import { classes, users } from "@/db/schema";
import { eq, sql } from "drizzle-orm";
import { DrizzleClient } from "@/lib/DrizzleClient";

export const classService = {
    getAllClasses: async () => {
        return await DrizzleClient.query.classes.findMany();
    },

    assignClass: async (userId: string, classId: bigint, tx?: any) => {
        const execute = async (txFn: any) => {
            const cls = await txFn.query.classes.findFirst({
                where: eq(classes.id, classId),
            });

            if (!cls) throw new Error("Class not found");

            const [user] = await txFn.update(users)
                .set({ classId: classId })
                .where(eq(users.id, BigInt(userId)))
                .returning();

            return user;
        };
        return tx ? await execute(tx) : await DrizzleClient.transaction(execute);
    },
    getClassBalance: async (classId: bigint) => {
        const cls = await DrizzleClient.query.classes.findFirst({
            where: eq(classes.id, classId),
        });
        return cls?.balance || 0n;
    },
    modifyClassBalance: async (classId: bigint, amount: bigint, tx?: any) => {
        const execute = async (txFn: any) => {
            const cls = await txFn.query.classes.findFirst({
                where: eq(classes.id, classId),
            });

            if (!cls) throw new Error("Class not found");

            if (amount < 0n && (cls.balance ?? 0n) < -amount) {
                throw new Error("Insufficient class funds");
            }

            const [updatedClass] = await txFn.update(classes)
                .set({
                    balance: sql`${classes.balance} + ${amount}`,
                })
                .where(eq(classes.id, classId))
                .returning();

            return updatedClass;
        };
        return tx ? await execute(tx) : await DrizzleClient.transaction(execute);
    },

    updateClass: async (id: bigint, data: Partial<typeof classes.$inferInsert>, tx?: any) => {
        const execute = async (txFn: any) => {
            const [updatedClass] = await txFn.update(classes)
                .set(data)
                .where(eq(classes.id, id))
                .returning();
            return updatedClass;
        };
        return tx ? await execute(tx) : await DrizzleClient.transaction(execute);
    }
};