v0.0.1

batcher/batcher.go

@@ -0,0 +1,108 @@
+package batcher
+
+import (
+	"btchrr/models"
+	"errors"
+)
+
+// Batcher - encapsulates the batch size for splitting a slice into batches
+type Batcher struct {
+	batchSize    int
+	placeholders map[string]struct{}
+}
+
+// NewBatcher - Creates a new batcher instance with the specified batch size.
+// Returns an error if the batch size is invalid.
+func NewBatcher(batchSize int) (*Batcher, error) {
+	if batchSize <= 0 {
+		return nil, models.ErrInvalidBatchSize
+	}
+	b := &Batcher{
+		batchSize:    batchSize,
+		placeholders: make(map[string]struct{}),
+	}
+	for _, ph := range []string{"?", "$", ":", ":"} {
+		b.placeholders[ph] = struct{}{}
+	}
+	return b, nil
+}
+
+// BuildBatch - Builds a batch query from a single query
+func (b *Batcher) BuildBatches(singleQuery string, items []any) ([]models.BatchedQuery, error) {
+	batchedItems, err := b.batchItems(items)
+	if err != nil {
+		return []models.BatchedQuery{}, err
+	}
+
+	batches, err := b.BuildBatchQuery(singleQuery, b.batchSize, batchedItems)
+	if err != nil {
+		return []models.BatchedQuery{}, err
+	}
+
+	return batches, nil
+}
+
+// Batch - Splits the input slice into batches of the specified size.
+// Returns an error if the input slice is empty.
+func (b *Batcher) batchItems(items []any) ([][]any, error) {
+	if len(items) == 0 {
+		return nil, models.ErrNoItems
+	}
+
+	totalItems := len(items)
+	numOfBatches := (totalItems + b.batchSize - 1) / b.batchSize // round up
+
+	batches := make([][]any, 0, numOfBatches)
+
+	for i := 0; i < totalItems; i += b.batchSize {
+		end := i + b.batchSize
+		if end > totalItems {
+			end = totalItems
+		}
+		// Copy elements to avoid possible side effects if the original slice is modified
+		batch := make([]any, end-i)
+		copy(batch, items[i:end])
+		batches = append(batches, batch)
+	}
+
+	return batches, nil
+}
+
+// BuildBatchQuery - builds a batch query from a single query
+func (b *Batcher) BuildBatchQuery(singleQuery string, batchSize int, batchedItems [][]any) (batchedQueries []models.BatchedQuery, err error) {
+	placeholder, err := b.detectPlaceholders(singleQuery)
+	if err != nil {
+		return []models.BatchedQuery{}, err
+	}
+	
+	switch placeholder {
+	case "?":
+		return b.buildSqliteQuery(singleQuery, batchSize, batchedItems)
+	case "$":
+		return b.buildPostgresQuery(singleQuery, batchSize, batchedItems)
+	default:
+		return b.buildQueryWithNamedPlaceholders(singleQuery, batchSize, placeholder, batchedItems)
+	}
+}
+
+// detectPlaceholder определяет тип плейсхолдера в SQL-запросе, ищет плейсхолдеры окружённые пробелами (" ? ", " $ ", " : ")
+func (b *Batcher) detectPlaceholders(query string) (string, error) {
+	for _, s := range query {
+		if _, ok := b.placeholders[string(s)]; ok {
+			return string(s), nil
+		}
+	}
+	return "", models.ErrCannotDetectPlaceholder
+}
+
+func (b *Batcher) buildSqliteQuery(singleQuery string, batchSize int, batchedItems [][]any) (batchedQueries []models.BatchedQuery, err error) {
+	return []models.BatchedQuery{}, errors.New("not implemented")
+}
+
+func (b *Batcher) buildPostgresQuery(singleQuery string, batchSize int, batchedItems [][]any) (batchedQueries []models.BatchedQuery, err error) {
+	return []models.BatchedQuery{}, errors.New("not implemented")
+}
+
+func (b *Batcher) buildQueryWithNamedPlaceholders(singleQuery string, batchSize int, placeholder string, batchedItems [][]any) (batchedQueries []models.BatchedQuery, err error) {
+	return []models.BatchedQuery{}, errors.New("not implemented")
+}