113 lines
2.9 KiB
Go
113 lines
2.9 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/beckn/beckn-onix/pkg/log"
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"github.com/google/uuid"
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)
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// Config holds the configuration settings for the application.
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type Config struct {
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ContextKeys []string // ContextKeys is a list of context keys used for request processing.
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Role string // Role specifies the role of the entity (e.g., subscriber, gateway).
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}
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type becknRequest struct {
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Context map[string]any `json:"context"`
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}
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const contextKey = "context"
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const subscriberIDKey = "subscriber_id"
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// NewPreProcessor creates a middleware that processes incoming HTTP requests by extracting
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// and modifying the request context based on the provided configuration.
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func NewPreProcessor(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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body, _ := io.ReadAll(r.Body)
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var req becknRequest
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ctx := r.Context()
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if err := json.Unmarshal(body, &req); 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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if req.Context == 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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var subID any
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switch cfg.Role {
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case "bap":
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subID = req.Context["bap_id"]
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case "bpp":
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subID = req.Context["bpp_id"]
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}
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if subID != nil {
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log.Debugf(ctx, "adding subscriberId to request:%s, %v", subscriberIDKey, subID)
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// TODO: Add a ContextKey type in model and use it here instead of raw context key.
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ctx = context.WithValue(ctx, subscriberIDKey, subID)
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}
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for _, key := range cfg.ContextKeys {
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value := uuid.NewString()
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updatedValue := update(req.Context, key, value)
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ctx = context.WithValue(ctx, key, updatedValue)
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}
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reqData := map[string]any{"context": req.Context}
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updatedBody, _ := json.Marshal(reqData)
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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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// Check if ContextKeys is empty.
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if len(cfg.ContextKeys) == 0 {
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return errors.New("ContextKeys cannot be empty")
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}
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// Validate that ContextKeys does not contain empty strings.
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for _, key := range cfg.ContextKeys {
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if key == "" {
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return errors.New("ContextKeys 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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