# 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

from fnmatch import fnmatch
from collections import defaultdict

from six.moves.urllib.parse import urlsplit

from taskgraph.optimize import register_strategy, registry, OptimizationStrategy
from taskgraph.util.bugbug import (
    BugbugTimeoutException,
    push_schedules,
    CT_HIGH,
    CT_MEDIUM,
    CT_LOW,
)
from taskgraph.util.hg import get_push_data

FALLBACK = "skip-unless-has-relevant-tests"


def merge_bugbug_replies(data, new_data):
    """Merge a bugbug reply (stored in the `new_data` argument) into another (stored
    in the `data` argument).
    """
    for key, value in new_data.items():
        if isinstance(value, dict):
            if key not in data:
                data[key] = {}

            if len(value) == 0:
                continue

            dict_value = next(iter(value.values()))
            if isinstance(dict_value, list):
                for name, configs in value.items():
                    if name not in data[key]:
                        data[key][name] = set()

                    data[key][name].update(configs)
            else:
                for name, confidence in value.items():
                    if name not in data[key] or data[key][name] < confidence:
                        data[key][name] = confidence
        elif isinstance(value, list):
            if key not in data:
                data[key] = set()

            data[key].update(value)


@register_strategy("bugbug-low", args=(CT_LOW,))
@register_strategy("bugbug-medium", args=(CT_MEDIUM,))
@register_strategy("bugbug-high", args=(CT_HIGH,))
@register_strategy("bugbug-tasks-medium", args=(CT_MEDIUM, True))
@register_strategy("bugbug-tasks-high", args=(CT_HIGH, True))
@register_strategy("bugbug-reduced", args=(CT_MEDIUM, True, True))
@register_strategy("bugbug-reduced-fallback", args=(CT_MEDIUM, True, True, FALLBACK))
@register_strategy("bugbug-reduced-high", args=(CT_HIGH, True, True))
@register_strategy("bugbug-reduced-manifests", args=(CT_MEDIUM, False, True))
@register_strategy(
    "bugbug-reduced-manifests-config-selection",
    args=(CT_MEDIUM, False, True, None, 1, True),
)
@register_strategy(
    "bugbug-reduced-manifests-fallback-low", args=(CT_LOW, False, True, FALLBACK)
)
@register_strategy(
    "bugbug-reduced-manifests-fallback", args=(CT_MEDIUM, False, True, FALLBACK)
)
@register_strategy(
    "bugbug-reduced-manifests-fallback-last-10-pushes",
    args=(0.3, False, True, FALLBACK, 10),
)
class BugBugPushSchedules(OptimizationStrategy):
    """Query the 'bugbug' service to retrieve relevant tasks and manifests.

    Args:
        confidence_threshold (float): The minimum confidence threshold (in
            range [0, 1]) needed for a task to be scheduled.
        tasks_only (bool): Whether or not to only use tasks and no groups
            (default: False)
        use_reduced_tasks (bool): Whether or not to use the reduced set of tasks
            provided by the bugbug service (default: False).
        fallback (str): The fallback strategy to use if there
            was a failure in bugbug (default: None)
        num_pushes (int): The number of pushes to consider for the selection
            (default: 1).
        select_configs (bool): Whether to select configurations for manifests
            too (default: False).
    """

    def __init__(
        self,
        confidence_threshold,
        tasks_only=False,
        use_reduced_tasks=False,
        fallback=None,
        num_pushes=1,
        select_configs=False,
    ):
        self.confidence_threshold = confidence_threshold
        self.use_reduced_tasks = use_reduced_tasks
        self.fallback = fallback
        self.tasks_only = tasks_only
        self.num_pushes = num_pushes
        self.select_configs = select_configs
        self.timedout = False

    def should_remove_task(self, task, params, importance):
        project = params["project"]

        if project not in ("autoland", "try"):
            return False

        current_push_id = int(params["pushlog_id"])

        branch = urlsplit(params["head_repository"]).path.strip("/")
        rev = params["head_rev"]

        if self.timedout:
            return registry[self.fallback].should_remove_task(task, params, importance)

        data = {}

        start_push_id = current_push_id - self.num_pushes + 1
        if self.num_pushes != 1:
            push_data = get_push_data(
                params["head_repository"], project, start_push_id, current_push_id - 1
            )

        for push_id in range(start_push_id, current_push_id + 1):
            if push_id == current_push_id:
                rev = params["head_rev"]
            else:
                rev = push_data[push_id]["changesets"][-1]

            try:
                new_data = push_schedules(branch, rev)
                merge_bugbug_replies(data, new_data)
            except BugbugTimeoutException:
                if not self.fallback:
                    raise

                self.timedout = True
                return self.should_remove_task(task, params, importance)

        key = "reduced_tasks" if self.use_reduced_tasks else "tasks"
        tasks = set(
            task
            for task, confidence in data.get(key, {}).items()
            if confidence >= self.confidence_threshold
        )

        test_manifests = task.attributes.get("test_manifests")
        if test_manifests is None or self.tasks_only:
            if data.get("known_tasks") and task.label not in data["known_tasks"]:
                return False

            if task.label not in tasks:
                return True

            return False

        # If a task contains more than one group, use the max confidence.
        groups = data.get("groups", {})
        confidences = [c for g, c in groups.items() if g in test_manifests]
        if not confidences or max(confidences) < self.confidence_threshold:
            return True

        # If the task configuration doesn't match the ones selected by bugbug for
        # the manifests, optimize out.
        if self.select_configs:
            selected_groups = [
                g
                for g, c in groups.items()
                if g in test_manifests and c > self.confidence_threshold
            ]

            config_groups = data.get("config_groups", defaultdict(list))

            if not any(
                fnmatch(task.label, config)
                for group in selected_groups
                for config in config_groups[group]
            ):
                return True

        # Store group importance so future optimizers can access it.
        for manifest in test_manifests:
            if manifest not in groups:
                continue

            confidence = groups[manifest]
            if confidence >= CT_HIGH:
                importance[manifest] = "high"
            elif confidence >= CT_MEDIUM:
                importance[manifest] = "medium"
            elif confidence >= CT_LOW:
                importance[manifest] = "low"
            else:
                importance[manifest] = "lowest"

        return False


@register_strategy("platform-debug")
class SkipUnlessDebug(OptimizationStrategy):
    """Only run debug platforms."""

    def should_remove_task(self, task, params, arg):
        return (
            "build_type" in task.attributes and task.attributes["build_type"] != "debug"
        )


@register_strategy("platform-disperse")
@register_strategy("platform-disperse-no-unseen", args=(None, 0))
@register_strategy(
    "platform-disperse-only-one",
    args=(
        {
            "high": 1,
            "medium": 1,
            "low": 1,
            "lowest": 0,
        },
        0,
    ),
)
class DisperseGroups(OptimizationStrategy):
    """Disperse groups across test configs.

    Each task has an associated 'importance' dict passed in via the arg. This
    is of the form `{<group>: <importance>}`.

    Where 'group' is a test group id (usually a path to a manifest), and 'importance' is
    one of `{'lowest', 'low', 'medium', 'high'}`.

    Each importance value has an associated 'count' as defined in
    `self.target_counts`. It guarantees that 'manifest' will run in at least
    'count' different configurations (assuming there are enough tasks
    containing 'manifest').

    On configurations that haven't been seen before, we'll increase the target
    count by `self.unseen_modifier` to increase the likelihood of scheduling a
    task on that configuration.

    Args:
        target_counts (dict): Override DEFAULT_TARGET_COUNTS with custom counts. This
            is a dict mapping the importance value ('lowest', 'low', etc) to the
            minimum number of configurations manifests with this value should run
            on.

        unseen_modifier (int): Override DEFAULT_UNSEEN_MODIFIER to a custom
            value. This is the amount we'll increase 'target_count' by for unseen
            configurations.
    """

    DEFAULT_TARGET_COUNTS = {
        "high": 3,
        "medium": 2,
        "low": 1,
        "lowest": 0,
    }
    DEFAULT_UNSEEN_MODIFIER = 1

    def __init__(self, target_counts=None, unseen_modifier=DEFAULT_UNSEEN_MODIFIER):
        self.target_counts = self.DEFAULT_TARGET_COUNTS.copy()
        if target_counts:
            self.target_counts.update(target_counts)
        self.unseen_modifier = unseen_modifier

        self.count = defaultdict(int)
        self.seen_configurations = set()

    def should_remove_task(self, task, params, importance):
        test_manifests = task.attributes.get("test_manifests")
        test_platform = task.attributes.get("test_platform")

        if not importance or not test_manifests or not test_platform:
            return False

        # Build the test configuration key.
        key = test_platform
        if "unittest_variant" in task.attributes:
            key += "-" + task.attributes["unittest_variant"]

        if not task.attributes["e10s"]:
            key += "-1proc"

        important_manifests = set(test_manifests) & set(importance)
        for manifest in important_manifests:
            target_count = self.target_counts[importance[manifest]]

            # If this configuration hasn't been seen before, increase the
            # likelihood of scheduling the task.
            if key not in self.seen_configurations:
                target_count += self.unseen_modifier

            if self.count[manifest] < target_count:
                # Update manifest counts and seen configurations.
                self.seen_configurations.add(key)
                for manifest in important_manifests:
                    self.count[manifest] += 1
                return False

        # Should remove task because all manifests have reached their
        # importance count (or there were no important manifests).
        return True