/**
 * @file Verarbeitet das Hochladen, Abrufen und Entfernen von Bildanhängen mit Zugriffskontrolle.
 */
import express from "express";
import {mkdirSync} from "node:fs";
import {unlink} from "node:fs/promises";
import {asyncHandler} from "../middleware/asyncHandler.js";
import multer from "multer";
import {requireLogin} from "../middleware/auth.js";
import {AttachmentError} from "../services/attachmentService.js";

export function createUploadsRouter(service, config) {
    const router = express.Router();
    mkdirSync(config.uploadTmpDir, {recursive: true});
    const activeUploads = new Map();
    const upload = multer({storage: multer.diskStorage({destination: config.uploadTmpDir}), limits: {
        fileSize: config.uploadMaxSizeMb * 1024 * 1024, files: 1, fields: 0, parts: 1
    }}).single("image");
    const fail = (res, error) => res.status(error instanceof AttachmentError ? error.status : 500).json({error:
        error instanceof AttachmentError ? error.message : "Image operation failed. Please retry."});
    router.get("/uploads/config", requireLogin, (_req, res) => res.json({maxSizeMb: config.uploadMaxSizeMb, maxFiles: config.uploadMaxFiles}));
    router.post("/uploads", requireLogin, (req, res) => {
        const user = req.session.user;
        const active = activeUploads.get(user) || 0;
        if (active >= config.uploadMaxFiles) return res.status(429).json({error: "Too many simultaneous uploads. Please wait."});
        activeUploads.set(user, active + 1);
        res.once("close", () => {
            const remaining = (activeUploads.get(user) || 1) - 1;
            if (remaining) activeUploads.set(user, remaining); else activeUploads.delete(user);
        });
        upload(req, res, async error => {
            if (error) { if (req.file?.path) await unlink(req.file.path).catch(() => {}); return res.status(error.code === "LIMIT_FILE_SIZE" ? 413 : 400).json({error:
                error.code === "LIMIT_FILE_SIZE" ? `Image exceeds ${config.uploadMaxSizeMb} MB` : "Upload one PNG, JPEG or WebP image per request"});
            }
            try { res.status(201).json(await service.upload(req.file, req.session.user)); }
            catch (failure) { fail(res, failure); }
        });
    });
    router.get("/attachments/:id", requireLogin, asyncHandler(async (req, res) => {
        try {
            const row = service.owned(req.params.id, req.session.user);
            const buffer = await service.storage.read(row.storage_key);
            res.set({"Content-Type": row.mime_type, "Content-Length": buffer.length, "Cache-Control": "private, no-store",
                "X-Content-Type-Options": "nosniff", "Content-Disposition": "inline"}).send(buffer);
        } catch (error) { fail(res, error); }
    }));
    router.delete("/attachments/:id", requireLogin, asyncHandler(async (req, res) => {
        try { await service.remove(req.params.id, req.session.user); res.json({success: true}); }
        catch (error) { fail(res, error); }
    }));
    return router;
}