// Package bootstrap loads config and owns process lifecycle.
package bootstrap

import (
	"fmt"
	"os"
	"strings"
	"time"

	"gopkg.in/yaml.v3"
)

type Config struct {
	Env           string              `yaml:"env"`
	Server        ServerConfig        `yaml:"server"`
	Log           LogConfig           `yaml:"log"`
	ID            IDConfig            `yaml:"id"`
	MySQL         MySQLConfig         `yaml:"mysql"`
	Redis         RedisConfig         `yaml:"redis"`
	JWT           JWTConfig           `yaml:"jwt"`
	TaskPool      TaskPoolConfig      `yaml:"taskpool"`
	Deliver       DeliverConfig       `yaml:"deliver"`
	Session       SessionConfig       `yaml:"session"`
	RateLimit     RateLimitConfig     `yaml:"rate_limit"`
	Message       MessageConfig       `yaml:"message"`
	ObjectStorage ObjectStorageConfig `yaml:"object_storage"`
}

type LogConfig struct {
	Level    string        `yaml:"level"`
	Encoding string        `yaml:"encoding"`
	Console  bool          `yaml:"console"`
	File     LogFileConfig `yaml:"file"`
}

type LogFileConfig struct {
	Path       string `yaml:"path"`
	MaxSizeMB  int    `yaml:"max_size_mb"`
	MaxBackups int    `yaml:"max_backups"`
	MaxAgeDays int    `yaml:"max_age_days"`
	Compress   bool   `yaml:"compress"`
}

type ServerConfig struct {
	HTTP HTTPConfig `yaml:"http"`
	TCP  TCPConfig  `yaml:"tcp"`
}

type HTTPConfig struct {
	Addr string `yaml:"addr"`
}

type TCPConfig struct {
	Addr            string        `yaml:"addr"`
	ProxyProtocol   bool          `yaml:"proxy_protocol"`
	TLS             TLSConfig     `yaml:"tls"`
	MaxFrameSize    int           `yaml:"max_frame_size"`
	IdleTimeout     time.Duration `yaml:"idle_timeout"`
	KeepAlive       time.Duration `yaml:"keepalive"`
	RecvBuffer      int           `yaml:"recv_buffer"`
	SendBuffer      int           `yaml:"send_buffer"`
	Multicore       bool          `yaml:"multicore"`
	CompressMinSize int           `yaml:"compress_min_size"`
}

type TLSConfig struct {
	CertFile string `yaml:"cert_file"`
	KeyFile  string `yaml:"key_file"`
}

type IDConfig struct {
	SnowflakeWorkerID int64 `yaml:"snowflake_worker_id"`
}

type MySQLConfig struct {
	DSN             string        `yaml:"dsn"`
	SlowThreshold   time.Duration `yaml:"slow_threshold"`
	LogLevel        string        `yaml:"log_level"`
	MaxOpenConns    int           `yaml:"max_open_conns"`
	MaxIdleConns    int           `yaml:"max_idle_conns"`
	ConnMaxLifetime time.Duration `yaml:"conn_max_lifetime"`
	ConnMaxIdleTime time.Duration `yaml:"conn_max_idle_time"`
}

type RedisConfig struct {
	Addr                 string `yaml:"addr"`
	Username             string `yaml:"username"`
	Password             string `yaml:"password"`
	DB                   int    `yaml:"db"`
	DeliverQueueKey      string `yaml:"deliver_queue_key"`
	DeliverProcessingKey string `yaml:"deliver_processing_key"`
	DeliverDonePrefix    string `yaml:"deliver_done_prefix"`
}

type TaskPoolConfig struct {
	Size  int `yaml:"size"`
	Queue int `yaml:"queue"`
}

type DeliverConfig struct {
	Workers     int           `yaml:"workers"`
	TakeTimeout time.Duration `yaml:"take_timeout"`
	DoneTTL     time.Duration `yaml:"done_ttl"`
}

type SessionConfig struct {
	OutboundQueueSize int `yaml:"outbound_queue_size"`
}

type RateLimitConfig struct {
	MessagePerSecond      int `yaml:"message_per_second"`
	AuthPerSecond         int `yaml:"auth_per_second"`
	SyncInboxPerMinute    int `yaml:"sync_inbox_per_minute"`
	SyncMessagesPerMinute int `yaml:"sync_messages_per_minute"`
	HistoryPerMinute      int `yaml:"history_per_minute"`
	UploadPerSecond       int `yaml:"upload_per_second"`
}

type ObjectStorageConfig struct {
	Endpoint       string        `yaml:"endpoint"`
	AccessKey      string        `yaml:"access_key"`
	SecretKey      string        `yaml:"secret_key"`
	Bucket         string        `yaml:"bucket"`
	Region         string        `yaml:"region"`
	UseSSL         bool          `yaml:"use_ssl"`
	PresignTTL     time.Duration `yaml:"presign_ttl"`
	ChatExpireDays int           `yaml:"chat_expire_days"`
}

type MessageConfig struct {
	MaxContentSize int   `yaml:"max_content_size"`
	SyncLimit      int   `yaml:"sync_limit"`
	MsgIDExpireMS  int64 `yaml:"msgid_expire_ms"`
}

type JWTConfig struct {
	Secret         string        `yaml:"secret"`
	Issuer         string        `yaml:"issuer"`
	TTL            time.Duration `yaml:"ttl"`
	RefreshTTL     time.Duration `yaml:"refresh_ttl"`
	DenylistPrefix string        `yaml:"denylist_prefix"`
	RefreshPrefix  string        `yaml:"refresh_prefix"`
}

func Load(path string) (*Config, error) {
	raw, err := os.ReadFile(path)
	if err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}
	cfg := &Config{}
	if err := yaml.Unmarshal(raw, cfg); err != nil {
		return nil, fmt.Errorf("parse config: %w", err)
	}
	if err := cfg.normalize(); err != nil {
		return nil, err
	}
	return cfg, nil
}

const (
	EnvDev  = "dev"
	EnvProd = "prod"
	// DefaultJWTSecret is rejected when env is prod.
	DefaultJWTSecret = "dev-only-change-me"
)

func (cfg *Config) Production() bool {
	return cfg != nil && cfg.Env == EnvProd
}

func (cfg *Config) normalize() error {
	if cfg == nil {
		return fmt.Errorf("config is nil")
	}
	applyDefaults(cfg)
	return cfg.validate()
}

func applyDefaults(cfg *Config) {
	if v := os.Getenv("SPARK_ENV"); v != "" {
		cfg.Env = v
	}
	cfg.Env = parseEnv(cfg.Env)
	if v := os.Getenv("SPARK_JWT_SECRET"); v != "" {
		cfg.JWT.Secret = v
	}
	if v := os.Getenv("SPARK_REDIS_PASSWORD"); v != "" {
		cfg.Redis.Password = v
	}
	if cfg.JWT.Issuer == "" {
		cfg.JWT.Issuer = "spark-im"
	}
	if cfg.JWT.TTL <= 0 {
		cfg.JWT.TTL = 7 * 24 * time.Hour
	}
	if cfg.JWT.RefreshTTL <= 0 {
		cfg.JWT.RefreshTTL = 30 * 24 * time.Hour
	}
	if cfg.JWT.DenylistPrefix == "" {
		cfg.JWT.DenylistPrefix = "denylist:"
	}
	if cfg.JWT.RefreshPrefix == "" {
		cfg.JWT.RefreshPrefix = "refresh:"
	}
	if cfg.Redis.DeliverQueueKey == "" {
		cfg.Redis.DeliverQueueKey = "deliver:queue"
	}
	if cfg.Redis.DeliverProcessingKey == "" {
		cfg.Redis.DeliverProcessingKey = "deliver:processing"
	}
	if cfg.Redis.DeliverDonePrefix == "" {
		cfg.Redis.DeliverDonePrefix = "deliver:done:"
	}
	if cfg.Deliver.Workers < 1 {
		cfg.Deliver.Workers = 8
	}
	if cfg.Deliver.TakeTimeout <= 0 {
		cfg.Deliver.TakeTimeout = 5 * time.Second
	}
	if cfg.Deliver.DoneTTL <= 0 {
		cfg.Deliver.DoneTTL = 10 * time.Minute
	}
	if cfg.RateLimit.AuthPerSecond < 1 {
		cfg.RateLimit.AuthPerSecond = 5
	}
	if cfg.RateLimit.MessagePerSecond < 1 {
		cfg.RateLimit.MessagePerSecond = 20
	}
	if v := os.Getenv("SPARK_S3_ENDPOINT"); v != "" {
		cfg.ObjectStorage.Endpoint = v
	}
	if v := os.Getenv("SPARK_S3_ACCESS_KEY"); v != "" {
		cfg.ObjectStorage.AccessKey = v
	}
	if v := os.Getenv("SPARK_S3_SECRET_KEY"); v != "" {
		cfg.ObjectStorage.SecretKey = v
	}
	if v := os.Getenv("SPARK_S3_BUCKET"); v != "" {
		cfg.ObjectStorage.Bucket = v
	}
	if cfg.ObjectStorage.Bucket == "" {
		cfg.ObjectStorage.Bucket = "spark"
	}
	if cfg.ObjectStorage.Region == "" {
		cfg.ObjectStorage.Region = "us-east-1"
	}
	if cfg.ObjectStorage.PresignTTL <= 0 {
		cfg.ObjectStorage.PresignTTL = 15 * time.Minute
	}
	if cfg.ObjectStorage.ChatExpireDays < 1 {
		cfg.ObjectStorage.ChatExpireDays = 365
	}
	if cfg.RateLimit.UploadPerSecond < 1 {
		cfg.RateLimit.UploadPerSecond = 10
	}
}

func parseEnv(raw string) string {
	switch strings.ToLower(strings.TrimSpace(raw)) {
	case "prod", "production":
		return EnvProd
	default:
		return EnvDev
	}
}

func (cfg *Config) validate() error {
	if !cfg.Production() {
		return nil
	}
	if strings.TrimSpace(cfg.MySQL.DSN) == "" {
		return fmt.Errorf("prod: mysql.dsn is required")
	}
	if strings.TrimSpace(cfg.Redis.Addr) == "" {
		return fmt.Errorf("prod: redis.addr is required")
	}
	if strings.TrimSpace(cfg.JWT.Secret) == "" || strings.TrimSpace(cfg.JWT.Secret) == DefaultJWTSecret {
		return fmt.Errorf("prod: jwt.secret must be set via config or SPARK_JWT_SECRET")
	}
	if ep := strings.TrimSpace(cfg.ObjectStorage.Endpoint); ep != "" {
		if strings.TrimSpace(cfg.ObjectStorage.AccessKey) == "" || strings.TrimSpace(cfg.ObjectStorage.SecretKey) == "" {
			return fmt.Errorf("prod: object_storage access_key and secret_key are required")
		}
	}
	return nil
}