"""GPU specifications database for NVIDIA datacenter GPUs."""

import os
import shutil
import subprocess
from typing import List, Optional

# GPU name patterns -> internal key mapping
# Order matters: longer/more-specific patterns must come before shorter ones.
GPU_NAME_PATTERNS = {
    "A100": "a100",
    "A800": "a800",
    "H100": "h100",
    "H200": "h200",
    "H20":  "h20",   # H20 / H20-3e is the China-compliance export variant, REDUCED peaks
    "B200": "b200",
    "B300": "b300",
}

# Specs database — ALL values are DENSE (non-sparse) TFLOPS
GPU_SPECS = {
    "h100": {
        "full_name": "NVIDIA H100 SXM5",
        "architecture": "Hopper",
        "compute_capability": 9.0,
        "hbm_capacity_gb": 80,
        "hbm_type": "HBM3",
        "memory_bandwidth_gbps": 3400,      # GB/s (3.4 TB/s)
        "fp32_tflops": 67,
        "tf32_tflops": 495,                 # dense (989 sparse)
        "fp16_tflops": 990,                 # dense (1979 sparse w/ 2:4)
        "bf16_tflops": 990,                 # dense
        "fp8_tflops": 1979,                 # dense
        "tdp_watts": 700,
        "nvlink_gen": 4,
        "nvlink_bandwidth_gbps": 900,       # bidirectional
        "pcie_gen": 5,
        "min_driver_version": "535",
        "min_cuda_version": "12.1",
    },
    "h200": {
        "full_name": "NVIDIA H200 SXM",
        "architecture": "Hopper",
        "compute_capability": 9.0,
        "hbm_capacity_gb": 141,
        "hbm_type": "HBM3e",
        "memory_bandwidth_gbps": 4800,      # GB/s (4.8 TB/s) — THIS IS THE CORRECT VALUE, NOT 989!
        "fp32_tflops": 67,
        "tf32_tflops": 495,                 # dense
        "fp16_tflops": 990,                 # dense
        "bf16_tflops": 990,                 # dense
        "fp8_tflops": 1979,                 # dense
        "tdp_watts": 700,
        "nvlink_gen": 4,
        "nvlink_bandwidth_gbps": 900,
        "pcie_gen": 5,
        "min_driver_version": "535",
        "min_cuda_version": "12.1",
    },
    "h20": {
        # China-compliance export variant of H200 (reported as "H20" / "H20-3e" by nvidia-smi).
        # Same silicon family / HBM as H200, but Tensor Core peaks are throttled.
        # Peaks below are sourced from supplier / NVIDIA China and confirmed against
        # measured throughput on 8x H20-3e (FP16 ~741, BF16 ~770, FP8 ~1328 TFLOPS).
        "full_name": "NVIDIA H20 / H20-3e",
        "architecture": "Hopper",
        "compute_capability": 9.0,
        "hbm_capacity_gb": 141,
        "hbm_type": "HBM3e",
        "memory_bandwidth_gbps": 4800,
        "fp32_tflops": 54,                  # China spec (matches measured ~51-52)
        "tf32_tflops": 372,                 # ~75% of H200 (matches measured ~362)
        "fp16_tflops": 744,                 # dense, China spec
        "bf16_tflops": 739,                 # dense, China spec
        "fp8_tflops": 1420,                 # dense, China spec
        "tdp_watts": 700,
        "nvlink_gen": 4,
        "nvlink_bandwidth_gbps": 900,
        "pcie_gen": 5,
        "min_driver_version": "535",
        "min_cuda_version": "12.1",
    },
    "b200": {
        "full_name": "NVIDIA B200 SXM",
        "architecture": "Blackwell",
        "compute_capability": 10.0,
        "hbm_capacity_gb": 180,
        "hbm_type": "HBM3e",
        "memory_bandwidth_gbps": 8000,      # GB/s (8 TB/s)
        "fp32_tflops": 90,
        "tf32_tflops": 1125,                # dense
        "fp16_tflops": 2250,                # dense
        "bf16_tflops": 2250,                # dense
        "fp8_tflops": 4500,                 # dense
        "tdp_watts": 1000,
        "nvlink_gen": 5,
        "nvlink_bandwidth_gbps": 1800,
        "pcie_gen": 5,
        "min_driver_version": "550",
        "min_cuda_version": "12.4",
    },
    "a100": {
        "full_name": "NVIDIA A100 SXM",
        "architecture": "Ampere",
        "compute_capability": 8.0,
        "hbm_capacity_gb": 80,
        "hbm_type": "HBM2e",
        "memory_bandwidth_gbps": 2039,      # GB/s (~2.0 TB/s)
        "fp32_tflops": 19.5,
        "tf32_tflops": 156,                 # dense
        "fp16_tflops": 312,                 # dense
        "bf16_tflops": 312,                 # dense
        "fp8_tflops": 0,                    # Ampere has no FP8
        "tdp_watts": 400,
        "nvlink_gen": 3,
        "nvlink_bandwidth_gbps": 600,       # bidirectional
        "pcie_gen": 4,
        "min_driver_version": "470",
        "min_cuda_version": "11.0",
    },
    "a800": {
        "full_name": "NVIDIA A800 SXM",
        "architecture": "Ampere",
        "compute_capability": 8.0,
        "hbm_capacity_gb": 80,
        "hbm_type": "HBM2e",
        "memory_bandwidth_gbps": 2039,      # GB/s (~2.0 TB/s)
        "fp32_tflops": 19.5,
        "tf32_tflops": 156,                 # dense
        "fp16_tflops": 312,                 # dense
        "bf16_tflops": 312,                 # dense
        "fp8_tflops": 0,                    # Ampere has no FP8
        "tdp_watts": 400,
        "nvlink_gen": 3,
        "nvlink_bandwidth_gbps": 600,       # bidirectional (NVLink 3, limited vs A100)
        "pcie_gen": 4,
        "min_driver_version": "470",
        "min_cuda_version": "11.0",
    },
    "b300": {
        "full_name": "NVIDIA B300 SXM (Blackwell Ultra)",
        "architecture": "Blackwell Ultra",
        "compute_capability": 10.0,
        "hbm_capacity_gb": 288,
        "hbm_type": "HBM3e",
        "memory_bandwidth_gbps": 8000,      # GB/s (8 TB/s)
        "fp32_tflops": 125,
        "tf32_tflops": 1750,                # dense (estimated)
        "fp16_tflops": 3500,                # dense
        "bf16_tflops": 3500,                # dense
        "fp8_tflops": 7000,                 # dense
        "tdp_watts": 1200,
        "nvlink_gen": 5,
        "nvlink_bandwidth_gbps": 1800,
        "pcie_gen": 5,
        "min_driver_version": "550",
        "min_cuda_version": "12.4",
    },
}

# Fallback for unknown / unsupported GPUs
_UNKNOWN_SPECS = {
    "full_name": "Unknown GPU",
    "architecture": "unknown",
    "compute_capability": 0.0,
    "hbm_capacity_gb": 0,
    "hbm_type": "unknown",
    "memory_bandwidth_gbps": 0,
    "fp32_tflops": 0,
    "tf32_tflops": 0,
    "fp16_tflops": 0,
    "bf16_tflops": 0,
    "fp8_tflops": 0,
    "tdp_watts": 700,
    "nvlink_gen": 0,
    "nvlink_bandwidth_gbps": 0,
    "pcie_gen": 0,
    "min_driver_version": "",
    "min_cuda_version": "",
}


def detect_gpu_type() -> str:
    """Detect GPU type via nvidia-smi and return the internal key (e.g. 'h200').

    Returns 'unknown' if nvidia-smi is unavailable or the GPU is not recognized.
    """
    nvidia_smi = shutil.which("nvidia-smi")
    if not nvidia_smi:
        return "unknown"

    try:
        r = subprocess.run(
            [nvidia_smi, "--query-gpu=name", "--format=csv,noheader"],
            capture_output=True, text=True, timeout=10,
        )
        if r.returncode != 0:
            return "unknown"

        first_line = r.stdout.strip().splitlines()[0].strip().upper()
        # Iterate longest-pattern-first so "H200" doesn't get matched by "H20".
        for pattern, key in sorted(GPU_NAME_PATTERNS.items(), key=lambda kv: -len(kv[0])):
            if pattern in first_line:
                return key
        return "unknown"
    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
        return "unknown"


def get_gpu_specs(gpu_type: str = None) -> dict:
    """Return specs dict for the given gpu_type, auto-detecting if None.

    Returns a minimal 'unknown' fallback dict with zero peaks for unsupported GPUs.
    """
    if gpu_type is None:
        gpu_type = detect_gpu_type()
    return GPU_SPECS.get(gpu_type, dict(_UNKNOWN_SPECS))


def get_supported_gpus() -> list:
    """Return list of supported GPU type keys."""
    return list(GPU_SPECS.keys())


def get_gpu_label(gpu_type: str) -> str:
    """Return a short human-readable label like 'H200 SXM' for display in tables."""
    specs = GPU_SPECS.get(gpu_type)
    if specs:
        full = specs["full_name"]
        # Strip the "NVIDIA " prefix for display
        return full.replace("NVIDIA ", "")
    return "Unknown GPU"


# ---------------------------------------------------------------------------
# Tools path resolution
# ---------------------------------------------------------------------------

def resolve_tools_dir(config: dict) -> str:
    """Resolve tools installation directory with smart fallback.

    Priority: GPU_TOOLS_DIR env > config value > /opt/gpu-test-tools > /tmp/gpu-test-tools
    """
    # 1. Env var override
    env_dir = os.environ.get("GPU_TOOLS_DIR")
    if env_dir:
        return env_dir
    # 2. Config value if explicitly set
    cfg_dir = config.get("tools", {}).get("install_dir", "")
    if cfg_dir:
        return cfg_dir
    # 3. /opt/gpu-test-tools if it already exists or /opt is writable
    default = "/opt/gpu-test-tools"
    if os.path.isdir(default) or os.access("/opt", os.W_OK):
        return default
    # 4. Fallback to /tmp
    return "/tmp/gpu-test-tools"


# ---------------------------------------------------------------------------
# Driver / CUDA compatibility validation
# ---------------------------------------------------------------------------

def _query_nvidia_smi(field: str) -> Optional[str]:
    """Query a single nvidia-smi field, return value string or None."""
    nvidia_smi = shutil.which("nvidia-smi")
    if not nvidia_smi:
        return None
    try:
        r = subprocess.run(
            [nvidia_smi, f"--query-gpu={field}", "--format=csv,noheader,nounits"],
            capture_output=True, text=True, timeout=10,
        )
        if r.returncode == 0 and r.stdout.strip():
            return r.stdout.strip().splitlines()[0].strip()
    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
        pass
    return None


def _version_lt(actual: str, minimum: str) -> bool:
    """Return True if actual version < minimum (numeric dotted comparison)."""
    def to_tuple(v: str):
        parts = []
        for p in v.split("."):
            try:
                parts.append(int(p))
            except ValueError:
                break
        return tuple(parts) if parts else (0,)
    return to_tuple(actual) < to_tuple(minimum)


def validate_driver_compatibility(gpu_type: str) -> List[str]:
    """Check if current driver/CUDA meets minimum requirements for the detected GPU.

    Returns a list of warning strings (empty if everything is fine).
    """
    specs = get_gpu_specs(gpu_type)
    warnings: List[str] = []

    min_driver = specs.get("min_driver_version", "")
    min_cuda = specs.get("min_cuda_version", "")
    if not min_driver and not min_cuda:
        return warnings

    actual_driver = _query_nvidia_smi("driver_version")
    # nvidia-smi reports the highest CUDA version supported by the driver
    actual_cuda = _query_nvidia_smi("cuda_version")

    gpu_label = get_gpu_label(gpu_type)

    if actual_driver and min_driver and _version_lt(actual_driver, min_driver):
        warnings.append(
            f"Driver {actual_driver} < minimum {min_driver} required for {gpu_label}"
        )
    if actual_cuda and min_cuda and _version_lt(actual_cuda, min_cuda):
        warnings.append(
            f"CUDA {actual_cuda} < minimum {min_cuda} required for {gpu_label}"
        )
    return warnings