const express = require("express");
const bodyParser = require("body-parser");

const app = express();
const PORT = 8080;

// Middleware to parse JSON
app.use(bodyParser.json());

// In-memory data store for demonstration
let items = [];
let currentId = 1;

// Middleware to handle dynamic headers
app.use((req, res, next) => {
  const dynamicHeaders = req.headers;
  req.dynamicHeaders = dynamicHeaders; // Store headers for use in routes
  next();
});

// Routes

// CREATE - Add a new item
app.post("/items", (req, res) => {
  const { headers, body, query } = req;
  const { stateParams } = req.body; // State parameters passed in body
  
  // Dynamic handling example for headers, query params, and state params
  console.log("Headers:", headers);
  console.log("Query Params:", query);
  console.log("State Params:", stateParams);

  const { name, description } = body;

  if (!name) {
    return res.status(400).json({ error: "Name is required" });
  }

  const newItem = { id: currentId++, name, description };
  items.push(newItem);
  res.status(201).json({
    message: "Item created successfully",
    headers: req.dynamicHeaders,
    queryParams: query,
    stateParams,
    item: newItem,
  });
});

// READ - Get all items
app.get("/items", (req, res) => {
  const { query } = req;

  // Filter by query parameters if provided
  let filteredItems = items;
  if (query.name) {
    filteredItems = filteredItems.filter((item) =>
      item.name.toLowerCase().includes(query.name.toLowerCase())
    );
  }

  if (query.description) {
    filteredItems = filteredItems.filter((item) =>
      item.description &&
      item.description.toLowerCase().includes(query.description.toLowerCase())
    );
  }

  res.json({
    message: "Items retrieved successfully",
    headers: req.dynamicHeaders,
    queryParams: query,
    items: filteredItems,
  });
});

// READ - Get an item by ID
app.get("/items/:id", (req, res) => {
  const { id } = req.params;

  const item = items.find((i) => i.id === parseInt(id));
  if (!item) {
    return res.status(404).json({ error: "Item not found" });
  }

  res.json({
    message: "Item retrieved successfully",
    headers: req.dynamicHeaders,
    queryParams: req.query,
    item,
  });
});

// UPDATE - Update an item by ID
app.put("/items/:id", (req, res) => {
  const { id } = req.params;
  const { name, description } = req.body;

  const item = items.find((i) => i.id === parseInt(id));
  if (!item) {
    return res.status(404).json({ error: "Item not found" });
  }

  if (name) item.name = name;
  if (description) item.description = description;

  res.json({
    message: "Item updated successfully",
    headers: req.dynamicHeaders,
    stateParams: req.body.stateParams,
    updatedItem: item,
  });
});

// DELETE - Remove an item by ID
app.delete("/items/:id", (req, res) => {
  const { id } = req.params;

  const index = items.findIndex((i) => i.id === parseInt(id));
  if (index === -1) {
    return res.status(404).json({ error: "Item not found" });
  }

  items.splice(index, 1);
  res.status(204).send({
    message: "Item deleted successfully",
    headers: req.dynamicHeaders,
  });
});

// READ - Get items with optional dynamic query parameters
app.get("/items/search", (req, res) => {
  const { query } = req;

  // Filter items based on query parameters
  let filteredItems = items;

  if (query.name) {
    filteredItems = filteredItems.filter((item) =>
      item.name.toLowerCase().includes(query.name.toLowerCase())
    );
  }

  if (query.description) {
    filteredItems = filteredItems.filter(
      (item) =>
        item.description &&
        item.description.toLowerCase().includes(query.description.toLowerCase())
    );
  }

  res.json({
    message: "Filtered items retrieved successfully",
    headers: req.dynamicHeaders,
    queryParams: query,
    items: filteredItems,
  });
});

// Start the server
app.listen(PORT, () => {
  console.log(`Server is running on http://localhost:${PORT}`);
});