"use strict";

const defaultValue = require("default-value");
const mapObj = require("map-obj");

module.exports = function createDependencyMap(configuration) {
	let dependencyMap = mapObj(configuration.tasks, (task, definition) => {
		return [
			task,
			defaultValue(definition.dependsOn, []).map((dependencyName) => {
				let dependency = configuration.tasks[dependencyName];

				if (dependency != null) {
					return {
						task: dependencyName,
						// TODO: Do defaults processing in configuration loading/validation instead
						taskVersion: defaultValue(dependency.version, "0")
					};
				} else {
					throw new Error(`Invalid dependency specified, task does not exist: ${dependencyName}`);
				}
			})
		];
	});

	// NOTE: When inverting the dependencyMap, we totally ignore the taskVersion of dependencies when keying this mapping. While the taskVersion of specific tasks *may* matter to the code that uses these mappings, we don't support more than one version of a task simultaneously existing, and so keying by the task name alone is sufficient.
	let dependentMap = {};

	for (let [ task, dependencies ] of Object.entries(dependencyMap)) {
		let taskDefinition = configuration.tasks[task];

		for (let dependency of dependencies) {
			if (dependentMap[dependency.task] == null) {
				dependentMap[dependency.task] = [];
			}

			dependentMap[dependency.task].push({
				task: task,
				taskVersion: defaultValue(taskDefinition.version, "0")
			});
		}
	}

	return {
		dependencyMap,
		dependentMap
	};
};