package config

import (
	"errors"
	"fmt"
	"net/url"
	"os"
	"strconv"
	"strings"
	"time"
)

type Config struct {
	MySQL     MySQLConfig
	Redis     RedisConfig
	CDC       CDCConfig
	Dashboard DashboardConfig
	Health    HealthConfig
}

type MySQLConfig struct {
	AppDSN       string
	CDCAddr      string
	CDCUser      string
	CDCPassword  string
	Schema       string
	WalletSchema string
	MaxOpenConns int
	MaxIdleConns int
}

type RedisConfig struct {
	Enabled  bool
	Addr     string
	Username string
	Password string
	DB       int
}

type CDCConfig struct {
	ServerID       uint32
	StartMode      string
	DryRun         bool
	IncludeTables  []string
	FlushInterval  time.Duration
	HeartbeatEvery time.Duration
}

type DashboardConfig struct {
	SysOrigins         []string
	StatTimezones      []string
	StorageTimezone    string
	RedisKeyPrefix     string
	RealtimeRedisTTL   time.Duration
	UnknownCountryCode string
}

type HealthConfig struct {
	Addr string
}

func Load() (Config, error) {
	cfg := Config{
		MySQL: MySQLConfig{
			AppDSN:       env("DASHBOARD_MYSQL_DSN", env("MYSQL_DSN", "")),
			CDCAddr:      env("CDC_MYSQL_ADDR", ""),
			CDCUser:      env("CDC_MYSQL_USER", ""),
			CDCPassword:  env("CDC_MYSQL_PASSWORD", ""),
			Schema:       env("CDC_MYSQL_SCHEMA", "likei"),
			WalletSchema: env("CDC_WALLET_SCHEMA", "likei_wallet"),
			MaxOpenConns: envInt("MYSQL_MAX_OPEN_CONNS", 8),
			MaxIdleConns: envInt("MYSQL_MAX_IDLE_CONNS", 4),
		},
		Redis: RedisConfig{
			Enabled:  envBool("REDIS_ENABLED", false),
			Addr:     env("REDIS_ADDR", ""),
			Username: env("REDIS_USERNAME", ""),
			Password: env("REDIS_PASSWORD", ""),
			DB:       envInt("REDIS_DB", 0),
		},
		CDC: CDCConfig{
			ServerID:       uint32(envInt("CDC_SERVER_ID", 29301)),
			StartMode:      strings.ToLower(env("CDC_START_MODE", "checkpoint")),
			DryRun:         envBool("CDC_DRY_RUN", true),
			IncludeTables:  csv(env("CDC_INCLUDE_TABLES", defaultTables())),
			FlushInterval:  envDuration("CDC_FLUSH_INTERVAL", 3*time.Second),
			HeartbeatEvery: envDuration("CDC_HEARTBEAT_EVERY", 30*time.Second),
		},
		Dashboard: DashboardConfig{
			SysOrigins:         csv(env("DASHBOARD_SYS_ORIGINS", "LIKEI")),
			StatTimezones:      csv(env("DASHBOARD_STAT_TIMEZONES", "Asia/Riyadh")),
			StorageTimezone:    env("DASHBOARD_STORAGE_TIMEZONE", "Asia/Riyadh"),
			RedisKeyPrefix:     env("DASHBOARD_REDIS_KEY_PREFIX", "country_dashboard"),
			RealtimeRedisTTL:   envDuration("DASHBOARD_REALTIME_REDIS_TTL", 48*time.Hour),
			UnknownCountryCode: env("DASHBOARD_UNKNOWN_COUNTRY_CODE", "UNKNOWN"),
		},
		Health: HealthConfig{
			Addr: env("HEALTH_ADDR", ":2910"),
		},
	}

	if cfg.MySQL.AppDSN == "" {
		return Config{}, errors.New("DASHBOARD_MYSQL_DSN or MYSQL_DSN is required")
	}
	if cfg.MySQL.CDCAddr == "" || cfg.MySQL.CDCUser == "" {
		return Config{}, errors.New("CDC_MYSQL_ADDR and CDC_MYSQL_USER are required")
	}
	if cfg.CDC.CDCPasswordRequired() && cfg.MySQL.CDCPassword == "" {
		return Config{}, errors.New("CDC_MYSQL_PASSWORD is required")
	}
	if cfg.Redis.Enabled && cfg.Redis.Addr == "" {
		return Config{}, errors.New("REDIS_ADDR is required when REDIS_ENABLED=true")
	}
	if cfg.CDC.ServerID == 0 {
		return Config{}, errors.New("CDC_SERVER_ID must be greater than 0")
	}
	if cfg.CDC.StartMode != "checkpoint" && cfg.CDC.StartMode != "current" {
		return Config{}, fmt.Errorf("unsupported CDC_START_MODE=%s", cfg.CDC.StartMode)
	}
	if len(cfg.Dashboard.SysOrigins) == 0 {
		return Config{}, errors.New("DASHBOARD_SYS_ORIGINS is empty")
	}
	if len(cfg.Dashboard.StatTimezones) == 0 {
		return Config{}, errors.New("DASHBOARD_STAT_TIMEZONES is empty")
	}
	return cfg, nil
}

func (c CDCConfig) CDCPasswordRequired() bool {
	return true
}

func defaultTables() string {
	return strings.Join([]string{
		"likei.user_base_info",
		"likei.order_purchase_history",
		"likei.order_user_purchase_pay",
		"likei.game_lucky_gift_count",
		"likei.game_lucky_box_count",
		"likei.baishun_order_idempotency",
		"likei.game_open_callback_log",
		"likei.baishun_game_catalog",
		"likei.lingxian_game_catalog",
		"likei.sys_game_list_config",
		"likei_wallet.wallet_gold_asset_record_1",
		"likei_wallet.wallet_gold_asset_record_2",
		"likei_wallet.wallet_gold_asset_record_3",
		"likei_wallet.wallet_gold_asset_record_4",
		"likei_wallet.wallet_gold_asset_record_5",
		"likei_wallet.wallet_gold_asset_record_6",
		"likei_wallet.wallet_gold_asset_record_7",
		"likei_wallet.wallet_gold_asset_record_8",
		"likei_wallet.wallet_gold_asset_record_9",
		"likei_wallet.wallet_gold_asset_record_10",
		"likei_wallet.wallet_gold_asset_record_11",
		"likei_wallet.wallet_gold_asset_record_12",
		"likei_wallet.user_freight_balance_running_water",
		"likei_wallet.user_salary_account_running_water",
		"likei_wallet.user_salary_diamond_running_water",
	}, ",")
}

func env(key string, fallback string) string {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	return value
}

func envBool(key string, fallback bool) bool {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	parsed, err := strconv.ParseBool(value)
	if err != nil {
		return fallback
	}
	return parsed
}

func envInt(key string, fallback int) int {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	parsed, err := strconv.Atoi(value)
	if err != nil {
		return fallback
	}
	return parsed
}

func envDuration(key string, fallback time.Duration) time.Duration {
	value := strings.TrimSpace(os.Getenv(key))
	if value == "" {
		return fallback
	}
	parsed, err := time.ParseDuration(value)
	if err == nil {
		return parsed
	}
	seconds, err := strconv.Atoi(value)
	if err != nil {
		return fallback
	}
	return time.Duration(seconds) * time.Second
}

func csv(value string) []string {
	if strings.TrimSpace(value) == "" {
		return nil
	}
	items := strings.Split(value, ",")
	out := make([]string, 0, len(items))
	seen := make(map[string]struct{}, len(items))
	for _, item := range items {
		item = strings.TrimSpace(item)
		if item == "" {
			continue
		}
		if _, exists := seen[item]; exists {
			continue
		}
		seen[item] = struct{}{}
		out = append(out, item)
	}
	return out
}

func RedactedDSN(dsn string) string {
	parsed, err := url.Parse("mysql://" + dsn)
	if err != nil || parsed.User == nil {
		return "mysql://***"
	}
	parsed.User = url.UserPassword(parsed.User.Username(), "***")
	return strings.TrimPrefix(parsed.String(), "mysql://")
}