import { NextRequest } from 'next/server';
import { db } from '@/lib/db';
import { auth } from '@/lib/auth';
import { rateLimit } from '@/lib/rate-limit';
import { buildBillingAccessWhereInput, getWorkspaceCreationEligibility } from '@/lib/billing';
import { apiErrors, successResponse, withCacheControl } from '@/lib/api-response';
import { logError } from '@/lib/logger';

// GET /api/workspaces - List all workspaces for the authenticated user
export async function GET(request: NextRequest) {
  try {
    const session = await auth();
    const MAX_LIMIT = 100;
    const MAX_PAGE = 1000;
    const MAX_OFFSET = 10000;

    if (!session?.user?.id) {
      return apiErrors.unauthorized();
    }

    const searchParams = request.nextUrl.searchParams;
    const pageParam = searchParams.get('page');
    const limitParam = searchParams.get('limit');

    const pageRaw = pageParam === null ? 1 : Number(pageParam);
    if (!Number.isSafeInteger(pageRaw) || pageRaw < 1 || pageRaw > MAX_PAGE) {
      return apiErrors.badRequest('Invalid page. Must be a positive integer.');
    }

    const limitRaw = limitParam === null ? 20 : Number(limitParam);
    if (!Number.isSafeInteger(limitRaw) || limitRaw < 1 || limitRaw > MAX_LIMIT) {
      return apiErrors.badRequest('Invalid limit. Must be a positive integer between 1 and 100.');
    }

    const page = pageRaw;
    const limit = limitRaw;
    const skip = (page - 1) * limit;
    if (!Number.isSafeInteger(skip) || skip > MAX_OFFSET) {
      return apiErrors.badRequest('Invalid page range. Offset must be 10000 or less.');
    }

    const where = {
      OR: [
        { ownerId: session.user.id, owner: buildBillingAccessWhereInput() },
        { members: { some: { userId: session.user.id } }, owner: buildBillingAccessWhereInput() },
      ],
    };

    // Get workspaces where user is owner OR a member
    const [workspaces, total] = await Promise.all([
      db.workspace.findMany({
        where,
        include: {
          owner: { select: { id: true, name: true, image: true } },
          _count: { select: { projects: true, members: true } },
        },
        orderBy: { updatedAt: 'desc' },
        skip,
        take: limit,
      }),
      db.workspace.count({ where }),
    ]);

    const response = successResponse({ workspaces }, 200, {
      page,
      limit,
      total,
      totalPages: Math.ceil(total / limit),
    });
    return withCacheControl(response, 'private, max-age=60, stale-while-revalidate=120');
  } catch (error) {
    logError('Error fetching workspaces:', error);
    return apiErrors.internalError('Failed to fetch workspaces');
  }
}

// POST /api/workspaces - Create a new workspace
export async function POST(request: NextRequest) {
  try {
    const limited = await rateLimit(request, 'create-workspace');
    if (limited) return limited;

    const session = await auth();

    if (!session?.user?.id) {
      return apiErrors.unauthorized();
    }

    const billing = await getWorkspaceCreationEligibility(session.user.id);
    if (!billing.canCreateWorkspace) {
      return apiErrors.forbidden(
        billing.reason || 'Upgrade your account to create another workspace'
      );
    }

    const body = await request.json();
    const { name, description } = body;

    if (!name || typeof name !== 'string' || name.trim().length === 0) {
      return apiErrors.badRequest('Workspace name is required');
    }

    // Generate slug
    const baseSlug = name
      .toLowerCase()
      .trim()
      .replace(/[^a-z0-9\s-]/g, '')
      .replace(/\s+/g, '-')
      .replace(/-+/g, '-');

    // Find all existing slugs with the same prefix in a single query
    const existingWorkspaces = await db.workspace.findMany({
      where: { slug: { startsWith: baseSlug } },
      select: { slug: true },
    });

    // Generate unique slug from the results
    const usedSlugs = new Set(existingWorkspaces.map((w) => w.slug));
    let slug = baseSlug;
    let counter = 1;
    while (usedSlugs.has(slug)) {
      slug = `${baseSlug}-${counter}`;
      counter++;
    }

    const workspace = await db.workspace.create({
      data: {
        name: name.trim(),
        description: description?.trim() || null,
        slug,
        ownerId: session.user.id,
      },
      include: {
        owner: { select: { id: true, name: true, image: true } },
        _count: { select: { projects: true, members: true } },
      },
    });

    const response = successResponse(workspace, 201);
    return withCacheControl(response, 'private, no-store');
  } catch (error) {
    logError('Error creating workspace:', error);
    return apiErrors.internalError('Failed to create workspace');
  }
}