// Command worker runs background jobs for the analytics service:
// computed-trait refresh, segment refresh, reverse-ETL pushes, webhook fan-out.
//
// Jobs are scheduled and dispatched via riverqueue/river backed by PostgreSQL.
// New job kinds are registered in registerWorkers below; periodic schedules
// are wired in periodicJobs.
package main

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

	"github.com/go-chi/chi/v5"
	"github.com/jackc/pgx/v5/pgxpool"
	"github.com/riverqueue/river"
	"github.com/riverqueue/river/riverdriver/riverpgxv5"
	"go.uber.org/zap"

	"github.com/dbiz/cdp/data-layer/workers/internal/config"
)

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()

	// ---- Postgres pool ----------------------------------------------------
	pool, err := pgxpool.New(ctx, cfg.PostgresDSN)
	if err != nil {
		return err
	}
	defer pool.Close()

	// ---- river client -----------------------------------------------------
	workers := river.NewWorkers()
	registerWorkers(workers, logger)

	client, err := river.NewClient(riverpgxv5.New(pool), &river.Config{
		Queues: map[string]river.QueueConfig{
			river.QueueDefault: {MaxWorkers: cfg.MaxWorkers},
		},
		Workers:      workers,
		PeriodicJobs: periodicJobs(cfg),
		Logger:       newSlogAdapter(logger),
	})
	if err != nil {
		return err
	}

	if err := client.Start(ctx); err != nil {
		return err
	}

	// ---- HTTP (health) ----------------------------------------------------
	r := chi.NewRouter()
	r.Get("/health", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ok"})
	})
	r.Get("/ready", func(w http.ResponseWriter, _ *http.Request) {
		writeJSON(w, http.StatusOK, map[string]string{"status": "ready"})
	})

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

	httpErr := make(chan error, 1)
	go func() {
		logger.Info("worker http listening", zap.String("addr", cfg.HTTPAddr))
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			httpErr <- err
		}
	}()

	// ---- Signals ----------------------------------------------------------
	sigCh := make(chan os.Signal, 1)
	signal.Notify(sigCh, syscall.SIGINT, syscall.SIGTERM)
	select {
	case <-sigCh:
		logger.Info("shutdown signal received")
	case err := <-httpErr:
		logger.Error("http stopped unexpectedly", zap.Error(err))
	}

	shutCtx, shutCancel := context.WithTimeout(context.Background(), cfg.ShutdownTimeout)
	defer shutCancel()
	_ = srv.Shutdown(shutCtx)
	if err := client.Stop(shutCtx); err != nil {
		logger.Error("river client stop", zap.Error(err))
	}
	return nil
}

// registerWorkers adds job workers to the registry. Each new job kind
// (ComputeTraits, RefreshSegment, ReverseETL, ...) calls river.AddWorker here.
func registerWorkers(_ *river.Workers, _ *zap.Logger) {
	// e.g. river.AddWorker(workers, &job.ComputeTraitsWorker{Repo: traitsRepo, Log: logger})
}

// periodicJobs returns the recurring schedules driven by river's built-in
// scheduler. Idempotent jobs only — river may retry on failure.
func periodicJobs(_ *config.Config) []*river.PeriodicJob {
	// Real schedules land here once the corresponding workers are wired up.
	// See CLAUDE_analytics.md → Job Queue (river).
	return nil
}

func writeJSON(w http.ResponseWriter, status int, body any) {
	w.Header().Set("Content-Type", "application/json")
	w.WriteHeader(status)
	_ = json.NewEncoder(w).Encode(body)
}

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()
}