"""Inspect a static Metal worker using Apple's tools, without executing it."""
import re
import subprocess
from pathlib import Path

MAGIC = {b"\xcf\xfa\xed\xfe", b"\xfe\xed\xfa\xcf", b"\xca\xfe\xba\xbe",
         b"\xbe\xba\xfe\xca", b"\xca\xfe\xba\xbf", b"\xbf\xba\xfe\xca"}
SYSTEM_LIBRARIES = {"/usr/lib/libSystem.B.dylib", "/usr/lib/libc++.1.dylib",
                    "/usr/lib/libc++abi.dylib", "/usr/lib/libobjc.A.dylib"}
FRAMEWORKS = {"Foundation", "CoreFoundation", "Metal", "MetalKit", "Accelerate"}


def system_dependency(name):
    if name in SYSTEM_LIBRARIES:
        return True
    return any(re.fullmatch(rf"/System/Library/Frameworks/{framework}\.framework/Versions/[A-Z]/{framework}", name)
               for framework in FRAMEWORKS)


def validate_inventory(manifest, worker):
    with Path(worker).open("rb") as stream:
        if stream.read(4) not in MAGIC:
            raise RuntimeError("macOS worker is not a Mach-O artifact")
    arches = manifest.get("architectures")
    dependencies = manifest.get("system_libraries")
    if (manifest.get("platform") != "macos" or manifest.get("layout") != "static-metal-embedded" or manifest.get("libraries") != []
            or manifest.get("metal_embedded") is not True
            or not isinstance(arches, list) or not 1 <= len(arches) <= 2
            or not all(isinstance(arch, str) for arch in arches)
            or len(set(arches)) != len(arches) or not set(arches) <= {"arm64", "x86_64"}
            or not isinstance(dependencies, list) or not 1 <= len(dependencies) <= 32
            or not all(isinstance(name, str) and system_dependency(name) for name in dependencies)
            or not any("/Metal.framework/" in name for name in dependencies)):
        raise RuntimeError("Invalid static Metal runtime inventory")


def inspect(worker):
    worker = Path(worker)

    def tool(arguments):
        try:
            output = subprocess.check_output(arguments, text=True, timeout=30)
        except FileNotFoundError as error:
            raise RuntimeError("macOS runtime inspection requires Apple lipo/otool") from error
        if len(output.encode("utf-8")) > 65536:
            raise RuntimeError("macOS metadata exceeds inspection limit")
        return output

    arches = tool(["lipo", "-archs", str(worker)]).split()
    dependencies = []
    for line in tool(["otool", "-L", str(worker)]).splitlines():
        if not line.strip():
            continue
        if line == f"{worker}:" or line in {f"{worker} (architecture {arch}):" for arch in arches}:
            continue
        match = re.fullmatch(r"\s+(.+?) \(compatibility version [0-9.]+, current version [0-9.]+\)", line)
        if not match:
            raise RuntimeError("Unrecognized Mach-O dependency metadata")
        if match[1] not in dependencies:
            dependencies.append(match[1])
    sections = tool(["otool", "-l", str(worker)])
    sizes = re.findall(r"sectname\s+__ggml_metallib\s+segname\s+__DATA\s+addr\s+0x[0-9a-fA-F]+\s+size\s+(0x[0-9a-fA-F]+)", sections)
    if len(sizes) != len(arches) or not all(int(size, 16) > 0 for size in sizes):
        raise RuntimeError("Each Mach-O architecture must contain nonempty embedded Metal kernels")
    result = {"platform": "macos", "layout": "static-metal-embedded",
              "architectures": arches, "system_libraries": sorted(dependencies),
              "metal_embedded": True, "libraries": []}
    validate_inventory(result, worker)
    return result