import { getEffectiveTier, QuotaExceededError } from '@/lib/entitlements'
import { reserveAiUsageOrThrow } from '@/lib/ai-quota'
import type { SubscriptionTier } from '@/lib/plan-entitlements'
import type { FeatureName } from '@/lib/quota-utils'

/** MCP (clés API + outils externes) réservé aux plans payants + 1 unité chat par invocation. */
export function isMcpTierAllowed(tier: SubscriptionTier): boolean {
  return tier !== 'BASIC'
}

export class McpTierLimitedError extends Error {
  code = 'MCP_TIER_LIMITED' as const

  constructor(public tier: SubscriptionTier) {
    super('MCP requires a Pro plan or higher')
  }
}

export async function assertMcpAccess(userId: string): Promise<SubscriptionTier> {
  const tier = await getEffectiveTier(userId)
  if (!isMcpTierAllowed(tier)) {
    throw new McpTierLimitedError(tier)
  }
  return tier
}

/** Tier gate + monthly chat quota (MCP tool calls bill like chat). */
export async function assertMcpAccessWithQuota(
  userId: string,
  feature: FeatureName = 'chat',
): Promise<SubscriptionTier> {
  const tier = await assertMcpAccess(userId)
  await reserveAiUsageOrThrow(userId, feature, { lane: 'chat' })
  return tier
}