103 lines
2.3 KiB
Go
103 lines
2.3 KiB
Go
package reqpreprocessor
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import (
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"bytes"
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"context"
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"encoding/json"
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"errors"
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"fmt"
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"io"
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"net/http"
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"github.com/google/uuid"
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)
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type Config struct {
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checkKeys []string
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}
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type contextKeyType string
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const contextKey = "context"
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func NewUUIDSetter(cfg *Config) (func(http.Handler) http.Handler, error) {
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if err := validateConfig(cfg); err != nil {
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return nil, err
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}
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return func(next http.Handler) http.Handler {
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return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
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var data map[string]any
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body, err := io.ReadAll(r.Body)
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if err != nil {
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http.Error(w, "Failed to read request body", http.StatusInternalServerError)
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return
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}
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if err := json.Unmarshal(body, &data); err != nil {
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http.Error(w, "Failed to decode request body", http.StatusBadRequest)
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return
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}
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contextRaw := data[contextKey]
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if contextRaw == nil {
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http.Error(w, fmt.Sprintf("%s field not found.", contextKey), http.StatusBadRequest)
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return
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}
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contextData, ok := contextRaw.(map[string]any)
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if !ok {
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http.Error(w, fmt.Sprintf("%s field is not a map.", contextKey), http.StatusBadRequest)
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return
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}
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ctx := r.Context()
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for _, key := range cfg.checkKeys {
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value := uuid.NewString()
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updatedValue := update(contextData, key, value)
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ctx = context.WithValue(ctx, contextKeyType(key), updatedValue)
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}
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data[contextKey] = contextData
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updatedBody, err := json.Marshal(data)
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if err != nil {
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http.Error(w, "Failed to marshal updated JSON", http.StatusInternalServerError)
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return
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}
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r.Body = io.NopCloser(bytes.NewBuffer(updatedBody))
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r.ContentLength = int64(len(updatedBody))
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r = r.WithContext(ctx)
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next.ServeHTTP(w, r)
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})
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}, nil
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}
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func update(wrapper map[string]any, key string, value any) any {
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field, exists := wrapper[key]
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if !exists || isEmpty(field) {
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wrapper[key] = value
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return value
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}
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return field
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}
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func isEmpty(v any) bool {
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switch v := v.(type) {
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case string:
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return v == ""
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case nil:
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return true
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default:
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return false
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}
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}
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func validateConfig(cfg *Config) error {
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if cfg == nil {
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return errors.New("config cannot be nil")
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}
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if len(cfg.checkKeys) == 0 {
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return errors.New("checkKeys cannot be empty")
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}
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for _, key := range cfg.checkKeys {
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if key == "" {
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return errors.New("checkKeys cannot contain empty strings")
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}
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}
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return nil
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}
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