package pgdb

import (
	"context"
	"database/sql"
	"encoding/json"
	"errors"
	"fmt"

	dberrors "git-molva.ru/Molva/molva-backend/services/api_gateway/internal/database/errors"
	dbtypes "git-molva.ru/Molva/molva-backend/services/api_gateway/internal/database/types"
	"github.com/Masterminds/squirrel"
)

func getTransactionTypeByAmount(amount int64) dbtypes.TransactionType {
	if amount > 0 {
		return dbtypes.TransactionTypeDeposit
	}

	return dbtypes.TransactionTypeWithdrawal
}

// TODO: add migration to rebind statuses

func TransactionStatusIdToString(status int32) dbtypes.TransactionStatus {
	switch status {
	case 0:
		return dbtypes.TransactionStatusPending
	case 1:
		return dbtypes.TransactionStatusApproved
	case 2:
		return dbtypes.TransactionStatusRejected
	case 3:
		return dbtypes.TransactionStatusNew
	default:
		return dbtypes.TransactionStatusPending
	}
}

func TransactionStatusStringToId(status dbtypes.TransactionStatus) int32 {
	switch status {
	case dbtypes.TransactionStatusNew:
		return 3
	case dbtypes.TransactionStatusPending:
		return 0
	case dbtypes.TransactionStatusApproved:
		return 1
	case dbtypes.TransactionStatusRejected:
		return 2
	default:
		return 3
	}
}

//nolint:gocognit // not so hard
func (c *client) GetTransactionList(
	ctx context.Context,
	request *dbtypes.TransactionListGetRequest,
) (*dbtypes.TransactionListGetResponse, error) {
	if request == nil {
		return nil, nil
	}

	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		transactionsTable = fmt.Sprintf("%s.%s", c.config.Schema, TransactionsTableName)
	)

	getTransactions := psql.Select(
		"id", "owner_id", "bank_account_id", "amount", "currency", "status", "created_at", "payload",
	).From(transactionsTable).
		Where(squirrel.Eq{"owner_id": request.OwnerId}).
		Limit(request.PageSize).
		Offset(countOffset(request.Page, request.PageSize))

	getTransactions, err := c.setGetTransactionsQueryFilters(getTransactions, request.Filters)
	if err != nil {
		return nil, fmt.Errorf("%w: error setting get transactions query filters: %v", dberrors.ErrBadRequest, err)
	}

	query, args, err := getTransactions.ToSql()
	if err != nil {
		return nil, fmt.Errorf("%w: error building get transactions query: %v", dberrors.ErrInternal, err)
	}

	rows, err := c.db.QueryContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("%w: error executing get transactions query: %v", dberrors.ErrInternal, err)
	}

	defer rows.Close()

	transList := &dbtypes.TransactionListGetResponse{
		Transactions: make([]dbtypes.Transaction, 0, request.PageSize),
	}

	for rows.Next() {
		var (
			transStatus            int32
			ownerId                string
			payload, bankAccountId sql.NullString
			transaction            dbtypes.Transaction
		)

		if err := rows.Scan(
			&transaction.Id, &ownerId, &bankAccountId, &transaction.Amount, &transaction.Currency,
			&transStatus, &transaction.CreatedAt, &payload,
		); err != nil {
			if errors.Is(err, sql.ErrNoRows) {
				return nil, dberrors.ErrNotFound
			}

			return nil, fmt.Errorf("%w: error scanning row: %v", dberrors.ErrInternal, err)
		}

		if bankAccountId.Valid {
			bankAccountInfo, err := c.getBankAccountInfoById(ctx, c.db, bankAccountId.String)
			if err != nil {
				return nil, fmt.Errorf("%w: error getting bank account info: %v", dberrors.ErrInternal, err)
			}

			transaction.BankAccountInfo = bankAccountInfo

			ownerInfo, err := c.getOwnerInfoById(ctx, c.db, ownerId, bankAccountInfo.OwnerType)
			if err != nil {
				return nil, fmt.Errorf("%w: error getting owner info: %v", dberrors.ErrInternal, err)
			}

			transaction.OwnerInfo = ownerInfo
		}

		transaction.Type = getTransactionTypeByAmount(transaction.Amount)
		transaction.Status = TransactionStatusIdToString(transStatus)

		if payload.Valid {
			var payloadData dbtypes.TransactionPayload

			if err := json.Unmarshal([]byte(payload.String), &payloadData); err != nil {
				return nil, fmt.Errorf("%w: error unmarshaling transaction payload: %v", dberrors.ErrInternal, err)
			}

			transaction.Payload = &payloadData
		}

		transList.Transactions = append(transList.Transactions, transaction)
	}

	return transList, nil
}

func (c *client) setGetTransactionsQueryFilters(
	query squirrel.SelectBuilder,
	filters *dbtypes.TransactionListFilters,
) (squirrel.SelectBuilder, error) {
	if filters == nil {
		return query, nil
	}

	if filters.Type != nil {
		switch *filters.Type {
		case dbtypes.TransactionTypeDeposit:
			query = query.Where(squirrel.Gt{
				"amount": 0,
			})

		case dbtypes.TransactionTypeWithdrawal:
			query = query.Where(squirrel.Lt{
				"amount": 0,
			})

		default:
			return query, fmt.Errorf("%w: invalid transaction type: %v", dberrors.ErrBadRequest, *filters.Type)
		}
	}

	if filters.Status != nil {
		query = query.Where(squirrel.Eq{"status": TransactionStatusStringToId(*filters.Status)})
	}

	if filters.BankAccountId != nil {
		query = query.Where(squirrel.Eq{"bank_account_id": *filters.BankAccountId})
	}

	return query, nil
}

func (c *client) getOwnerInfoById(
	ctx context.Context,
	driver Driver,
	ownerId string,
	ownerType string,
) (*dbtypes.TransactionOwnerInfo, error) {
	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		clientTableName  = fmt.Sprintf("%s.%s", c.config.Schema, UsersTableName)
		companyTableName = fmt.Sprintf("%s.%s", c.config.Schema, CompaniesTableName)
	)

	var getOwnerInfoById squirrel.SelectBuilder

	// TODO: reingeneer the DB
	switch ownerType {
	case "agent":
		getOwnerInfoById = psql.Select(
			"uid",
			"name",
		).
			From(clientTableName).
			Where(squirrel.Eq{"uid": ownerId})

	case "company":
		getOwnerInfoById = psql.Select(
			"id",
			"name",
		).
			From(companyTableName).
			Where(squirrel.Eq{"id": ownerId})

	default:
		return nil, fmt.Errorf("%w: invalid owner type", dberrors.ErrBadRequest)
	}

	query, args, err := getOwnerInfoById.ToSql()
	if err != nil {
		return nil, fmt.Errorf("%w: error building get owner info by id query: %v", dberrors.ErrInternal, err)
	}

	row := driver.QueryRowContext(ctx, query, args...)

	var ownerInfo dbtypes.TransactionOwnerInfo

	if err := row.Scan(
		&ownerInfo.Id,
		&ownerInfo.Name,
	); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, dberrors.ErrNotFound
		}

		return nil, fmt.Errorf("%w: error scanning row for get owner info by id query: %v", dberrors.ErrInternal, err)
	}

	return &ownerInfo, nil
}

func (c *client) getBankAccountInfoById(
	ctx context.Context,
	driver Driver,
	bankAccountId string,
) (*dbtypes.BankAccountInfo, error) {
	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		bankAccountsTableName = fmt.Sprintf("%s.%s", c.config.Schema, BankAccountsTableName)
	)

	getBankAccountInfoById := psql.Select(
		"id",
		"account_number",
		"bank_name",
		"bik",
		"correspondent_account",
		"owner_type",
	).
		From(bankAccountsTableName).
		Where(squirrel.Eq{"id": bankAccountId})

	query, args, err := getBankAccountInfoById.ToSql()
	if err != nil {
		return nil, fmt.Errorf("%w: error building get bank account info by id query: %v", dberrors.ErrInternal, err)
	}

	row := driver.QueryRowContext(ctx, query, args...)

	var accountInfo dbtypes.BankAccountInfo

	if err := row.Scan(
		&accountInfo.Id,
		&accountInfo.AccountNumber,
		&accountInfo.BankName,
		&accountInfo.Bik,
		&accountInfo.CorrespondentAccount,
		&accountInfo.OwnerType,
	); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return nil, dberrors.ErrNotFound
		}

		return nil, fmt.Errorf("%w: error scanning row for get bank account info by id query: %v", dberrors.ErrInternal, err)
	}

	return &accountInfo, nil
}

func (c *client) CreateTransaction(
	ctx context.Context,
	request *dbtypes.TransactionCreateRequest,
) (*dbtypes.TransactionCreateResponse, error) {
	if request == nil {
		return nil, fmt.Errorf("%w: request is nil", dberrors.ErrBadRequest)
	}

	tx, err := c.db.BeginTx(ctx, nil)
	if err != nil {
		return nil, fmt.Errorf("%w: error starting transaction: %v", dberrors.ErrInternal, err)
	}

	defer func() { _ = tx.Rollback() }()

	result, err := c.createTransactionWithDriver(ctx, tx, request)
	if err != nil {
		return nil, fmt.Errorf("error creating transaction: %w", err)
	}

	if err := tx.Commit(); err != nil {
		return nil, fmt.Errorf("%w: error committing transaction: %w", dberrors.ErrInternal, err)
	}

	return result, nil
}

func (c *client) createTransactionWithDriver(
	ctx context.Context,
	driver Driver,
	request *dbtypes.TransactionCreateRequest,
) (*dbtypes.TransactionCreateResponse, error) {
	if _, err := c.getRawBalanceForUpdate(ctx, driver, request.OwnerId); err != nil {
		return nil, fmt.Errorf("error getting raw balance for update: %w", err)
	}

	result, err := c.createTransaction(ctx, driver, request)
	if err != nil {
		if errors.Is(err, dberrors.ErrConflict) {
			return result, nil
		}

		return nil, fmt.Errorf("error creating transaction: %w", err)
	}

	if err := c.updateBalance(ctx, driver, request.Amount, request.OwnerId); err != nil {
		return nil, fmt.Errorf("error updating balance: %w", err)
	}

	return result, nil
}

func (c *client) getRawBalanceForUpdate(
	ctx context.Context,
	driver Driver,
	ownerId string,
) (int64, error) {
	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		balancesTable = fmt.Sprintf("%s.%s", c.config.Schema, BalancesTableName)
	)

	getBalance := psql.Select(
		"raw_balance",
	).From(balancesTable).
		Where(squirrel.Eq{"owner_id": ownerId}).
		Suffix("FOR UPDATE")

	query, args, err := getBalance.ToSql()
	if err != nil {
		return 0, fmt.Errorf("%w: error building 'get balance' query: %v", dberrors.ErrInternal, err)
	}

	row := driver.QueryRowContext(ctx, query, args...)

	var rawBalance int64

	if err := row.Scan(&rawBalance); err != nil {
		if errors.Is(err, sql.ErrNoRows) {
			return 0, dberrors.ErrNotFound
		}

		return 0, fmt.Errorf("%w: error scanning row: %v", dberrors.ErrInternal, err)
	}

	return rawBalance, nil
}

func (c *client) updateBalance(
	ctx context.Context,
	driver Driver,
	amountDelta int64,
	ownerId string,
) error {
	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		balancesTable = fmt.Sprintf("%s.%s", c.config.Schema, BalancesTableName)
	)

	updateBalance := psql.Update(balancesTable).
		SetMap(map[string]any{
			"raw_balance": squirrel.Expr("raw_balance + ?", amountDelta),
			"updated_at":  squirrel.Expr("NOW()"),
		}).
		Where(squirrel.Eq{"owner_id": ownerId})

	query, args, err := updateBalance.ToSql()
	if err != nil {
		return fmt.Errorf("%w: error building 'update balance' query: %v", dberrors.ErrInternal, err)
	}

	res, err := driver.ExecContext(ctx, query, args...)
	if err != nil {
		return fmt.Errorf("%w: error executing 'update balance' query: %v", dberrors.ErrInternal, err)
	}

	rowsAffected, err := res.RowsAffected()
	if err != nil {
		return fmt.Errorf("%w: error getting rows affected for 'update balance' query: %v", dberrors.ErrInternal, err)
	}

	if rowsAffected == 0 {
		return dberrors.ErrInternal
	}

	return nil
}

func (c *client) createTransaction(
	ctx context.Context,
	driver Driver,
	request *dbtypes.TransactionCreateRequest,
) (*dbtypes.TransactionCreateResponse, error) {
	var (
		psql = squirrel.StatementBuilder.PlaceholderFormat(squirrel.Dollar)

		transactionsTable = fmt.Sprintf("%s.%s", c.config.Schema, TransactionsTableName)
	)

	var payload []byte

	if request.Payload == nil {
		payload = []byte("{}")
	} else {
		payloadBytes, err := json.Marshal(request.Payload)
		if err != nil {
			return nil, fmt.Errorf("%w: error marshaling transaction payload: %v", dberrors.ErrInternal, err)
		}

		payload = payloadBytes
	}

	createTransaction := psql.Insert(transactionsTable).
		Columns(
			"id", "owner_id", "bank_account_id", "amount", "currency", "status", "created_at", "payload",
		).
		Values(
			request.RequestId, request.OwnerId, request.BankAccountId, request.Amount, request.Currency,
			dbtypes.TransactionStatusNew, squirrel.Expr("CURRENT_TIMESTAMP"), payload,
		).
		Suffix("ON CONFLICT (id, owner_id) DO NOTHING")

	query, args, err := createTransaction.ToSql()
	if err != nil {
		return nil, fmt.Errorf("%w: error building 'create transaction' query: %v", dberrors.ErrInternal, err)
	}

	res, err := driver.ExecContext(ctx, query, args...)
	if err != nil {
		return nil, fmt.Errorf("%w: error executing 'create transaction' query: %v", dberrors.ErrInternal, err)
	}

	rowsAffected, err := res.RowsAffected()
	if err != nil {
		return nil, fmt.Errorf("%w: error getting rows affected for 'create transaction' query: %v", dberrors.ErrInternal, err)
	}

	if rowsAffected == 0 {
		return &dbtypes.TransactionCreateResponse{
			Id: request.RequestId,
		}, dberrors.ErrConflict
	}

	return &dbtypes.TransactionCreateResponse{
		Id: request.RequestId,
	}, nil
}