须为0～65535")
    if not 1 <= quantity <= 2000:
        raise ValueError("线圈数量必须为1～2000")
    if address + quantity > 0x10000:
        raise ValueError("地址与数量之和超过65536")

    frame = bytearray(
        (
            slave,
            0x01,
            address >> 8,
            address & 0xFF,
            quantity >> 8,
            quantity & 0xFF,
        )
    )
    crc = modbus_crc(frame)
    frame.extend((crc & 0xFF, crc >> 8))
    return bytes(frame)


def send_request(
    port_name, frame, gap_us, timeout_ms, baud_rate, character_us
):
    """Send one RTU request and return received bytes and host timing data."""
    write_starts = []
    write_costs = []

    with serial.Serial(
        port=port_name,
        baudrate=baud_rate,
        bytesize=serial.EIGHTBITS,
        parity=serial.PARITY_EVEN,
        stopbits=serial.STOPBITS_ONE,
        timeout=0,
        write_timeout=1,
    ) as port:
        port.reset_input_buffer()
        port.reset_output_buffer()

        if gap_us is None:
            port.write(frame)
            port.flush()
        else:
            for index, value in enumerate(frame):
                write_start = time.perf_counter_ns()
                write_starts.append(write_start)
                port.write(bytes((value,)))
                port.flush()
                write_costs.append(
                    (time.perf_counter_ns() - write_start) / 1000.0
                )

                if index + 1 < len(frame):
                    # 下一次write的目标时刻=本次write开始时刻+一个字符时间
                    # +目标静默时间。这样write、flush和循环开销都会被自动
                    # 计入并从剩余等待时间中扣除。
                    next_write_deadline = write_start + (
                        gap_us + character_us
                    ) * 1000

                    while time.perf_counter_ns() < next_write_deadline:
                        pass

        deadline = time.perf_counter() + timeout_ms / 1000.0
        response = bytearray()

        while time.perf_counter() < deadline:
            waiting = port.in_waiting

            if waiting:
                response.extend(port.read(waiting))

            time.sleep(0.001)

        waiting = port.in_waiting
        if waiting:
            response.extend(port.read(waiting))

    head_to_head = [
        (write_starts[index] - write_starts[index - 1]) / 1000.0
        for index in range(1, len(write_starts))
    ]
    estimated_silence = [
        interval - character_us for interval in head_to_head
    ]
    timing = {
        "baud_rate": baud_rate,
        "character_us": character_us,
        "write_costs": write_costs,
        "head_to_head": head_to_head,
        "estimated_silence": estimated_silence,
    }
    return bytes(response), timing


def describe_response(response, slave):
    """Perform basic RTU response checks and return a readable result."""
    if not response:
        return "未收到响应"
    if len(response) < 5:
        return "响应长度不足5字节"

    received_crc = response[-2] | (response[-1] << 8)
    calculated_crc = modbus_crc(response[:-2])
    if received_crc != calculated_crc:
        return "响应CRC错误"
    if response[0] != slave:
        return "响应从站地址不匹配"
    if response[1] == 0x81:
        return f"从站返回异常码0x{response[2]:02X}"
    if response[1] != 0x01:
        return f"响应功能码错误：0x{response[1]:02X}"

    return "01响应格式及CRC正确"


class TimingTester:
    """Tkinter user interface for the timing tests."""

    def __init__(self, root):
        self.root = root
        self.root.title("Modbus RTU T1.5/T3.5测试工具")
        self.root.resizable(False, False)
        self.result_queue = queue.Queue()

        self.port_var = tk.StringVar()
        self.baud_var = tk.StringVar(value="9600")
        self.slave_var = tk.StringVar(value="1")
        self.address_var = tk.StringVar(value="0")
        self.quantity_var = tk.StringVar(value="1")
        self.timeout_var = tk.StringVar(value="300")
        self.custom_gap_var = tk.StringVar()
        self.status_var = tk.StringVar(value="就绪")
        self._update_timing_values()
        self.custom_gap_var.set(str(self.t12_us))

        self._build_ui()
        self.refresh_ports()
        self.root.after(50, self._poll_result)

    def _build_ui(self):
        settings = ttk.LabelFrame(self.root, text="通信参数（8E1）")
        settings.grid(row=0, column=0, padx=10, pady=8, sticky="ew")

        ttk.Label(settings, text="串口").grid(row=0, column=0, padx=5, pady=5)
        self.port_box = ttk.Combobox(
            settings, textvariable=self.port_var, width=14, state="readonly"
        )
        self.port_box.grid(row=0, column=1, padx=5, pady=5)
        ttk.Button(settings, text="刷新", command=self.refresh_ports).grid(
            row=0, column=2, padx=5, pady=5
        )

        ttk.Label(settings, text="波特率").grid(row=1, column=0, padx=5, pady=5)
        self.baud_box = ttk.Combobox(
            settings,
            textvariable=self.baud_var,
            values=[str(value) for value in BAUD_RATES],
            width=14,
            state="readonly",
        )
        self.baud_box.grid(row=1, column=1, padx=5, pady=5)
        self.baud_box.bind("<<ComboboxSelected>>", self._on_baud_changed)

        ttk.Label(settings, text="从站地址").grid(row=2, column=0, padx=5, pady=5)
        ttk.Entry(settings, textvariable=self.slave_var, width=16).grid(
            row=2, column=1, padx=5, pady=5
        )
        ttk.Label(settings, text="起始线圈地址").grid(
            row=3, column=0, padx=5, pady=5
        )
        ttk.Entry(settings, textvariable=self.address_var, width=16).grid(
            row=3, column=1, padx=5, pady=5
        )
        ttk.Label(settings, text="线圈数量").grid(row=4, column=0, padx=5, pady=5)
        ttk.Entry(settings, textvariable=self.quantity_var, width=16).grid(
            row=4, column=1, padx=5, pady=5
        )
        ttk.Label(settings, text="接收等待/ms").grid(row=5, column=0, padx=5, pady=5)
        ttk.Entry(settings, textvariable=self.timeout_var, width=16).grid(
            row=5, column=1, padx=5, pady=5
        )

        timing = ttk.LabelFrame(self.root, text="定时测试")
        timing.grid(row=1, column=0, padx=10, pady=2, sticky="ew")

        self.timing_info = ttk.Label(timing, text=self._timing_info_text())
        self.timing_info.grid(
            row=0, column=0, columnspan=3, padx=5, pady=6
        )

        ttk.Button(
            timing,
            text="正常连续帧",
            command=lambda: self.start_test("正常连续帧", None),
            width=20,
        ).grid(row=1, column=0, padx=5, pady=5)
        self.t12_button = ttk.Button(
            timing,
            text=f"T1.2（{self.t12_us}us）",
            command=lambda: self.start_test("T1.2有效帧", self.t12_us),
            width=20,
        )
        self.t12_button.grid(row=1, column=1, padx=5, pady=5)
        self.invalid_button = ttk.Button(
            timing,
            text=f"T1.5～T3.5（{self.invalid_gap_us}us）",
            command=lambda: self.start_test(
                "T1.5至T3.5无效帧", self.invalid_gap_us
            ),
            width=20,
        )
        self.invalid_button.grid(row=2, column=0, padx=5, pady=5)
        ttk.Button(
            timing,
            text=f">T3.5（{NEW_FRAME_GAP_US}us）",
            command=lambda: self.start_test(
                "超过T3.5的残帧", NEW_FRAME_GAP_US
            ),
            width=20,
        ).grid(row=2, column=1, padx=5, pady=5)

        ttk.Label(timing, text="自定义字节间隔/us").grid(
            row=3, column=0, padx=5, pady=5
        )
        ttk.Entry(timing, textvariable=self.custom_gap_var, width=12).grid(
            row=3, column=1, padx=5, pady=5, sticky="w"
        )
        ttk.Button(timing, text="自定义测试", command=self.start_custom_test).grid(
            row=3, column=2, padx=5, pady=5
        )

        output = ttk.LabelFrame(self.root, text="测试记录")
        output.grid(row=2, column=0, padx=10, pady=8, sticky="ew")
        self.log = tk.Text(output, width=76, height=16, state="disabled")
        self.log.grid(row=0, column=0, padx=5, pady=5)
        ttk.Label(self.root, textvariable=self.status_var).grid(
            row=3, column=0, padx=10, pady=(0, 8), sticky="w"
        )

    def _update_timing_values(self):
        baud_rate = int(self.baud_var.get())
        (
            self.character_us,
            self.t12_us,
            self.t15_us,
            self.t35_us,
            self.invalid_gap_us,
        ) = calculate_timing(baud_rate)

    def _timing_info_text(self):
        return (
            f"1字符={self.character_us}us，T1.5={self.t15_us}us，"
            f"T3.5={self.t35_us}us"
        )

    def _on_baud_changed(self, _event=None):
        self._update_timing_values()
        self.custom_gap_var.set(str(self.t12_us))
        self.timing_info.configure(text=self._timing_info_text())
        self.t12_button.configure(text=f"T1.2（{self.t12_us}us）")
        self.invalid_button.configure(
            text=f"T1.5～T3.5（{self.invalid_gap_us}us）"
        )

    def refresh_ports(self):
        ports = [item.device for item in list_ports.comports()]
        self.port_box["values"] = ports

        if ports and self.port_var.get() not in ports:
            self.port_var.set(ports[0])
        elif not ports:
            self.port_var.set("")

    @staticmethod
    def _parse_integer(value, name):
        try:
            return int(value.strip(), 0)
        except ValueError as error:
            raise ValueError(f"{name}不是有效整数") from error

    def start_custom_test(self):
        try:
            gap_us = self._parse_integer(self.custom_gap_var.get(), "自定义间隔")
            if gap_us < 0:
                raise ValueError("自定义间隔不能小于0")
        except ValueError as error:
            messagebox.showerror("参数错误", str(error))
            return

        self.start_test("自定义间隔", gap_us)

    def start_test(self, test_name, gap_us):
        try:
            port_name = self.port_var.get()
            if not port_name:
                raise ValueError("没有检测到串口，请连接USB转RS-485设备")

            slave = self._parse_integer(self.slave_var.get(), "从站地址")
            address = self._parse_integer(self.address_var.get(), "线圈地址")
            quantity = self._parse_integer(self.quantity_var.get(), "线圈数量")
            timeout_ms = self._parse_integer(self.timeout_var.get(), "接收等待时间")
            baud_rate = self._parse_integer(self.baud_var.get(), "波特率")
            if not 10 <= timeout_ms <= 10000:
                raise ValueError("接收等待时间必须为10～10000ms")

            frame = build_read_coils_request(slave, address, quantity)
        except ValueError as error:
            messagebox.showerror("参数错误", str(error))
            return

        self.status_var.set(f"正在执行：{test_name}")
        worker = threading.Thread(
            target=self._run_test,
            args=(
                test_name,
                port_name,
                slave,
                frame,
                gap_us,
                timeout_ms,
                baud_rate,
                self.character_us,
            ),
            daemon=True,
        )
        worker.start()

    def _run_test(
        self,
        test_name,
        port_name,
        slave,
        frame,
        gap_us,
        timeout_ms,
        baud_rate,
        character_us,
    ):
        try:
            response, timing = send_request(
                port_name,
                frame,
                gap_us,
                timeout_ms,
                baud_rate,
                character_us,
            )
            result = describe_response(response, slave)
            self.result_queue.put(
                (True, test_name, frame, response, gap_us, timing, result)
            )
        except (OSError, serial.SerialException) as error:
            self.result_queue.put((False, str(error)))

    def _poll_result(self):
        try:
            result = self.result_queue.get_nowait()
        except queue.Empty:
            self.root.after(50, self._poll_result)
            return

        if result[0]:
            _, name, request, response, gap_us, timing, description = result
            gap_text = "连续发送" if gap_us is None else f"设定{gap_us}us"
            if timing["head_to_head"]:
                costs = timing["write_costs"]
                intervals = timing["head_to_head"]
                silence = timing["estimated_silence"]
                character_us = timing["character_us"]
                gap_text += (
                    f"\nwrite+flush耗时{min(costs):.0f}～{max(costs):.0f}us"
                    f"，主机头到头{min(intervals):.0f}～{max(intervals):.0f}us"
                    f"，减去{character_us}us后估算线路静默"
                    f"{min(silence):.0f}～{max(silence):.0f}us"
                )
            lines = (
                f"[{name}] {gap_text}\n"
                f"TX: {request.hex(' ').upper()}\n"
                f"RX: {response.hex(' ').upper() if response else '<无>'}\n"
                f"结果: {description}\n\n"
            )
            self._append_log(lines)
            self.status_var.set("测试完成")
        else:
            self._append_log(f"串口错误: {result[1]}\n\n")
            self.status_var.set("测试失败")

        self.root.after(50, self._poll_result)

    def _append_log(self, text):
        self.log.configure(state="normal")
        self.log.insert("end", text)
        self.log.see("end")
        self.log.configure(state="disabled")


def self_test():
    """Check calculations without opening a serial port or GUI."""
    request = build_read_coils_request(1, 0, 1)
    expected = bytes.fromhex("01 01 00 00 00 01 FD CA")
    if request != expected:
        raise RuntimeError(
            f"CRC self-test failed: {request.hex(' ').upper()}"
        )
    for baud_rate in BAUD_RATES:
        character_us, t12_us, t15_us, t35_us, invalid_gap_us = (
            calculate_timing(baud_rate)
        )
        if not (t12_us < t15_us < invalid_gap_us < t35_us < NEW_FRAME_GAP_US):
            raise RuntimeError(f"Timing self-test failed at {baud_rate}")
        print(
            f"Baud={baud_rate}, Char={character_us}us, T1.2={t12_us}us, "
            f"T1.5={t15_us}us, T3.5={t35_us}us"
        )
    print("Self-test passed")
    print(f"Request: {request.hex(' ').upper()}")


def main():
    parser = argparse.ArgumentParser()
    parser.add_argument("--self-test", action="store_true")
    args = parser.parse_args()

    if args.self_test:
        self_test()
        return

    root = tk.Tk()
    TimingTester(root)
    root.mainloop()


if __name__ == "__main__":
    main()