import { getUserIdFromSession } from '../../utils/auth';
import { VILLAGE_GRID_SIZE, ITEM_COSTS } from '../../utils/village';
import { VillageObjectType } from '@prisma/client';

// --- Handler ---
export default defineEventHandler(async (event) => {
    const userId = await getUserIdFromSession(event);
    const { type, x, y } = await readBody(event);

    // 1. --- Validation ---
    if (!type || typeof x !== 'number' || typeof y !== 'number') {
        throw createError({ statusCode: 400, statusMessage: 'Invalid request body. "type", "x", and "y" are required.' });
    }
    if (x < 0 || x >= VILLAGE_GRID_SIZE.width || y < 0 || y >= VILLAGE_GRID_SIZE.height) {
        throw createError({ statusCode: 400, statusMessage: 'Object placed outside of village bounds.' });
    }
    const cost = ITEM_COSTS[type as VillageObjectType];
    if (cost === undefined) {
        throw createError({ statusCode: 400, statusMessage: 'Cannot place objects of this type.' });
    }

    // 2. --- Fetch current state and enforce rules ---
    const village = await prisma.village.findUnique({
        where: { userId },
        include: { objects: true },
    });

    if (!village) {
        // This should not happen if GET /village is called first, but as a safeguard:
        throw createError({ statusCode: 404, statusMessage: 'Village not found.' });
    }

    // Rule: Cell must be empty
    if (village.objects.some(obj => obj.x === x && obj.y === y)) {
        throw createError({ statusCode: 409, statusMessage: 'A building already exists on this cell.' });
    }

    // Rule: Fields require available workers
    if (type === 'FIELD') {
        const houseCount = village.objects.filter(obj => obj.type === 'HOUSE').length;
        const fieldCount = village.objects.filter(obj => obj.type === 'FIELD').length;
        if (fieldCount >= houseCount) {
            throw createError({ statusCode: 400, statusMessage: 'Not enough available workers to build a new field. Build more houses first.' });
        }
    }

    // 3. --- Perform atomic transaction ---
    try {
        const [, newObject] = await prisma.$transaction([
            prisma.user.update({
                where: { id: userId, coins: { gte: cost } },
                data: { coins: { decrement: cost } },
            }),
            prisma.villageObject.create({
                data: {
                    villageId: village.id,
                    type,
                    x,
                    y,
                },
            }),
        ]);

        setResponseStatus(event, 201);
        return {
            id: newObject.id,
            type: newObject.type,
            x: newObject.x,
            y: newObject.y,
            cropType: null,
            isGrown: null,
        };

    } catch (e) {
        // Catches failed transactions, likely from the user.update 'where' clause (insufficient funds)
        throw createError({ statusCode: 402, statusMessage: 'Insufficient coins to build.' });
    }
});