package netmap

import (
	"context"
	"errors"
	"fmt"

	"git.frostfs.info/TrueCloudLab/frostfs-node/pkg/morph/client"
	"github.com/nspcc-dev/neo-go/pkg/encoding/bigint"
	"github.com/nspcc-dev/neo-go/pkg/vm/stackitem"
)

const (
	MaxObjectSizeConfig           = "MaxObjectSize"
	MaxECParityCountConfig        = "MaxECParityCount"
	MaxECDataCountConfig          = "MaxECDataCount"
	EpochDurationConfig           = "EpochDuration"
	ContainerFeeConfig            = "ContainerFee"
	ContainerAliasFeeConfig       = "ContainerAliasFee"
	IrCandidateFeeConfig          = "InnerRingCandidateFee"
	WithdrawFeeConfig             = "WithdrawFee"
	HomomorphicHashingDisabledKey = "HomomorphicHashingDisabled"
	MaintenanceModeAllowedConfig  = "MaintenanceModeAllowed"
)

// MaxObjectSize receives max object size configuration
// value through the Netmap contract call.
func (c *Client) MaxObjectSize() (uint64, error) {
	objectSize, err := c.readUInt64Config(MaxObjectSizeConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get epoch number: %w", c, err)
	}

	return objectSize, nil
}

// EpochDuration returns number of sidechain blocks per one FrostFS epoch.
func (c *Client) EpochDuration() (uint64, error) {
	epochDuration, err := c.readUInt64Config(EpochDurationConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get epoch duration: %w", c, err)
	}

	return epochDuration, nil
}

// ContainerFee returns fee paid by container owner to each alphabet node
// for container registration.
func (c *Client) ContainerFee() (uint64, error) {
	fee, err := c.readUInt64Config(ContainerFeeConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get container fee: %w", c, err)
	}

	return fee, nil
}

// ContainerAliasFee returns additional fee paid by container owner to each
// alphabet node for container nice name registration.
func (c *Client) ContainerAliasFee() (uint64, error) {
	fee, err := c.readUInt64Config(ContainerAliasFeeConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get container alias fee: %w", c, err)
	}

	return fee, nil
}

// HomomorphicHashDisabled returns global configuration value of homomorphic hashing
// settings.
//
// Returns (false, nil) if config key is not found in the contract.
func (c *Client) HomomorphicHashDisabled() (bool, error) {
	return c.readBoolConfig(HomomorphicHashingDisabledKey)
}

// InnerRingCandidateFee returns global configuration value of fee paid by
// node to be in inner ring candidates list.
func (c *Client) InnerRingCandidateFee() (uint64, error) {
	fee, err := c.readUInt64Config(IrCandidateFeeConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get inner ring candidate fee: %w", c, err)
	}

	return fee, nil
}

// WithdrawFee returns global configuration value of fee paid by user to
// withdraw assets from FrostFS contract.
func (c *Client) WithdrawFee() (uint64, error) {
	fee, err := c.readUInt64Config(WithdrawFeeConfig)
	if err != nil {
		return 0, fmt.Errorf("(%T) could not get withdraw fee: %w", c, err)
	}

	return fee, nil
}

// MaintenanceModeAllowed reads admission of "maintenance" state from the
// FrostFS network configuration stored in the Sidechain. The admission means
// that storage nodes are allowed to switch their state to "maintenance".
//
// By default, maintenance state is disallowed.
func (c *Client) MaintenanceModeAllowed() (bool, error) {
	return c.readBoolConfig(MaintenanceModeAllowedConfig)
}

func (c *Client) readUInt64Config(key string) (uint64, error) {
	v, err := c.config([]byte(key), IntegerAssert)
	if err != nil {
		return 0, err
	}

	// IntegerAssert is guaranteed to return int64 if the error is nil.
	return uint64(v.(int64)), nil
}

// reads boolean value by the given key from the FrostFS network configuration
// stored in the Sidechain. Returns false if key is not presented.
func (c *Client) readBoolConfig(key string) (bool, error) {
	v, err := c.config([]byte(key), BoolAssert)
	if err != nil {
		if errors.Is(err, ErrConfigNotFound) {
			return false, nil
		}

		return false, fmt.Errorf("read boolean configuration value %s from the Sidechain: %w", key, err)
	}

	// BoolAssert is guaranteed to return bool if the error is nil.
	return v.(bool), nil
}

// SetConfigPrm groups parameters of SetConfig operation.
type SetConfigPrm struct {
	id    []byte
	key   []byte
	value any

	client.InvokePrmOptional
}

// SetID sets ID of the config value.
func (s *SetConfigPrm) SetID(id []byte) {
	s.id = id
}

// SetKey sets key of the config value.
func (s *SetConfigPrm) SetKey(key []byte) {
	s.key = key
}

// SetValue sets value of the config value.
func (s *SetConfigPrm) SetValue(value any) {
	s.value = value
}

// SetConfig sets config field.
func (c *Client) SetConfig(ctx context.Context, p SetConfigPrm) error {
	prm := client.InvokePrm{}
	prm.SetMethod(setConfigMethod)
	prm.SetArgs(p.id, p.key, p.value)
	prm.InvokePrmOptional = p.InvokePrmOptional

	_, err := c.client.Invoke(ctx, prm)
	return err
}

// RawNetworkParameter is a FrostFS network parameter which is transmitted but
// not interpreted by the FrostFS API protocol.
type RawNetworkParameter struct {
	// Name of the parameter.
	Name string

	// Raw parameter value.
	Value []byte
}

// NetworkConfiguration represents FrostFS network configuration stored
// in the FrostFS Sidechain.
type NetworkConfiguration struct {
	MaxObjectSize uint64

	EpochDuration uint64

	ContainerFee uint64

	ContainerAliasFee uint64

	IRCandidateFee uint64

	WithdrawalFee uint64

	HomomorphicHashingDisabled bool

	MaintenanceModeAllowed bool

	Raw []RawNetworkParameter
}

// ReadNetworkConfiguration reads NetworkConfiguration from the FrostFS Sidechain.
func (c *Client) ReadNetworkConfiguration() (NetworkConfiguration, error) {
	var res NetworkConfiguration
	prm := client.TestInvokePrm{}
	prm.SetMethod(configListMethod)

	items, err := c.client.TestInvoke(prm)
	if err != nil {
		return res, fmt.Errorf("could not perform test invocation (%s): %w",
			configListMethod, err)
	}

	if ln := len(items); ln != 1 {
		return res, fmt.Errorf("unexpected stack item count (%s): %d", configListMethod, ln)
	}

	arr, err := client.ArrayFromStackItem(items[0])
	if err != nil {
		return res, fmt.Errorf("record list (%s): %w", configListMethod, err)
	}

	m := make(map[string]struct{}, len(arr))
	res.Raw = make([]RawNetworkParameter, 0, len(arr))

	err = iterateRecords(arr, func(name string, value []byte) error {
		_, ok := m[name]
		if ok {
			return fmt.Errorf("duplicated config name %s", name)
		}

		m[name] = struct{}{}

		switch name {
		default:
			res.Raw = append(res.Raw, RawNetworkParameter{
				Name:  name,
				Value: value,
			})
		case MaxObjectSizeConfig:
			res.MaxObjectSize = bytesToUint64(value)
		case EpochDurationConfig:
			res.EpochDuration = bytesToUint64(value)
		case ContainerFeeConfig:
			res.ContainerFee = bytesToUint64(value)
		case ContainerAliasFeeConfig:
			res.ContainerAliasFee = bytesToUint64(value)
		case IrCandidateFeeConfig:
			res.IRCandidateFee = bytesToUint64(value)
		case WithdrawFeeConfig:
			res.WithdrawalFee = bytesToUint64(value)
		case HomomorphicHashingDisabledKey:
			res.HomomorphicHashingDisabled = bytesToBool(value)
		case MaintenanceModeAllowedConfig:
			res.MaintenanceModeAllowed = bytesToBool(value)
		}

		return nil
	})

	return res, err
}

func bytesToUint64(val []byte) uint64 {
	if len(val) == 0 {
		return 0
	}
	return bigint.FromBytes(val).Uint64()
}

func bytesToBool(val []byte) bool {
	for i := range val {
		if val[i] != 0 {
			return true
		}
	}

	return false
}

// ErrConfigNotFound is returned when the requested key was not found
// in the network config (returned value is `Null`).
var ErrConfigNotFound = errors.New("config value not found")

// config performs the test invoke of get config value
// method of FrostFS Netmap contract.
//
// Returns ErrConfigNotFound if config key is not found in the contract.
func (c *Client) config(key []byte, assert func(stackitem.Item) (any, error)) (any, error) {
	prm := client.TestInvokePrm{}
	prm.SetMethod(configMethod)
	prm.SetArgs(key)

	items, err := c.client.TestInvoke(prm)
	if err != nil {
		return nil, fmt.Errorf("could not perform test invocation (%s): %w",
			configMethod, err)
	}

	if ln := len(items); ln != 1 {
		return nil, fmt.Errorf("unexpected stack item count (%s): %d",
			configMethod, ln)
	}

	if _, ok := items[0].(stackitem.Null); ok {
		return nil, ErrConfigNotFound
	}

	return assert(items[0])
}

// IntegerAssert converts stack item to int64.
func IntegerAssert(item stackitem.Item) (any, error) {
	return client.IntFromStackItem(item)
}

// StringAssert converts stack item to string.
func StringAssert(item stackitem.Item) (any, error) {
	return client.StringFromStackItem(item)
}

// BoolAssert converts stack item to bool.
func BoolAssert(item stackitem.Item) (any, error) {
	return client.BoolFromStackItem(item)
}

// iterateRecords iterates over all config records and passes them to f.
//
// Returns f's errors directly.
func iterateRecords(arr []stackitem.Item, f func(key string, value []byte) error) error {
	for i := range arr {
		fields, err := client.ArrayFromStackItem(arr[i])
		if err != nil {
			return fmt.Errorf("record fields: %w", err)
		}

		if ln := len(fields); ln != 2 {
			return fmt.Errorf("unexpected record fields number: %d", ln)
		}

		k, err := client.BytesFromStackItem(fields[0])
		if err != nil {
			return fmt.Errorf("record key: %w", err)
		}

		v, err := client.BytesFromStackItem(fields[1])
		if err != nil {
			return fmt.Errorf("record value: %w", err)
		}

		if err := f(string(k), v); err != nil {
			return err
		}
	}

	return nil
}