/*
 * 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.
 */

/** Input to [[labelName]]. */
export interface Labels {
	/** Project environment, e.g., "staging" or "production". */
	environment: string;
	/** Project purpose, e.g., "general" or "skill". */
	purpose: string;
	/** Project user, e.g., "internal" or "customer". */
	user: string;
	/** Maximum length of string to return. */
	length?: number;
	/** Resource prefix to prepend to string. */
	resource?: string;
}

/**
 * Create valid Atomist GCP resource labels from `labels`.
 */
export function resourceLabels(
	labels: Pick<Labels, "environment" | "purpose" | "user">,
): Record<"atm-env" | "atm-purpose" | "atm-user", string> {
	return {
		"atm-env": labels.environment,
		"atm-purpose": labels.purpose,
		"atm-user": labels.user,
	};
}

/** Only include purpose if it provides information. */
function includePurpose(labels: Labels): boolean {
	return (
		labels.purpose !== "general" && labels.purpose !== labels.environment
	);
}

/**
 * Generate name from environment, purpose, and user. The returned
 * name will be lower cased and not exceed `labels.length`, if
 * provided. If the name is truncated to `labels.length`, it is
 * truncated to an alphanumeric character.
 *
 * @param labels components of name, see [[Labels]].
 * @return name generated from labels
 */
export function labelName(labels: Labels): string {
	const parts: string[] = [];
	if (labels.resource) {
		parts.push(labels.resource);
	}
	parts.push(labels.user);
	if (includePurpose(labels)) {
		parts.push(labels.purpose);
	}
	parts.push(labels.environment);
	let name = parts.join("-").toLowerCase();
	if (labels.length && labels.length > 0) {
		if (name.length > labels.length) {
			name = name.substring(0, labels.length).replace(/[^a-z0-9]*$/, "");
		}
	}
	return name;
}

/**
 * Create array of tags from labels.  Ensure tags are lower cased.
 */
export function labelTags(
	labels: Pick<Labels, "environment" | "purpose" | "user">,
): string[] {
	const tags: string[] = [labels.user];
	if (includePurpose(labels)) {
		tags.push(labels.purpose);
	}
	tags.push(labels.environment);
	return tags.map(t => t.toLowerCase());
}