feat: VariableSubstitutionService

Author: dmcg310

src/main/java/com/syncapi/dto/request/SubstitutedRequest.java

@@ -0,0 +1,37 @@
+package com.syncapi.dto.request;
+
+import java.util.Map;
+
+/**
+ * DTO containing a request with substituted variables.
+ */
+public class SubstitutedRequest {
+    private final String url;
+    private final Map<String, String> headers;
+    private final Map<String, Object> body;
+
+    /**
+     * Parameterized constructor.
+     *
+     * @param url     the substituted URL
+     * @param headers the substituted headers
+     * @param body    the substituted body
+     */
+    public SubstitutedRequest(String url, Map<String, String> headers, Map<String, Object> body) {
+        this.url = url;
+        this.headers = headers;
+        this.body = body;
+    }
+
+    public String getUrl() {
+        return url;
+    }
+
+    public Map<String, String> getHeaders() {
+        return headers;
+    }
+
+    public Map<String, Object> getBody() {
+        return body;
+    }
+}

src/main/java/com/syncapi/service/substitution/VariableSubstitutionService.java

@@ -0,0 +1,112 @@
+package com.syncapi.service.substitution;
+
+import com.syncapi.dto.request.SubstitutedRequest;
+import org.springframework.stereotype.Service;
+
+import java.util.HashMap;
+import java.util.Map;
+
+/**
+ * Service for variable substitution in strings and requests.
+ */
+@Service
+public class VariableSubstitutionService {
+    /**
+     * Substitutes variables in the input string based on the provided variables.
+     * <p>
+     * For example, substitute("Hello, {{name}}!", Map.of("name", "World")) returns "Hello, World!"
+     * <p>
+     * Variables not found in the map are left unchanged.
+     *
+     * @param input     the input string containing {{key}} patterns
+     * @param variables the map of variable keys and their corresponding values
+     * @return the input string with variables substituted
+     */
+    public String substitute(String input, Map<String, String> variables) {
+        if (input == null || input.isEmpty()) {
+            return input;
+        }
+
+        if (variables == null || variables.isEmpty()) {
+            return input;
+        }
+
+        String result = input;
+        for (Map.Entry<String, String> entry : variables.entrySet()) {
+            String token = "{{" + entry.getKey() + "}}";
+
+            String value = entry.getValue();
+            if (value != null) {
+                result = result.replace(token, value);
+            }
+        }
+
+        return result;
+    }
+
+    /**
+     * Substitutes variables in the Request's URL, headers, and body.
+     * <p>
+     * Returns a new SubstitutedRequest DTO to avoid mutating the JPA entity.
+     *
+     * @param url       the request URL
+     * @param headers   the request headers
+     * @param body      the request body
+     * @param variables the map of variable keys and their corresponding values
+     * @return a new SubstitutedRequest with variables substituted
+     */
+    public SubstitutedRequest substituteRequest(String url, Map<String, String> headers, Map<String, Object> body,
+                                                Map<String, String> variables) {
+        String substitutedUrl = substitute(url, variables);
+        Map<String, String> substitutedHeaders = substituteHeaders(headers, variables);
+        Map<String, Object> substitutedBody = substituteBody(body, variables);
+
+        return new SubstitutedRequest(substitutedUrl, substitutedHeaders, substitutedBody);
+    }
+
+    /**
+     * Substitutes variables in header values.
+     *
+     * @param headers   the request headers
+     * @param variables the map of variable keys and their corresponding values
+     * @return a new map with substituted header values
+     */
+    private Map<String, String> substituteHeaders(Map<String, String> headers, Map<String, String> variables) {
+        if (headers == null || headers.isEmpty()) {
+            return headers;
+        }
+
+        Map<String, String> substitutedHeaders = new HashMap<>();
+        for (Map.Entry<String, String> entry : headers.entrySet()) {
+            String substitutedValue = substitute(entry.getValue(), variables);
+            substitutedHeaders.put(entry.getKey(), substitutedValue);
+        }
+
+        return substitutedHeaders;
+    }
+
+    /**
+     * Substitutes variables in body values (only for String values).
+     *
+     * @param body      the request body
+     * @param variables the map of variable keys and their corresponding values
+     * @return a new map with substituted body values
+     */
+    private Map<String, Object> substituteBody(Map<String, Object> body, Map<String, String> variables) {
+        if (body == null || body.isEmpty()) {
+            return body;
+        }
+
+        Map<String, Object> substitutedBody = new HashMap<>();
+        for (Map.Entry<String, Object> entry : body.entrySet()) {
+            Object value = entry.getValue();
+            if (value instanceof String) {
+                substitutedBody.put(entry.getKey(), substitute((String) value, variables));
+            } else {
+                substitutedBody.put(entry.getKey(), value);
+            }
+        }
+
+        return substitutedBody;
+    }
+}