/*
 * Copyright © 2020 Atomist, Inc.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

import {
    EventHandler,
    Value,
} from "@atomist/automation-client/lib/decorators";
import { automationClientInstance } from "@atomist/automation-client/lib/globals";
import { subscription } from "@atomist/automation-client/lib/graph/graphQL";
import {
    EventFired,
    HandleEvent,
} from "@atomist/automation-client/lib/HandleEvent";
import { HandlerContext } from "@atomist/automation-client/lib/HandlerContext";
import {
    HandlerResult,
    Success,
} from "@atomist/automation-client/lib/HandlerResult";
import { logger } from "@atomist/automation-client/lib/util/logger";
import { fetchGoalsFromPush } from "../../../../../api-helper/goal/fetchGoalsOnCommit";
import { mapKeyToGoal } from "../../../../../api-helper/goal/sdmGoal";
import { updateGoal } from "../../../../../api-helper/goal/storeGoals";
import { SdmGoalEvent } from "../../../../../api/goal/SdmGoalEvent";
import { SdmGoalKey } from "../../../../../api/goal/SdmGoalMessage";
import { SoftwareDeliveryMachineConfiguration } from "../../../../../api/machine/SoftwareDeliveryMachineOptions";
import {
    OnAnyFailedSdmGoal,
    SdmGoalState,
} from "../../../../../typings/types";
import { shouldHandle } from "../../../../delivery/goals/support/validateGoal";
import { verifyGoal } from "../../../../signing/goalSigning";

/**
 * Skip downstream goals on failed or stopped goal
 */
@EventHandler("Skip downstream goals on failed, stopped or canceled goal",
    () => subscription({
        name: "OnAnyFailedSdmGoal",
        variables: { registration: () => [automationClientInstance()?.configuration?.name] },
    }))
export class SkipDownstreamGoalsOnGoalFailure implements HandleEvent<OnAnyFailedSdmGoal.Subscription> {

    @Value("")
    public configuration: SoftwareDeliveryMachineConfiguration;

    public async handle(event: EventFired<OnAnyFailedSdmGoal.Subscription>,
                        context: HandlerContext): Promise<HandlerResult> {
        let failedGoal = event.data.SdmGoal[0] as SdmGoalEvent;

        if (!shouldHandle(failedGoal)) {
            logger.debug(`Goal ${failedGoal.uniqueName} skipped because not managed by this SDM`);
            return Success;
        }

        failedGoal = await verifyGoal(failedGoal, this.configuration.sdm.goalSigning, context);

        const goals = fetchGoalsFromPush(failedGoal);

        const goalsToSkip = goals.filter(g => isDependentOn(failedGoal, g, mapKeyToGoal(goals)))
            .filter(g => g.state === "planned");

        let failedGoalState;
        let failedGoalDescription;
        switch (failedGoal.state) {
            case SdmGoalState.failure:
                failedGoalDescription = "failed";
                failedGoalState = SdmGoalState.skipped;
                break;
            case SdmGoalState.stopped:
                failedGoalDescription = "stopped goals";
                failedGoalState = SdmGoalState.skipped;
                break;
            case SdmGoalState.canceled:
                failedGoalDescription = "was canceled";
                failedGoalState = SdmGoalState.canceled;
                break;
        }
        await Promise.all(goalsToSkip.map(g => updateGoal(context, g, {
            state: failedGoalState,
            description: `${failedGoalState === SdmGoalState.skipped ? "Skipped" : "Canceled"
            } ${g.name} because ${failedGoal.name} ${failedGoalDescription}`,
        })));

        return Success;
    }
}

function isDependentOn(failedGoal: SdmGoalKey, goal: SdmGoalEvent, preconditionToGoal: (g: SdmGoalKey) => SdmGoalEvent): boolean {
    if (!goal) {
        return false;
    }
    if (!goal.preConditions || goal.preConditions.length === 0) {
        return false; // no preconditions? not dependent
    }
    if (mapKeyToGoal(goal.preConditions)(failedGoal)) {
        return true; // the failed goal is one of my preconditions? dependent
    }
    // otherwise, recurse on my preconditions
    return !!goal.preConditions
        .map(precondition => isDependentOn(failedGoal, preconditionToGoal(precondition), preconditionToGoal))
        .find(a => a); // if one is true, return true
}