package config

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

	"github.com/spf13/viper"

	sharedconfig "github.com/geo-platform/tenant-api/internal/shared/config"
)

type Config struct {
	Server             sharedconfig.ServerConfig   `mapstructure:"server"`
	Database           sharedconfig.DatabaseConfig `mapstructure:"database"`
	MonitoringDatabase sharedconfig.DatabaseConfig `mapstructure:"monitoring_database"`
	Redis              sharedconfig.RedisConfig    `mapstructure:"redis"`
	Cache              sharedconfig.CacheConfig    `mapstructure:"cache"`
	Log                sharedconfig.LogConfig      `mapstructure:"log"`
	JWT                JWTConfig                   `mapstructure:"jwt"`
	DefaultAdmin       DefaultAdminConfig          `mapstructure:"default_admin"`
	AdminUsers         AdminUsersConfig            `mapstructure:"admin_users"`
	IPRegion           IPRegionConfig              `mapstructure:"ip_region"`
}

type JWTConfig struct {
	Secret    string        `mapstructure:"secret"`
	AccessTTL time.Duration `mapstructure:"access_ttl"`
}

type DefaultAdminConfig struct {
	Username    string `mapstructure:"username"`
	Password    string `mapstructure:"password"`
	DisplayName string `mapstructure:"display_name"`
	Email       string `mapstructure:"email"`
}

type AdminUsersConfig struct {
	DefaultPlanCode string `mapstructure:"default_plan_code"`
}

type IPRegionConfig struct {
	V4XDBPath string `mapstructure:"v4_xdb_path"`
	V6XDBPath string `mapstructure:"v6_xdb_path"`
}

func Load(path string) (*Config, error) {
	v := viper.New()
	v.SetConfigFile(path)

	v.SetEnvPrefix("OPS")
	v.SetEnvKeyReplacer(strings.NewReplacer(".", "_"))
	v.AutomaticEnv()

	v.SetDefault("server.port", 8090)
	v.SetDefault("server.mode", "debug")
	v.SetDefault("redis.addr", "localhost:6379")
	v.SetDefault("redis.db", 0)
	v.SetDefault("cache.driver", "redis")
	v.SetDefault("log.level", "info")
	v.SetDefault("log.format", "json")
	v.SetDefault("jwt.access_ttl", 8*time.Hour)
	v.SetDefault("default_admin.username", "admin")
	v.SetDefault("default_admin.display_name", "Administrator")
	v.SetDefault("admin_users.default_plan_code", "free")
	v.SetDefault("ip_region.v4_xdb_path", "")
	v.SetDefault("ip_region.v6_xdb_path", "")

	if err := v.ReadInConfig(); err != nil {
		return nil, fmt.Errorf("read config: %w", err)
	}

	var cfg Config
	if err := v.Unmarshal(&cfg); err != nil {
		return nil, fmt.Errorf("unmarshal config: %w", err)
	}

	if err := applyEnvOverrides(&cfg); err != nil {
		return nil, err
	}

	if cfg.JWT.Secret == "" {
		return nil, fmt.Errorf("jwt.secret is required (set jwt.secret in yaml or OPS_JWT_SECRET env)")
	}
	if cfg.MonitoringDatabase.DBName == "" {
		cfg.MonitoringDatabase = cfg.Database
	}

	return &cfg, nil
}

func applyEnvOverrides(cfg *Config) error {
	if v := os.Getenv("OPS_JWT_SECRET"); v != "" {
		cfg.JWT.Secret = v
	}
	if v := os.Getenv("OPS_DEFAULT_ADMIN_USERNAME"); v != "" {
		cfg.DefaultAdmin.Username = v
	}
	if v := os.Getenv("OPS_DEFAULT_ADMIN_PASSWORD"); v != "" {
		cfg.DefaultAdmin.Password = v
	}
	if v := os.Getenv("OPS_DEFAULT_ADMIN_DISPLAY_NAME"); v != "" {
		cfg.DefaultAdmin.DisplayName = v
	}
	if v := os.Getenv("OPS_DEFAULT_ADMIN_EMAIL"); v != "" {
		cfg.DefaultAdmin.Email = v
	}
	if v := os.Getenv("OPS_ADMIN_USERS_DEFAULT_PLAN_CODE"); v != "" {
		cfg.AdminUsers.DefaultPlanCode = v
	}
	if v := os.Getenv("OPS_IP_REGION_V4_XDB_PATH"); v != "" {
		cfg.IPRegion.V4XDBPath = v
	}
	if v := os.Getenv("OPS_IP_REGION_V6_XDB_PATH"); v != "" {
		cfg.IPRegion.V6XDBPath = v
	}
	return nil
}