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

// Simple configurable curve: Base * (Level ^ Exponent)
const XP_BASE = 1000;
const XP_EXPONENT = 1.5;

export const levelingService = {
    // Calculate XP required for a specific level
    getXpForLevel: (level: number) => {
        return Math.floor(XP_BASE * Math.pow(level, XP_EXPONENT));
    },

    addXp: async (id: string, amount: bigint, tx?: any) => {
        const execute = async (txFn: any) => {
            // Get current state
            const user = await txFn.query.users.findFirst({
                where: eq(users.id, BigInt(id)),
            });

            if (!user) throw new Error("User not found");

            let newXp = (user.xp ?? 0n) + amount;
            let currentLevel = user.level ?? 1;
            let levelUp = false;

            // Check for level up loop
            let xpForNextLevel = BigInt(levelingService.getXpForLevel(currentLevel));

            while (newXp >= xpForNextLevel) {
                newXp -= xpForNextLevel;
                currentLevel++;
                levelUp = true;
                xpForNextLevel = BigInt(levelingService.getXpForLevel(currentLevel));
            }

            // Update user
            const [updatedUser] = await txFn.update(users)
                .set({
                    xp: newXp,
                    level: currentLevel,
                })
                .where(eq(users.id, BigInt(id)))
                .returning();

            return { user: updatedUser, levelUp, currentLevel };
        }

        if (tx) {
            return await execute(tx);
        } else {
            return await DrizzleClient.transaction(async (t) => {
                return await execute(t);
            })
        }
    },
};