import os
import pathlib
import platform
import re
import subprocess
import sys

import pytest

from numpy._core._multiarray_umath import (
    __cpu_baseline__,
    __cpu_dispatch__,
    __cpu_features__,
)


def assert_features_equal(actual, desired, fname):
    __tracebackhide__ = True  # Hide traceback for py.test
    actual, desired = str(actual), str(desired)
    if actual == desired:
        return
    detected = str(__cpu_features__).replace("'", "")
    try:
        with open("/proc/cpuinfo") as fd:
            cpuinfo = fd.read(2048)
    except Exception as err:
        cpuinfo = str(err)

    try:
        import subprocess
        auxv = subprocess.check_output(['/bin/true'], env={"LD_SHOW_AUXV": "1"})
        auxv = auxv.decode()
    except Exception as err:
        auxv = str(err)

    import textwrap
    error_report = textwrap.indent(
f"""
###########################################
### Extra debugging information
###########################################
-------------------------------------------
--- NumPy Detections
-------------------------------------------
{detected}
-------------------------------------------
--- SYS / CPUINFO
-------------------------------------------
{cpuinfo}....
-------------------------------------------
--- SYS / AUXV
-------------------------------------------
{auxv}
""", prefix='\r')

    raise AssertionError(
        "Failure Detection\n"
        f" NAME: '{fname}'\n"
        f" ACTUAL: {actual}\n"
        f" DESIRED: {desired}\n"
        f"{error_report}")

def _text_to_list(txt):
    out = txt.strip("][\n").replace("'", "").split(', ')
    return None if out[0] == "" else out

class AbstractTest:
    features = []
    features_groups = {}
    features_map = {}
    features_flags = set()

    def load_flags(self):
        # a hook
        pass

    def test_features(self):
        self.load_flags()
        for gname, features in self.features_groups.items():
            test_features = [self.cpu_have(f) for f in features]
            assert_features_equal(
                __cpu_features__.get(gname),
                all(test_features),
                gname,
            )

        for feature_name in self.features:
            cpu_have = self.cpu_have(feature_name)
            npy_have = __cpu_features__.get(feature_name)
            assert_features_equal(npy_have, cpu_have, feature_name)

    def cpu_have(self, feature_name):
        map_names = self.features_map.get(feature_name, feature_name)
        if isinstance(map_names, str):
            return map_names in self.features_flags
        return any(f in self.features_flags for f in map_names)

    def load_flags_cpuinfo(self, magic_key):
        self.features_flags = self.get_cpuinfo_item(magic_key)

    def get_cpuinfo_item(self, magic_key):
        values = set()
        with open('/proc/cpuinfo') as fd:
            for line in fd:
                if not line.startswith(magic_key):
                    continue
                flags_value = [s.strip() for s in line.split(':', 1)]
                if len(flags_value) == 2:
                    values = values.union(flags_value[1].upper().split())
        return values

    def load_flags_auxv(self):
        auxv = subprocess.check_output(['/bin/true'], env={"LD_SHOW_AUXV": "1"})
        for at in auxv.split(b'\n'):
            if not at.startswith(b"AT_HWCAP"):
                continue
            hwcap_value = [s.strip() for s in at.split(b':', 1)]
            if len(hwcap_value) == 2:
                self.features_flags = self.features_flags.union(
                    hwcap_value[1].upper().decode().split()
                )

@pytest.mark.skipif(
    sys.platform == 'emscripten',
    reason=(
        "The subprocess module is not available on WASM platforms and"
        " therefore this test class cannot be properly executed."
    ),
)
@pytest.mark.thread_unsafe(
    reason="setup & tmp_path_factory threads-unsafe, modifies environment variables",
)
class TestEnvPrivation:
    cwd = pathlib.Path(__file__).parent.resolve()
    env = os.environ.copy()
    _enable = os.environ.pop('NPY_ENABLE_CPU_FEATURES', None)
    _disable = os.environ.pop('NPY_DISABLE_CPU_FEATURES', None)
    SUBPROCESS_ARGS = {"cwd": cwd, "capture_output": True, "text": True, "check": True}
    unavailable_feats = [
        feat for feat in __cpu_dispatch__ if not __cpu_features__[feat]
    ]
    UNAVAILABLE_FEAT = (
        None if len(unavailable_feats) == 0
        else unavailable_feats[0]
    )
    BASELINE_FEAT = None if len(__cpu_baseline__) == 0 else __cpu_baseline__[0]
    SCRIPT = """
def main():
    from numpy._core._multiarray_umath import (
        __cpu_features__,
        __cpu_dispatch__
    )

    detected = [feat for feat in __cpu_dispatch__ if __cpu_features__[feat]]
    print(detected)

if __name__ == "__main__":
    main()
    """

    @pytest.fixture(autouse=True)
    def setup_class(self, tmp_path_factory):
        file = tmp_path_factory.mktemp("runtime_test_script")
        file /= "_runtime_detect.py"
        file.write_text(self.SCRIPT)
        self.file = file

    def _run(self):
        return subprocess.run(
            [sys.executable, self.file],
            env=self.env,
            **self.SUBPROCESS_ARGS,
            )

    # Helper function mimicking pytest.raises for subprocess call
    def _expect_error(
        self,
        msg,
        err_type,
        no_error_msg="Failed to generate error"
    ):
        try:
            self._run()
        except subprocess.CalledProcessError as e:
            assertion_message = f"Expected: {msg}\nGot: {e.stderr}"
            assert re.search(msg, e.stderr), assertion_message

            assertion_message = (
                f"Expected error of type: {err_type}; see full "
                f"error:\n{e.stderr}"
            )
            assert re.search(err_type, e.stderr), assertion_message
        else:
            assert False, no_error_msg

    def setup_method(self):
        """Ensure that the environment is reset"""
        self.env = os.environ.copy()

    def test_runtime_feature_selection(self):
        """
        Ensure that when selecting `NPY_ENABLE_CPU_FEATURES`, only the
        features exactly specified are dispatched.
        """

        # Capture runtime-enabled features
        out = self._run()
        non_baseline_features = _text_to_list(out.stdout)

        if non_baseline_features is None:
            pytest.skip(
                "No dispatchable features outside of baseline detected."
            )
        feature = non_baseline_features[0]

        # Capture runtime-enabled features when `NPY_ENABLE_CPU_FEATURES` is
        # specified
        self.env['NPY_ENABLE_CPU_FEATURES'] = feature
        out = self._run()
        enabled_features = _text_to_list(out.stdout)

        # Ensure that only one feature is enabled, and it is exactly the one
        # specified by `NPY_ENABLE_CPU_FEATURES`
        assert set(enabled_features) == {feature}

        if len(non_baseline_features) < 2:
            pytest.skip("Only one non-baseline feature detected.")
        # Capture runtime-enabled features when `NPY_ENABLE_CPU_FEATURES` is
        # specified
        self.env['NPY_ENABLE_CPU_FEATURES'] = ",".join(non_baseline_features)
        out = self._run()
        enabled_features = _text_to_list(out.stdout)

        # Ensure that both features are enabled, and they are exactly the ones
        # specified by `NPY_ENABLE_CPU_FEATURES`
        assert set(enabled_features) == set(non_baseline_features)

    @pytest.mark.parametrize("enabled, disabled",
    [
        ("feature", "feature"),
        ("feature", "same"),
    ])
    def test_both_enable_disable_set(self, enabled, disabled):
        """
        Ensure that when both environment variables are set then an
        ImportError is thrown
        """
        self.env['NPY_ENABLE_CPU_FEATURES'] = enabled
        self.env['NPY_DISABLE_CPU_FEATURES'] = disabled
        msg = "Both NPY_DISABLE_CPU_FEATURES and NPY_ENABLE_CPU_FEATURES"
        err_type = "ImportError"
        self._expect_error(msg, err_type)

    @pytest.mark.skipif(
        not __cpu_dispatch__,
        reason=(
            "NPY_*_CPU_FEATURES only parsed if "
            "`__cpu_dispatch__` is non-empty"
        )
    )
    @pytest.mark.parametrize("action", ["ENABLE", "DISABLE"])
    def test_variable_too_long(self, action):
        """
        Test that an error is thrown if the environment variables are too long
        to be processed. Current limit is 1024, but this may change later.
        """
        MAX_VAR_LENGTH = 1024
        # Actual length is MAX_VAR_LENGTH + 1 due to null-termination
        self.env[f'NPY_{action}_CPU_FEATURES'] = "t" * MAX_VAR_LENGTH
        msg = (
            f"Length of environment variable 'NPY_{action}_CPU_FEATURES' is "
            f"{MAX_VAR_LENGTH + 1}, only {MAX_VAR_LENGTH} accepted"
        )
        err_type = "RuntimeError"
        self._expect_error(msg, err_type)

    @pytest.mark.skipif(
        not __cpu_dispatch__,
        reason=(
            "NPY_*_CPU_FEATURES only parsed if "
            "`__cpu_dispatch__` is non-empty"
        )
    )
    @pytest.mark.parametrize("action", ["ENABLE", "DISABLE"])
    def test_max_length_nonexistent_feature(self, action):
        """
        Test that the maximum accepted environment variable length can be
        processed even if the whole value is an invalid feature name.
        """
        MAX_VAR_LENGTH = 1024
        self.env[f'NPY_{action}_CPU_FEATURES'] = "t" * (MAX_VAR_LENGTH - 1)
        self._run()

    @pytest.mark.skipif(
        not __cpu_dispatch__,
        reason=(
            "NPY_*_CPU_FEATURES only parsed if "
            "`__cpu_dispatch__` is non-empty"
        )
    )
    def test_impossible_feature_disable(self):
        """
        Test that a RuntimeError is thrown if an impossible feature-disabling
        request is made. This includes disabling a baseline feature.
        """

        if self.BASELINE_FEAT is None:
            pytest.skip("There are no unavailable features to test with")
        bad_feature = self.BASELINE_FEAT
        self.env['NPY_DISABLE_CPU_FEATURES'] = bad_feature
        msg = (
            f"You cannot disable CPU feature '{bad_feature}', since it is "
            "part of the baseline optimizations"
        )
        err_type = "RuntimeError"
        self._expect_error(msg, err_type)

    def test_impossible_feature_enable(self):
        """
        Test that a RuntimeError is thrown if an impossible feature-enabling
        request is made. This includes enabling a feature not supported by the
        machine, or disabling a baseline optimization.
        """

        if self.UNAVAILABLE_FEAT is None:
            pytest.skip("There are no unavailable features to test with")
        bad_feature = self.UNAVAILABLE_FEAT
        self.env['NPY_ENABLE_CPU_FEATURES'] = bad_feature
        msg = (
            f"You cannot enable CPU features \\({bad_feature}\\), since "
            "they are not supported by your machine."
        )
        err_type = "RuntimeError"
        self._expect_error(msg, err_type)

        # Ensure that it fails even when providing garbage in addition
        feats = f"{bad_feature}, Foobar"
        self.env['NPY_ENABLE_CPU_FEATURES'] = feats
        msg = (
            f"You cannot enable CPU features \\({bad_feature}\\), since they "
            "are not supported by your machine."
        )
        self._expect_error(msg, err_type)

        if self.BASELINE_FEAT is not None:
            # Ensure that only the bad feature gets reported
            feats = f"{bad_feature}, {self.BASELINE_FEAT}"
            self.env['NPY_ENABLE_CPU_FEATURES'] = feats
            msg = (
                f"You cannot enable CPU features \\({bad_feature}\\), since "
                "they are not supported by your machine."
            )
            self._expect_error(msg, err_type)

    @pytest.mark.parametrize("action", ["ENABLE", "DISABLE"])
    def test_repeated_unavailable_feature(self, action):
        """
        Test that repeated unavailable features can be processed without
        overflowing the diagnostic buffer.
        """
        if self.UNAVAILABLE_FEAT is None:
            pytest.skip("There are no unavailable features to test with")

        bad_feature = self.UNAVAILABLE_FEAT
        feature_repeats = 1024 // (len(bad_feature) + 1)
        self.env[f'NPY_{action}_CPU_FEATURES'] = ",".join(
            [bad_feature] * feature_repeats
        )

        if action == "ENABLE":
            msg = "You cannot enable CPU features"
            err_type = "RuntimeError"
            self._expect_error(msg, err_type)
        else:
            self._run()


is_linux = sys.platform.startswith('linux')
is_cygwin = sys.platform.startswith('cygwin')
machine = platform.machine()
is_x86 = re.match(r"^(amd64|x86|i386|i686)", machine, re.IGNORECASE)
@pytest.mark.skipif(
    not (is_linux or is_cygwin) or not is_x86,
    reason="Only for Linux and x86",
)
class Test_X86_Features(AbstractTest):
    features = []

    features_groups = {
        "X86_V2": [
            "SSE", "SSE2", "SSE3", "SSSE3", "SSE41", "SSE42",
            "POPCNT", "LAHF", "CX16"
        ],
    }
    features_groups["X86_V3"] = features_groups["X86_V2"] + [
        "AVX", "AVX2", "FMA3", "BMI", "BMI2",
        "LZCNT", "F16C", "MOVBE"
    ]
    features_groups["X86_V4"] = features_groups["X86_V3"] + [
        "AVX512F", "AVX512CD", "AVX512BW", "AVX512DQ", "AVX512VL"
    ]
    features_groups["AVX512_ICL"] = features_groups["X86_V4"] + [
        "AVX512IFMA", "AVX512VBMI", "AVX512VNNI",
        "AVX512VBMI2", "AVX512BITALG", "AVX512VPOPCNTDQ",
        "VAES", "VPCLMULQDQ", "GFNI"
    ]
    features_groups["AVX512_SPR"] = (
        features_groups["AVX512_ICL"] + ["AVX512FP16", "AVX512BF16"]
    )

    features_map = {
        "SSE3": "PNI", "SSE41": "SSE4_1", "SSE42": "SSE4_2", "FMA3": "FMA",
        "BMI": "BMI1", "LZCNT": "ABM", "LAHF": "LAHF_LM",
        "AVX512VNNI": "AVX512_VNNI", "AVX512BITALG": "AVX512_BITALG",
        "AVX512VBMI2": "AVX512_VBMI2", "AVX5124FMAPS": "AVX512_4FMAPS",
        "AVX5124VNNIW": "AVX512_4VNNIW", "AVX512VPOPCNTDQ": "AVX512_VPOPCNTDQ",
        "AVX512FP16": "AVX512_FP16", "AVX512BF16": "AVX512_BF16"
    }

    def load_flags(self):
        self.load_flags_cpuinfo("flags")


is_power = re.match(r"^(powerpc|ppc)64", machine, re.IGNORECASE)
@pytest.mark.skipif(not is_linux or not is_power, reason="Only for Linux and Power")
class Test_POWER_Features(AbstractTest):
    features = ["VSX", "VSX2", "VSX3", "VSX4"]
    features_map = {
        "VSX":  "ARCH_2_06",
        "VSX2": "ARCH_2_07",
        "VSX3": "ARCH_3_00",
        "VSX4": "ARCH_3_1B"
    }

    def load_flags(self):
        self.load_flags_auxv()
        platform = self._get_platform()

        if platform:
            power_match = re.search(r'power(\d+)', platform, re.IGNORECASE)
            if power_match:
                power_gen = int(power_match.group(1))
                if power_gen >= 7:
                    self.features_flags.add("ARCH_2_06")
                if power_gen >= 8:
                    self.features_flags.add("ARCH_2_07")
                if power_gen >= 9:
                    self.features_flags.add("ARCH_3_00")
                if power_gen >= 10:
                    self.features_flags.add("ARCH_3_1B")

    def _get_platform(self):
        """Get the AT_PLATFORM value from AUXV"""
        try:
            auxv = subprocess.check_output(['/bin/true'], env={"LD_SHOW_AUXV": "1"})
            for line in auxv.split(b'\n'):
                if line.startswith(b'AT_PLATFORM'):
                    parts = line.split(b':', 1)
                    if len(parts) == 2:
                        return parts[1].strip().decode().lower()
        except Exception:
            pass
        return None


is_zarch = re.match(r"^(s390x)", machine, re.IGNORECASE)
@pytest.mark.skipif(not is_linux or not is_zarch,
                    reason="Only for Linux and IBM Z")
class Test_ZARCH_Features(AbstractTest):
    features = ["VX", "VXE", "VXE2"]

    def load_flags(self):
        self.load_flags_cpuinfo("features")


is_arm = re.match(r"^(arm|aarch64)", machine, re.IGNORECASE)
@pytest.mark.skipif(not is_linux or not is_arm, reason="Only for Linux and ARM")
class Test_ARM_Features(AbstractTest):
    features = [
        "SVE", "NEON", "ASIMD", "FPHP", "ASIMDHP", "ASIMDDP", "ASIMDFHM"
    ]
    features_groups = {
        "NEON_FP16":  ["NEON", "HALF"],
        "NEON_VFPV4": ["NEON", "VFPV4"],
    }

    def load_flags(self):
        self.load_flags_cpuinfo("Features")
        arch = self.get_cpuinfo_item("CPU architecture")
        # in case of mounting virtual filesystem of aarch64 kernel without linux32
        is_rootfs_v8 = (
            not re.match(r"^armv[0-9]+l$", machine) and
            (int('0' + next(iter(arch))) > 7 if arch else 0)
        )
        if re.match(r"^(aarch64|AARCH64)", machine) or is_rootfs_v8:
            self.features_map = {
                "NEON": "ASIMD", "HALF": "ASIMD", "VFPV4": "ASIMD"
            }
        else:
            self.features_map = {
                # ELF auxiliary vector and /proc/cpuinfo on Linux kernel(armv8 aarch32)
                # doesn't provide information about ASIMD
                # so we assume that ASIMD is supported
                # if the kernel reports any one of the following ARM8 features.
                "ASIMD": ("AES", "SHA1", "SHA2", "PMULL", "CRC32")
            }


is_loongarch = re.match(r"^(loongarch)", machine, re.IGNORECASE)
@pytest.mark.skipif(
    not is_linux or not is_loongarch,
    reason="Only for Linux and LoongArch",
)
class Test_LOONGARCH_Features(AbstractTest):
    features = ["LSX"]

    def load_flags(self):
        self.load_flags_cpuinfo("Features")


is_riscv = re.match(r"^(riscv)", machine, re.IGNORECASE)
@pytest.mark.skipif(not is_linux or not is_riscv, reason="Only for Linux and RISC-V")
class Test_RISCV_Features(AbstractTest):
    features = ["RVV"]

    def load_flags(self):
        self.load_flags_auxv()
        if not self.features_flags:
            # Let the test fail and dump if we cannot read HWCAP.
            return
        hwcap = int(next(iter(self.features_flags)), 16)
        if hwcap & (1 << 21):  # HWCAP_RISCV_V
            self.features_flags.add("RVV")
