# Copyright (c) Facebook, Inc. and its affiliates. (http://www.facebook.com)
import argparse
import dis
import types

from typing import Dict, List, Tuple


CountAssocs = List[Tuple[str, int]]
Histogram = Dict[str, int]


def count_bytecode(func: types.FunctionType, histo: Histogram) -> None:
    """Return a distribution of bytecode in func"""
    for instr in dis.get_instructions(func):
        if instr.opname in histo:
            histo[instr.opname] += 1
        else:
            histo[instr.opname] = 1


def summarize(obj: object, histo: Histogram) -> None:
    """Compute the bytecode histogram of all functions reachable from obj"""
    if isinstance(obj, types.FunctionType):
        count_bytecode(obj, histo)
    elif isinstance(obj, type):
        for child in obj.__dict__.values():
            summarize(child, histo)


SORT_ALPHA = "alpha"
SORT_COUNT = "count"
SORT_OPTIONS = (SORT_ALPHA, SORT_COUNT)

def sort_alpha(histo: Histogram) -> CountAssocs:
    ordered = sorted(histo.items(), key=lambda p: p[0])
    return list(ordered)


def sort_count(histo: Histogram) -> CountAssocs:
    ordered = sorted(histo.items(), key=lambda p: p[1], reverse=True)
    return list(ordered)


SORT_FUNCS = {
    SORT_ALPHA: sort_alpha,
    SORT_COUNT: sort_count,
}


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description=
    """
Read and exec the contents of path and dump the distribution of
bytecode for every function that was created.
"""
    )
    parser.add_argument("path", help="path to file to exec")
    parser.add_argument("--sort", help="how to sort the output",
                        default=SORT_COUNT, choices=SORT_OPTIONS)
    args = parser.parse_args()
    with open(args.path) as f:
        data = f.read()
    globals = {}
    exec(data, globals, globals)
    histo = {}
    for obj in globals.values():
        summarize(obj, histo)
    ordered = SORT_FUNCS[args.sort](histo)
    for name, count in ordered:
        print("%-20s %d" % (name, count))