// Command server runs the CDP analytics HTTP API.
package main

import (
	"context"
	"errors"
	"log"
	"net/http"
	"os"
	"os/signal"
	"syscall"
	"time"

	"github.com/go-chi/chi/v5"
	"github.com/redis/rueidis"
	"go.uber.org/zap"

	"github.com/dbiz/cdp/data-layer/api/internal/cache"
	"github.com/dbiz/cdp/data-layer/api/internal/config"
	"github.com/dbiz/cdp/data-layer/api/internal/handler"
	mw "github.com/dbiz/cdp/data-layer/api/internal/middleware"
	"github.com/dbiz/cdp/data-layer/api/internal/repo"
	"github.com/dbiz/cdp/data-layer/api/internal/service"
	"github.com/dbiz/cdp/data-layer/api/internal/templates"
)

func main() {
	if err := run(); err != nil {
		log.Fatal(err)
	}
}

func run() error {
	cfg, err := config.Load()
	if err != nil {
		return err
	}

	logger, err := newLogger(cfg.LogLevel)
	if err != nil {
		return err
	}
	defer func() { _ = logger.Sync() }()

	ctx, cancel := context.WithCancel(context.Background())
	defer cancel()

	// ---- infra clients ----------------------------------------------------
	pg, err := repo.NewPool(ctx, cfg.PostgresDSN)
	if err != nil {
		return err
	}
	defer pg.Close()

	redisClient, err := rueidis.NewClient(rueidis.ClientOption{
		InitAddress: []string{cfg.RedisAddr},
	})
	if err != nil {
		return err
	}
	defer redisClient.Close()

	chMain, err := repo.NewClickHouse(ctx, cfg.ClickHouseAddr, cfg.ClickHouseDB, cfg.ClickHouseUser, cfg.ClickHousePassword)
	if err != nil {
		return err
	}
	defer func() { _ = chMain.Close() }()

	chRO, err := repo.NewClickHouseReadOnly(ctx, cfg.ClickHouseAddr, cfg.ClickHouseDB, cfg.ClickHouseSQLUser, cfg.ClickHouseSQLPassword)
	if err != nil {
		// Read-only user might not be provisioned in dev. Log + fall back to
		// the main connection so /query/sql still works locally; production
		// must provide separate credentials.
		logger.Warn("read-only clickhouse user unavailable; /query/sql will use the main connection (dev only)",
			zap.Error(err))
		chRO = chMain
	} else {
		defer func() { _ = chRO.Close() }()
	}

	// ---- shared singletons ------------------------------------------------
	tpl := templates.New(cfg.ClickHouseTemplatesDir)
	c := cache.New(redisClient)

	eventRepo := repo.NewEventRepo(chMain, tpl)
	analyticsRepo := repo.NewAnalyticsRepo(chMain, tpl)
	profileRepo := repo.NewProfileRepo(pg)
	savedRepo := repo.NewSavedQueryRepo(pg)

	querySvc := service.NewQueryService(eventRepo, analyticsRepo, c, cfg.CacheTTLQuery, logger)
	sqlSvc := service.NewSQLService(chRO, logger)
	profileSvc := service.NewProfileService(profileRepo, eventRepo, c, cfg.CacheTTLProfile, logger)

	eventH := handler.NewEventHandler(querySvc, logger)
	sqlH := handler.NewSQLHandler(sqlSvc, logger)
	profileH := handler.NewProfileHandler(profileSvc, logger)
	analyticsH := handler.NewAnalyticsHandler(querySvc, logger)
	savedH := handler.NewSavedQueryHandler(savedRepo, logger)

	// ---- HTTP router ------------------------------------------------------
	r := chi.NewRouter()
	r.Use(mw.RequestID)
	r.Use(mw.Recover(logger))
	r.Use(mw.Logger(logger))
	r.Use(mw.CORS)

	r.Get("/health", eventH.Health)
	r.Get("/ready", eventH.Ready)

	r.Group(func(rr chi.Router) {
		rr.Use(mw.Workspace)

		rr.Post("/query/events", eventH.QueryEvents)
		rr.Post("/query/sql", sqlH.CustomSQL)
		rr.Post("/query/funnel", analyticsH.Funnel)
		rr.Post("/query/retention", analyticsH.Retention)
		rr.Post("/query/session", analyticsH.Session)

		rr.Get("/profiles/{id}", profileH.Get)
		rr.Get("/profiles/{id}/events", profileH.Timeline)

		rr.Post("/queries", savedH.Create)
		rr.Get("/queries", savedH.List)
		rr.Get("/queries/{id}", savedH.Get)
		rr.Put("/queries/{id}", savedH.Update)
		rr.Delete("/queries/{id}", savedH.Delete)
	})

	srv := &http.Server{
		Addr:              cfg.HTTPAddr,
		Handler:           r,
		ReadHeaderTimeout: 5 * time.Second,
		ReadTimeout:       60 * time.Second,
		WriteTimeout:      60 * time.Second,
		IdleTimeout:       120 * time.Second,
	}

	// ---- graceful shutdown ------------------------------------------------
	shutdownErr := make(chan error, 1)
	go func() {
		sigCh := make(chan os.Signal, 1)
		signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
		<-sigCh
		logger.Info("shutdown signal received; draining...")
		shutCtx, cancel := context.WithTimeout(context.Background(), cfg.ShutdownTimeout)
		defer cancel()
		shutdownErr <- srv.Shutdown(shutCtx)
	}()

	logger.Info("analytics api listening", zap.String("addr", cfg.HTTPAddr))
	if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
		return err
	}
	return <-shutdownErr
}

func newLogger(level string) (*zap.Logger, error) {
	lvl, err := zap.ParseAtomicLevel(level)
	if err != nil {
		lvl = zap.NewAtomicLevelAt(zap.InfoLevel)
	}
	cfg := zap.NewProductionConfig()
	cfg.Level = lvl
	cfg.EncoderConfig.TimeKey = "ts"
	cfg.EncoderConfig.MessageKey = "msg"
	return cfg.Build()
}