import asm
import intr.idt as idt
import platform.pch.pic as pic


define MOUSE_DATA    = 0x60
define MOUSE_STATUS = 0x64
define MOUSE_COMMAND = 0x64

define MOUSE_BUF_SIZE = 1024

define MOUSE_LEFT = 0x01
define MOUSE_RIGHT = 0x02
define MOUSE_MIDDLE = 0x04

class mouse_packet:
    flags:    uint8
    dx:       uint8   # 原始幅值字节（符号在 flags.bit4）
    dy:       uint8   # 原始幅值字节（符号在 flags.bit5）
    buttons:  uint8
    wheel:    int8    # IntelliMouse 第 4 字节低 4 位的 Z 增量（3 字节模式恒 0）

packets:     [MOUSE_BUF_SIZE]mouse_packet
static pack_head:   uint32 = 0
static pack_tail:   uint32 = 0
static pack_count:  uint32 = 0
static mse_irq_cnt: uint64 = 0

static cycle: uint8 = 0
static byte1: uint8 = 0
static byte2: uint8 = 0
static byte3: uint8 = 0
static byte4: uint8 = 0
# 0 = 标准 3 字节 PS/2 包；1 = IntelliMouse 4 字节包（第 4 字节带滚轮）
static wheel_mode: int = 0

static mouse_x:       int32 = 0
static mouse_y:       int32 = 0
static mouse_buttons: uint8 = 0

def _wait_read():
    timeout: uint32 = 100000
    for _ in range(timeout, 0, -1):
        if (asm.inb(MOUSE_STATUS) & 0x01) != 0: return

def _wait_write():
    timeout: uint32 = 100000
    for _ in range(timeout, 0, -1):
        if (asm.inb(MOUSE_STATUS) & 0x02) == 0: return

def _write_cmd(cmd: uint8):
    _wait_write()
    asm.outb(MOUSE_COMMAND, 0xD4)
    _wait_write()
    asm.outb(MOUSE_DATA, cmd)
    _wait_read()
    asm.inb(MOUSE_DATA)

def _read_data() -> uint8:
    _wait_read()
    return asm.inb(MOUSE_DATA)

def irq_handler() -> int:
    global cycle, byte1, byte2, byte3, byte4, pack_tail, pack_count, mse_irq_cnt
    mse_irq_cnt += 1
    status: uint8 = asm.inb(MOUSE_STATUS)
    if (status & 0x20) == 0: return 0
    data: uint8 = asm.inb(MOUSE_DATA)
    if cycle == 0:
        if (data & 0x08) != 0:
            byte1 = data
            cycle = 1
        return 0
    if cycle == 1:
        byte2 = data
        cycle = 2
        return 0
    if cycle == 2:
        byte3 = data
        if wheel_mode != 0:
            cycle = 3
            return 0
        cycle = 0
    else:
        byte4 = data
        cycle = 0
    # 丢弃带溢出位的包（bit6/bit7 = X/Y overflow）：此时设备给的是饱和值，
    # 直接采用会产生 ±127 级跳变（表现为光标“飞”）。
    if (byte1 & 0xC0) != 0:
        return 0
    # IntelliMouse 第 4 字节低 4 位是有符号 Z 增量（4-bit two's complement）。
    # 实测该 Z 轴符号与“向上 = 正值”的事件约定相反，这里统一翻符号：
    # 下游（Explorer/应用）按正值表示滚轮向上处理。
    w: int = 0
    if wheel_mode != 0:
        w = int(byte4 & uint8(0x0F))
        if w >= 8: w = w - 16
        w = 0 - w
    if pack_count < MOUSE_BUF_SIZE:
        packets[pack_tail].flags = byte1
        packets[pack_tail].dx = byte2
        packets[pack_tail].dy = byte3
        packets[pack_tail].buttons = byte1 & uint8(0x07)
        packets[pack_tail].wheel = int8(w)
        pack_tail = pack_tail + 1
        if pack_tail >= MOUSE_BUF_SIZE:
            pack_tail = 0
        pack_count += 1
    return 0

def read_packet(out: mouse_packet*) -> int:
    global pack_head, pack_count
    asm.cli()
    if pack_count == 0:
        asm.sti()
        out.flags = 0
        out.dx = 0
        out.dy = 0
        out.buttons = 0
        out.wheel = 0
        return -1
    out.flags = packets[pack_head].flags
    out.dx = packets[pack_head].dx
    out.dy = packets[pack_head].dy
    out.buttons = packets[pack_head].buttons
    out.wheel = packets[pack_head].wheel
    pack_head = pack_head + 1
    if pack_head >= MOUSE_BUF_SIZE:
        pack_head = 0
    pack_count -= 1
    asm.sti()
    return 0

def has_data() -> int:
    return pack_count

def get_x() -> int32:
    return mouse_x

def get_y() -> int32:
    return mouse_y

def get_buttons() -> uint8:
    return mouse_buttons

def init():
    global wheel_mode
    wheel_mode = 0
    _wait_write()
    asm.outb(MOUSE_COMMAND, 0xA8)
    # 读-改-写 CCB 期间屏蔽 IRQ1：与 keyboard.init 同理 —— 0x20 读 CCB 会把 CCB 值放进
    # 0x60 输出缓冲并拉高 IRQ1，键盘 ISR 一旦运行就会把它当扫描码抢走（现场：sc=0x47
    # 正是这里清 bit5 后的 CCB），于是下面的 inb(0x60) 只能拿到残留值 ⇒ 可能把错误 CCB 写回。
    pic.setMask(1)
    _wait_write()
    asm.outb(MOUSE_COMMAND, 0x20)
    _wait_read()
    status: uint8 = asm.inb(MOUSE_DATA)
    status = status | 0x02
    status = status & 0xDF
    _wait_write()
    asm.outb(MOUSE_COMMAND, 0x60)
    _wait_write()
    asm.outb(MOUSE_DATA, status)
    pic.clearMask(1)
    _write_cmd(0xF6)
    # IntelliMouse 魔数：采样率 200 → 100 → 80。成功后设备 ID 变成 3（滚轮）
    # 或 4（滚轮 + 侧键），之后每个包变成 4 字节（第 4 字节低 4 位是 Z 增量）。
    _write_cmd(0xF3)
    _write_cmd(200)
    _write_cmd(0xF3)
    _write_cmd(100)
    _write_cmd(0xF3)
    _write_cmd(80)
    _write_cmd(0xF2)
    dev_id: uint8 = _read_data()
    if dev_id == uint8(3) or dev_id == uint8(4):
        wheel_mode = 1
    # 魔数序列会把采样率停在 80；恢复正常采样率 100 后再设分辨率/使能。
    _write_cmd(0xF3)
    _write_cmd(100)
    # 分辨率设为 8 counts/mm：0xF6(Set Defaults) 会把它重置为最粗的 4 counts/mm，
    # 于是每个计数对应的位移偏大。设细一档后光标更稳、不易“飞”。
    _write_cmd(0xE8)
    _write_cmd(0x03)
    _write_cmd(0xF4)
    pic.clearMask(12)
    idt.irqInstallHandler(12, irq_handler, "mouse")