import { sql } from "drizzle-orm";
import { messages } from "~~/drizzle/schema";
import { db } from "~~/server/lib/db";
import { topicEvents } from "~~/server/utils/events";

async function deeplyDeleteMessage(messageId: string, topicId: string, userId: string) {
    const children = await db.query.messages.findMany({
        where: {
            parentMessageId: messageId,
            userId,
        }
    } as any);

    for (const child of children) {
        await deeplyDeleteMessage(child.id, topicId, userId);
    }

    await db.delete(messages).where(sql`${messages.id} = ${messageId} AND ${messages.userId} = ${userId}`);

    topicEvents.emit(topicId, {
        type: 'MESSAGE_DELETED',
        payload: { id: messageId },
    });
}

export default defineEventHandler(async (event) => {
    await protectRoute(event);

    const userId = event.context.user!.id;
    const messageId = getRouterParam(event, 'messageId')!;

    const message = await db.query.messages.findFirst({
        where: {
            id: messageId,
            userId,
        }
    } as any);

    if (!message) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Invalid message',
        });
    }

    const topicId = message.topicId;

    const allTopicMessages = await db.query.messages.findMany({
        where: {
            topicId,
            userId,
        },
        orderBy: {
            createdAt: 'asc',
        },
    });

    const messagesMap = new Map(allTopicMessages.map(m => [m.id, { ...m, children: [] as typeof m[] }]));

    for (const msg of messagesMap.values()) {
        if (msg.parentMessageId && messagesMap.has(msg.parentMessageId)) {
            messagesMap.get(msg.parentMessageId)!.children.push(msg);
        }
    }

    const rootMessage = messagesMap.get(messageId);
    if (!rootMessage) {
        throw createError({
            statusCode: 400,
            statusMessage: 'Invalid message',
        });
    }

    if (rootMessage.role === 'user') {
        await deeplyDeleteMessage(rootMessage.id, topicId, userId);
        return { ok: true };
    }

    if (rootMessage.deleted === true) {
        const childMessage = rootMessage.children[rootMessage.focusedIndex!];
        if (!childMessage) {
            console.error('Message not found');
            return { ok: false };
        }

        await deeplyDeleteMessage(childMessage.id, topicId, userId);

        const remainingChildren = rootMessage.children.filter(child => child!.id !== childMessage.id);
        if (remainingChildren.length === 0) {
            await deeplyDeleteMessage(rootMessage.id, topicId, userId);
        } else {
            const newFocusedIndex = rootMessage.focusedIndex && rootMessage.focusedIndex > 0
                ? Math.min(rootMessage.focusedIndex - 1, remainingChildren.length - 1)
                : 0;

            await db.update(messages).set({ focusedIndex: newFocusedIndex }).where(sql`${messages.id} = ${rootMessage.id} AND ${messages.userId} = ${userId}`);

            topicEvents.emit(topicId, {
                type: 'MESSAGE_UPDATED',
                payload: { ...rootMessage, focusedIndex: newFocusedIndex },
            });
        }
        return { ok: true };
    }

    if (
        (rootMessage.focusedIndex !== undefined && rootMessage.focusedIndex !== null)
        && rootMessage.focusedIndex > 0
        && rootMessage.children.length > 0
    ) {
        const childMessage = rootMessage.children[rootMessage.focusedIndex - 1];
        if (!childMessage) {
            console.error('Message not found');
            return { ok: false };
        }

        await deeplyDeleteMessage(childMessage.id, topicId, userId);

        const remainingChildren = rootMessage.children.filter(child => child!.id !== childMessage.id);
        const newFocusedIndex = remainingChildren.length > 0
            ? Math.min(rootMessage.focusedIndex - 1, remainingChildren.length - 1)
            : 0;

        await db.update(messages).set({ focusedIndex: newFocusedIndex }).where(sql`${messages.id} = ${rootMessage.id} AND ${messages.userId} = ${userId}`);

        topicEvents.emit(topicId, {
            type: 'MESSAGE_UPDATED',
            payload: { ...rootMessage, focusedIndex: newFocusedIndex },
        });
        return { ok: true };
    }

    if (rootMessage.children.length === 0) {
        await deeplyDeleteMessage(rootMessage.id, topicId, userId);
        return { ok: true };
    }

    await db.update(messages).set({ deleted: true }).where(sql`${messages.id} = ${rootMessage.id} AND ${messages.userId} = ${userId}`);

    topicEvents.emit(topicId, {
        type: 'MESSAGE_UPDATED',
        payload: { ...rootMessage, deleted: true },
    });

    return { ok: true };
});