# 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/.

# Combined with build/autoconf/config.status.m4, ConfigStatus is an almost
# drop-in replacement for autoconf 2.13's config.status, with features
# borrowed from autoconf > 2.5, and additional features.

import logging
import os
import sys
import time
from argparse import ArgumentParser
from itertools import chain
from multiprocessing import Pool, get_start_method
from time import process_time

from mach.logging import LoggingManager

from mozbuild.backend import backends, get_backend_class
from mozbuild.backend.configenvironment import ConfigEnvironment
from mozbuild.base import MachCommandConditions
from mozbuild.frontend.emitter import TreeMetadataEmitter
from mozbuild.frontend.reader import BuildReader
from mozbuild.mozinfo import write_mozinfo
from mozbuild.util import FileAvoidWrite

log_manager = LoggingManager()


ANDROID_IDE_ADVERTISEMENT = """
=============
ADVERTISEMENT

You are building GeckoView. After your build completes, you can open
the top source directory in Android Studio directly and build using Gradle.
See the documentation at

https://firefox-source-docs.mozilla.org/mobile/android/index.html#build-using-android-studio
=============
""".strip()


## Parallel backend setup
# Distributing each backend on different process is costly because we need to
# copy the definitions across each process. These definitions are read-only, so
# only copy them once when each process starts.


class BackendPool:
    per_process_definitions = None

    def __init__(self, definitions, *, processes=None):
        definitions = list(definitions)
        BackendPool._init_worker(definitions)
        self.pool = Pool(
            initializer=BackendPool._init_worker,
            initargs=(definitions,),
            processes=processes,
        )

    def run(self, backends):
        # We're trying to spawn a minimal number of new processes there, and
        # limit the number of times we serialize the task state. As a
        # consequence:
        # 1. we initialize each process with a copy of `definitions'
        # 2. instead of spawning as many processes as backend, we use current
        #    process to handle one of the backend and asynchronously run the
        #    others.
        async_tasks = self.pool.map_async(BackendPool._run_worker, backends[1:])
        BackendPool._run_worker(backends[0])
        async_tasks.wait()

    @staticmethod
    def _init_worker(state):
        BackendPool.per_process_definitions = state

    @staticmethod
    def _run_worker(backend):
        return backend.consume(BackendPool.per_process_definitions)


def config_status(
    topobjdir=".",
    topsrcdir=".",
    defines=None,
    substs=None,
    source=None,
    mozconfig=None,
    args=sys.argv[1:],
):
    """Main function, providing config.status functionality.

    Contrary to config.status, it doesn't use CONFIG_FILES or CONFIG_HEADERS
    variables.

    Without the -n option, this program acts as config.status and considers
    the current directory as the top object directory, even when config.status
    is in a different directory. It will, however, treat the directory
    containing config.status as the top object directory with the -n option.

    The options to this function are passed when creating the
    ConfigEnvironment. These lists, as well as the actual wrapper script
    around this function, are meant to be generated by configure.
    See build/autoconf/config.status.m4.
    """

    if "CONFIG_FILES" in os.environ:
        raise Exception("Using the CONFIG_FILES environment variable is not supported.")
    if "CONFIG_HEADERS" in os.environ:
        raise Exception(
            "Using the CONFIG_HEADERS environment variable is not supported."
        )

    if not os.path.isabs(topsrcdir):
        raise Exception(
            "topsrcdir must be defined as an absolute directory: %s" % topsrcdir
        )

    default_backends = ["RecursiveMake"]
    default_backends = (substs or {}).get("BUILD_BACKENDS", ["RecursiveMake"])

    parser = ArgumentParser()
    parser.add_argument(
        "-v",
        "--verbose",
        dest="verbose",
        action="store_true",
        help="display verbose output",
    )
    parser.add_argument(
        "-n",
        dest="not_topobjdir",
        action="store_true",
        help="do not consider current directory as top object directory",
    )
    parser.add_argument(
        "-d", "--diff", action="store_true", help="print diffs of changed files."
    )
    parser.add_argument(
        "-b",
        "--backend",
        nargs="+",
        choices=sorted(backends),
        default=default_backends,
        help="what backend to build (default: %s)." % " ".join(default_backends),
    )
    parser.add_argument(
        "--dry-run", action="store_true", help="do everything except writing files out."
    )
    options = parser.parse_args(args)

    # Without -n, the current directory is meant to be the top object directory
    if not options.not_topobjdir:
        topobjdir = os.path.realpath(".")

    env = ConfigEnvironment(
        topsrcdir,
        topobjdir,
        defines=defines,
        substs=substs,
        source=source,
        mozconfig=mozconfig,
    )

    with FileAvoidWrite(os.path.join(topobjdir, "mozinfo.json")) as f:
        write_mozinfo(f, env, os.environ)

    cpu_start = process_time()
    time_start = time.monotonic()

    # Make appropriate backend instances, defaulting to RecursiveMakeBackend,
    # or what is in BUILD_BACKENDS.
    selected_backends = [get_backend_class(b)(env) for b in options.backend]

    if options.dry_run:
        for b in selected_backends:
            b.dry_run = True

    reader = BuildReader(env)
    emitter = TreeMetadataEmitter(env)
    # This won't actually do anything because of the magic of generators.
    definitions = emitter.emit(reader.read_topsrcdir())

    log_level = logging.DEBUG if options.verbose else logging.INFO
    log_manager.add_terminal_logging(level=log_level)
    log_manager.enable_unstructured()

    print("Reticulating splines...", file=sys.stderr)

    # `definitions` objects are unfortunately not picklable, which is a
    # requirement for "spawn" method. It's fine under "fork" method. This
    # basically excludes Windows from our optimization, we can live with it.
    if len(selected_backends) > 1 and get_start_method() == "fork":
        # See https://github.com/python/cpython/commit/39889864c09741909da4ec489459d0197ea8f1fc
        # For why we cap the process count. There's also an overhead to setup
        # new processes, and not that many backends anyway.
        processes = min(len(selected_backends) - 1, 4)
        pool = BackendPool(definitions, processes=processes)
        pool.run(selected_backends)
    else:
        if len(selected_backends) > 1:
            definitions = list(definitions)

        for backend in selected_backends:
            backend.consume(definitions)

    execution_time = 0.0
    for obj in chain((reader, emitter), selected_backends):
        summary = obj.summary()
        print(summary, file=sys.stderr)
        execution_time += summary.execution_time
        if hasattr(obj, "gyp_summary"):
            summary = obj.gyp_summary()
            print(summary, file=sys.stderr)

    cpu_time = process_time() - cpu_start
    wall_time = time.monotonic() - time_start
    efficiency = cpu_time / wall_time if wall_time else 100
    untracked = wall_time - execution_time

    print(
        f"Total wall time: {wall_time:.2f}s; CPU time: {cpu_time:.2f}s; Efficiency: "
        f"{efficiency:.0%}; Untracked: {untracked:.2f}s",
        file=sys.stderr,
    )

    if options.diff:
        for the_backend in selected_backends:
            for path, diff in sorted(the_backend.file_diffs.items()):
                print("\n".join(diff))

    # Advertise Android Studio if it is appropriate.
    if MachCommandConditions.is_android(env):
        print(ANDROID_IDE_ADVERTISEMENT)
