Init V4 community edition (#2265)

* Init V4 community edition

* Init V4 community edition

inventory/common.go

@@ -0,0 +1,124 @@
+package inventory
+
+import (
+	"encoding/base64"
+	"encoding/json"
+	"entgo.io/ent/dialect/sql"
+	"fmt"
+	"github.com/cloudreve/Cloudreve/v4/pkg/conf"
+	"github.com/cloudreve/Cloudreve/v4/pkg/hashid"
+	"time"
+)
+
+type (
+	OrderDirection string
+	PaginationArgs struct {
+		UseCursorPagination bool
+		Page                int
+		PageToken           string
+		PageSize            int
+		OrderBy             string
+		Order               OrderDirection
+	}
+
+	PaginationResults struct {
+		Page          int    `json:"page"`
+		PageSize      int    `json:"page_size"`
+		TotalItems    int    `json:"total_items,omitempty"`
+		NextPageToken string `json:"next_token,omitempty"`
+		IsCursor      bool   `json:"is_cursor,omitempty"`
+	}
+
+	PageToken struct {
+		Time          *time.Time `json:"time,omitempty"`
+		ID            int        `json:"-"`
+		IDHash        string     `json:"id,omitempty"`
+		String        string     `json:"string,omitempty"`
+		Int           int        `json:"int,omitempty"`
+		StartWithFile bool       `json:"start_with_file,omitempty"`
+	}
+)
+
+const (
+	OrderDirectionAsc  = OrderDirection("asc")
+	OrderDirectionDesc = OrderDirection("desc")
+)
+
+var (
+	ErrTooManyArguments = fmt.Errorf("too many arguments")
+)
+
+func pageTokenFromString(s string, hasher hashid.Encoder, idType int) (*PageToken, error) {
+	sB64Decoded, err := base64.StdEncoding.DecodeString(s)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode base64 for page token: %w", err)
+	}
+
+	token := &PageToken{}
+	if err := json.Unmarshal(sB64Decoded, token); err != nil {
+		return nil, fmt.Errorf("failed to unmarshal page token: %w", err)
+	}
+
+	id, err := hasher.Decode(token.IDHash, idType)
+	if err != nil {
+		return nil, fmt.Errorf("failed to decode id: %w", err)
+	}
+
+	if token.Time == nil {
+		token.Time = &time.Time{}
+	}
+
+	token.ID = id
+	return token, nil
+}
+
+func (p *PageToken) Encode(hasher hashid.Encoder, encodeFunc hashid.EncodeFunc) (string, error) {
+	p.IDHash = encodeFunc(hasher, p.ID)
+	res, err := json.Marshal(p)
+	if err != nil {
+		return "", fmt.Errorf("failed to marshal page token: %w", err)
+	}
+
+	return base64.StdEncoding.EncodeToString(res), nil
+}
+
+// sqlParamLimit returns the max number of sql parameters.
+func sqlParamLimit(dbType conf.DBType) int {
+	switch dbType {
+	case conf.PostgresDB:
+		return 34464
+	case conf.SQLiteDB, conf.SQLite3DB:
+		// https://www.sqlite.org/limits.html
+		return 32766
+	default:
+		return 32766
+	}
+}
+
+// getOrderTerm returns the order term for ent.
+func getOrderTerm(d OrderDirection) sql.OrderTermOption {
+	switch d {
+	case OrderDirectionDesc:
+		return sql.OrderDesc()
+	default:
+		return sql.OrderAsc()
+	}
+}
+
+func capPageSize(maxSQlParam, preferredSize, margin int) int {
+	// Page size should not be bigger than max SQL parameter
+	pageSize := preferredSize
+	if maxSQlParam > 0 && pageSize > maxSQlParam-margin || pageSize == 0 {
+		pageSize = maxSQlParam - margin
+	}
+
+	return pageSize
+}
+
+type StorageDiff map[int]int64
+
+func (s *StorageDiff) Merge(diff StorageDiff) {
+	for k, v := range diff {
+		(*s)[k] += v
+	}
+}