// Package billing is the Billing & Subscription bounded context: plans,
// Stripe checkout/portal, webhook ingestion, and the per-plan daily
// message quota. System of record for `subscriptions`, `stripe_events`
// and `usage_daily` (see services/billing/migrations/0001_init.sql).
//
// Mirrors internal/handlers/billing.go + internal/billing/*.go +
// internal/db/subscriptions.go.
syntax = "proto3";

package enkly.billing.v1;

option go_package = "enkly/gen/billing/v1;billingv1";

import "google/protobuf/timestamp.proto";

service BillingService {
  // GetOrCreateSubscription replaces db.GetOrCreateSubscription: lazily
  // inserts the default free-plan row the first time a user's
  // subscription is looked up.
  rpc GetOrCreateSubscription(GetOrCreateSubscriptionRequest) returns (Subscription);

  // GetPlanCatalog replaces billing.Catalog + billing.PlanPriceIDs for
  // rendering /subscription — returns every plan and whether its Stripe
  // price is currently configured (so an unconfigured plan renders as
  // "Unavailable", same as today).
  rpc GetPlanCatalog(GetPlanCatalogRequest) returns (GetPlanCatalogResponse);

  // CreateCheckoutSession replaces Handlers.CreateCheckout.
  rpc CreateCheckoutSession(CreateCheckoutSessionRequest) returns (CreateCheckoutSessionResponse);

  // SyncCheckoutSession replaces Handlers.syncCheckoutSession, the
  // fallback path SubscriptionSuccess uses when the webhook hasn't
  // landed yet.
  rpc SyncCheckoutSession(SyncCheckoutSessionRequest) returns (Subscription);

  // CreateBillingPortalSession replaces Handlers.BillingPortal.
  rpc CreateBillingPortalSession(CreateBillingPortalSessionRequest) returns (CreateBillingPortalSessionResponse);

  // IngestStripeWebhook replaces Handlers.StripeWebhook /
  // applyStripeEvent. The gateway still terminates the public
  // POST /webhooks/stripe route (so the URL Stripe is configured with
  // never changes) but forwards the raw body and signature header here
  // untouched — signature verification needs STRIPE_WEBHOOK_SECRET,
  // which only billing holds.
  rpc IngestStripeWebhook(IngestStripeWebhookRequest) returns (IngestStripeWebhookResponse);

  // CheckAndIncrementUsage replaces the daily-cap check + db.
  // IncrementDailyUsage call in Handlers.Chat. Called by the agent
  // service once per chat turn, after the message is accepted and
  // before the agent run starts (same ordering as the monolith).
  rpc CheckAndIncrementUsage(CheckAndIncrementUsageRequest) returns (CheckAndIncrementUsageResponse);

  // GetDailyUsage replaces db.DailyUsage — a read-only lookup (no
  // increment) used by the gateway's /subscription page to show
  // today's count without miscounting it as a sent message.
  rpc GetDailyUsage(GetDailyUsageRequest) returns (GetDailyUsageResponse);
}

enum Plan {
  PLAN_UNSPECIFIED = 0;
  PLAN_FREE = 1;
  PLAN_BASIC = 2;
  PLAN_PRO = 3;
  PLAN_PREMIUM = 4;
}

message PlanInfo {
  Plan plan = 1;
  string name = 2;
  int32 price_eur = 3;
  int32 daily_message_limit = 4; // 0 = unlimited
  bool available = 5;            // Stripe price configured (always true for free)
}

message Subscription {
  int64 user_id = 1;
  Plan plan = 2;
  string status = 3; // Stripe's subscription status, or "active" for free
  google.protobuf.Timestamp current_period_end = 4;
  bool cancel_at_period_end = 5;
  // has_billing_account reports whether a Stripe customer exists for
  // this user (so the gateway knows whether to show "Manage billing"),
  // without exposing the actual customer ID. The raw
  // stripe_customer_id / stripe_subscription_id / stripe_price_id are
  // deliberately NOT exposed here, mirroring models.Subscription's
  // json:"-" — they never need to leave billing.
  bool has_billing_account = 6;
}

message GetOrCreateSubscriptionRequest {
  int64 user_id = 1;
}

message GetPlanCatalogRequest {}

message GetPlanCatalogResponse {
  repeated PlanInfo plans = 1;
  string publishable_key = 2; // Stripe publishable key, for Checkout.js
}

message CreateCheckoutSessionRequest {
  int64 user_id = 1;
  string email = 2;
  Plan plan = 3;
  string success_url = 4;
  string cancel_url = 5;
}

message CreateCheckoutSessionResponse {
  string checkout_url = 1;
}

message SyncCheckoutSessionRequest {
  int64 user_id = 1;
  string stripe_session_id = 2;
}

message CreateBillingPortalSessionRequest {
  int64 user_id = 1;
  string return_url = 2;
}

message CreateBillingPortalSessionResponse {
  string portal_url = 1;
}

message IngestStripeWebhookRequest {
  bytes payload = 1;
  string signature_header = 2;
}

message IngestStripeWebhookResponse {
  bool accepted = 1;
}

message CheckAndIncrementUsageRequest {
  int64 user_id = 1;
}

message CheckAndIncrementUsageResponse {
  bool allowed = 1;
  int32 used = 2;
  int32 limit = 3; // 0 = unlimited
  string plan_name = 4;
}

message GetDailyUsageRequest {
  int64 user_id = 1;
}

message GetDailyUsageResponse {
  int32 used = 1;
}