intrn(manager): make method to check if a role is the only related one

database/managers/helpers/condition.ts

@@ -10,6 +10,7 @@ import DatabaseError from "$!/errors/database"
 import isUndefined from "$/type_guards/is_undefined"
 import cleanQuery from "%/managers/helpers/clean_query"
 
+type Column = string
 type Literal = ReturnType<typeof literal>
 type Where = ReturnType<typeof Sequelize["where"]>
 
@@ -32,32 +33,32 @@ export default class Condition<T = any> {
 		}
 	}
 
-	not(column: string, value: any): Condition {
+	not(column: Column, value: any): Condition {
 		this.currentCondition[column] = { [Op.not]: value }
 		return this
 	}
 
-	is(column: string, value: any): Condition {
+	is(column: Column, value: any): Condition {
 		this.currentCondition[column] = { [Op.is]: value }
 		return this
 	}
 
-	equal(column: string, value: any): Condition {
+	equal(column: Column, value: any): Condition {
 		this.currentCondition[column] = { [Op.eq]: value }
 		return this
 	}
 
-	greaterThanOrEqual(column: string, value: any): Condition {
+	greaterThanOrEqual(column: Column, value: any): Condition {
 		this.currentCondition[column] = { [Op.gte]: value }
 		return this
 	}
 
-	lessThanOrEqual(column: string, value: any): Condition {
+	lessThanOrEqual(column: Column, value: any): Condition {
 		this.currentCondition[column] = { [Op.lte]: value }
 		return this
 	}
 
-	search(column: string, value: string): Condition {
+	search(column: Column, value: string): Condition {
 		/*
 		 * `findAndCountAll` uses `findAll`. See
 		 * https://github.com/sequelize/sequelize/blob/0c5ca3fc398a99eddb412fe3b2aba99f157bf59d/src/model.js#L2070
@@ -72,12 +73,12 @@ export default class Condition<T = any> {
 		return this
 	}
 
-	isIncludedIn(column: string, value: any[]|Literal): Condition {
+	isIncludedIn(column: Column, value: any[]|Literal): Condition {
 		this.currentCondition[column] = { [Op.in]: value }
 		return this
 	}
 
-	isOnDay(column: string, value: Day): Condition {
+	isOnDay(column: Column, value: Day): Condition {
 		let query: any = ""
 		const escapedColumn = Sequelize.col(column)
 
@@ -105,7 +106,7 @@ export default class Condition<T = any> {
 		return this
 	}
 
-	onOrAfterTime(column: string, time: Time): Condition {
+	onOrAfterTime(column: Column, time: Time): Condition {
 		let hourQuery: any = ""
 		let minuteQuery: any = ""
 		const escapedColumn = Sequelize.col(column)
@@ -148,7 +149,7 @@ export default class Condition<T = any> {
 		)
 	}
 
-	onOrBeforeTime(column: string, time: Time): Condition {
+	onOrBeforeTime(column: Column, time: Time): Condition {
 		let hourQuery: any = ""
 		let minuteQuery: any = ""
 		const escapedColumn = Sequelize.col(column)

database/managers/role.ts

@@ -1,3 +1,5 @@
+import { Op } from "sequelize"
+
 import type { Pipe } from "$/types/database"
 import type { Serializable } from "$/types/general"
 import type { RoleQueryParameters } from "$/types/query"
@@ -117,4 +119,69 @@ export default class extends BaseManager<
 			})
 		}
 	}
+
+	async isTheOnlyRoleToAnyUser(roleID: number): Promise<boolean> {
+		try {
+			if (!Model.sequelize || !AttachedRole.sequelize) {
+				throw new DatabaseError("Developer may have forgot to register the models.")
+			}
+
+			const subselectQuery = Model.sequelize.literal(`(${
+				trimRight(
+					// @ts-ignore
+					AttachedRole.sequelize.getQueryInterface().queryGenerator.selectQuery(
+						AttachedRole.tableName, {
+							"attributes": [ "userID" ],
+							"where": new Condition().equal(
+								"roleID",
+								roleID
+							)
+							.build()
+						}
+					),
+					";"
+				)
+			})`)
+			const [ rawUserIDs ] = await AttachedRole.sequelize.query(
+				// @ts-ignore
+				AttachedRole.sequelize.getQueryInterface().queryGenerator.selectQuery(
+					AttachedRole.tableName, {
+						"attributes": [
+							"userID",
+							"roleID"
+						],
+						"where": new Condition().equal("roleID", roleID).build()
+					}
+				)
+			) as unknown as [ { id: number, userID: string }[] ]
+			const userIDs = rawUserIDs.map(info => info.userID)
+
+			if (userIDs.length === 0) return false
+
+			const [ counts ] = await Model.sequelize.query(
+				// @ts-ignore
+				AttachedRole.sequelize.getQueryInterface().queryGenerator.selectQuery(
+					AttachedRole.tableName, {
+						"attributes": [
+							"userID",
+							[
+								AttachedRole.sequelize.fn(
+									"count", "roleID"
+								),
+								"roleIDCount"
+							]
+						],
+						"group": [
+							[ "userID" ]
+						],
+						"having": new Condition().equal("roleIDCount", 1).build(),
+						"where": new Condition().isIncludedIn("userID", userIDs)
+					}
+				)
+			) as unknown as [ { id: number, count: string }[] ]
+			return counts.length > 0
+		} catch (error) {
+			throw this.makeBaseError(error)
+		}
+	}
 }