package service

import (
	"fmt"
	"strconv"
	"time"

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

	"github.com/google/uuid"
	"github.com/jmoiron/sqlx"
	"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, transaction types.TransactionInput) (*types.Transaction, error)
	Update(user *types.User, transaction types.TransactionInput) (*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

	RecalculateBalances(user *types.User) error
}

type TransactionImpl struct {
	db       *sqlx.DB
	clock    Clock
	random   Random
	settings *types.Settings
}

func NewTransaction(db *sqlx.DB, random Random, clock Clock, settings *types.Settings) Transaction {
	return TransactionImpl{
		db:       db,
		clock:    clock,
		random:   random,
		settings: settings,
	}
}

func (s TransactionImpl) Add(user *types.User, transactionInput types.TransactionInput) (*types.Transaction, error) {
	transactionMetric.WithLabelValues("add").Inc()

	if user == nil {
		return nil, ErrUnauthorized
	}

	transaction, err := s.validateAndEnrichTransaction(nil, user.Id, transactionInput)
	if err != nil {
		return nil, err
	}

	r, err := s.db.NamedExec(`
		INSERT INTO "transaction" (id, user_id, account_id, treasure_chest_id, value, timestamp, note, created_at, created_by)
		VALUES (:id, :user_id, :account_id, :treasure_chest_id, :value, :timestamp, :note, :created_at, :created_by)`, transaction)
	err = db.TransformAndLogDbError("transaction Insert", r, err)
	if err != nil {
		return nil, err
	}

	if transaction.AccountId != nil {
		r, err = s.db.Exec(`
			UPDATE account
			SET current_balance = current_balance + ?
			WHERE id = ? AND user_id = ?`, transaction.Value, transaction.AccountId, user.Id)
		err = db.TransformAndLogDbError("transaction UpdateAccount", r, err)
		if err != nil {
			return nil, err
		}
	}

	return transaction, nil
}

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

	transaction := &types.Transaction{}
	err = s.db.Get(transaction, `SELECT * FROM "transaction" WHERE user_id = ? AND id = ?`, user.Id, uuid)
	err = db.TransformAndLogDbError("transaction Update", nil, err)
	if err != nil {
		if err == db.ErrNotFound {
			return nil, fmt.Errorf("transaction %v not found: %w", input.Id, ErrBadRequest)
		}
		return nil, types.ErrInternal
	}

	if transaction.AccountId != nil {
		r, err := s.db.Exec(`
			UPDATE account
			SET current_balance = current_balance - ?
			WHERE id = ? AND user_id = ?`, transaction.Value, transaction.AccountId, user.Id)
		err = db.TransformAndLogDbError("transaction UpdateAccount", r, err)
		if err != nil {
			return nil, err
		}
	}

	transaction, err = s.validateAndEnrichTransaction(transaction, user.Id, input)
	if err != nil {
		return nil, err
	}

	if transaction.AccountId != nil {
		r, err := s.db.Exec(`
			UPDATE account
			SET current_balance = current_balance + ?
			WHERE id = ? AND user_id = ?`, transaction.Value, transaction.AccountId, user.Id)
		err = db.TransformAndLogDbError("transaction UpdateAccount", r, err)
		if err != nil {
			return nil, err
		}
	}

	r, err := s.db.NamedExec(`
		UPDATE "transaction"
		SET
			account_id = :account_id,
			treasure_chest_id = :treasure_chest_id,
			value = :value,
			timestamp = :timestamp,
			note = :note,
			updated_at = :updated_at,
			updated_by = :updated_by
		WHERE id = :id
			AND user_id = :user_id`, transaction)
	err = db.TransformAndLogDbError("transaction Update", r, err)
	if err != nil {
		return nil, err
	}

	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)
	}

	var transaction types.Transaction
	err = s.db.Get(&transaction, `SELECT * FROM "transaction" WHERE user_id = ? AND id = ?`, user.Id, uuid)
	err = db.TransformAndLogDbError("transaction Get", nil, err)
	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 := make([]*types.Transaction, 0)
	err := s.db.Select(&transactions, `SELECT * FROM "transaction" WHERE user_id = ? ORDER BY timestamp`, user.Id)
	err = db.TransformAndLogDbError("transaction GetAll", nil, err)
	if err != nil {
		return nil, err
	}

	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)
	}

	r, err := s.db.Exec(`
		UPDATE account
		SET current_balance = current_balance - (SELECT value FROM "transaction" WHERE id = ? AND user_id = ?)
		WHERE id = (SELECT account_id FROM "transaction" WHERE id = ? AND user_id = ?)
		`, uuid, user.Id, uuid, user.Id)
	err = db.TransformAndLogDbError("transaction Delete", r, err)
	if err != nil {
		return err
	}

	r, err = s.db.Exec("DELETE FROM \"transaction\" WHERE id = ? AND user_id = ?", uuid, user.Id)
	err = db.TransformAndLogDbError("transaction Delete", r, err)
	if err != nil {
		return err
	}

	return nil
}

func (s TransactionImpl) validateAndEnrichTransaction(transaction *types.Transaction, userId uuid.UUID, input types.TransactionInput) (*types.Transaction, error) {

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

		err      error
		rowCount int
	)

	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 input.AccountId != "" {
		temp, err := uuid.Parse(input.AccountId)
		if err != nil {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("could not parse accountId: %w", ErrBadRequest)
		}
		accountUuid = &temp
		err = s.db.Get(&rowCount, `SELECT COUNT(*) FROM account WHERE id = ? AND user_id = ?`, accountUuid, userId)
		err = db.TransformAndLogDbError("transaction validate", nil, err)
		if err != nil {
			return nil, err
		}
		if rowCount == 0 {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("account not found: %w", ErrBadRequest)
		}

	}

	if input.TreasureChestId != "" {
		temp, err := uuid.Parse(input.TreasureChestId)
		if err != nil {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("could not parse treasureChestId: %w", ErrBadRequest)
		}
		treasureChestUuid = &temp
		err = s.db.Get(&rowCount, `SELECT COUNT(*) FROM treasure_chest WHERE id = ? AND user_id = ?`, treasureChestUuid, userId)
		err = db.TransformAndLogDbError("transaction validate", nil, err)
		if err != nil {
			return nil, err
		}
		if rowCount == 0 {
			log.Error("transaction validate: %v", err)
			return nil, fmt.Errorf("treasure chest not found: %w", ErrBadRequest)
		}
	}

	valueFloat, err := strconv.ParseFloat(input.Value, 64)
	if err != nil {
		log.Error("transaction validate: %v", err)
		return nil, fmt.Errorf("could not parse value: %w", ErrBadRequest)
	}
	valueInt := int64(valueFloat * 100)

	timestampTime, err := time.Parse("2006-01-02T15:04", input.Timestamp)
	if err != nil {
		log.Error("transaction validate: %v", err)
		return nil, fmt.Errorf("could not parse timestamp: %w", ErrBadRequest)
	}

	if input.TimezoneOffsetMinutes != "" {
		timezoneOffsetMinutes, err := strconv.Atoi(input.TimezoneOffsetMinutes)
		if err != nil {
			return nil, fmt.Errorf("could not parse timezone offset: %w", ErrBadRequest)
		}
		timestampTime = timestampTime.Add(time.Duration(-1*timezoneOffsetMinutes) * time.Minute)
	}

	if input.Note != "" {
		err = validateString(input.Note, "note")
		if err != nil {
			return nil, err
		}
	}

	return &types.Transaction{
		Id:     id,
		UserId: userId,

		AccountId:       accountUuid,
		TreasureChestId: treasureChestUuid,
		Value:           valueInt,
		Timestamp:       timestampTime,
		Note:            input.Note,

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

func (s TransactionImpl) RecalculateBalances(user *types.User) error {
	transactionMetric.WithLabelValues("recalculate").Inc()
	if user == nil {
		return ErrUnauthorized
	}

	r, err := s.db.Exec(`
		UPDATE account
		SET current_balance = 0
		WHERE user_id = ?`, user.Id)
	err = db.TransformAndLogDbError("transaction RecalculateBalances", r, err)
	if err != nil && err != db.ErrNotFound {
		return err
	}

	r, err = s.db.Exec(`
		UPDATE treasure_chest
		SET current_balance = 0
		WHERE user_id = ?`, user.Id)
	err = db.TransformAndLogDbError("transaction RecalculateBalances", r, err)
	if err != nil && err != db.ErrNotFound {
		return err
	}

	rows, err := s.db.Queryx(`SELECT account_id, treasure_chest_id, value FROM "transaction" WHERE user_id = ?`, user.Id)
	err = db.TransformAndLogDbError("transaction RecalculateBalances", nil, err)
	if err != nil && err != db.ErrNotFound {
		return err
	}
	defer func() {
		err := rows.Close()
		if err != nil {
			log.Error("transaction RecalculateBalances: %v", err)
		}
	}()

	transaction := &types.Transaction{}
	for rows.Next() {
		err = rows.StructScan(transaction)
		err = db.TransformAndLogDbError("transaction RecalculateBalances", nil, err)
		if err != nil {
			return err
		}

		if transaction.AccountId != nil {
			r, err = s.db.Exec(`
				UPDATE account
				SET current_balance = current_balance + ?
				WHERE id = ? AND user_id = ?`, transaction.Value, transaction.AccountId, user.Id)
			err = db.TransformAndLogDbError("transaction RecalculateBalances", r, err)
			if err != nil {
				return err
			}
		}
		if transaction.TreasureChestId != nil {
			r, err = s.db.Exec(`
				UPDATE treasure_chest
				SET current_balance = current_balance + ?
				WHERE id = ? AND user_id = ?`, transaction.Value, transaction.TreasureChestId, user.Id)
			err = db.TransformAndLogDbError("transaction RecalculateBalances", r, err)
			if err != nil {
				return err
			}
		}
	}

	return nil
}