import argparse
import datetime
import logging
import re
import sys
from collections import defaultdict

import torch
from torch._C import parse_schema, Tag


FORMAT = "[%(levelname)s %(asctime)s %(filename)s:%(lineno)s] %(message)s"

log = logging.getLogger("log")
log.setLevel(logging.INFO)

handler = logging.StreamHandler()
formatter = logging.Formatter(FORMAT)
handler.setFormatter(formatter)

log.addHandler(handler)
log.propagate = False  # Avoid double logging if root logger has handlers

# How to run this test locally:
# 1 Have two virtual environments (eg conda env), one without PyTorch installed (venv_nightly)
#   one with your local changes (venv_yours).
# In venv_nightly:
# 2. First ensure that Pytorch is uninstalled, but all prereqs are installed
# 3. Install torch nightly build with
#    `pip install --pre torch -f https://download.pytorch.org/whl/nightly/cpu/torch_nightly.html`
# 4. Generate original schemas with
#    `python test/forward_backward_compatibility/dump_all_function_schemas.py --filename nightly_schemas.txt`
# Now in venv_yours:
# 5. Run this test with
#    `python test/forward_backward_compatibility/check_forward_backward_compatibility.py --existing-schemas nightly_schemas.txt`

# The date specifies how long the allowlist exclusion should apply to. Note that core ATen opset
# (https://pytorch.org/docs/stable/torch.compiler_ir.html#core-aten-ir) is guaranteed to be BC, based on this policy
# (https://dev-discuss.pytorch.org/t/core-aten-opset-backward-forward-compatibility-policy/1772) and hence the
# allowlist does not apply (or the date is always arbitrarily far for core ATen ops).
#
#   - If we NEVER give BC guarantee for an operator, you can put the
#     date arbitrarily far in the future.
#   - Otherwise, pick a date that is far enough in the future that you
#     believe you can land your diff before then.
#
# Allowlist entries can be removed after the date listed on them passes.
#
# Allowlist item format:
# [
#   0: function name regex
#   1: date until which the allowlist entry is valid
#   2: (optional, default: None) function argument regex
#   3: (optional, default: False) If True, tells us that you are NOT a core ATen op
#                                 See Note [Op removal core ATen detection]
# ]
#
# NB: function name DOES NOT include overload name!
ALLOW_LIST = [
    ("c10_experimental", datetime.date(9999, 1, 1)),
    # Internal
    ("static", datetime.date(9999, 1, 1)),
    ("prim::ModuleDictIndex", datetime.date(9999, 1, 1)),
    ("prim::MKLDNNRelu6", datetime.date(9999, 1, 1)),
    ("prim::MKLDNNRelu6_", datetime.date(9999, 1, 1)),
    ("prim::is_ort", datetime.date(9999, 1, 1)),
    ("prim::Concat", datetime.date(9999, 1, 1)),
    ("aten::_NestedTensor_GeneralizedBMM", datetime.date(9999, 1, 1)),
    # Internal, profiler-specific ops
    ("profiler::_call_end_callbacks_on_jit_fut*", datetime.date(9999, 1, 1)),
    ("profiler::_record_function_enter", datetime.date(9999, 1, 1)),
    ("aten::_cholesky_helper", datetime.date(9999, 1, 1)),
    ("aten::_cslt_sparse_mm", datetime.date(9999, 1, 1)),
    ("aten::_lstsq_helper", datetime.date(9999, 1, 1)),
    ("aten::_syevd_helper", datetime.date(9999, 1, 1)),
    ("aten::_linalg_solve_out_helper_", datetime.date(9999, 1, 1)),
    ("aten::select_backward", datetime.date(9999, 1, 1)),
    ("aten::lstsq", datetime.date(9999, 1, 1)),
    ("aten::lstsq.X", datetime.date(9999, 1, 1)),
    ("aten::slice_backward", datetime.date(9999, 1, 1)),
    ("aten::diagonal_backward", datetime.date(9999, 1, 1)),
    ("aten::rowwise_prune", datetime.date(9999, 1, 1)),
    ("aten::eig", datetime.date(9999, 1, 1)),
    ("aten::eig.e", datetime.date(9999, 1, 1)),
    ("aten::adaptive_avg_pool3d_backward", datetime.date(9999, 1, 1)),
    ("aten::_embedding_bag_dense_backward", datetime.date(9999, 1, 1)),
    ("aten::matrix_rank", datetime.date(9999, 1, 1)),
    ("aten::matrix_rank.tol", datetime.date(9999, 1, 1)),
    ("aten::randperm", datetime.date(9999, 1, 1)),
    ("aten::solve", datetime.date(9999, 1, 1)),
    ("aten::solve.solution", datetime.date(9999, 1, 1)),
    ("aten::_solve_helper", datetime.date(9999, 1, 1)),
    ("aten::_convolution_nogroup", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_backward", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_backward_bias", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_backward_input", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_backward_weight", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_transpose_backward", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_transpose_backward_input", datetime.date(9999, 1, 1)),
    ("aten::miopen_convolution_transpose_backward_weight", datetime.date(9999, 1, 1)),
    ("aten::miopen_depthwise_convolution_backward", datetime.date(9999, 1, 1)),
    ("aten::miopen_depthwise_convolution_backward_input", datetime.date(9999, 1, 1)),
    ("aten::miopen_depthwise_convolution_backward_weight", datetime.date(9999, 1, 1)),
    ("aten::_nested_tensor", datetime.date(9999, 1, 1)),
    ("prepacked::unpack_prepacked_sizes_conv2d", datetime.date(9999, 1, 1)),
    ("prepacked::unpack_prepacked_sizes_linear", datetime.date(9999, 1, 1)),
    ("aten::_symeig_helper", datetime.date(9999, 1, 1)),
    ("aten::symeig", datetime.date(9999, 1, 1)),
    ("aten::symeig.e", datetime.date(9999, 1, 1)),
    ("aten::native_multi_head_self_attention", datetime.date(9999, 1, 1)),
    ("aten::_native_multi_head_self_attention", datetime.date(9999, 1, 1)),
    ("aten::grid_sampler_3d_backward", datetime.date(9999, 1, 1)),
    ("aten::_transform_bias_rescale_qkv", datetime.date(9999, 1, 1)),
    ("prim::infer_squeeze_size.dim", datetime.date(9999, 1, 1)),
    ("prim::infer_squeeze_size", datetime.date(9999, 1, 1)),
    ("aten::_weight_norm_cuda_interface", datetime.date(9999, 1, 1)),
    ("aten::_weight_norm_cuda_interface_backward", datetime.date(9999, 1, 1)),
    ("aten::empty.SymInt", datetime.date(9999, 1, 1)),
    # nested tensor temporary auxiliary ops
    ("aten::_reshape_nested", datetime.date(9999, 1, 1)),
    ("aten::_reshape_nested_backward", datetime.date(9999, 1, 1)),
    ("aten::mps_linear", datetime.date(9999, 1, 1)),
    ("aten::_mps_linear", datetime.date(9999, 1, 1)),
    ("aten::_mps_max_pool2d", datetime.date(9999, 1, 1)),
    ("aten::_mps_max_pool2d.out", datetime.date(9999, 1, 1)),
    ("aten::mps_max_pool2d_backward", datetime.date(9999, 1, 1)),
    ("aten::mps_max_pool2d_backward.out", datetime.date(9999, 1, 1)),
    # TODO: FIXME: prims shouldn't be checked
    ("prims::.*", datetime.date(9999, 1, 1)),
    ("aten::_scaled_dot_product_cudnn_attention", datetime.date(9999, 1, 1)),
    # BetterTransformer 1.0 internal operators
    ("aten::_transformer_decoder_only_layer_fwd", datetime.date(9999, 1, 1)),
    ("aten::_native_decoder_only_multi_head_attention", datetime.date(9999, 1, 1)),
    # These ops were moved to python under the c10d_functional namespace
    ("aten::wait_tensor", datetime.date(9999, 1, 30)),
    ("aten::reduce_scatter_tensor", datetime.date(9999, 1, 30)),
    ("aten::all_gather_into_tensor", datetime.date(9999, 1, 30)),
    ("aten::all_reduce", datetime.date(9999, 1, 30)),
    # These ops are defined in torch/csrc/distributed/c10d/Ops.cpp
    # TODO: add back restriction when c10d ops can be exported
    ("c10d::.*", datetime.date(9999, 1, 1)),
    # Previously MPS_only did not support backward
    ("aten::_fused_rms_norm", datetime.date(2025, 12, 30)),
]

ALLOW_LIST_COMPILED = [
    (
        re.compile(item[0]),
        item[1],
        re.compile(item[2]) if (len(item) > 2 and item[2] is not None) else None,
        item[3] if len(item) > 3 else False,
    )
    for item in ALLOW_LIST
    if item[1] >= datetime.date.today()
]


def allow_listed(schema):
    for item in ALLOW_LIST_COMPILED:
        if item[0].search(str(schema)):
            if len(item) > 2 and item[2] is not None:
                # if arguments regex is present, use it
                return bool(item[2].search(str(schema))), item[3]
            return True, item[3]
    return False, None


# The nightly will fail to parse newly added syntax to schema declarations
# Add new schemas that will fail the nightly here
dont_parse_list = [
    ("_TorchScriptTesting.*", datetime.date(2099, 9, 17)),
    ("test_backend", datetime.date(2099, 9, 17)),
    ("dist_c10d", datetime.date(2099, 9, 17)),
    ("__backends__.nnc", datetime.date(2099, 9, 17)),
]


def has_valid_upgraders(schema, version_map):
    # we want to parse through the map to find if
    # the schema has valid upgraders. Since the
    # version map has entry for each overload
    # we need to do some ugly parsing.

    # the name of the operator
    schema_name = schema.name

    if schema_name not in version_map:
        return False

    entries = version_map[schema_name]

    possible_overloads = []
    possible_schemas = []
    for key, upgrader_schema_entries in entries.items():
        possible_overloads.append(key)
        possible_schemas.extend(upgrader_schema_entries)

    # let's make sure this existing schema is part of possible
    # schemas
    for old_schema in possible_schemas:
        if old_schema == schema:
            return True

    return False


def dont_parse(schema_line):
    for item in dont_parse_list:
        if item[1] < datetime.date.today():
            continue
        regexp = re.compile(item[0])
        if regexp.search(schema_line):
            return True
    return False


def load_schemas_to_dict():
    new_schemas = torch._C._jit_get_all_schemas()
    new_schemas += torch._C._jit_get_custom_class_schemas()
    new_schema_dict = defaultdict(list)
    for s in new_schemas:
        new_schema_dict[s.name].append(s)
    return new_schema_dict


def process_version_map(version_map):
    # version map maps full schema name to
    # list of upgraders. Since we only have
    # the name of the schema (aka no overload)
    # we want to first process the map to make
    # the key lookup easier. After this it will be:
    # Dict[schema_name, Dict[overload, List[schema]]]

    output = defaultdict(dict)
    for key, entries in version_map.items():
        operator_name = key.split(".")[0]
        schema_entries = [parse_schema(entry.old_schema) for entry in entries]
        output[operator_name][key] = schema_entries
    return output


def is_core_aten_op(schema) -> bool:
    # Check if the schema is a core ATen op
    if "::" not in schema.name:
        return False
    res = torch._C._get_operation_overload(schema.name, schema.overload_name)
    if res is None:
        # Note [Op removal core ATen detection]
        #
        # If the core ATen op has been removed, we cannot be sure whether it
        # was previously a core ATen op or not via checking tags this way.
        # Conservatively assume that you are ARE a core ATen op in this case.
        # This means that deleting a core ATen op will still be caught.
        # But if you're deleting an operator that is not a core ATen op
        # and add it to the allow_list, you would need to additionally specify
        # a flag in the ALLOW_LIST to tell us you are not a core ATen op.
        # See the comment block above ALLOW_LIST for more info.
        #
        # See https://github.com/pytorch/pytorch/issues/146049
        return True
    _, _, tags = res
    return Tag.core in tags


def check_bc(existing_schemas):
    new_schema_dict = load_schemas_to_dict()
    version_map = process_version_map(torch._C._get_operator_version_map())
    is_bc = True
    broken_ops = []
    for existing_schema in existing_schemas:
        is_allow_list, trust_not_core_aten = allow_listed(existing_schema)
        if is_allow_list:
            if trust_not_core_aten or not is_core_aten_op(existing_schema):
                log.info("schema: %s found on allowlist, skipping", existing_schema)
                continue
            else:
                log.info(
                    "schema: %s found on allowlist, but is a core ATen op, checking BC. "
                    "NOTE: If you have removed an operator we will conservatively assume that "
                    "it is a core ATen op. If the operator you removed is not a core ATen op, "
                    "please specify that in the ALLOW_LIST entry (see comment block on top "
                    "of ALLOW_LIST more info)",
                    existing_schema,
                )
        if has_valid_upgraders(existing_schema, version_map):
            if not is_core_aten_op(existing_schema):
                log.info("schema: %s has valid upgrader, skipping", existing_schema)
                continue
            else:
                log.info(
                    "schema: %s has a valid upgrader, but is a core ATen op, checking BC"
                )
        log.debug("processing existing schema: %s", existing_schema)
        matching_new_schemas = new_schema_dict.get(existing_schema.name, [])
        found = False
        for matching_new_schema in matching_new_schemas:
            if matching_new_schema.is_backward_compatible_with(existing_schema):
                found = True
                break
        if not found:
            log.warning(
                "Can NOT find backward compatible schemas after changes "
                "for schema %s from the following candidates:\n[\n%s\n]",
                str(existing_schema),
                "\n\t".join(str(s) for s in matching_new_schemas),
            )
            # TODO Print out more details about why candidates don't match.
            broken_ops.append(str(existing_schema))
            is_bc = False
    if is_bc:
        log.info("Found backward compatible schemas for all existing schemas")
    else:
        log.warning(
            "The PR is introducing backward incompatible changes to the "
            "operator library. Please contact PyTorch team to confirm "
            "whether this change is wanted or not. \n\nBroken ops: "
            "[\n\t%s\n]",
            "\n\t".join(broken_ops),
        )
    return is_bc


def check_fc(existing_schemas):
    new_schema_dict = load_schemas_to_dict()
    is_fc = True
    broken_ops = []
    for existing_schema in existing_schemas:
        is_allow_list, _ = allow_listed(existing_schema)
        if is_allow_list:
            log.info("schema: %s found on allowlist, skipping", existing_schema)
            continue
        log.info("processing existing schema: %s", existing_schema)
        matching_new_schemas = new_schema_dict.get(existing_schema.name, [])
        found = False
        possible_failure_reasons = []
        for matching_new_schema in matching_new_schemas:
            is_compatible, reason = matching_new_schema.check_forward_compatible_with(
                existing_schema
            )
            if is_compatible:
                found = True
                break
            if reason != "":
                possible_failure_reasons.append(reason)
        if not found:
            log.warning(
                "Can NOT find forward compatible schemas after changes "
                "for schema %s from the following candidates:\n[\n\t%s\n]",
                str(existing_schema),
                "\n\t".join(str(s) for s in matching_new_schemas),
            )
            log.warning(
                "Refer to following reasons for failure to find FC schema:\n[\n%s\n]",
                "\n\t".join(str(r) for r in possible_failure_reasons),
            )
            broken_ops.append(str(existing_schema))
            is_fc = False
    if is_fc:
        log.info("Found forward compatible schemas for all existing schemas")
    else:
        log.warning(
            "The PR is introducing a potentially forward incompatible changes to the "
            "operator library. Please contact PyTorch team to confirm "
            "whether this change is wanted or not. \n\nBroken ops: "
            "[\n\t%s\n]",
            "\n\t".join(broken_ops),
        )


if __name__ == "__main__":
    parser = argparse.ArgumentParser(description="Process some integers.")
    parser.add_argument(
        "--existing-schemas",
        help="filename to load existing schemas",
        type=str,
        default="schemas.txt",
    )
    args = parser.parse_args()
    existing_schema_dict = {}
    slist = []
    with open(args.existing_schemas) as f:
        while True:
            line = f.readline()
            if not line:
                break

            if dont_parse(line.strip()):
                log.info("Not parsing schema line: %s", line.strip())
                continue
            s = parse_schema(line.strip())
            slist.append(s)

    # TODO in case there is FC breaking changes,
    # we just warn for now until there is a policy.
    check_fc(slist)

    if not check_bc(slist):
        sys.exit(1)
