package types

import (
	"database/sql/driver"
	"encoding/json"
	"errors"
	"fmt"
	"net/netip"

	"tailscale.com/tailcfg"
)

var ErrCannotParsePrefix = errors.New("cannot parse prefix")

// This is a "wrapper" type around tailscales
// Hostinfo to allow us to add database "serialization"
// methods. This allows us to use a typed values throughout
// the code and not have to marshal/unmarshal and error
// check all over the code.
type HostInfo tailcfg.Hostinfo

func (hi *HostInfo) Scan(destination interface{}) error {
	switch value := destination.(type) {
	case []byte:
		return json.Unmarshal(value, hi)

	case string:
		return json.Unmarshal([]byte(value), hi)

	default:
		return fmt.Errorf("%w: unexpected data type %T", ErrNodeAddressesInvalid, destination)
	}
}

// Value return json value, implement driver.Valuer interface.
func (hi HostInfo) Value() (driver.Value, error) {
	bytes, err := json.Marshal(hi)

	return string(bytes), err
}

type IPPrefix netip.Prefix

func (i *IPPrefix) Scan(destination interface{}) error {
	switch value := destination.(type) {
	case string:
		prefix, err := netip.ParsePrefix(value)
		if err != nil {
			return err
		}
		*i = IPPrefix(prefix)

		return nil
	default:
		return fmt.Errorf("%w: unexpected data type %T", ErrCannotParsePrefix, destination)
	}
}

// Value return json value, implement driver.Valuer interface.
func (i IPPrefix) Value() (driver.Value, error) {
	prefixStr := netip.Prefix(i).String()

	return prefixStr, nil
}

type IPPrefixes []netip.Prefix

func (i *IPPrefixes) Scan(destination interface{}) error {
	switch value := destination.(type) {
	case []byte:
		return json.Unmarshal(value, i)

	case string:
		return json.Unmarshal([]byte(value), i)

	default:
		return fmt.Errorf("%w: unexpected data type %T", ErrNodeAddressesInvalid, destination)
	}
}

// Value return json value, implement driver.Valuer interface.
func (i IPPrefixes) Value() (driver.Value, error) {
	bytes, err := json.Marshal(i)

	return string(bytes), err
}

type StringList []string

func (i *StringList) Scan(destination interface{}) error {
	switch value := destination.(type) {
	case []byte:
		return json.Unmarshal(value, i)

	case string:
		return json.Unmarshal([]byte(value), i)

	default:
		return fmt.Errorf("%w: unexpected data type %T", ErrNodeAddressesInvalid, destination)
	}
}

// Value return json value, implement driver.Valuer interface.
func (i StringList) Value() (driver.Value, error) {
	bytes, err := json.Marshal(i)

	return string(bytes), err
}

type StateUpdateType int

const (
	StateFullUpdate StateUpdateType = iota
	StatePeerChanged
	StatePeerRemoved
	StateDERPUpdated
)

// StateUpdate is an internal message containing information about
// a state change that has happened to the network.
type StateUpdate struct {
	// The type of update
	Type StateUpdateType

	// Changed must be set when Type is StatePeerChanged and
	// contain the Node IDs of nodes that have changed.
	Changed Nodes

	// Removed must be set when Type is StatePeerRemoved and
	// contain a list of the nodes that has been removed from
	// the network.
	Removed []tailcfg.NodeID

	// DERPMap must be set when Type is StateDERPUpdated and
	// contain the new DERP Map.
	DERPMap tailcfg.DERPMap
}