// Command addrkitd runs the address resolution service.
//
// It loads the canonical registry into memory, wires the optional adapters
// (ArcGIS portal, LLM rewriter) and serves the versioned JSON API. The process
// fails closed: if the registry cannot be loaded it exits rather than serving
// an empty index.
package main

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

	"git.totmin.ru/en2zmax/addrkit/internal/adapters/arcgis"
	"git.totmin.ru/en2zmax/addrkit/internal/adapters/httpapi"
	"git.totmin.ru/en2zmax/addrkit/internal/adapters/llm"
	"git.totmin.ru/en2zmax/addrkit/internal/adapters/registrystore"
	"git.totmin.ru/en2zmax/addrkit/internal/config"
	"git.totmin.ru/en2zmax/addrkit/internal/domain/match"
	"git.totmin.ru/en2zmax/addrkit/internal/domain/outages"
)

func main() {
	cfgPath := flag.String("config", "config.json", "path to the JSON config file")
	flag.Parse()

	cfg, err := config.Load(*cfgPath)
	if err != nil {
		slog.Error("config", "error", err)
		os.Exit(1)
	}

	logger := newLogger(cfg.LogLevel)

	version, entries, err := registrystore.Load(cfg.DataPath)
	if err != nil {
		// Fail closed: no registry, no service.
		logger.Error("load registry", "error", err, "path", cfg.DataPath)
		os.Exit(1)
	}
	logger.Info("registry loaded", "version", version, "entries", len(entries))

	index := match.NewIndex(version, entries, match.Options{
		FuzzyThreshold:  cfg.Resolve.FuzzyThreshold,
		AmbiguityMargin: cfg.Resolve.AmbiguityMargin,
		MaxCandidates:   cfg.Resolve.MaxCandidates,
	})

	var rewriter match.Rewriter
	if cfg.LLM.Enabled {
		rewriter = llm.New(cfg.LLM)
		logger.Info("llm rewriter enabled", "url", cfg.LLM.URL, "model", cfg.LLM.Model)
	}
	resolver := match.NewResolver(index, rewriter)

	var portal outages.Source
	if cfg.Portal.URL != "" {
		portal = arcgis.New(
			cfg.Portal.URL,
			time.Duration(cfg.Portal.TimeoutSeconds)*time.Second,
			cfg.Portal.Retries,
		)
		logger.Info("outages module enabled", "url", cfg.Portal.URL)
	} else {
		// portal.url is optional: without it only /v1/resolve is served.
		logger.Info("outages module disabled (portal.url not set)")
	}

	loc := operationalLocation()
	srv := httpapi.New(resolver, portal, logger, loc)

	httpServer := &http.Server{
		Addr:              cfg.Addr,
		Handler:           srv.Handler(),
		ReadHeaderTimeout: 5 * time.Second,
	}

	ctx, stop := signal.NotifyContext(context.Background(), syscall.SIGINT, syscall.SIGTERM)
	defer stop()

	go func() {
		logger.Info("listening", "addr", cfg.Addr, "tz", loc.String())
		if err := httpServer.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			logger.Error("serve", "error", err)
			stop()
		}
	}()

	<-ctx.Done()
	logger.Info("shutting down")

	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := httpServer.Shutdown(shutdownCtx); err != nil {
		logger.Error("shutdown", "error", err)
	}
}

func newLogger(level string) *slog.Logger {
	var lvl slog.Level
	switch level {
	case "debug":
		lvl = slog.LevelDebug
	case "warn":
		lvl = slog.LevelWarn
	case "error":
		lvl = slog.LevelError
	default:
		lvl = slog.LevelInfo
	}
	return slog.New(slog.NewJSONHandler(os.Stdout, &slog.HandlerOptions{Level: lvl}))
}

// operationalLocation returns Asia/Novosibirsk when the tz database is
// available and falls back to a fixed UTC+7 offset otherwise (containers
// without tzdata).
func operationalLocation() *time.Location {
	if loc, err := time.LoadLocation("Asia/Novosibirsk"); err == nil {
		return loc
	}
	return time.FixedZone("Asia/Novosibirsk", 7*3600)
}