# Copyright 2024 The JAX Authors.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
from __future__ import annotations

from dataclasses import dataclass, field
from typing import Any, Callable, Protocol, Sequence
import numpy as np

import jax.numpy as jnp
from jax.sharding import NamedSharding
from jax._src import api
from jax._src import core
from jax._src import source_info_util
from jax._src import traceback_util
from jax._src import util
from jax._src.api import make_jaxpr
from jax._src.interpreters.partial_eval import dce_jaxpr
from jax._src.mesh import AbstractMesh, Mesh
from jax._src.tree_util import broadcast_prefix, tree_flatten, tree_unflatten, tree_map
from jax._src.util import foreach
from jax.experimental import shard_map


ShapeDtypeStructTree = Any


map = util.safe_map


@dataclass(frozen=True, slots=True, kw_only=True)
class RooflineRuleContext:
  name_stack: source_info_util.NameStack
  primitive: core.Primitive
  avals_in: Sequence[core.AbstractValue]
  avals_out: Sequence[core.AbstractValue]
  jaxpr_eqn_ctx: core.JaxprEqnContext
  mesh: Mesh | AbstractMesh | None
  pin_lhs_in_vmem: bool
  pin_rhs_in_vmem: bool


@dataclass(frozen=True, slots=True, kw_only=True)
class RooflineShape:
  shape: tuple[int, ...]
  dtype: np.dtype

  @classmethod
  def from_aval(cls, aval: core.AbstractValue) -> "RooflineShape":
    if not isinstance(aval, core.ShapedArray):
      raise TypeError(f"Expected ShapedArray, got {type(aval)}.")
    if not isinstance(aval.dtype, np.dtype):
      raise TypeError(f"Expected numpy dtype, got {type(aval.dtype)}.")
    return cls(shape=aval.shape, dtype=aval.dtype)

  @property
  def size(self) -> int:
    return int(np.prod(self.shape))

  @property
  def bytes(self) -> int:
    return int(self.size * self.dtype.itemsize)

  @classmethod
  def total_bytes(cls, avals: Sequence[core.AbstractValue]) -> int:
    return sum(cls.from_aval(aval).bytes for aval in avals)


@dataclass(frozen=True, slots=True, kw_only=True)
class RooflineResult:
  flops: int = 0
  unfused_flops: int = 0
  ici_bytes: dict[str, int] = field(default_factory=dict)
  ici_latency: dict[str, int] = field(default_factory=dict)
  hbm_bytes: int = 0
  peak_hbm_bytes: int = 0
  unfused_hbm_bytes: int = 0

  @classmethod
  def zeros(cls) -> "RooflineResult":
    return cls()

  def __add__(self, other: "RooflineResult") -> "RooflineResult":
    def merge_ici_dicts(d1: dict[str, int], d2: dict[str, int]) -> dict[str, int]:
      return {k: d1.get(k, 0) + d2.get(k, 0) for k in set(d1) | set(d2)}

    return RooflineResult(
        flops=self.flops + other.flops,
        unfused_flops=self.unfused_flops + other.unfused_flops,
        ici_bytes=merge_ici_dicts(self.ici_bytes, other.ici_bytes),
        ici_latency=merge_ici_dicts(self.ici_latency, other.ici_latency),
        hbm_bytes=self.hbm_bytes + other.hbm_bytes,
        peak_hbm_bytes=max(self.peak_hbm_bytes, other.peak_hbm_bytes),
        unfused_hbm_bytes=self.unfused_hbm_bytes + other.unfused_hbm_bytes,
    )

  def __mul__(self, constant: int | float) -> "RooflineResult":
    return RooflineResult(
        flops=int(self.flops * constant),
        unfused_flops=int(self.unfused_flops * constant),
        ici_bytes={k: int(v * constant) for k, v in self.ici_bytes.items()},
        ici_latency={k: int(v * constant) for k, v in self.ici_latency.items()},
        hbm_bytes=int(self.hbm_bytes * constant),
        peak_hbm_bytes=int(self.peak_hbm_bytes * constant),
        unfused_hbm_bytes=int(self.unfused_hbm_bytes * constant),
    )

  def __rmul__(self, constant: int | float) -> "RooflineResult":
    return self.__mul__(constant)


class _RooflineRule(Protocol):
  def __call__(
    self, ctx: RooflineRuleContext, *args: RooflineShape, **kw
  ) -> RooflineResult: ...


_rooflines: dict[core.Primitive, _RooflineRule] = {}


def _roofline_interpreter(
  f_name: str,
  jaxpr: core.Jaxpr,
  mesh: Mesh | AbstractMesh,
  *,
  pin_lhs_in_vmem: bool = False,
  pin_rhs_in_vmem: bool = False,
) -> RooflineResult:
  name_stack = source_info_util.new_name_stack(util.wrap_name(f_name, "roofline"))

  result = RooflineResult.zeros()

  env: dict[core.Var, RooflineShape] = {}

  def write(v: core.Var, node: RooflineShape):
    assert node is not None
    env[v] = node

  def read(v: core.Atom) -> RooflineShape:
    if type(v) is core.Literal:
      return RooflineShape.from_aval(core.abstractify(v.val))
    else:
      assert isinstance(v, core.Var)
      return env[v]

  def aval(v: core.Atom) -> core.AbstractValue:
    if type(v) is core.Literal:
      return core.abstractify(v.val)
    else:
      return v.aval

  def calculate_peak_hbm_bytes() -> int:
    return int(
      sum(np.prod(shape.shape) * shape.dtype.itemsize for shape in env.values())
    )

  jaxpr = jaxpr.jaxpr if isinstance(jaxpr, core.ClosedJaxpr) else jaxpr
  make_roofline_shape = lambda x: RooflineShape.from_aval(aval(x))
  foreach(
    write,
    jaxpr.constvars,
    map(make_roofline_shape, jaxpr.constvars),
  )
  foreach(write, jaxpr.invars, map(make_roofline_shape, jaxpr.invars))
  last_used = core.last_used(jaxpr)
  for eqn in jaxpr.eqns:
    source_info = eqn.source_info.replace(
      name_stack=name_stack + eqn.source_info.name_stack
    )
    with source_info_util.user_context(
      eqn.source_info.traceback, name_stack=source_info.name_stack
    ):
      if "jaxpr" in eqn.params:
        result += _roofline_interpreter(
          util.wrap_name(f_name, eqn.primitive.name),
          eqn.params["jaxpr"],
          mesh,
          pin_lhs_in_vmem=pin_lhs_in_vmem,
          pin_rhs_in_vmem=pin_rhs_in_vmem,
        )
      else:
        if eqn.primitive not in _rooflines:
          msg = f"No roofline rule for {eqn.primitive}."
          for attr in dir(eqn):
            if not attr.startswith("_"):
              msg += f"\n{attr}: {getattr(eqn, attr)}"
          raise NotImplementedError(msg)
        rule = _rooflines[eqn.primitive]
        result += rule(
          RooflineRuleContext(
            name_stack=source_info.name_stack,
            primitive=eqn.primitive,
            avals_in=map(aval, eqn.invars),
            avals_out=map(aval, eqn.outvars),
            jaxpr_eqn_ctx=eqn.ctx,
            mesh=mesh,
            pin_lhs_in_vmem=pin_lhs_in_vmem,
            pin_rhs_in_vmem=pin_rhs_in_vmem,
          ),
          *map(read, eqn.invars),
          **eqn.params,
        )

      foreach(write, eqn.outvars, map(make_roofline_shape, eqn.outvars))
      core.clean_up_dead_vars(eqn, env, last_used)
      result += RooflineResult(peak_hbm_bytes=calculate_peak_hbm_bytes())

  return result


def _f_with_vjp(f: Callable):
  @util.wraps(f)
  def wrapped(*args):
    primals, f_vjp = api.vjp(f, *args)
    return f_vjp(tree_map(jnp.bfloat16, primals))

  return wrapped


def roofline(
    f: Callable,
    mesh: Mesh | AbstractMesh | None = None,
    in_specs: shard_map.Specs | None = None,
    out_specs: shard_map.Specs | None = None,
    *,
    pin_lhs_in_vmem: bool = False,
    pin_rhs_in_vmem: bool = False,
    vjp: bool = False,
    print_jaxpr: bool = False,
) -> Callable[..., tuple[ShapeDtypeStructTree, RooflineResult]]:
  @util.wraps(f)
  @traceback_util.api_boundary
  def wrapped(*args):
    wrapped_f = f
    if in_specs is not None and out_specs is not None and mesh is not None:
      wrapped_f = shard_map.shard_map(wrapped_f, mesh, in_specs, out_specs)
    if vjp:
      wrapped_f = _f_with_vjp(wrapped_f)

    jaxpr, out_shapes = make_jaxpr(wrapped_f, return_shape=True)(*args)

    def make_sharded_shape_dtype_struct(
      shape: api.ShapeDtypeStruct, out_spec: shard_map.Specs
    ) -> api.ShapeDtypeStruct:
      return api.ShapeDtypeStruct(
        shape.shape, shape.dtype, sharding=NamedSharding(mesh, out_spec)  # type: ignore
      )

    if out_specs is not None and mesh is not None:
      out_specs_flat = broadcast_prefix(out_specs, out_shapes)
      flat_out_shapes, treedef = tree_flatten(out_shapes)
      flat_out_shapes = map(
          make_sharded_shape_dtype_struct, flat_out_shapes, out_specs_flat
      )
      out_shapes = tree_unflatten(treedef, flat_out_shapes)

    used_outputs = (True,) * len(jaxpr.jaxpr.outvars)
    jaxpr, _ = dce_jaxpr(jaxpr.jaxpr, used_outputs)
    shard_map_eqns = [
        e for e in jaxpr.eqns if e.primitive == shard_map.shard_map_p
    ]
    if shard_map_eqns:
      try:
        jaxpr = shard_map_eqns[-1].params["jaxpr"]
      except KeyError:
        raise ValueError(f"Missing shard_map jaxpr in {jaxpr}.")

    if print_jaxpr:
      print(jaxpr)

    return out_shapes, _roofline_interpreter(
        util.fun_qual_name(f),
        jaxpr,
        mesh,
        pin_lhs_in_vmem=pin_lhs_in_vmem,
        pin_rhs_in_vmem=pin_rhs_in_vmem,
    )

  return wrapped


def register_roofline(prim: core.Primitive):
  def register(rule: _RooflineRule):
    _rooflines[prim] = rule
    return rule

  return register


def register_standard_roofline(prim: core.Primitive):
  def standard_rule(ctx: RooflineRuleContext, *args, **kwargs):
    return RooflineResult.zeros()

  _rooflines[prim] = standard_rule


def roofline_and_grad(
  f: Callable,
  mesh: Mesh | AbstractMesh,
  in_specs: shard_map.Specs,
  out_specs: shard_map.Specs,
  *,
  pin_lhs_in_vmem: bool = False,
  pin_rhs_in_vmem: bool = False,
  print_jaxpr: bool = False,
) -> Callable[..., tuple[ShapeDtypeStructTree, RooflineResult, RooflineResult]]:
  @util.wraps(f)
  @traceback_util.api_boundary
  def wrapped(*args):
    primal_shapes, fwd_result = roofline(
      f,
      mesh,
      in_specs,
      out_specs,
      pin_lhs_in_vmem=pin_lhs_in_vmem,
      pin_rhs_in_vmem=pin_rhs_in_vmem,
      print_jaxpr=print_jaxpr,
    )(*args)

    return (
      primal_shapes,
      fwd_result,
      roofline(
        f,
        mesh,
        in_specs,
        out_specs,
        pin_lhs_in_vmem=pin_lhs_in_vmem,
        pin_rhs_in_vmem=pin_rhs_in_vmem,
        vjp=True,
        print_jaxpr=print_jaxpr,
      )(
        *tree_map(
          lambda x: api.ShapeDtypeStruct(
            x.shape,
            jnp.int32 if x.dtype == jnp.int32 else jnp.bfloat16,
            sharding=x.sharding,
          ),
          args,
        )
      )[1],
    )

  return wrapped