package service

import (
	"fmt"
	"strconv"
	"time"

	"spend-sparrow/db"
	"spend-sparrow/log"
	"spend-sparrow/types"

	"github.com/google/uuid"
	"github.com/prometheus/client_golang/prometheus"
	"github.com/prometheus/client_golang/prometheus/promauto"
)

var (
	transactionMetric = promauto.NewCounterVec(
		prometheus.CounterOpts{
			Name: "spendsparrow_transaction_total",
			Help: "The total of transaction operations",
		},
		[]string{"operation"},
	)
)

type Transaction interface {
	Add(user *types.User, accountId, treasureChestId, internal, value, timestamp, note string) (*types.Transaction, error)
	Update(user *types.User, id, accountId, treasureChestId, internal, value, timestamp, note string) (*types.Transaction, error)
	Get(user *types.User, id string) (*types.Transaction, error)
	GetAll(user *types.User) ([]*types.Transaction, error)
	Delete(user *types.User, id string) error
	CanDeleteTreasureChest(user *types.User, treasureChestId uuid.UUID) (bool, error)
	CanDeleteAccount(user *types.User, accountId uuid.UUID) (bool, error)
}

type TransactionImpl struct {
	db            db.Transaction
	account       Account
	treasureChest TreasureChest
	clock         Clock
	random        Random
	settings      *types.Settings
}

func NewTransaction(db db.Transaction, account Account, treasureChest TreasureChest, random Random, clock Clock, settings *types.Settings) Transaction {
	return TransactionImpl{
		db:            db,
		account:       account,
		treasureChest: treasureChest,
		clock:         clock,
		random:        random,
		settings:      settings,
	}
}

func (s TransactionImpl) Add(user *types.User, accountId, treasureChestId, internal, value, timestamp, note string) (*types.Transaction, error) {
	transactionMetric.WithLabelValues("add").Inc()

	if user == nil {
		return nil, ErrUnauthorized
	}

	transaction, err := s.validateTransaction(nil, user.Id, accountId, treasureChestId, internal, value, timestamp, note)
	if err != nil {
		return nil, err
	}

	err = s.db.Insert(user.Id, transaction)
	if err != nil {
		return nil, types.ErrInternal
	}

	savedTransaction, err := s.db.Get(user.Id, transaction.Id)
	if err != nil {
		log.Error("transaction %v not found after insert: %v", transaction.Id, err)
		return nil, types.ErrInternal
	}
	return savedTransaction, nil
}

func (s TransactionImpl) Update(user *types.User, id, accountId, treasureChestId, internal, value, timestamp, note string) (*types.Transaction, error) {
	transactionMetric.WithLabelValues("update").Inc()
	if user == nil {
		return nil, ErrUnauthorized
	}
	uuid, err := uuid.Parse(id)
	if err != nil {
		log.Error("transaction update: %v", err)
		return nil, fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	transaction, err := s.db.Get(user.Id, uuid)
	if err != nil {
		if err == db.ErrNotFound {
			return nil, fmt.Errorf("transaction %v not found: %w", id, ErrBadRequest)
		}
		return nil, types.ErrInternal
	}

	transaction, err = s.validateTransaction(transaction, user.Id, accountId, treasureChestId, internal, value, timestamp, note)
	if err != nil {
		return nil, err
	}

	err = s.db.Update(user.Id, transaction)
	if err != nil {
		return nil, types.ErrInternal
	}

	return transaction, nil
}

func (s TransactionImpl) Get(user *types.User, id string) (*types.Transaction, error) {
	transactionMetric.WithLabelValues("get").Inc()

	if user == nil {
		return nil, ErrUnauthorized
	}
	uuid, err := uuid.Parse(id)
	if err != nil {
		log.Error("transaction get: %v", err)
		return nil, fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	transaction, err := s.db.Get(user.Id, uuid)
	if err != nil {
		if err == db.ErrNotFound {
			return nil, fmt.Errorf("transaction %v not found: %w", id, ErrBadRequest)
		}
		return nil, types.ErrInternal
	}

	return transaction, nil
}

func (s TransactionImpl) GetAll(user *types.User) ([]*types.Transaction, error) {
	transactionMetric.WithLabelValues("get_all").Inc()
	if user == nil {
		return nil, ErrUnauthorized
	}

	transactions, err := s.db.GetAll(user.Id)
	if err != nil {
		return nil, types.ErrInternal
	}

	return transactions, nil
}

func (s TransactionImpl) Delete(user *types.User, id string) error {
	transactionMetric.WithLabelValues("delete").Inc()
	if user == nil {
		return ErrUnauthorized
	}
	uuid, err := uuid.Parse(id)
	if err != nil {
		log.Error("transaction delete: %v", err)
		return fmt.Errorf("could not parse Id: %w", ErrBadRequest)
	}

	transaction, err := s.db.Get(user.Id, uuid)
	if err != nil {
		if err == db.ErrNotFound {
			return fmt.Errorf("transaction %v not found: %w", id, ErrBadRequest)
		}
		return types.ErrInternal
	}

	if transaction.UserId != user.Id {
		return types.ErrUnauthorized
	}

	err = s.db.Delete(user.Id, transaction.Id)
	if err != nil {
		return types.ErrInternal
	}

	return nil
}

func (s TransactionImpl) validateTransaction(transaction *types.Transaction, userId uuid.UUID, accountId, treasureChestId, internal, value, timestamp, note string) (*types.Transaction, error) {

	var (
		id                uuid.UUID
		accountUuid       uuid.UUID
		treasureChestUuid uuid.UUID
		internalBool      bool
		createdAt         time.Time
		createdBy         uuid.UUID
		updatedAt         *time.Time
		updatedBy         uuid.UUID

		err error
	)

	if transaction == nil {
		id, err = s.random.UUID()
		if err != nil {
			return nil, types.ErrInternal
		}
		createdAt = s.clock.Now()
		createdBy = userId
	} else {
		id = transaction.Id
		createdAt = transaction.CreatedAt
		createdBy = transaction.CreatedBy
		time := s.clock.Now()
		updatedAt = &time
		updatedBy = userId
	}

	if accountId != "" {
		accountUuid, err = uuid.Parse(accountId)
		if err != nil {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("could not parse accountId: %w", ErrBadRequest)
		}
	}

	if treasureChestId != "" {
		treasureChestUuid, err = uuid.Parse(treasureChestId)
		if err != nil {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("could not parse treasureChestId: %w", ErrBadRequest)
		}
	}

	internalBool, err = strconv.ParseBool(internal)
	if err != nil {
		log.Error("transaction validate: %v", err)
		return nil, fmt.Errorf("could not parse internal: %w", ErrBadRequest)
	}

	valueInt, err := strconv.ParseInt(value, 10, 64)
	if err != nil {
		log.Error("transaction validate: %v", err)
		return nil, fmt.Errorf("could not parse value: %w", ErrBadRequest)
	}

	timestampTime, err := time.Parse(time.RFC3339, timestamp)
	if err != nil {
		log.Error("transaction validate: %v", err)
		return nil, fmt.Errorf("could not parse timestamp: %w", ErrBadRequest)
	}

	err = validateString(note)
	if err != nil {
		return nil, err
	}

	result := types.Transaction{
		Id:     id,
		UserId: userId,

		AccountId:       accountUuid,
		TreasureChestId: &treasureChestUuid,
		Internal:        internalBool,
		Value:           valueInt,
		Timestamp:       timestampTime,
		Note:            note,

		CreatedAt: createdAt,
		CreatedBy: createdBy,
		UpdatedAt: updatedAt,
		UpdatedBy: &updatedBy,
	}

	return &result, nil
}