package main

import (
	"context"
	"encoding/json"
	"errors"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"
	"strconv"
	"strings"
	"syscall"
	"time"
)

const (
	defaultMaxObjectSize          = 1024 * 1024 * 1024
	defaultMinFreeBytes           = 1024 * 1024 * 1024
	defaultPresignedMaxExpiry     = 24 * time.Hour
	defaultMultipartMaxAge        = 24 * time.Hour
	defaultMaxRestoreBytes        = 10 * 1024 * 1024 * 1024
	defaultReplicationMaxJobs     = 10_000
	defaultReplicationMaxAttempts = 100
)

func main() {
	cmd := "serve"
	if len(os.Args) > 1 {
		cmd = os.Args[1]
	}
	if cmd == "version" {
		printJSON(versionInfo())
		return
	}
	if cmd == "help" || cmd == "-h" || cmd == "--help" {
		printUsage()
		return
	}

	cfg := configFromEnv()
	var store *FileStore
	openStore := func() *FileStore {
		if store != nil {
			return store
		}
		opened, err := NewFileStore(cfg.DataDir)
		if err != nil {
			log.Fatalf("init store: %v", err)
		}
		store = opened
		return store
	}

	switch cmd {
	case "serve":
		serve(cfg, openStore())
	case "reindex":
		mustJSON(openStore().Reindex())
	case "stats":
		stats, err := openStore().Stats()
		if err != nil {
			log.Fatal(err)
		}
		printJSON(stats)
	case "scrub":
		report, err := openStore().Scrub()
		if err != nil {
			log.Fatal(err)
		}
		printJSON(report)
	case "repair":
		count, err := openStore().EnqueueRepair(cfg.ReplicationPeers)
		if err != nil {
			log.Fatal(err)
		}
		printJSON(map[string]any{"status": "queued", "jobs": count})
	case "backup":
		if len(os.Args) < 3 {
			log.Fatal("usage: magpie backup <archive.tar.gz>")
		}
		mustJSON(BackupDir(cfg.DataDir, os.Args[2]))
	case "restore":
		if len(os.Args) < 3 {
			log.Fatal("usage: magpie restore <archive.tar.gz>")
		}
		mustJSON(RestoreDirWithLimit(os.Args[2], cfg.DataDir, cfg.MaxRestoreBytes))
	case "smoke":
		mustJSON(runSmoke(openStore()))
	default:
		log.Fatalf("unknown command %q", sanitizeLogValue(cmd))
	}
}

func serve(cfg Config, store *FileStore) {
	if cfg.ReindexOnStart {
		log.Printf("reindexing metadata from %s", cfg.DataDir)
		if err := store.Reindex(); err != nil {
			log.Fatalf("reindex store: %v", err)
		}
	}

	server := NewServerInstance(store, cfg)
	srv := &http.Server{
		Addr:              cfg.Addr,
		Handler:           server.Handler(),
		ReadHeaderTimeout: 5 * time.Second,
		ReadTimeout:       2 * time.Minute,
		WriteTimeout:      2 * time.Minute,
		IdleTimeout:       60 * time.Second,
		MaxHeaderBytes:    16 * 1024,
	}

	go func() {
		log.Printf("object store listening on %s, data=%s", cfg.Addr, cfg.DataDir)
		if err := srv.ListenAndServe(); err != nil && !errors.Is(err, http.ErrServerClosed) {
			log.Fatalf("listen: %v", err)
		}
	}()

	ctx, stop := signal.NotifyContext(context.Background(), os.Interrupt, syscall.SIGTERM)
	defer stop()
	server.startMultipartCleanup(ctx)
	server.startReplicationWorker(ctx)
	<-ctx.Done()

	shutdownCtx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
	defer cancel()
	if err := srv.Shutdown(shutdownCtx); err != nil {
		log.Printf("shutdown: %v", err)
	}
}

type Config struct {
	Addr                     string
	DataDir                  string
	AuthToken                string
	S3AccessKeyID            string
	S3SecretAccessKey        string
	S3Keys                   []AccessKey
	S3Region                 string
	AllowUnsignedLocal       bool
	MaxObjectSize            int64
	MinFreeBytes             uint64
	PresignedMaxExpiry       time.Duration
	MultipartMaxAge          time.Duration
	ReindexOnStart           bool
	ReplicationPeers         []string
	ReplicationSecret        string
	AllowInsecureReplication bool
	ReplicationMaxJobs       int
	ReplicationMaxAttempts   int
	MaxRestoreBytes          int64
	AllowedBuckets           map[string]bool
	PublicPrefixes           map[string]bool
	RateLimitPerMinute       int
	TrustProxyHeaders        bool
}

type AccessKey struct {
	ID          string
	Secret      string
	Permissions map[string]bool
}

func configFromEnv() Config {
	addr := getenv("MAGPIE_ADDR", "127.0.0.1:8090")
	dataDir := getenv("MAGPIE_DATA_DIR", "./data")
	authToken := os.Getenv("MAGPIE_AUTH_TOKEN")
	s3AccessKeyID := os.Getenv("MAGPIE_S3_ACCESS_KEY_ID")
	s3SecretAccessKey := os.Getenv("MAGPIE_S3_SECRET_ACCESS_KEY")
	s3Keys := parseAccessKeys(os.Getenv("MAGPIE_S3_KEYS"), s3AccessKeyID, s3SecretAccessKey)
	s3Region := getenv("MAGPIE_S3_REGION", "auto")
	maxObjectSize := mustParseBytes("MAGPIE_MAX_OBJECT_SIZE", defaultMaxObjectSize)
	minFreeBytes := mustParseUint("MAGPIE_MIN_FREE_BYTES", defaultMinFreeBytes)
	presignedMaxExpiry := mustParseDuration("MAGPIE_PRESIGNED_MAX_EXPIRY", defaultPresignedMaxExpiry)
	multipartMaxAge := mustParseDuration("MAGPIE_MULTIPART_MAX_AGE", defaultMultipartMaxAge)
	reindexOnStart := mustParseBool("MAGPIE_REINDEX_ON_START", false)
	allowInsecureReplication := mustParseBool("MAGPIE_ALLOW_INSECURE_REPLICATION", false)
	replicationPeers := parseReplicationPeers(os.Getenv("MAGPIE_REPLICATION_PEERS"), allowInsecureReplication)
	replicationSecret := os.Getenv("MAGPIE_REPLICATION_SECRET")
	replicationMaxJobs := mustParseInt("MAGPIE_REPLICATION_MAX_JOBS", defaultReplicationMaxJobs)
	replicationMaxAttempts := mustParseInt("MAGPIE_REPLICATION_MAX_ATTEMPTS", defaultReplicationMaxAttempts)
	maxRestoreBytes := mustParseBytes("MAGPIE_MAX_RESTORE_BYTES", defaultMaxRestoreBytes)
	allowedBuckets := parseSet(os.Getenv("MAGPIE_ALLOWED_BUCKETS"))
	// MAGPIE_PUBLIC_BUCKETS is a legacy whole-bucket public-read list (e.g. app-uploads).
	// MAGPIE_PUBLIC_PREFIXES is preferred and takes bucket/prefix values.
	publicPrefixes := parsePublicPrefixes(os.Getenv("MAGPIE_PUBLIC_PREFIXES"))
	for bucket := range parseSet(os.Getenv("MAGPIE_PUBLIC_BUCKETS")) {
		publicPrefixes[bucket] = true
	}
	rateLimitPerMinute := mustParseInt("MAGPIE_RATE_LIMIT_PER_MINUTE", 600)
	trustProxyHeaders := mustParseBool("MAGPIE_TRUST_PROXY_HEADERS", false)
	allowUnsignedLocal := mustParseBool("MAGPIE_ALLOW_UNSIGNED_PAYLOADS", false)

	if authToken == "" && len(s3Keys) == 0 {
		log.Fatal("MAGPIE_AUTH_TOKEN or MAGPIE_S3_ACCESS_KEY_ID/MAGPIE_S3_SECRET_ACCESS_KEY or MAGPIE_S3_KEYS is required")
	}
	if len(replicationPeers) > 0 && replicationSecret == "" {
		log.Fatal("MAGPIE_REPLICATION_SECRET is required when MAGPIE_REPLICATION_PEERS is set")
	}

	if raw := os.Getenv("MAGPIE_MAX_PROCS"); raw != "" {
		if _, err := strconv.Atoi(raw); err != nil {
			log.Fatalf("MAGPIE_MAX_PROCS must be an integer: %v", err)
		}
	}

	return Config{
		Addr:                     addr,
		DataDir:                  dataDir,
		AuthToken:                authToken,
		S3AccessKeyID:            s3AccessKeyID,
		S3SecretAccessKey:        s3SecretAccessKey,
		S3Keys:                   s3Keys,
		S3Region:                 s3Region,
		AllowUnsignedLocal:       allowUnsignedLocal,
		MaxObjectSize:            maxObjectSize,
		MinFreeBytes:             minFreeBytes,
		PresignedMaxExpiry:       presignedMaxExpiry,
		MultipartMaxAge:          multipartMaxAge,
		ReindexOnStart:           reindexOnStart,
		ReplicationPeers:         replicationPeers,
		ReplicationSecret:        replicationSecret,
		AllowInsecureReplication: allowInsecureReplication,
		ReplicationMaxJobs:       replicationMaxJobs,
		ReplicationMaxAttempts:   replicationMaxAttempts,
		MaxRestoreBytes:          maxRestoreBytes,
		AllowedBuckets:           allowedBuckets,
		PublicPrefixes:           publicPrefixes,
		RateLimitPerMinute:       rateLimitPerMinute,
		TrustProxyHeaders:        trustProxyHeaders,
	}
}

func parseAccessKeys(raw string, legacyID string, legacySecret string) []AccessKey {
	keys := make([]AccessKey, 0)
	if legacyID != "" && legacySecret != "" {
		keys = append(keys, AccessKey{ID: legacyID, Secret: legacySecret, Permissions: permissions("read,write,admin")})
	}
	for _, entry := range strings.Split(raw, ";") {
		entry = strings.TrimSpace(entry)
		if entry == "" {
			continue
		}
		parts := strings.Split(entry, ":")
		if len(parts) < 2 || parts[0] == "" || parts[1] == "" {
			log.Fatal("MAGPIE_S3_KEYS entries must be id:secret[:read,write,admin]")
		}
		perms := "read,write"
		if len(parts) >= 3 {
			perms = parts[2]
		}
		keys = append(keys, AccessKey{ID: parts[0], Secret: parts[1], Permissions: permissions(perms)})
	}
	return keys
}

func permissions(raw string) map[string]bool {
	result := map[string]bool{}
	for _, part := range strings.Split(raw, ",") {
		part = strings.TrimSpace(strings.ToLower(part))
		if part != "" {
			result[part] = true
		}
	}
	return result
}

func parseCSV(raw string) []string {
	parts := make([]string, 0)
	for _, part := range strings.Split(raw, ",") {
		part = strings.TrimSpace(part)
		if part != "" {
			parts = append(parts, strings.TrimRight(part, "/"))
		}
	}
	return parts
}

func parseReplicationPeers(raw string, allowInsecure bool) []string {
	peers := parseCSV(raw)
	for _, peer := range peers {
		if err := validateReplicationPeer(peer, allowInsecure); err != nil {
			log.Fatal(err)
		}
	}
	return peers
}

func parseSet(raw string) map[string]bool {
	values := map[string]bool{}
	for _, value := range parseCSV(raw) {
		values[value] = true
	}
	return values
}

func parsePublicPrefixes(raw string) map[string]bool {
	value := strings.TrimSpace(strings.ToLower(raw))
	if value == "none" || value == "false" || value == "0" {
		return map[string]bool{}
	}
	if strings.TrimSpace(raw) == "" {
		return map[string]bool{}
	}
	prefixes := parseSet(raw)
	for prefix := range prefixes {
		cleaned := strings.Trim(prefix, "/")
		if cleaned == "" {
			log.Fatal("MAGPIE_PUBLIC_PREFIXES entries must not be empty")
		}
		// Allow bare bucket names (whole-bucket public read) or bucket/prefix paths.
		if err := ValidateKey(cleaned); err != nil {
			log.Fatal("MAGPIE_PUBLIC_PREFIXES entries must be valid bucket or bucket/prefix values")
		}
	}
	return prefixes
}

func printUsage() {
	fmt.Println("usage: magpie [serve|reindex|stats|scrub|repair|version|backup|restore|smoke]")
}

func mustJSON(err error) {
	if err != nil {
		log.Fatal(err)
	}
	printJSON(map[string]string{"status": "ok"})
}

func printJSON(value any) {
	encoder := json.NewEncoder(os.Stdout)
	encoder.SetIndent("", "  ")
	if err := encoder.Encode(value); err != nil {
		log.Fatal(err)
	}
}

func getenv(key, fallback string) string {
	if value := os.Getenv(key); value != "" {
		return value
	}
	return fallback
}

func mustParseBytes(key string, fallback int64) int64 {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseInt(value, 10, 64)
	if err != nil || parsed < 0 {
		log.Fatal(fmt.Sprintf("%s must be a non-negative integer byte count", key))
	}
	return parsed
}

func mustParseUint(key string, fallback uint64) uint64 {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseUint(value, 10, 64)
	if err != nil {
		log.Fatal(fmt.Sprintf("%s must be a non-negative integer byte count", key))
	}
	return parsed
}

func mustParseDuration(key string, fallback time.Duration) time.Duration {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := time.ParseDuration(value)
	if err != nil || parsed <= 0 {
		log.Fatal(fmt.Sprintf("%s must be a positive duration like 1h or 24h", key))
	}
	return parsed
}

func mustParseBool(key string, fallback bool) bool {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseBool(value)
	if err != nil {
		log.Fatal(fmt.Sprintf("%s must be true or false", key))
	}
	return parsed
}

func mustParseInt(key string, fallback int) int {
	value := os.Getenv(key)
	if value == "" {
		return fallback
	}
	parsed, err := strconv.Atoi(value)
	if err != nil || parsed < 0 {
		log.Fatal(fmt.Sprintf("%s must be a non-negative integer", key))
	}
	return parsed
}

func runSmoke(store *FileStore) error {
	key := "smoke/test.txt"
	if _, err := store.Put(key, strings.NewReader("ok"), "text/plain"); err != nil {
		return err
	}
	obj, err := store.Open(key)
	if err != nil {
		return err
	}
	_ = obj.Close()
	if _, err := store.List("smoke/", 10); err != nil {
		return err
	}
	if _, err := store.Scrub(); err != nil {
		return err
	}
	return store.Delete(key)
}