ProductController.java

package com.SpringRestAPI.Controllers;

import com.SpringRestAPI.Exceptions.InvalidPriceRangeException;
import com.SpringRestAPI.Exceptions.MissingApiKeyException;
import com.SpringRestAPI.Exceptions.ProductNotFoundException;
import com.SpringRestAPI.Models.Product;
import com.SpringRestAPI.Models.ProductCategories;
import com.SpringRestAPI.Services.ProductService;
import jakarta.validation.Valid;
// @Valid Annotations provide a consistent approach to validation, which improves readability and maintainability.
// It gives you automatic error feedback to the client, indicating exactly which fields are incorrect and why.
// @Valid is used for incoming data validation. Like 'Post' and 'Put' requests. It's not needed for others.
import org.springframework.http.ResponseEntity;
import org.springframework.web.bind.annotation.*;

import java.util.List;
import java.util.logging.Logger;

@RestController
@RequestMapping("/api")
public class ProductController {


    ProductService productService;

    public ProductController(ProductService productService) {
        this.productService = productService;
    }

    // Create new product
    @PostMapping("/products") // http://localhost:8080/api/products/
    public Product addNewProduct(
            @RequestHeader("API-Key") String apiKey,
            @Valid @RequestBody Product product ) {
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        Logger myLogger = Logger.getLogger("ProductController");
        myLogger.info("Create a new Product");

        return productService.addNewProduct(
                product.getProductName(),
                product.getProductPrice(),
                product.getProductCategory(),
                product.getProductQuantity()
        );
    }

    // get all products
    @GetMapping("/products") // http://localhost:8080/api/products/
    public List<Product> getAllProducts(@RequestHeader("API-Key") String apiKey) {
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        Logger myLogger = Logger.getLogger("ProductList");
        myLogger.info("Get all the Product list");

        return productService.getProductList();
    }

    // Get product by name
    @GetMapping("/products/{productName}")
    public Product getProductByName(
            @RequestHeader(value="API-Key") String apiKey,
            @PathVariable String productName) {
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        return productService.getProductByName(productName)
                .orElseThrow(() -> new ProductNotFoundException("Product not found"));
    }

    // change product name
    @PutMapping("/products/{productName}/{newName}") // http://localhost:8080/api/products/{name}/{newName}
    public Product updateProductName(
            @Valid @PathVariable String productName,
            @PathVariable String newName,
            @RequestHeader("API-Key") String apiKey) {
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        Logger myLogger = Logger.getLogger(" by Name");
        myLogger.info("change Product Name");

        return productService.updateProductName(productName, newName);
    }

    // delete product by name
    @DeleteMapping("/products/{productName}") // http://localhost:8080/api/products/{productName}
    public Product deleteProduct(
            @PathVariable String productName,
            @RequestHeader("API-Key") String apiKey) {
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        Logger myLogger = Logger.getLogger("ProductList by Name");
        myLogger.info("delete Product by Name" +  productName);

        return productService.deleteProduct(productName)
                .orElseThrow(() -> new ProductNotFoundException("Product not found"));
    }

    // get item by category
    @GetMapping("/products/category/{category}") // http://localhost:8080/api/products/category/{category}
    public List<Product> getProductByCategory(
            @PathVariable ProductCategories category,
            @RequestHeader("API-Key") String apiKey) {
        if (!"123456".equals(apiKey)) {
            throw new RuntimeException("Invalid API Key");
        }
        Logger myLogger = Logger.getLogger("ProductList by Category");
        myLogger.info("get Product by Category");

        return productService.getProductByCategory(category);
    }

    // get products by price range
    @GetMapping("/products/price") // http://localhost:8080/api/products/price?min=10&max=30
    public ResponseEntity<List<Product>> getProductsByPriceRange(
            @RequestParam double min, // @RequestParam is /price > ?min=VALUE
            @RequestParam double max, // &max=VALUE
            @RequestHeader(value="API-Key") String apiKey) {
        // Check API Key presence and validity
        if (!"123456".equals(apiKey)) {
            throw new MissingApiKeyException("API-Key header is missing or invalid");
        }
        // Check for valid price range
        if (min > max) {
            throw new InvalidPriceRangeException("Min price cannot be greater than max price");
        }
        // Business logic to find products by price range
        List<Product> products = productService.getProductsByPriceRange(min, max);

        if (products == null || products.isEmpty()) {
            throw new ProductNotFoundException("No product found in this price range");
        }
        return ResponseEntity.ok(products);
    }

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    /*
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            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣴⣿⡿⠋⠈⠻⣮⣳⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣠⣴⣾⡿⠋⠀⠀⠀⠀⠙⣿⣿⣤⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣤⣶⣿⡿⠟⠛⠉⠀⠀⠀⠀⠀⠀⠀⠈⠛⠛⠿⠿⣿⣷⣶⣤⣄⣀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀
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            ⠀⠀⠀⣀⣠⣤⣤⣀⡀⠀⠀⣀⣴⣿⡿⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣷⣦⣄⡀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣤⣄⠀⠀
            ⢀⣤⣾⡿⠟⠛⠛⢿⣿⣶⣾⣿⠟⠉⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠛⠿⣿⣷⣦⣀⣀⣤⣶⣿⡿⠿⢿⣿⡀⠀
            ⣿⣿⠏⠀⢰⡆⠀⠀⠉⢿⣿⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⠻⢿⡿⠟⠋⠁⠀⠀⢸⣿⠇⠀
            ⣿⡟⠀⣀⠈⣀⡀⠒⠃⠀⠙⣿⡆⠀⠀⠀⠀⠀⠀⠀⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢸⣿⠇⠀
            ⣿⡇⠀⠛⢠⡋⢙⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣿⣿⠄⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⣿⠀⠀
            ⣿⣧⠀⠀⠀⠓⠛⠁⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⠛⠋⠀⠀⢸⣧⣤⣤⣶⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢰⣿⡿⠀⠀
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            ⠈⠛⠻⠿⢿⣿⣷⣶⣦⣤⣄⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣴⣿⣷⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣾⣿⡏⠀⠀⠀
            ⠀⠀⠀⠀⠀⠀⠀⠉⠙⠛⠻⠿⢿⣿⣷⣶⣦⣤⣄⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠙⠿⠛⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠘⢿⣿⡄⠀⠀
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠉⠙⠛⠻⠿⢿⣿⣷⣶⣦⣤⣄⣀⡀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢿⣿⡄⠀
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠉⠛⠛⠿⠿⣿⣷⣶⣶⣤⣤⣀⡀⠀⠀⠀⢀⣴⡆⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⢿⡿⣄
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠉⠉⠛⠛⠿⠿⣿⣷⣶⡿⠋⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⣿⣹
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⣿⣿⠃⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢀⣀⣀⠀⠀⠀⠀⠀⠀⢸⣧
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⢻⣿⣆⠀⠀⠀⠀⠀⠀⢀⣀⣠⣤⣶⣾⣿⣿⣿⣿⣤⣄⣀⡀⠀⠀⠀⣿
            ⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀⠈⠻⢿⣻⣷⣶⣾⣿⣿⡿⢯⣛⣛⡋⠁⠀⠀⠉⠙⠛⠛⠿⣿⣿⡷⣶⣿
     */

}