// Copyright 2016-2018, Pulumi Corporation.
//
// 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 { all, Input, Output, output } from "./output";
import { CustomResource, CustomResourceOptions } from "./resource";

/**
 * Manages a reference to a Pulumi stack. The referenced stack's outputs are available via the
 * `outputs` property or the `output` method.
 */
export class StackReference extends CustomResource {
    /**
     * The name of the referenced stack.
     */
    public readonly name!: Output<string>;

    /**
     * The outputs of the referenced stack.
     */
    public readonly outputs!: Output<{[name: string]: any}>;

    /**
     * The names of any stack outputs which contain secrets.
     */
    public readonly secretOutputNames!: Output<string[]>;

    /**
     * Create a StackReference resource with the given unique name, arguments, and options.
     *
     * If args is not specified, the name of the referenced stack will be the name of the StackReference resource.
     *
     * @param name The _unique_ name of the stack reference.
     * @param args The arguments to use to populate this resource's properties.
     * @Param opts A bag of options that control this resource's behavior.
     */
    constructor(name: string, args?: StackReferenceArgs, opts?: CustomResourceOptions) {
        args = args || {};

        const stackReferenceName = args.name || name;

        super("pulumi:pulumi:StackReference", name, {
            name: stackReferenceName,
            outputs: undefined,
            secretOutputNames: undefined,
        }, { ...opts, id: stackReferenceName });
    }

    /**
     * Fetches the value of the named stack output, or undefined if the stack output was not found.
     *
     * @param name The name of the stack output to fetch.
     */
    public getOutput(name: Input<string>): Output<any> {
        // Note that this is subtly different from "apply" here. A default "apply" will set the secret bit if any
        // of the inputs are a secret, and this.outputs is always a secret if it contains any secrets. We do this dance
        // so we can ensure that the Output we return is not needlessly tainted as a secret.
        const value = all([output(name), this.outputs]).apply(([n, os]) => os[n]);

        // 'value' is an Output produced by our own `.apply` implementation.  So it's safe to
        // `.allResources!` on it.
        return new Output(
            value.resources(), value.promise(),
            value.isKnown, isSecretOutputName(this, output(name)),
            value.allResources!());
    }

    /**
     * Fetches the value of the named stack output, or throws an error if the output was not found.
     *
     * @param name The name of the stack output to fetch.
     */
    public requireOutput(name: Input<string>): Output<any> {
        const value = all([output(this.name), output(name), this.outputs]).apply(([stackname, n, os]) => {
            if (!os.hasOwnProperty(n)) {
                throw new Error(`Required output '${n}' does not exist on stack '${stackname}'.`);
            }
            return os[n];
        });
        return new Output(
            value.resources(), value.promise(),
            value.isKnown, isSecretOutputName(this, output(name)),
            value.allResources!());
    }

    /**
     * Fetches the value promptly of the named stack output. May return undefined if the value is
     * not known for some reason.
     *
     * This operation is not supported (and will throw) if the named stack output is a secret.
     *
     * @param name The name of the stack output to fetch.
     */
    public async getOutputValue(name: string): Promise<any> {
        const [out, isSecret] = await this.readOutputValue("getOutputValue", name, false /*required*/);
        if (isSecret) {
            throw new Error("Cannot call 'getOutputValue' if the referenced stack output is a secret. Use 'getOutput' instead.");
        }
        return out;
    }

    /**
     * Fetches the value promptly of the named stack output. Throws an error if the stack output is
     * not found.
     *
     * This operation is not supported (and will throw) if the named stack output is a secret.
     *
     * @param name The name of the stack output to fetch.
     */
    public async requireOutputValue(name: string): Promise<any> {
        const [out, isSecret] = await this.readOutputValue("requireOutputSync", name, true /*required*/);
        if (isSecret) {
            throw new Error("Cannot call 'requireOutputValue' if the referenced stack output is a secret. Use 'requireOutput' instead.");
        }
        return out;
    }

    private async readOutputValue(callerName: string, outputName: string, required: boolean): Promise<[any, boolean]> {
        const out = required ? this.requireOutput(outputName) : this.getOutput(outputName);
        return Promise.all([out.promise(), out.isSecret]);
    }
}

// Shape of the result that the engine returns to us when we invoke 'pulumi:pulumi:readStackOutputs'
interface ReadStackOutputsResult {
    name: string;
    outputs: Record<string, any>;
    secretOutputNames: string[];
}

/**
 * The set of arguments for constructing a StackReference resource.
 */
export interface StackReferenceArgs {
    /**
     * The name of the stack to reference.
     */
    readonly name?: Input<string>;
}

async function isSecretOutputName(sr: StackReference, name: Input<string>): Promise<boolean> {
    const nameOutput = output(name);

    // If either the name or set of secret outputs is unknown, we can't do anything smart, so we just copy the
    // secretness from the entire outputs value.
    if (!((await nameOutput.isKnown) && (await sr.secretOutputNames.isKnown))) {
        return await sr.outputs.isSecret;
    }

    // Otherwise, if we have a list of outputs we know are secret, we can use that list to determine if this
    // output should be secret. Names could be falsy here in cases where we are using an older CLI that did
    // not return this information (in this case we again fallback to the secretness of outputs value).
    const names = await sr.secretOutputNames.promise();
    if (!names) {
        return await sr.outputs.isSecret;
    }

    return names.includes(await nameOutput.promise());
}