# 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/.

from __future__ import absolute_import, print_function, unicode_literals

import json
import os
import re
import sys
from collections import defaultdict

from mozboot.util import get_state_dir
from mozbuild.base import MozbuildObject
from mozpack.files import FileFinder
from moztest.resolve import TestResolver, get_suite_definition

import taskgraph
from taskgraph.generator import TaskGraphGenerator
from taskgraph.parameters import (
    ParameterMismatch,
    parameters_loader,
)
from taskgraph.taskgraph import TaskGraph

here = os.path.abspath(os.path.dirname(__file__))
build = MozbuildObject.from_environment(cwd=here)

# Some tasks show up in the target task set, but are possibly special cases,
# uncommon tasks, or tasks running against limited hardware set that they
# should only be selectable with --full.
TARGET_TASK_FILTERS = (
    r'-ccov/',
    r'windows10-aarch64/opt',
    r'win64-aarch64-laptop',
    r'windows10-64-ref-hw-2017',
    r'android-hw',
    r'android-geckoview-docs',
    r'linux1804-32',   # hide linux32 tests - bug 1599197
    r'linux-',  # hide all linux32 tasks by default - bug 1599197
    r'linux.*web-platform-tests.*-fis-',  # hide wpt linux fission tests - bug 1610879
)

PARAMETER_MISMATCH = """
ERROR - The parameters being used to generate tasks differ from those expected
by your working copy:

    {}

To fix this, either rebase onto the latest mozilla-central or pass in
-p/--parameters. For more information on how to define parameters, see:
https://firefox-source-docs.mozilla.org/taskcluster/taskcluster/mach.html#parameters
"""


def invalidate(cache):
    try:
        cmod = os.path.getmtime(cache)
    except OSError as e:
        # File does not exist. We catch OSError rather than use `isfile`
        # because the recommended watchman hook could possibly invalidate the
        # cache in-between the check to `isfile` and the call to `getmtime`
        # below.
        if e.errno == 2:
            return
        raise

    tc_dir = os.path.join(build.topsrcdir, 'taskcluster')
    tmod = max(os.path.getmtime(os.path.join(tc_dir, p)) for p, _ in FileFinder(tc_dir))

    if tmod > cmod:
        os.remove(cache)


def generate_tasks(params=None, full=False):
    cache_dir = os.path.join(get_state_dir(srcdir=True), 'cache', 'taskgraph')
    attr = 'full_task_set' if full else 'target_task_set'
    cache = os.path.join(cache_dir, attr)

    invalidate(cache)
    if os.path.isfile(cache):
        with open(cache, 'r') as fh:
            return TaskGraph.from_json(json.load(fh))[1]

    if not os.path.isdir(cache_dir):
        os.makedirs(cache_dir)

    print("Task configuration changed, generating {}".format(attr.replace('_', ' ')))

    taskgraph.fast = True
    cwd = os.getcwd()
    os.chdir(build.topsrcdir)

    root = os.path.join(build.topsrcdir, 'taskcluster', 'ci')
    params = parameters_loader(params, strict=False, overrides={'try_mode': 'try_select'})

    # Cache both full_task_set and target_task_set regardless of whether or not
    # --full was requested. Caching is cheap and can potentially save a lot of
    # time.
    generator = TaskGraphGenerator(root_dir=root, parameters=params)

    def generate(attr):
        try:
            tg = getattr(generator, attr)
        except ParameterMismatch as e:
            print(PARAMETER_MISMATCH.format(e.args[0]))
            sys.exit(1)

        # write cache
        with open(os.path.join(cache_dir, attr), 'w') as fh:
            json.dump(tg.to_json(), fh)
        return tg

    tg_full = generate('full_task_set')
    tg_target = generate('target_task_set')
    # discard results from these, we only need cache.
    if full:
        generate('full_task_graph')
    generate('target_task_graph')

    os.chdir(cwd)
    if full:
        return tg_full
    return tg_target


def filter_tasks_by_blacklist(task):
    """Checks task label against known task filters.

    Args:
        task (str): String representing the task name.

    Returns:
        (Boolean): True if task does not match any known filters.
        False otherwise.
    """
    return not any(re.search(pattern, task) for pattern in TARGET_TASK_FILTERS)


def filter_tasks_by_paths(tasks, paths):
    resolver = TestResolver.from_environment(cwd=here)
    run_suites, run_tests = resolver.resolve_metadata(paths)
    flavors = set([(t['flavor'], t.get('subsuite')) for t in run_tests])

    task_regexes = set()
    for flavor, subsuite in flavors:
        _, suite = get_suite_definition(flavor, subsuite, strict=True)
        if 'task_regex' not in suite:
            print("warning: no tasks could be resolved from flavor '{}'{}".format(
                    flavor, " and subsuite '{}'".format(subsuite) if subsuite else ""))
            continue

        task_regexes.update(suite['task_regex'])

    def match_task(task):
        return any(re.search(pattern, task) for pattern in task_regexes)

    return filter(match_task, tasks)


def resolve_tests_by_suite(paths):
    resolver = TestResolver.from_environment(cwd=here)
    _, run_tests = resolver.resolve_metadata(paths)

    suite_to_tests = defaultdict(list)

    # A dictionary containing all the input paths that we haven't yet
    # assigned to a specific test flavor.
    remaining_paths_by_suite = defaultdict(lambda: set(paths))

    for test in run_tests:
        key, _ = get_suite_definition(test['flavor'], test.get('subsuite'), strict=True)

        test_path = test.get('srcdir_relpath')
        if test_path is None:
            continue
        found_path = None
        for path in remaining_paths_by_suite[key]:
            if test_path.startswith(path):
                found_path = path
                break
        if found_path:
            suite_to_tests[key].append(found_path)
            remaining_paths_by_suite[key].remove(found_path)

    return suite_to_tests