github.com/zntrio/harp/v2@v2.0.9/pkg/sdk/value/signature/transformer.go (about)

     1  // Licensed to Elasticsearch B.V. under one or more contributor
     2  // license agreements. See the NOTICE file distributed with
     3  // this work for additional information regarding copyright
     4  // ownership. Elasticsearch B.V. licenses this file to you under
     5  // the Apache License, Version 2.0 (the "License"); you may
     6  // not use this file except in compliance with the License.
     7  // You may obtain a copy of the License at
     8  //
     9  //     http://www.apache.org/licenses/LICENSE-2.0
    10  //
    11  // Unless required by applicable law or agreed to in writing,
    12  // software distributed under the License is distributed on an
    13  // "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
    14  // KIND, either express or implied.  See the License for the
    15  // specific language governing permissions and limitations
    16  // under the License.
    17  
    18  package signature
    19  
    20  import (
    21  	"errors"
    22  	"fmt"
    23  	"strings"
    24  
    25  	"github.com/zntrio/harp/v2/pkg/sdk/types"
    26  	"github.com/zntrio/harp/v2/pkg/sdk/value"
    27  )
    28  
    29  // FromKey returns the value transformer that match the value format.
    30  func FromKey(keyValue string) (value.Transformer, error) {
    31  	var (
    32  		transformer value.Transformer
    33  		err         error
    34  	)
    35  
    36  	// Check arguments
    37  	if keyValue == "" {
    38  		return nil, fmt.Errorf("unable to select a value transformer with blank value")
    39  	}
    40  
    41  	// Extract prefix
    42  	parts := strings.SplitN(keyValue, ":", 2)
    43  	if len(parts) != 2 {
    44  		// Fallback to fernet
    45  		parts = []string{"fernet", keyValue}
    46  	}
    47  
    48  	// Clean prefix
    49  	prefix := strings.ToLower(strings.TrimSpace(parts[0]))
    50  
    51  	// Build the value transformer according to used prefix.
    52  	tf, ok := registry[prefix]
    53  	if !ok {
    54  		return nil, fmt.Errorf("no transformer registered for %q as prefix", prefix)
    55  	}
    56  
    57  	// Build the transformer instance
    58  	transformer, err = tf(keyValue)
    59  
    60  	// Check transformer initialization error
    61  	if transformer == nil || err != nil {
    62  		return nil, fmt.Errorf("unable to initialize value transformer: %w", err)
    63  	}
    64  
    65  	// No error
    66  	return transformer, nil
    67  }
    68  
    69  // Must is used to panic when a transformer initialization failed.
    70  func Must(t value.Transformer, err error) value.Transformer {
    71  	if err != nil {
    72  		panic(err)
    73  	}
    74  	if types.IsNil(t) {
    75  		panic(errors.New("transformer is nil with a nil error"))
    76  	}
    77  
    78  	return t
    79  }