first steps of implementing permissions

src/lib/permissions.config.json

@@ -0,0 +1,15 @@
+{
+	"USERADMIN": {
+		"size": 8,
+		"permissions": {
+			"VIEW": 0,
+			"ADD": 1,
+			"DELETE": 2,
+			"EDIT": 3,
+			"EDIT_PASSWORD": 4
+		},
+		"meta_permissions": {
+			"MANAGE": ["VIEW", "ADD", "DELETE", "EDIT"]
+		}
+	},
+}

src/lib/permissions.ts

@@ -0,0 +1,94 @@
+
+type GroupPermissionsDef = Record<string, number>
+
+interface GroupDef {
+	size: number
+	permissions: GroupPermissionsDef
+	meta_permissions?: Record<string, Array<string>>
+}
+
+type PermissionDef = Record<string, GroupDef>
+
+
+
+
+import raw from "./permissions.config.json"
+const config = raw as const
+
+const __validate_config = (config: unknown): config is PermissionDef => {
+	const error = (message: string) => new Error("Failed to parse permissions.config.json: " + message)
+
+	if (typeof config !== "object" || config === null) throw error("configuration is not an object or null.")
+	
+	for (const [group, definition] of Object.entries(config)) {
+		if (typeof definition !== "object") 
+			throw error(`definition for ${group} is not an object (is ${typeof definition})`)
+		if (definition === null) 
+			throw error(`definition for ${group} is null`)
+
+		if (typeof definition.size !== "number") 
+			throw error(`type of size in group ${group} is not number (is ${typeof definition.size})`)
+		
+		if (typeof definition.permissions !== "object") 
+			throw error(`definition of permissions for group ${group} is not an object`)
+		for (const [name, position] of Object.entries(definition.permissions)) {
+			if (typeof position !== "number") 
+				throw error(`position of ${name} in group ${group} is not a number (is ${typeof position})`)
+			if (position >= definition.size)
+				throw error(`position ${position} of permission ${name} in group ${group} is out of bounds (size is ${definition.size})`)
+		}
+
+		if (definition.meta_permissions !== undefined) {
+			const permissions = Object.keys(definition.permissions)
+			
+			if (typeof definition.meta_permissions !== "object")
+				throw error(`meta_permissions of group ${group} is not an object (is ${typeof definition.meta_permissions})`)
+			for (const [name, parts] of Object.entries(definition.meta_permissions)) {
+				if (Object.keys(definition.permissions).includes(name))
+					throw error(`meta permission ${name} uses the same name as the permission`)
+				if (typeof parts !== "object" && !(parts instanceof Array) || parts === null) 
+					throw error(`definition of meta permission ${name} in group ${group} is not an array`)
+				for (const partial of (parts as Array<any>)) {
+					if (!permissions.includes(partial))
+						throw error(`permission ${partial} of definition of meta permission ${name} in group ${group} is not a permission of this group`)
+				}
+			}
+		}
+	}
+
+	return true
+}
+
+type PermissionGroups = keyof typeof config
+
+function toPermissionObj(config: PermissionDef): Record<PermissionGroups, Record<string, number>>  {
+	let curr_pos = 0
+	const obj: Record<string, Record<string, number>> = {}
+
+	for (const [name, definition] of Object.entries(config)) {
+		obj[name] = {}
+		for (const [permission, value] of Object.entries(definition.permissions)) {
+			obj[name][permission] = 1 << (curr_pos + value)
+		}
+		for (const [meta, permissions] of Object.entries(definition?.meta_permissions ?? {})) {
+			let mask = 0;
+			for (const permission in permissions) {
+				mask |= 1 << definition.permissions[permission]
+			}
+
+			obj[name][meta] = mask << curr_pos
+		}
+
+		curr_pos += definition.size
+	}
+	return obj
+}
+
+__validate_config(config)
+
+
+export default {
+	...toPermissionObj(config),
+
+	has: (user_permissions: number, permission: number): boolean => (user_permissions & permission) > 0
+}