import { eq, sql } from "drizzle-orm"
import { db } from "@/lib/db"
import { profiles, properties, tenants } from "@/lib/db/schema"
import { PLAN_LIMITS, checkLimit } from "@/lib/stripe/plans"
import { getUserStorageBytes } from "@/lib/storage"
import type { Plan } from "@/types"

/**
 * Server-side plan-limit enforcement helpers. Single source of truth is
 * PLAN_LIMITS in lib/stripe/plans.ts — never hardcode limit numbers in routes.
 */

/** The user's current plan (defaults to "starter" if no profile row). */
export async function getUserPlan(userId: string): Promise<Plan> {
  const profile = await db.query.profiles.findFirst({
    where: eq(profiles.id, userId),
    columns: { plan: true },
  })
  return (profile?.plan ?? "starter") as Plan
}

/**
 * Returns an error message if storing `incomingBytes` more would exceed the
 * user's plan storage cap, otherwise null. Reads actual usage from the storage
 * backend so it stays accurate regardless of which tables reference the files.
 */
export async function checkStorageLimit(
  userId: string,
  incomingBytes: number
): Promise<string | null> {
  const plan = await getUserPlan(userId)
  const maxBytes = PLAN_LIMITS[plan].maxStorageMB * 1024 * 1024
  if (!Number.isFinite(maxBytes)) return null // unlimited plan

  const used = await getUserStorageBytes(userId)
  if (used + incomingBytes > maxBytes) {
    const limitMb = PLAN_LIMITS[plan].maxStorageMB
    return `Storage limit reached (${limitMb} MB on your plan). Upgrade for more space.`
  }
  return null
}

// ── countable resource caps ──────────────────────────────────────────────────
// These live here, not inline in route handlers, because there is more than one
// way into the app: the session routes AND the public v1 API both create
// properties. When the check was written inline, v1 simply did not have it and a
// Starter user could mint an API key and create unlimited properties. Every
// creation path MUST call the helper for its resource — mirroring the same rule
// the upload allowlist follows in lib/storage.ts.

/**
 * Returns a user-facing error message if the owner is at their plan's property
 * cap, otherwise null. Call before every property insert, on every entry point.
 */
export async function checkPropertyLimit(ownerId: string): Promise<string | null> {
  const plan = await getUserPlan(ownerId)
  const [{ count }] = await db
    .select({ count: sql<number>`count(*)::int` })
    .from(properties)
    .where(eq(properties.user_id, ownerId))
  if (!checkLimit(plan, "maxProperties", count)) {
    return "Plan limit reached. Upgrade to add more properties."
  }
  return null
}

/**
 * Returns a user-facing error message if the owner is at their plan's tenant
 * cap, otherwise null. Call before every tenant insert, on every entry point.
 */
export async function checkTenantLimit(ownerId: string): Promise<string | null> {
  const plan = await getUserPlan(ownerId)
  const [{ count }] = await db
    .select({ count: sql<number>`count(*)::int` })
    .from(tenants)
    .where(eq(tenants.user_id, ownerId))
  if (!checkLimit(plan, "maxTenants", count)) {
    return "Plan limit reached. Upgrade to add more tenants."
  }
  return null
}