# -*- coding: utf-8 -*-
# Copyright 2013 The ChromiumOS Authors
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Define a type that wraps a Benchmark instance."""


import math

# FIXME(denik): Fix the import in chroot.
# pylint: disable=import-error
from scipy import stats


# See crbug.com/673558 for how these are estimated.
_estimated_stddev = {
    "octane": 0.015,
    "kraken": 0.019,
    "speedometer": 0.007,
    "speedometer2": 0.006,
    "dromaeo.domcoreattr": 0.023,
    "dromaeo.domcoremodify": 0.011,
    "graphics_WebGLAquarium": 0.008,
    "page_cycler_v2.typical_25": 0.021,
    "loading.desktop": 0.021,  # Copied from page_cycler initially
}


# Get #samples needed to guarantee a given confidence interval, assuming the
# samples follow normal distribution.
def _samples(b):
    # TODO: Make this an option
    # CI = (0.9, 0.02), i.e., 90% chance that |sample mean - true mean| < 2%.
    p = 0.9
    e = 0.02
    if b not in _estimated_stddev:
        return 1
    d = _estimated_stddev[b]
    # Get at least 2 samples so as to calculate standard deviation, which is
    # needed in T-test for p-value.
    n = int(math.ceil((stats.norm.isf((1 - p) / 2) * d / e) ** 2))
    return n if n > 1 else 2


class Benchmark(object):
    """Class representing a benchmark to be run.

    Contains details of the benchmark suite, arguments to pass to the suite,
    iterations to run the benchmark suite and so on. Note that the benchmark name
    can be different to the test suite name. For example, you may want to have
    two different benchmarks which run the same test_name with different
    arguments.
    """

    def __init__(
        self,
        name,
        test_name,
        test_args,
        iterations,
        rm_chroot_tmp,
        perf_args,
        suite="",
        show_all_results=False,
        retries=0,
        run_local=False,
        cwp_dso="",
        weight=0,
    ):
        self.name = name
        # For telemetry, this is the benchmark name.
        self.test_name = test_name
        # For telemetry, this is the data.
        self.test_args = test_args
        self.iterations = iterations if iterations > 0 else _samples(name)
        self.perf_args = perf_args
        self.rm_chroot_tmp = rm_chroot_tmp
        self.iteration_adjusted = False
        self.suite = suite
        self.show_all_results = show_all_results
        self.retries = retries
        if self.suite == "telemetry":
            self.show_all_results = True
        if run_local and self.suite != "telemetry_Crosperf":
            raise RuntimeError(
                "run_local is only supported by telemetry_Crosperf."
            )
        self.run_local = run_local
        self.cwp_dso = cwp_dso
        self.weight = weight