/*
	Spacebar: A FOSS re-implementation and extension of the Discord.com backend.
	Copyright (C) 2023 Spacebar and Spacebar Contributors
	
	This program is free software: you can redistribute it and/or modify
	it under the terms of the GNU Affero General Public License as published
	by the Free Software Foundation, either version 3 of the License, or
	(at your option) any later version.
	
	This program is distributed in the hope that it will be useful,
	but WITHOUT ANY WARRANTY; without even the implied warranty of
	MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
	GNU Affero General Public License for more details.
	
	You should have received a copy of the GNU Affero General Public License
	along with this program.  If not, see <https://www.gnu.org/licenses/>.
*/

import { route } from "@spacebar/api";
import { Config, DiscordApiErrors, Relationship, RelationshipAddEvent, RelationshipRemoveEvent, User, emitEvent } from "@spacebar/util";
import { Request, Response, Router } from "express";
import { HTTPError } from "lambert-server";
import { PublicUserProjection, RelationshipType } from "@spacebar/schemas";

const router = Router({ mergeParams: true });

const userProjection: (keyof User)[] = ["relationships", ...PublicUserProjection];

router.get(
    "/",
    route({
        responses: {
            200: {
                body: "UserRelationshipsResponse",
            },
            404: {
                body: "APIErrorResponse",
            },
        },
    }),
    async (req: Request, res: Response) => {
        const user = await User.findOneOrFail({
            where: { id: req.user_id },
            relations: ["relationships", "relationships.to"],
            select: ["id", "relationships"],
        });

        const related_users = user.relationships.map((r) => r.toPublicRelationship());
        return res.json(related_users);
    },
);

router.put(
    "/:user_id",
    route({
        requestBody: "RelationshipPutSchema",
        responses: {
            204: {},
            400: {
                body: "APIErrorResponse",
            },
            404: {
                body: "APIErrorResponse",
            },
        },
    }),
    async (req: Request, res: Response) => {
        return await updateRelationship(
            req,
            res,
            await User.findOneOrFail({
                where: { id: req.params.user_id },
                relations: ["relationships", "relationships.to"],
                select: userProjection,
            }),
            req.body.type ?? RelationshipType.friends,
        );
    },
);

router.post(
    "/",
    route({
        requestBody: "RelationshipPostSchema",
        responses: {
            204: {},
            400: {
                body: "APIErrorResponse",
            },
            404: {
                body: "APIErrorResponse",
            },
        },
    }),
    async (req: Request, res: Response) => {
        return await updateRelationship(
            req,
            res,
            await User.findOneOrFail({
                relations: ["relationships", "relationships.to"],
                select: userProjection,
                where: {
                    discriminator: String(req.body.discriminator).padStart(4, "0"), //Discord send the discriminator as integer, we need to add leading zeroes
                    username: req.body.username,
                },
            }),
            req.body.type,
        );
    },
);

router.delete(
    "/:user_id",
    route({
        responses: {
            204: {},
            400: {
                body: "APIErrorResponse",
            },
            404: {
                body: "APIErrorResponse",
            },
        },
    }),
    async (req: Request, res: Response) => {
        const { user_id } = req.params;
        if (user_id === req.user_id) throw new HTTPError("You can't remove yourself as a friend");

        const user = await User.findOneOrFail({
            where: { id: req.user_id },
            select: userProjection,
            relations: ["relationships"],
        });
        const friend = await User.findOneOrFail({
            where: { id: user_id },
            select: userProjection,
            relations: ["relationships"],
        });

        const relationship = user.relationships.find((x) => x.to_id === user_id);
        const friendRequest = friend.relationships.find((x) => x.to_id === req.user_id);

        if (!relationship) throw new HTTPError("You are not friends with the user", 404);

        if (relationship?.type === RelationshipType.blocked) {
            // unblock user
            await Promise.all([
                Relationship.delete({ id: relationship.id }),
                emitEvent({
                    event: "RELATIONSHIP_REMOVE",
                    user_id: req.user_id,
                    data: relationship.toPublicRelationship(),
                } as RelationshipRemoveEvent),
            ]);
            return res.sendStatus(204);
        }
        if (friendRequest && friendRequest.type !== RelationshipType.blocked) {
            await Promise.all([
                Relationship.delete({ id: friendRequest.id }),
                await emitEvent({
                    event: "RELATIONSHIP_REMOVE",
                    data: friendRequest.toPublicRelationship(),
                    user_id: user_id,
                } as RelationshipRemoveEvent),
            ]);
        }

        await Promise.all([
            Relationship.delete({ id: relationship.id }),
            emitEvent({
                event: "RELATIONSHIP_REMOVE",
                data: relationship.toPublicRelationship(),
                user_id: req.user_id,
            } as RelationshipRemoveEvent),
        ]);

        return res.sendStatus(204);
    },
);

export default router;

async function updateRelationship(req: Request, res: Response, friend: User, type: RelationshipType) {
    const id = friend.id;
    if (id === req.user_id) throw new HTTPError("You can't add yourself as a friend");

    const user = await User.findOneOrFail({
        where: { id: req.user_id },
        relations: ["relationships", "relationships.to"],
        select: userProjection,
    });

    let relationship = user.relationships.find((x) => x.to_id === id);
    const friendRequest = friend.relationships.find((x) => x.to_id === req.user_id);

    // TODO: you can add infinitely many blocked users (should this be prevented?)
    if (type === RelationshipType.blocked) {
        if (relationship) {
            if (relationship.type === RelationshipType.blocked) throw new HTTPError("You already blocked the user");
            relationship.type = RelationshipType.blocked;
            await relationship.save();
        } else {
            relationship = await Relationship.create({
                to_id: id,
                type: RelationshipType.blocked,
                from_id: req.user_id,
            }).save();
        }

        if (friendRequest && friendRequest.type !== RelationshipType.blocked) {
            await Promise.all([
                Relationship.delete({ id: friendRequest.id }),
                emitEvent({
                    event: "RELATIONSHIP_REMOVE",
                    data: friendRequest.toPublicRelationship(),
                    user_id: id,
                } as RelationshipRemoveEvent),
            ]);
        }

        await emitEvent({
            event: "RELATIONSHIP_ADD",
            data: relationship.toPublicRelationship(),
            user_id: req.user_id,
        } as RelationshipAddEvent);

        return res.sendStatus(204);
    }

    const { maxFriends } = Config.get().limits.user;
    if (user.relationships.length >= maxFriends) throw DiscordApiErrors.MAXIMUM_FRIENDS.withParams(maxFriends);

    let incoming_relationship = Relationship.create({
        nickname: undefined,
        type: RelationshipType.incoming,
        to: user,
        from: friend,
    });
    let outgoing_relationship = Relationship.create({
        nickname: undefined,
        type: RelationshipType.outgoing,
        to: friend,
        from: user,
    });

    if (friendRequest) {
        if (friendRequest.type === RelationshipType.blocked) throw new HTTPError("The user blocked you");
        if (friendRequest.type === RelationshipType.friends) throw new HTTPError("You are already friends with the user");
        // accept friend request
        incoming_relationship = friendRequest;
        incoming_relationship.type = RelationshipType.friends;
    }

    if (relationship) {
        if (relationship.type === RelationshipType.outgoing) throw new HTTPError("You already sent a friend request");
        if (relationship.type === RelationshipType.blocked) throw new HTTPError("Unblock the user before sending a friend request");
        if (relationship.type === RelationshipType.friends) throw new HTTPError("You are already friends with the user");
        outgoing_relationship = relationship;
        outgoing_relationship.type = RelationshipType.friends;
    }

    await Promise.all([
        incoming_relationship.save(),
        outgoing_relationship.save(),
        emitEvent({
            event: "RELATIONSHIP_ADD",
            data: outgoing_relationship.toPublicRelationship(),
            user_id: req.user_id,
        } as RelationshipAddEvent),
        emitEvent({
            event: "RELATIONSHIP_ADD",
            data: {
                ...incoming_relationship.toPublicRelationship(),
                should_notify: true,
            },
            user_id: id,
        } as RelationshipAddEvent),
    ]);

    return res.sendStatus(204);
}