package main

import (
	"context"
	"log"
	"time"

	"github.com/gofiber/fiber/v3"
	"github.com/gofiber/fiber/v3/middleware/adaptor"

	appq "knowfoolery/backend/services/question-bank-service/internal/application/question"
	qcache "knowfoolery/backend/services/question-bank-service/internal/infra/cache"
	qbconfig "knowfoolery/backend/services/question-bank-service/internal/infra/config"
	qent "knowfoolery/backend/services/question-bank-service/internal/infra/persistence/ent"
	httpapi "knowfoolery/backend/services/question-bank-service/internal/interfaces/http"
	"knowfoolery/backend/shared/infra/auth/zitadel"
	sharedredis "knowfoolery/backend/shared/infra/database/redis"
	"knowfoolery/backend/shared/infra/observability/logging"
	sharedmetrics "knowfoolery/backend/shared/infra/observability/metrics"
	"knowfoolery/backend/shared/infra/observability/tracing"
	"knowfoolery/backend/shared/infra/utils/serviceboot"
	"knowfoolery/backend/shared/infra/utils/validation"
)

func main() {
	cfg := qbconfig.FromEnv()

	logger := logging.NewLogger(cfg.Logging)
	metrics := sharedmetrics.NewMetrics(cfg.Metrics)

	tracer, err := tracing.NewTracer(cfg.Tracing)
	if err != nil {
		logger.Fatal("failed to initialize tracer")
	}
	defer func() {
		_ = tracer.Shutdown(context.Background())
	}()

	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()

	persistence, err := qent.NewClient(ctx, cfg.Postgres)
	if err != nil {
		logger.WithError(err).Fatal("failed to initialize postgres client")
	}
	defer persistence.Close()

	repo := qent.NewQuestionRepository(persistence)
	if err := repo.EnsureSchema(ctx); err != nil {
		logger.WithError(err).Fatal("failed to ensure schema")
	}

	var redisClient *sharedredis.Client
	if c, redisErr := sharedredis.NewClient(cfg.Redis); redisErr == nil {
		redisClient = c
		defer func() { _ = redisClient.Close() }()
	} else {
		logger.WithError(redisErr).Warn("redis unavailable; running with local fallback cache")
	}

	randomCache := qcache.NewRandomQuestionCache(redisClient)
	service := appq.NewService(repo, randomCache, cfg.CacheTTL, cfg.MaxExclude)

	validator := validation.NewValidator()
	handler := httpapi.NewHandler(service, validator, logger, metrics, cfg.BulkMax)

	bootCfg := serviceboot.Config{
		AppName:     cfg.AppName,
		ServiceSlug: "question-bank",
		PortEnv:     "QUESTION_BANK_PORT",
		DefaultPort: cfg.Port,
	}
	app := serviceboot.NewFiberApp(bootCfg)
	serviceboot.RegisterHealth(app, bootCfg.ServiceSlug)
	registerReadiness(app, persistence, redisClient)
	app.Get("/metrics", adaptor.HTTPHandler(sharedmetrics.Handler()))

	adminMiddleware := buildAdminMiddleware(cfg)
	httpapi.RegisterRoutes(app, handler, adminMiddleware)

	addr := serviceboot.ListenAddress(bootCfg.PortEnv, bootCfg.DefaultPort)
	log.Fatal(serviceboot.Run(app, addr))
}

func buildAdminMiddleware(cfg qbconfig.Config) fiber.Handler {
	if cfg.ZitadelBaseURL == "" {
		return nil
	}

	client := zitadel.NewClient(zitadel.Config{
		BaseURL:      cfg.ZitadelBaseURL,
		ClientID:     cfg.ZitadelClientID,
		ClientSecret: cfg.ZitadelSecret,
		Issuer:       cfg.ZitadelIssuer,
		Audience:     cfg.ZitadelAudience,
		Timeout:      10 * time.Second,
	})

	return zitadel.JWTMiddleware(zitadel.JWTMiddlewareConfig{
		Client:         client,
		Issuer:         cfg.ZitadelIssuer,
		Audience:       cfg.ZitadelAudience,
		RequiredClaims: []string{"sub"},
		AdminEndpoints: []string{"/admin"},
	})
}

func registerReadiness(app *fiber.App, persistence *qent.Client, redisClient *sharedredis.Client) {
	app.Get("/ready", func(c fiber.Ctx) error {
		ctx, cancel := context.WithTimeout(c.Context(), 2*time.Second)
		defer cancel()

		checks := map[string]string{"postgres": "ok", "redis": "ok"}
		if err := persistence.Pool.Ping(ctx); err != nil {
			checks["postgres"] = "down"
		}
		if redisClient != nil {
			if err := redisClient.HealthCheck(ctx); err != nil {
				checks["redis"] = "down"
			}
		}

		status := fiber.StatusOK
		if checks["postgres"] != "ok" {
			status = fiber.StatusServiceUnavailable
		}
		return c.Status(status).JSON(fiber.Map{
			"status": "ready",
			"checks": checks,
		})
	})
}