import { Stat } from "@/interfaces/user";
import client from "@/lib/mongodb";

const db = client.db(process.env.MONGODB_DB);

export const getStatsByUser = async (id: string) => await db.collection("stats").find<Stat>({ user: id }).toArray();

export const getStatsByUsers = async (ids: string[]) =>
	await db
		.collection("stats")
		.find<Stat>({ user: { $in: ids } })
		.toArray();

export const getDetailedStatsByUser = async (id: string, query?: string) => {
	let aggregateArray: any[] = [
		{ $match: { user: id } },
		{ $sort: { "date": 1 } },
	]
	switch (query) {
		case "stats":
			{
				aggregateArray = aggregateArray.concat([{
					$group: {
						_id: "$session",
						modules: { $addToSet: "$module" },
						documents: { $push: "$$ROOT" },
						totalCorrect: { $sum: "$score.correct" },
						totalQuestions: { $sum: "$score.total" }
					}
				},
				{
					$project: {
						_id: 0,
						hasAllModules: {
							$eq: [
								{ $size: { $setIntersection: ["$modules", ["reading", "listening", "writing", "speaking"]] } },
								4
							]
						},
						uniqueModulesCount: { $size: "$modules" },
						averageScore: {
							$cond: [
								{ $gt: ["$totalQuestions", 0] },
								{ $multiply: [{ $divide: ["$totalCorrect", "$totalQuestions"] }, 100] },
								0
							]
						},
						documents: 1
					}
				},
				{
					$group: {
						_id: null,
						fullExams: { $sum: { $cond: ["$hasAllModules", 1, 0] } },
						uniqueModules: { $sum: "$uniqueModulesCount" },
						averageScore: {
							$avg: "$averageScore"
						},
						allStats: { $push: "$documents" }
					}
				},
				{
					$project: {
						_id: 0,
						fullExams: 1,
						uniqueModules: 1,
						averageScore: 1,
						allStats: {
							$reduce: {
								input: "$allStats",
								initialValue: [],
								in: { $concatArrays: ["$$value", "$$this"] }
							}
						}
					}
				}])
			}
			break;
		case "byModule": {
			aggregateArray = aggregateArray.concat([{
				$facet: {
					moduleCounts: [
						{
							$group: {
								_id: {
									module: "$module",
									session: "$session"
								}
							}
						},
						{
							$group: {
								_id: "$_id.module",
								count: {
									$count: {}
								}
							}
						},
						{
							$project: {
								_id: 0,
								module: "$_id",
								count: "$count"
							}
						}
					],
					allDocuments: [
						{
							$project: {
								_id: 0
							}
						}
					]
				}
			},
			{
				$project: {
					moduleCount: {
						$arrayToObject: {
							$map: {
								input: "$moduleCounts",
								as: "module",
								in: {
									k: "$$module.module",
									v: "$$module.count"
								}
							}
						}
					},
					allDocs: "$allDocuments"
				}
			}])

		}
		default:
	}

	return await db.collection("stats").aggregate(aggregateArray).toArray().then((result) => query ? result[0] : result
	);
}