package app

import (
	"context"
	"fmt"
	"io"
	"log/slog"

	"chatappgateway/internal/config"
	"chatappgateway/internal/integration/paygrpc"
	"chatappgateway/internal/integration/upstream"
	"chatappgateway/internal/integration/usergrpc"
	"chatappgateway/internal/lifecycle"
	"chatappgateway/internal/service/auth"
	"chatappgateway/internal/service/pay"
	httpserver "chatappgateway/internal/transport/http"
)

// Application 组合网关运行所需的全部组件。
type Application struct {
	server  *httpserver.Server
	closers []io.Closer
	hooks   lifecycle.Hooks
}

// New 构造完整应用，包括 gRPC 连接池、业务服务和 HTTP 服务。
func New(ctx context.Context, cfg config.Config, logger *slog.Logger) (*Application, error) {
	userPool, err := upstream.New(ctx, "ChatAppUser", cfg.GRPC.User)
	if err != nil {
		return nil, fmt.Errorf("build ChatAppUser pool: %w", err)
	}

	payPool, err := upstream.New(ctx, "ChatAppPay", cfg.GRPC.Pay)
	if err != nil {
		_ = userPool.Close()
		return nil, fmt.Errorf("build ChatAppPay pool: %w", err)
	}

	userClient := usergrpc.NewWithPool(userPool)
	payClient := paygrpc.NewWithPool(payPool)

	authService := auth.New(userClient)
	payService := pay.New(payClient)
	registryHooks := lifecycle.NewRegistryHooks(cfg.Registry, logger.With("component", "registry_hooks"))
	readinessChecker := newReadinessGroup(
		namedChecker{
			name:  "ChatAppUser",
			check: userPool.Ready,
		},
		namedChecker{
			name:  "ChatAppPay",
			check: payPool.Ready,
		},
	)
	server := httpserver.New(cfg.App.Name, cfg.App.HTTPAddr, cfg.App.ShutdownTimeout, logger, authService, payService, readinessChecker, registryHooks)

	return &Application{
		server:  server,
		closers: []io.Closer{userPool, payPool},
		hooks:   registryHooks,
	}, nil
}

// Run 启动 HTTP 服务。
func (a *Application) Run(ctx context.Context) error {
	if err := a.hooks.OnRegister(ctx); err != nil {
		return fmt.Errorf("register lifecycle hook: %w", err)
	}
	return a.server.Run(ctx)
}

// Close 关闭底层 gRPC 连接。
func (a *Application) Close() error {
	var firstErr error
	for _, closer := range a.closers {
		if err := closer.Close(); err != nil && firstErr == nil {
			firstErr = err
		}
	}
	return firstErr
}