package nkode

import (
	"errors"
	"fmt"
	"github.com/google/uuid"
	"go-nkode/core/model"
	"go-nkode/hashset"
	py "go-nkode/py-builtin"
	"go-nkode/util"
)

type Customer struct {
	CustomerId  uuid.UUID
	NKodePolicy model.NKodePolicy
	Attributes  CustomerAttributes
	Users       map[string]User
}

func NewCustomer(keypadSize model.KeypadSize, nkodePolicy model.NKodePolicy) (*Customer, error) {
	if keypadSize.TotalAttrs() < nkodePolicy.DistinctAttributes {
		return nil, errors.New(fmt.Sprintf("incompadible nkode policy and keypad size TotalAttrs: %d < DistinctAttributes: %d", keypadSize.TotalAttrs(), nkodePolicy.DistinctAttributes))
	}

	if keypadSize.AttrsPerKey < nkodePolicy.DistinctSets {
		return nil, errors.New(fmt.Sprintf("incompadible nkode policy and keypad size AttrPerKey: %d < DistinctSets: %d", keypadSize.AttrsPerKey, nkodePolicy.DistinctSets))
	}
	customerAttrs, err := NewCustomerAttributes(keypadSize)
	if err != nil {
		return nil, err
	}
	customer := Customer{
		CustomerId:  uuid.New(),
		NKodePolicy: nkodePolicy,
		Attributes:  *customerAttrs,
		Users:       make(map[string]User),
	}

	return &customer, nil
}

func (c *Customer) AddNewUser(username string, passcodeIdx []int, userInterface UserInterface) error {
	_, exists := c.Users[username]
	if exists {
		return errors.New(fmt.Sprintf("User %s already exists for customer %s exists", username, c.CustomerId.String()))
	}
	newKeys, err := NewUserCipherKeys(c.Attributes.KeypadSize, c.Attributes.SetVals, c.NKodePolicy.MaxNkodeLen)
	if err != nil {
		return err
	}
	encipheredNKode, err := newKeys.EncipherNKode(passcodeIdx, c.Attributes)
	if err != nil {
		return err
	}
	newUser := User{
		Username:           username,
		EncipheredPasscode: *encipheredNKode,
		UserKeys:           *newKeys,
		Interface:          userInterface,
	}
	c.Users[username] = newUser
	return nil
}

func (c *Customer) ValidKeyEntry(username string, selectedKeys []int) ([]int, error) {
	user, exists := c.Users[username]
	if !exists {
		return nil, errors.New(fmt.Sprintf("user %s does not exist for customer %s", username, c.CustomerId.String()))
	}

	validKeys := py.All[int](selectedKeys, func(idx int) bool {
		return 0 <= idx && idx < c.Attributes.KeypadSize.NumbOfKeys
	})
	if !validKeys {
		return nil, errors.New(fmt.Sprintf("one or more keys not in range 0-%d", c.Attributes.KeypadSize.NumbOfKeys-1))
	}
	presumedAttrIdxVals, err := c.getPresumedAttributeIdxVals(user, selectedKeys)
	if err != nil {
		return nil, err
	}
	err = c.IsValidNKode(presumedAttrIdxVals)
	if err != nil {
		return nil, err
	}
	err = user.UserKeys.ValidPassword(user.EncipheredPasscode.Code, presumedAttrIdxVals, c.Attributes)
	if err != nil {
		return nil, err
	}

	return presumedAttrIdxVals, nil
}

func (c *Customer) getPresumedAttributeIdxVals(user User, selectedKeys []int) ([]int, error) {

	passcodeLen := len(selectedKeys)
	if passcodeLen < c.NKodePolicy.MinNkodeLen || passcodeLen > c.NKodePolicy.MaxNkodeLen {
		return nil, errors.New(fmt.Sprintf("Invalid passcode length of %d. Passcode length must be in range %d-%d", passcodeLen, c.NKodePolicy.MinNkodeLen, c.NKodePolicy.MaxNkodeLen))
	}
	passcodeSetVals, err := user.DecipherMask(c.Attributes.SetVals, passcodeLen)
	if err != nil {
		return nil, err
	}
	presumedAttrIdxVals := make([]int, passcodeLen)

	for idx := range presumedAttrIdxVals {
		keyNumb := selectedKeys[idx]
		setIdx, err := c.Attributes.IndexOfSet(passcodeSetVals[idx])
		if err != nil {
			return nil, err
		}
		selectedAttrIdx, err := user.Interface.GetAttrIdxByKeyNumbSetIdx(setIdx, keyNumb)
		if err != nil {
			return nil, err
		}
		presumedAttrIdxVals[idx] = selectedAttrIdx
	}
	return presumedAttrIdxVals, nil
}

func (c *Customer) IsValidNKode(passcodeAttrIdx []int) error {
	nkodeLen := len(passcodeAttrIdx)
	if nkodeLen < c.NKodePolicy.MinNkodeLen {
		return errors.New(fmt.Sprintf("NKode length %d is too short. Minimum nKode length is %d", nkodeLen, c.NKodePolicy.MinNkodeLen))
	}

	validIdx := py.All[int](passcodeAttrIdx, func(i int) bool {
		return i >= 0 && i < c.Attributes.KeypadSize.TotalAttrs()
	})

	if !validIdx {
		return errors.New(fmt.Sprintf("One or more idx out of range 0-%d in IsValidNKode", c.Attributes.KeypadSize.TotalAttrs()-1))
	}
	passcodeSetVals := make(hashset.Set[uint64])
	passcodeAttrVals := make(hashset.Set[uint64])
	for idx := 0; idx < nkodeLen; idx++ {
		attrVal := c.Attributes.AttrVals[passcodeAttrIdx[idx]]
		setVal, err := c.Attributes.GetAttrSetVal(attrVal)
		if err != nil {
			return err
		}
		passcodeSetVals.Add(setVal)
		passcodeAttrVals.Add(attrVal)
	}

	if passcodeSetVals.Size() < c.NKodePolicy.DistinctSets {
		return errors.New(fmt.Sprintf("passcode has two few distinct sets min %d, has %d", c.NKodePolicy.DistinctSets, passcodeSetVals.Size()))
	}

	if passcodeAttrVals.Size() < c.NKodePolicy.DistinctAttributes {
		return errors.New(fmt.Sprintf("passcode has two few distinct attributes min %d, has %d", c.NKodePolicy.DistinctAttributes, passcodeAttrVals.Size()))
	}
	return nil
}

func (c *Customer) GetLoginInterface(username string) ([]int, error) {
	user, exists := c.Users[username]
	if !exists {
		return nil, errors.New(fmt.Sprintf("can't get login interface for non-existant user %s in customer %s", username, c.CustomerId.String()))
	}
	err := user.Interface.PartialInterfaceShuffle()

	if err != nil {
		return nil, err
	}
	c.Users[username] = user
	return user.Interface.IdxInterface, nil
}

func (c *Customer) RenewKeys() error {
	oldAttrs := make([]uint64, c.Attributes.KeypadSize.TotalAttrs())
	oldSets := make([]uint64, c.Attributes.KeypadSize.AttrsPerKey)
	copy(oldAttrs, c.Attributes.AttrVals)
	copy(oldSets, c.Attributes.SetVals)

	err := c.Attributes.Renew()
	if err != nil {
		return nil
	}
	attrsXor, err := util.XorLists(oldAttrs, c.Attributes.AttrVals)
	if err != nil {
		return nil
	}
	setXor, err := util.XorLists(oldSets, c.Attributes.SetVals)
	if err != nil {
		return nil
	}
	for _, user := range c.Users {
		err = user.RenewKeys(setXor, attrsXor)
		if err != nil {
			return nil
		}
	}
	return nil
}