"""
Pure-Python amdsmi shim using sysfs for ROCm platform detection.

Replaces the native amdsmi package (which requires libamd_smi.so linked
against glibc 2.38) with a lightweight implementation that reads GPU
information from sysfs (/sys/class/drm/*).

This is needed because the Ray base image (Ubuntu 22.04, glibc 2.35) cannot
load the ROCm 7.1 vendor libamd_smi.so (built for Ubuntu 24.04, glibc 2.38).

Provides the subset of the amdsmi API used by:
  - vLLM (platform detection, device info, topology)
  - PyTorch (device counting, memory/power/temp monitoring)
"""

from __future__ import annotations

import glob
import logging
import os
from enum import IntEnum
from pathlib import Path
from typing import Any

logger = logging.getLogger(__name__)

# ---------------------------------------------------------------------------
# Exception
# ---------------------------------------------------------------------------


class AmdSmiException(Exception):
    """Shim for amdsmi.AmdSmiException."""

    def __init__(self, message: str = "", err_code: int = -1):
        super().__init__(message)
        self.err_code = err_code


# ---------------------------------------------------------------------------
# Enums used by PyTorch monitoring helpers
# ---------------------------------------------------------------------------


class AmdSmiTemperatureType(IntEnum):
    EDGE = 0
    JUNCTION = 1
    VRAM = 2


class AmdSmiTemperatureMetric(IntEnum):
    CURRENT = 0
    MAX = 1
    MIN = 2


class AmdSmiClkType(IntEnum):
    GFX = 0
    MEM = 1


# ---------------------------------------------------------------------------
# sysfs helpers
# ---------------------------------------------------------------------------

_DRM_BASE = "/sys/class/drm"


def _read_sysfs(path: str, default: str = "") -> str:
    """Read a sysfs file, returning *default* on any error."""
    try:
        return Path(path).read_text().strip()
    except (OSError, IOError):
        return default


def _read_sysfs_int(path: str, default: int = 0) -> int:
    val = _read_sysfs(path)
    try:
        if val.startswith("0x"):
            return int(val, 16)
        return int(val)
    except (ValueError, TypeError):
        return default


def _discover_cards() -> list[str]:
    """Return sorted list of card directory names, e.g. ['card0', 'card1']."""
    cards = []
    for entry in sorted(glob.glob(os.path.join(_DRM_BASE, "card[0-9]*"))):
        name = os.path.basename(entry)
        # Exclude render nodes and connector entries like card0-DP-1
        if name.startswith("card") and "-" not in name:
            vendor = _read_sysfs(os.path.join(entry, "device", "vendor"))
            # 0x1002 = AMD
            if vendor == "0x1002":
                cards.append(name)
    return cards


def _find_hwmon(card: str) -> str | None:
    """Return the first hwmon directory path for a card, or None."""
    hwmon_base = os.path.join(_DRM_BASE, card, "device", "hwmon")
    entries = sorted(glob.glob(os.path.join(hwmon_base, "hwmon*")))
    return entries[0] if entries else None


# ---------------------------------------------------------------------------
# Handle management
# ---------------------------------------------------------------------------

# Each "handle" is just a dict with cached paths
_handles: list[dict[str, Any]] = []
_initialized = False


def amdsmi_init() -> None:
    """Initialise the shim by discovering AMD GPUs via sysfs."""
    global _handles, _initialized
    if _initialized:
        return
    cards = _discover_cards()
    _handles = []
    for card in cards:
        dev = os.path.join(_DRM_BASE, card, "device")
        _handles.append(
            {
                "card": card,
                "dev": dev,
                "hwmon": _find_hwmon(card),
                "vendor": _read_sysfs(os.path.join(dev, "vendor")),
                "device_id": _read_sysfs(os.path.join(dev, "device")),
            }
        )
    _initialized = True
    logger.debug("amdsmi-shim: discovered %d AMD GPU(s) via sysfs", len(_handles))


def amdsmi_shut_down() -> None:
    """Reset internal state."""
    global _handles, _initialized
    _handles = []
    _initialized = False


def amdsmi_get_processor_handles() -> list[dict[str, Any]]:
    """Return a list of opaque handles (one per GPU)."""
    if not _initialized:
        raise AmdSmiException("amdsmi not initialised", err_code=1)
    return list(_handles)


# ---------------------------------------------------------------------------
# Device info  (used by vLLM get_device_name + PyTorch UUID helpers)
# ---------------------------------------------------------------------------


def amdsmi_get_gpu_asic_info(handle: dict[str, Any]) -> dict[str, str]:
    """
    Return ASIC information for a GPU handle.

    Keys returned: device_id, market_name, asic_serial, vendor_id, rev_id
    """
    dev = handle["dev"]
    device_id_hex = _read_sysfs(os.path.join(dev, "device"), "0x0000")
    # Read marketing / product name (may not exist on all kernels)
    market = (
        _read_sysfs(os.path.join(dev, "product_name"))
        or _read_sysfs(os.path.join(dev, "marketing_name"))
        or f"AMD GPU {device_id_hex}"
    )
    # Unique ID for serial (not always available)
    serial = _read_sysfs(os.path.join(dev, "unique_id"), "0000000000000000")
    return {
        "device_id": device_id_hex,
        "market_name": market,
        "asic_serial": serial,
        "vendor_id": _read_sysfs(os.path.join(dev, "vendor"), "0x1002"),
        "rev_id": _read_sysfs(os.path.join(dev, "revision"), "0x00"),
    }


# ---------------------------------------------------------------------------
# Topology  (used by vLLM is_fully_connected)
# ---------------------------------------------------------------------------


def amdsmi_topo_get_link_type(
    handle: dict[str, Any], peer_handle: dict[str, Any]
) -> dict[str, int]:
    """
    Return link topology between two GPUs.

    For single-GPU systems this is essentially a no-op.
    type: 2 = XGMI, 1 = PCIe;  hops = number of hops.
    """
    if handle is peer_handle or handle["card"] == peer_handle["card"]:
        return {"type": 2, "hops": 0}  # same device
    # Default: not XGMI-connected
    return {"type": 1, "hops": 2}


# ---------------------------------------------------------------------------
# Memory  (used by PyTorch _get_amdsmi_device_memory_used)
# ---------------------------------------------------------------------------


def amdsmi_get_gpu_vram_usage(handle: dict[str, Any]) -> dict[str, int]:
    """
    Return VRAM usage in megabytes.

    Keys: vram_used, vram_total
    """
    dev = handle["dev"]
    total_bytes = _read_sysfs_int(os.path.join(dev, "mem_info_vram_total"))
    used_bytes = _read_sysfs_int(os.path.join(dev, "mem_info_vram_used"))
    return {
        "vram_used": used_bytes // (1024 * 1024),
        "vram_total": total_bytes // (1024 * 1024),
    }


# ---------------------------------------------------------------------------
# Activity  (used by PyTorch _get_amdsmi_utilization / memory_usage)
# ---------------------------------------------------------------------------


def amdsmi_get_gpu_activity(handle: dict[str, Any]) -> dict[str, int]:
    """
    Return GPU and memory controller activity percentages.

    Keys: gfx_activity, umc_activity, mm_activity
    """
    dev = handle["dev"]
    gfx = _read_sysfs_int(os.path.join(dev, "gpu_busy_percent"))
    # mem_busy_percent is not always available
    umc = _read_sysfs_int(os.path.join(dev, "mem_busy_percent"))
    return {"gfx_activity": gfx, "umc_activity": umc, "mm_activity": 0}


# ---------------------------------------------------------------------------
# Power  (used by PyTorch _get_amdsmi_power_draw)
# ---------------------------------------------------------------------------


def amdsmi_get_power_info(handle: dict[str, Any]) -> dict[str, int]:
    """
    Return power info in watts.

    Keys: average_socket_power, current_socket_power
    """
    hwmon = handle.get("hwmon")
    if not hwmon:
        return {"average_socket_power": 0, "current_socket_power": 0}
    # sysfs reports in microwatts
    avg_uw = _read_sysfs_int(os.path.join(hwmon, "power1_average"))
    cur_uw = _read_sysfs_int(os.path.join(hwmon, "power1_input"), avg_uw)
    return {
        "average_socket_power": avg_uw // 1_000_000,
        "current_socket_power": cur_uw // 1_000_000,
    }


# ---------------------------------------------------------------------------
# Temperature  (used by PyTorch _get_amdsmi_temperature)
# ---------------------------------------------------------------------------


def amdsmi_get_temp_metric(
    handle: dict[str, Any],
    sensor_type: AmdSmiTemperatureType = AmdSmiTemperatureType.JUNCTION,
    metric: AmdSmiTemperatureMetric = AmdSmiTemperatureMetric.CURRENT,
) -> int:
    """
    Return temperature in millidegrees Celsius.

    PyTorch uses JUNCTION / CURRENT and the result is divided by 1000.
    """
    hwmon = handle.get("hwmon")
    if not hwmon:
        return 0
    # Map sensor type to sysfs file: temp1=edge, temp2=junction, temp3=vram
    idx = {
        AmdSmiTemperatureType.EDGE: 1,
        AmdSmiTemperatureType.JUNCTION: 2,
        AmdSmiTemperatureType.VRAM: 3,
    }.get(sensor_type, 1)
    suffix = {
        AmdSmiTemperatureMetric.CURRENT: "input",
        AmdSmiTemperatureMetric.MAX: "max",
        AmdSmiTemperatureMetric.MIN: "min",
    }.get(metric, "input")
    # sysfs already reports millidegrees
    return _read_sysfs_int(os.path.join(hwmon, f"temp{idx}_{suffix}"))


# ---------------------------------------------------------------------------
# Clock  (used by PyTorch _get_amdsmi_clock_rate via vLLM reference)
# ---------------------------------------------------------------------------


def amdsmi_get_clock_info(
    handle: dict[str, Any],
    clk_type: AmdSmiClkType = AmdSmiClkType.GFX,
) -> dict[str, int]:
    """
    Return clock info in MHz.

    Keys: clk (current), max_clk, min_clk
    """
    dev = handle["dev"]
    sysfs_file = {
        AmdSmiClkType.GFX: "pp_dpm_sclk",
        AmdSmiClkType.MEM: "pp_dpm_mclk",
    }.get(clk_type, "pp_dpm_sclk")

    raw = _read_sysfs(os.path.join(dev, sysfs_file))
    current_mhz = 0
    min_mhz = 0
    max_mhz = 0
    for line in raw.splitlines():
        # Lines look like: "0: 600Mhz *"
        parts = line.split()
        if len(parts) >= 2:
            try:
                freq = int(parts[1].replace("Mhz", "").replace("MHz", ""))
            except ValueError:
                continue
            if min_mhz == 0 or freq < min_mhz:
                min_mhz = freq
            if freq > max_mhz:
                max_mhz = freq
            if "*" in line:
                current_mhz = freq
    return {"clk": current_mhz, "max_clk": max_mhz, "min_clk": min_mhz}