utils.go

// Copyright (C) 2023 Gobalsky Labs Limited
//
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as
// published by the Free Software Foundation, either version 3 of the
// License, or (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <http://www.gnu.org/licenses/>.

package sqlstore

import (
	"fmt"
	"reflect"
	"strconv"
	"strings"

	"code.vegaprotocol.io/vega/datanode/entities"

	"github.com/georgysavva/scany/dbscan"
)

// A handy little helper function for building queries. Appends 'value'
// to the 'args' slice and returns a string '$N' referring to the index
// of the value in args. For example:
//
//	var args []interface{}
//	query = "select * from foo where id=" + nextBindVar(&args, 100)
//	db.Query(query, args...)
func nextBindVar(args *[]interface{}, value interface{}) string {
	*args = append(*args, value)
	return "$" + strconv.Itoa(len(*args))
}

func orderAndPaginateWithCursor(query string, pagination entities.CursorPagination, cursors CursorQueryParameters,
	args ...interface{}) (string, []interface{},
) {
	var order string

	whereOrAnd := "WHERE"

	if strings.Contains(strings.ToUpper(query), "WHERE") {
		whereOrAnd = "AND"
	}

	var cursor string
	cursor, args = cursors.Where(args...)
	if cursor != "" {
		query = fmt.Sprintf("%s %s %s", query, whereOrAnd, cursor)
	}

	limit := calculateLimit(pagination)

	if limit == 0 {
		// return everything ordered by the cursor column ordered ascending
		order = cursors.OrderBy()
		query = fmt.Sprintf("%s ORDER BY %s", query, order)
		return query, args
	}

	order = cursors.OrderBy()
	query = fmt.Sprintf("%s ORDER BY %s", query, order)
	query = fmt.Sprintf("%s LIMIT %d", query, limit)

	return query, args
}

func calculateLimit(pagination entities.CursorPagination) int {
	var limit int32
	if pagination.HasForward() && pagination.Forward.Limit != nil {
		limit = *pagination.Forward.Limit + 1
		if pagination.Forward.HasCursor() {
			limit = *pagination.Forward.Limit + 2 // +2 to make sure we get the previous and next cursor
		}
	} else if pagination.HasBackward() && pagination.Backward.Limit != nil {
		limit = *pagination.Backward.Limit + 1
		if pagination.Backward.HasCursor() {
			limit = *pagination.Backward.Limit + 2 // +2 to make sure we get the previous and next cursor
		}
	}

	return int(limit)
}

func extractPaginationInfo(pagination entities.CursorPagination) (Sorting, Compare, string) {
	var cmp Compare
	var value string

	sort := ASC

	if pagination.NewestFirst {
		sort = DESC
	}

	if pagination.HasForward() {
		if pagination.Forward.HasCursor() {
			cmp = GE
			if pagination.NewestFirst {
				cmp = LE
			}
			value = pagination.Forward.Cursor.Value()
		}
	} else if pagination.HasBackward() {
		sort = DESC

		if pagination.NewestFirst {
			sort = ASC
		}

		if pagination.Backward.HasCursor() {
			cmp = LE
			if pagination.NewestFirst {
				cmp = GE
			}
			value = pagination.Backward.Cursor.Value()
		}
	}

	return sort, cmp, value
}

func extractCursorFromPagination(pagination entities.CursorPagination) (cursor string) {
	if pagination.HasForward() && pagination.Forward.HasCursor() {
		cursor = pagination.Forward.Cursor.Value()
	} else if pagination.HasBackward() && pagination.Backward.HasCursor() {
		cursor = pagination.Backward.Cursor.Value()
	}
	return
}

// StructValueForColumn replicates some of the unexported functionality from Scanny. You pass a
// struct (or pointer to a struct), and a column name. It converts the struct field names into
// database column names in a similar way to scanny and if one matches colName, that field value
// is returned. For example
//
//	type Foo struct {
//		Thingy        int `db:"wotsit"`
//		SomethingElse int
//	}
//
//	val, err := StructValueForColumn(foo, "wotsit")             -> 1
//	val, err := StructValueForColumn(&foo, "something_else")    -> 2
//
// NB - not all functionality of scanny is supported (but could be added if needed)
//   - we don't support embedded structs
//   - assumes the 'dbTag' is the default 'db'
func StructValueForColumn(obj any, colName string) (interface{}, error) {
	structType := reflect.TypeOf(obj)
	structValue := reflect.ValueOf(obj)

	if structType.Kind() == reflect.Pointer {
		structType = structType.Elem()
		structValue = structValue.Elem()
	}

	if structType.Kind() != reflect.Struct {
		return nil, fmt.Errorf("obj must be struct")
	}

	for i := 0; i < structType.NumField(); i++ {
		field := structType.Field(i)
		thisColName := field.Tag.Get("db")
		if thisColName == "" {
			thisColName = dbscan.SnakeCaseMapper(field.Name)
		}
		if thisColName == colName {
			fieldValue := structValue.Field(i)
			return fieldValue.Interface(), nil
		}
	}
	return nil, fmt.Errorf("no field matching column name %s", colName)
}

func filterDateRange(query, dateColumn string, dateRange entities.DateRange, isFirstCondition bool, args ...interface{}) (string, []interface{}) {
	conditions := []string{}

	if dateRange.Start != nil {
		conditions = append(conditions, fmt.Sprintf("%s >= %s", dateColumn, nextBindVar(&args, *dateRange.Start)))
	}

	if dateRange.End != nil {
		conditions = append(conditions, fmt.Sprintf("%s < %s", dateColumn, nextBindVar(&args, *dateRange.End)))
	}

	if len(conditions) <= 0 {
		return query, args
	}

	finalConditions := strings.Join(conditions, " AND ")
	if isFirstCondition {
		query = fmt.Sprintf("%s where %s", query, finalConditions)
	} else {
		query = fmt.Sprintf("%s AND %s", query, finalConditions)
	}

	return query, args
}