import { json, type Handle, type HandleServerError } from '@sveltejs/kit';
import { stringify } from 'devalue';
import { randomUUID } from 'node:crypto';
import { getSessionUser } from '$lib/server/auth/session';
import { getSiteAccessBlock, getSiteAccessSettings } from '$lib/server/site-access';
import { DATA_MODULES, proposalActionResult, queueDataProposal, shouldModerateDataMutation, type DataModule } from '$lib/server/data-moderation';

export const handle: Handle = async ({ event, resolve }) => {
	if (event.url.pathname === '/admin' || event.url.pathname.startsWith('/admin/')) {
		const location = `/isac${event.url.pathname.slice('/admin'.length)}${event.url.search}`;
		return new Response(null, { status: 308, headers: { location } });
	}
	const siteSettings = await getSiteAccessSettings();
	const sessionUser = await getSessionUser(event.cookies);
	const accessBlock = getSiteAccessBlock(siteSettings, event.url.pathname, Boolean(sessionUser));
	if (accessBlock) {
		const target = new URL('/coming-soon', event.url);
		if (accessBlock.kind === 'section') target.searchParams.set('unavailable', accessBlock.section);
		if (event.request.method === 'GET' || event.request.method === 'HEAD') {
			return new Response(null, { status: 303, headers: { location: `${target.pathname}${target.search}` } });
		}
		return json(
			{
				error: accessBlock.kind === 'section'
					? 'This section is not available.'
					: 'The public site is not available yet.'
			},
			{ status: 404 }
		);
	}
	if (event.request.method === 'POST') {
		const match = event.url.pathname.match(/^\/isac\/([^/]+)$/);
		const module = match?.[1] as DataModule | undefined;
		const action = event.url.search.startsWith('?/') ? event.url.search.slice(2) : '';
		if (module && DATA_MODULES.includes(module) && action) {
			// Publishing calculation rules is never a contributor proposal. The
			// action has its own dedicated permission and confirmation contract.
			if (module === 'calculations' && action === 'publishRevision') return resolve(event);
			const user = sessionUser;
			const access = await shouldModerateDataMutation(user);
			if (!access.canManage && access.canPropose && user) {
				if (!access.contributorEnabled) {
					if (event.request.headers.get('accept')?.includes('application/json')) {
						return json({ type: 'failure', status: 403, data: { contributorModeRequired: true } }, { status: 403 });
					}
					return new Response('Contributor mode must be enabled before submitting data changes.', { status: 403 });
				}
				const submittedForm = await event.request.formData();
				const proposal = await queueDataProposal(user, module, action, submittedForm);
				if (event.request.headers.get('accept')?.includes('application/json')) {
					const result = proposalActionResult(module, action, Boolean(proposal.entityId), proposal.id);
					if (module === 'attributes' && action === 'save') {
						Object.assign(result, {
							savedItem: {
								id: proposal.entityId ?? proposal.draftEntityId,
								name: String(submittedForm.get('name') ?? ''),
								type: String(submittedForm.get('type') ?? ''),
								category: String(submittedForm.get('category') ?? ''),
								calculation_type: String(submittedForm.get('calculationType') ?? ''),
								unit: String(submittedForm.get('unit') ?? ''),
								active: 1,
								pending: true,
								proposalId: proposal.id,
								proposerName: user.displayName
							}
						});
					}
					return json({
						type: 'success',
						status: 200,
						data: stringify(result)
					});
				}
				const target = new URL(event.url.pathname, event.url);
				target.searchParams.set('proposal', proposal.id);
				return new Response(null, { status: 303, headers: { location: `${target.pathname}${target.search}` } });
			}
		}
	}
	return resolve(event);
};

export const handleError: HandleServerError = ({ error, event, status, message }) => {
	const errorId = randomUUID().slice(0, 8).toUpperCase();
	console.error(`[${errorId}] ${event.request.method} ${event.url.pathname} -> ${status}`, error);
	return {
		message: status >= 500 ? 'An unexpected fault interrupted this operation. No further action was applied.' : message,
		errorId
	};
};