package db

import (
	"strings"

	mongoimpl "git.sendico.io/tech/sxchnge/bff/pkg/db/internal/mongo"
	"git.sendico.io/tech/sxchnge/bff/pkg/merrors"
	"git.sendico.io/tech/sxchnge/bff/pkg/model"
	"github.com/go-viper/mapstructure/v2"
	"go.uber.org/zap"
)

type DBDriver string

const (
	Mongo DBDriver = "mongodb"
)

type Config = model.DriverConfig[DBDriver]

// PermissionsDatabaseConfig is the explicit public contract for services that
// read authorization metadata from the central permissions database.
type PermissionsDatabaseConfig Config

// AsDatabaseConfig converts the permissions DB contract to the existing DB
// config type without duplicating driver parsing or connection behavior.
func (c *PermissionsDatabaseConfig) AsDatabaseConfig() *Config {
	if c == nil {
		return nil
	}
	converted := Config(*c)
	return &converted
}

// ResolvedDatabaseName identifies the database selected by a DB config.
type ResolvedDatabaseName struct {
	Name   string
	Source string
}

// ResolveDatabaseName resolves only the database name portion of a DB config.
// It intentionally mirrors the existing env-over-literal behavior and leaves
// low-level connection validation to the normal DB connection path.
func ResolveDatabaseName(config *Config) ResolvedDatabaseName {
	if config == nil {
		return ResolvedDatabaseName{}
	}
	return resolveDatabaseName(config)
}

// ResolvePermissionsDatabaseName resolves only the database name portion of a
// permissions DB config.
func ResolvePermissionsDatabaseName(config *PermissionsDatabaseConfig) ResolvedDatabaseName {
	return ResolveDatabaseName(config.AsDatabaseConfig())
}

// ValidateSplitDomainPermissionsDatabase verifies the generic split-domain
// invariant for services that must keep authorization metadata separate from
// domain storage.
func ValidateSplitDomainPermissionsDatabase(service string, domain *Config, permissions *PermissionsDatabaseConfig) (ResolvedDatabaseName, ResolvedDatabaseName, error) {
	domainName := ResolveDatabaseName(domain)
	permissionsName := ResolvePermissionsDatabaseName(permissions)

	if permissions == nil {
		return domainName, permissionsName, merrors.InvalidArgument(service+" permissions_database configuration is required", "permissions_database")
	}
	if strings.TrimSpace(domainName.Name) == "" {
		return domainName, permissionsName, merrors.InvalidArgument(service+" domain database name is required for split-domain validation", "database")
	}
	if strings.TrimSpace(permissionsName.Name) == "" {
		return domainName, permissionsName, merrors.InvalidArgument(service+" permissions database name is required for split-domain validation", "permissions_database")
	}
	if domainName.Name == permissionsName.Name {
		return domainName, permissionsName, merrors.InvalidArgument(service+" permissions_database must resolve to a different database than the domain database", "permissions_database")
	}

	return domainName, permissionsName, nil
}

func resolveDatabaseName(config *Config) ResolvedDatabaseName {
	if config == nil || config.Driver != Mongo {
		return ResolvedDatabaseName{}
	}
	var mongoConfig mongoimpl.Config
	if err := mapstructure.Decode(config.Settings, &mongoConfig); err != nil {
		return ResolvedDatabaseName{}
	}
	dbSettings := mongoimpl.Config2DBSettings(zap.NewNop(), &mongoConfig)
	source := ""
	if mongoConfig.DatabaseEnv != nil {
		source = "env:" + *mongoConfig.DatabaseEnv
	} else if mongoConfig.Database != nil {
		source = "settings.database"
	}
	if source != "" {
		return ResolvedDatabaseName{
			Name:   dbSettings.Database,
			Source: source,
		}
	}

	return ResolvedDatabaseName{}
}