Added basic NLP-powered query builder with preview endpoint (Issue #113)

medplat-web/src/main/java/com/argusoft/medplat/query/controller/NlpQueryController.java

@@ -0,0 +1,26 @@
+package com.argusoft.medplat.query.controller;
+
+import com.argusoft.medplat.query.service.NlpQueryService;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.web.bind.annotation.*;
+
+import java.util.Map;
+
+@RestController
+@RequestMapping("/api/nlp")
+public class NlpQueryController {
+
+    @Autowired
+    private NlpQueryService nlpQueryService;
+
+    @PostMapping("/preview")
+public Map<String, String> previewQuery(@RequestBody Map<String, String> request) {
+
+    try {
+        String input = request.get("query");
+        String sql = nlpQueryService.buildQuery(input);
+        return Map.of("previewSql", sql);
+    } catch (Exception e) {
+        return Map.of("error", e.getMessage());
+    }
+}

medplat-web/src/main/java/com/argusoft/medplat/query/service/NlpQueryService.java

@@ -0,0 +1,60 @@
+package com.argusoft.medplat.query.service;
+
+import org.springframework.stereotype.Service;
+
+import java.util.*;
+
+@Service
+public class NlpQueryService {
+
+    private static final Map<String, String> TABLE_MAP = Map.of(
+            "patients", "patients",
+            "users", "users"
+    );
+
+    private static final Set<String> ALLOWED_COLUMNS = Set.of(
+            "id", "name", "age", "gender"
+    );
+
+    public String buildQuery(String input) {
+
+        input = input.toLowerCase();
+
+        if (!input.startsWith("show")) {
+            throw new IllegalArgumentException("Only SELECT queries supported.");
+        }
+
+        String table = null;
+        for (String key : TABLE_MAP.keySet()) {
+            if (input.contains(key)) {
+                table = TABLE_MAP.get(key);
+                break;
+            }
+        }
+
+        if (table == null) {
+            throw new IllegalArgumentException("No valid table found.");
+        }
+
+        String query = "SELECT * FROM " + table;
+
+        if (input.contains("where")) {
+            String conditionPart = input.split("where")[1].trim();
+
+            String[] tokens = conditionPart.split(" ");
+            if (tokens.length >= 3) {
+                String column = tokens[0];
+                String operator = tokens[1];
+                String value = tokens[2];
+
+                if (!ALLOWED_COLUMNS.contains(column)) {
+                    throw new IllegalArgumentException("Invalid column.");
+                }
+
+                query += " WHERE " + column + " " + operator + " ?";
+            }
+        }
+
+        return query;
+    }
+}