package config

import (
	"encoding/json"
	"os"
	"path/filepath"
	"strconv"
	"strings"
)

const DefaultListen = ":33550"

var Version = "0.1.0"

type Config struct {
	BaseDir                string            `json:"base_dir"`
	ConfigPath             string            `json:"-"`
	Initialized            bool              `json:"initialized"`
	Listen                 string            `json:"listen"`
	BaseURL                string            `json:"base_url"`
	StorageDir             string            `json:"storage_dir"`
	DataDir                string            `json:"data_dir"`
	UpdatePublicDir        string            `json:"update_public_dir"`
	UpdateNoticeDir        string            `json:"update_notice_dir"`
	DownloadsDir           string            `json:"downloads_dir"`
	AdminWebDir            string            `json:"admin_web_dir"`
	PortalWebDir           string            `json:"portal_web_dir"`
	SetupWebDir            string            `json:"setup_web_dir"`
	LegacyUpdateDir        string            `json:"legacy_update_dir"`
	LegacyFeedbackDir      string            `json:"legacy_feedback_dir"`
	LegacyUpdateNoticeDir  string            `json:"legacy_update_notice_dir"`
	ClientSignatureKey     string            `json:"client_signature_key"`
	PackageEncryptionKey   string            `json:"package_encryption_key"`
	TimestampWindowSeconds int64             `json:"timestamp_window_seconds"`
	MaxRequestBytes        int64             `json:"max_request_bytes"`
	MaxPackageBytes        int64             `json:"max_package_bytes"`
	Database               DatabaseConfig    `json:"database"`
	UploadGuard            UploadGuardConfig `json:"upload_guard"`
	SourceCheckSeconds     int               `json:"source_check_seconds"`
}

type DatabaseConfig struct {
	Provider               string `json:"provider"`
	SQLitePath             string `json:"sqlite_path"`
	MySQLDSN               string `json:"mysql_dsn"`
	FailoverEnabled        bool   `json:"failover_enabled"`
	HotSyncEnabled         bool   `json:"hot_sync_enabled"`
	HealthIntervalSec      int    `json:"health_interval_sec"`
	MaxOpenConns           int    `json:"max_open_conns"`
	MaxIdleConns           int    `json:"max_idle_conns"`
	ConnMaxLifetimeSeconds int    `json:"conn_max_lifetime_seconds"`
}

type UploadGuardConfig struct {
	MaxZipFiles             int     `json:"max_zip_files"`
	MaxDecompressedBytes    int64   `json:"max_decompressed_bytes"`
	MaxSingleFileBytes      int64   `json:"max_single_file_bytes"`
	MaxCompressionRatio     float64 `json:"max_compression_ratio"`
	MaxReadableTextBytes    int64   `json:"max_readable_text_bytes"`
	AllowUnexpectedZipFiles bool    `json:"allow_unexpected_zip_files"`
}

func Load() (*Config, error) {
	root, err := ResolveBaseDir()
	if err != nil {
		return nil, err
	}
	cfg := defaults(root)
	path := firstNonEmpty(os.Getenv("YMHUT_UNIFIED_CONFIG"), filepath.Join(root, "config.json"))
	if data, err := os.ReadFile(path); err == nil {
		if err := json.Unmarshal(data, cfg); err != nil {
			return nil, err
		}
		cfg.Initialized = true
	}
	cfg.BaseDir = root
	cfg.ConfigPath = path
	applyEnv(cfg)
	normalize(root, cfg)
	return cfg, nil
}

func defaults(root string) *Config {
	return &Config{
		BaseDir:                root,
		ConfigPath:             filepath.Join(root, "config.json"),
		Initialized:            false,
		Listen:                 DefaultListen,
		BaseURL:                "https://update.ymhut.cn",
		StorageDir:             filepath.Join(root, "storage"),
		DataDir:                filepath.Join(root, "data"),
		UpdatePublicDir:        filepath.Join(root, "data", "update", "public"),
		UpdateNoticeDir:        filepath.Join(root, "data", "update-notice"),
		DownloadsDir:           filepath.Join(root, "data", "update", "public", "downloads"),
		AdminWebDir:            filepath.Join(root, "web", "admin", "dist"),
		PortalWebDir:           filepath.Join(root, "web", "portal", "dist"),
		SetupWebDir:            filepath.Join(root, "web", "setup", "dist"),
		LegacyUpdateDir:        filepath.Clean(filepath.Join(root, "..", "update")),
		LegacyFeedbackDir:      filepath.Clean(filepath.Join(root, "..", "feedback-mailer")),
		LegacyUpdateNoticeDir:  filepath.Clean(filepath.Join(root, "..", "..", "update-notice")),
		ClientSignatureKey:     "ymhut-box-feedback-client-v1",
		PackageEncryptionKey:   "ymhut-box-feedback-package-v1",
		TimestampWindowSeconds: 600,
		MaxRequestBytes:        12 * 1024 * 1024,
		MaxPackageBytes:        10 * 1024 * 1024,
		SourceCheckSeconds:     300,
		Database: DatabaseConfig{
			Provider:               "sqlite",
			SQLitePath:             filepath.Join(root, "storage", "unified.sqlite"),
			FailoverEnabled:        true,
			HotSyncEnabled:         true,
			HealthIntervalSec:      30,
			MaxOpenConns:           10,
			MaxIdleConns:           4,
			ConnMaxLifetimeSeconds: 300,
		},
		UploadGuard: UploadGuardConfig{
			MaxZipFiles:             80,
			MaxDecompressedBytes:    30 * 1024 * 1024,
			MaxSingleFileBytes:      8 * 1024 * 1024,
			MaxCompressionRatio:     120,
			MaxReadableTextBytes:    256 * 1024,
			AllowUnexpectedZipFiles: true,
		},
	}
}

func applyEnv(cfg *Config) {
	if value := os.Getenv("YMHUT_BASE_DIR"); value != "" {
		cfg.BaseDir = value
	}
	if value := os.Getenv("PORT"); value != "" {
		cfg.Listen = ":" + value
	}
	if value := os.Getenv("YMHUT_LISTEN"); value != "" {
		cfg.Listen = value
	}
	if value := os.Getenv("YMHUT_BASE_URL"); value != "" {
		cfg.BaseURL = value
	}
	if value := os.Getenv("YMHUT_STORAGE_DIR"); value != "" {
		cfg.StorageDir = value
	}
	if value := os.Getenv("YMHUT_DATA_DIR"); value != "" {
		cfg.DataDir = value
	}
	if value := os.Getenv("YMHUT_UPDATE_PUBLIC_DIR"); value != "" {
		cfg.UpdatePublicDir = value
	}
	if value := os.Getenv("YMHUT_UPDATE_NOTICE_DIR"); value != "" {
		cfg.UpdateNoticeDir = value
	}
	if value := os.Getenv("YMHUT_DOWNLOADS_DIR"); value != "" {
		cfg.DownloadsDir = value
	}
	if value := os.Getenv("YMHUT_LEGACY_UPDATE_DIR"); value != "" {
		cfg.LegacyUpdateDir = value
	}
	if value := os.Getenv("YMHUT_LEGACY_FEEDBACK_DIR"); value != "" {
		cfg.LegacyFeedbackDir = value
	}
	if value := os.Getenv("YMHUT_LEGACY_UPDATE_NOTICE_DIR"); value != "" {
		cfg.LegacyUpdateNoticeDir = value
	}
	if value := os.Getenv("YMHUT_DB_PROVIDER"); value != "" {
		cfg.Database.Provider = value
	}
	if value := os.Getenv("YMHUT_SQLITE_PATH"); value != "" {
		cfg.Database.SQLitePath = value
	}
	if value := os.Getenv("YMHUT_MYSQL_DSN"); value != "" {
		cfg.Database.MySQLDSN = value
	}
	if value := os.Getenv("YMHUT_CLIENT_SIGNATURE_KEY"); value != "" {
		cfg.ClientSignatureKey = value
	}
	if value := os.Getenv("YMHUT_PACKAGE_ENCRYPTION_KEY"); value != "" {
		cfg.PackageEncryptionKey = value
	}
	if value := os.Getenv("YMHUT_TIMESTAMP_WINDOW_SECONDS"); value != "" {
		if parsed, err := strconv.ParseInt(value, 10, 64); err == nil {
			cfg.TimestampWindowSeconds = parsed
		}
	}
	if value := os.Getenv("YMHUT_MAX_REQUEST_BYTES"); value != "" {
		if parsed, err := strconv.ParseInt(value, 10, 64); err == nil {
			cfg.MaxRequestBytes = parsed
		}
	}
	if value := os.Getenv("YMHUT_MAX_PACKAGE_BYTES"); value != "" {
		if parsed, err := strconv.ParseInt(value, 10, 64); err == nil {
			cfg.MaxPackageBytes = parsed
		}
	}
	if value := os.Getenv("YMHUT_SOURCE_CHECK_SECONDS"); value != "" {
		if parsed, err := strconv.Atoi(value); err == nil {
			cfg.SourceCheckSeconds = parsed
		}
	}
}

func normalize(root string, cfg *Config) {
	cfg.BaseDir = absPath(root, firstNonEmpty(cfg.BaseDir, root))
	if cfg.ConfigPath == "" {
		cfg.ConfigPath = filepath.Join(cfg.BaseDir, "config.json")
	}
	if cfg.Listen == "" {
		cfg.Listen = DefaultListen
	}
	if cfg.StorageDir == "" {
		cfg.StorageDir = filepath.Join(cfg.BaseDir, "storage")
	}
	cfg.StorageDir = absPath(cfg.BaseDir, cfg.StorageDir)
	if cfg.DataDir == "" {
		cfg.DataDir = filepath.Join(cfg.BaseDir, "data")
	}
	cfg.DataDir = absPath(cfg.BaseDir, cfg.DataDir)
	if cfg.UpdatePublicDir == "" {
		cfg.UpdatePublicDir = filepath.Join(cfg.DataDir, "update", "public")
	}
	cfg.UpdatePublicDir = absPath(cfg.BaseDir, cfg.UpdatePublicDir)
	if cfg.UpdateNoticeDir == "" {
		cfg.UpdateNoticeDir = filepath.Join(cfg.DataDir, "update-notice")
	}
	cfg.UpdateNoticeDir = absPath(cfg.BaseDir, cfg.UpdateNoticeDir)
	if cfg.DownloadsDir == "" {
		cfg.DownloadsDir = filepath.Join(cfg.UpdatePublicDir, "downloads")
	}
	cfg.DownloadsDir = absPath(cfg.BaseDir, cfg.DownloadsDir)
	if cfg.AdminWebDir == "" {
		cfg.AdminWebDir = filepath.Join(cfg.BaseDir, "web", "admin", "dist")
	}
	cfg.AdminWebDir = absPath(cfg.BaseDir, cfg.AdminWebDir)
	if cfg.PortalWebDir == "" {
		cfg.PortalWebDir = filepath.Join(cfg.BaseDir, "web", "portal", "dist")
	}
	cfg.PortalWebDir = absPath(cfg.BaseDir, cfg.PortalWebDir)
	if cfg.SetupWebDir == "" {
		cfg.SetupWebDir = filepath.Join(cfg.BaseDir, "web", "setup", "dist")
	}
	cfg.SetupWebDir = absPath(cfg.BaseDir, cfg.SetupWebDir)
	if cfg.LegacyUpdateDir == "" {
		cfg.LegacyUpdateDir = filepath.Clean(filepath.Join(cfg.BaseDir, "..", "update"))
	}
	cfg.LegacyUpdateDir = absPath(cfg.BaseDir, cfg.LegacyUpdateDir)
	if cfg.LegacyFeedbackDir == "" {
		cfg.LegacyFeedbackDir = filepath.Clean(filepath.Join(cfg.BaseDir, "..", "feedback-mailer"))
	}
	cfg.LegacyFeedbackDir = absPath(cfg.BaseDir, cfg.LegacyFeedbackDir)
	if cfg.LegacyUpdateNoticeDir == "" {
		cfg.LegacyUpdateNoticeDir = filepath.Clean(filepath.Join(cfg.BaseDir, "..", "..", "update-notice"))
	}
	cfg.LegacyUpdateNoticeDir = absPath(cfg.BaseDir, cfg.LegacyUpdateNoticeDir)
	if cfg.Database.Provider == "" {
		cfg.Database.Provider = "sqlite"
	}
	if cfg.Database.SQLitePath == "" {
		cfg.Database.SQLitePath = filepath.Join(cfg.StorageDir, "unified.sqlite")
	}
	cfg.Database.SQLitePath = absPath(cfg.BaseDir, cfg.Database.SQLitePath)
	if cfg.Database.HealthIntervalSec <= 0 {
		cfg.Database.HealthIntervalSec = 30
	}
	if cfg.Database.MaxOpenConns <= 0 {
		cfg.Database.MaxOpenConns = 10
	}
	if cfg.Database.MaxIdleConns <= 0 {
		cfg.Database.MaxIdleConns = 4
	}
	if cfg.Database.ConnMaxLifetimeSeconds <= 0 {
		cfg.Database.ConnMaxLifetimeSeconds = 300
	}
	if cfg.ClientSignatureKey == "" {
		cfg.ClientSignatureKey = "ymhut-box-feedback-client-v1"
	}
	if cfg.PackageEncryptionKey == "" {
		cfg.PackageEncryptionKey = "ymhut-box-feedback-package-v1"
	}
	if cfg.TimestampWindowSeconds <= 0 {
		cfg.TimestampWindowSeconds = 600
	}
	if cfg.MaxRequestBytes <= 0 {
		cfg.MaxRequestBytes = 12 * 1024 * 1024
	}
	if cfg.MaxPackageBytes <= 0 {
		cfg.MaxPackageBytes = 10 * 1024 * 1024
	}
	if cfg.UploadGuard.MaxZipFiles <= 0 {
		cfg.UploadGuard.MaxZipFiles = 80
	}
	if cfg.UploadGuard.MaxDecompressedBytes <= 0 {
		cfg.UploadGuard.MaxDecompressedBytes = 30 * 1024 * 1024
	}
	if cfg.UploadGuard.MaxSingleFileBytes <= 0 {
		cfg.UploadGuard.MaxSingleFileBytes = 8 * 1024 * 1024
	}
	if cfg.UploadGuard.MaxCompressionRatio <= 0 {
		cfg.UploadGuard.MaxCompressionRatio = 120
	}
	if cfg.UploadGuard.MaxReadableTextBytes <= 0 {
		cfg.UploadGuard.MaxReadableTextBytes = 256 * 1024
	}
	if cfg.SourceCheckSeconds <= 0 {
		cfg.SourceCheckSeconds = 300
	}
}

func ResolveBaseDir() (string, error) {
	if value := os.Getenv("YMHUT_BASE_DIR"); value != "" {
		return filepath.Abs(value)
	}
	if cwd, err := os.Getwd(); err == nil {
		if filepath.Base(cwd) == "unified-management" {
			return filepath.Abs(cwd)
		}
		candidate := filepath.Join(cwd, "server", "unified-management")
		if info, err := os.Stat(candidate); err == nil && info.IsDir() {
			return filepath.Abs(candidate)
		}
	}
	exe, err := os.Executable()
	if err != nil {
		return os.Getwd()
	}
	return filepath.Abs(filepath.Dir(exe))
}

func Save(cfg *Config) error {
	if cfg == nil {
		return nil
	}
	normalize(firstNonEmpty(cfg.BaseDir, "."), cfg)
	if err := os.MkdirAll(filepath.Dir(cfg.ConfigPath), 0o750); err != nil {
		return err
	}
	data, err := json.MarshalIndent(cfg, "", "  ")
	if err != nil {
		return err
	}
	return os.WriteFile(cfg.ConfigPath, data, 0o600)
}

func absPath(base, value string) string {
	if strings.TrimSpace(value) == "" {
		return value
	}
	if filepath.IsAbs(value) || strings.HasPrefix(strings.ToLower(value), "file:") {
		return filepath.Clean(value)
	}
	return filepath.Clean(filepath.Join(base, value))
}

func firstNonEmpty(values ...string) string {
	for _, value := range values {
		if value != "" {
			return value
		}
	}
	return ""
}