# This Source Code Form is subject to the terms of the Mozilla Public
# License, v. 2.0. If a copy of the MPL was not distributed with this
# file, You can obtain one at http://mozilla.org/MPL/2.0/.

# Write out a C++ enum definition whose members are the names of
# histograms as well as the following other members:
#
#   - HistogramCount
#   - HistogramFirstUseCounter
#   - HistogramLastUseCounter
#   - HistogramUseCounterCount
#
# The histograms are defined in files provided as command-line arguments.

import histogram_tools
import itertools
import sys

banner = """/* This file is auto-generated, see gen-histogram-enum.py.  */
"""

def main(argv):
    filenames = argv

    print banner
    print "enum ID : uint32_t {"

    groups = itertools.groupby(histogram_tools.from_files(filenames),
                               lambda h: h.name().startswith("USE_COUNTER_"))
    seen_use_counters = False

    # Note that histogram_tools.py guarantees that all of the USE_COUNTER_*
    # histograms are defined in a contiguous block.  We therefore assume
    # that there's at most one group for which use_counter_group is true.
    for (use_counter_group, histograms) in groups:
        if use_counter_group:
            seen_use_counters = True

        # The HistogramDUMMY* enum variables are used to make the computation
        # of Histogram{First,Last}UseCounter easier.  Otherwise, we'd have to
        # special case the first and last histogram in the group.
        if use_counter_group:
            print "  HistogramFirstUseCounter,"
            print "  HistogramDUMMY1 = HistogramFirstUseCounter - 1,"

        for histogram in histograms:
            cpp_guard = histogram.cpp_guard()
            if cpp_guard:
                print "#if defined(%s)" % cpp_guard
            print "  %s," % histogram.name()
            if cpp_guard:
                print "#endif"

        if use_counter_group:
            print "  HistogramDUMMY2,"
            print "  HistogramLastUseCounter = HistogramDUMMY2 - 1,"

    print "  HistogramCount,"
    if seen_use_counters:
        print "  HistogramUseCounterCount = HistogramLastUseCounter - HistogramFirstUseCounter + 1"
    else:
        print "  HistogramUseCounterCount = 0"
    print "};"

main(sys.argv[1:])