const fs = require("fs");
const express = require("express");

function readUsersFromJSONFile(JSON_filename) {
    /*
     ** Return the list of users stored in the JSON file
     ** JSON_filename: path to the JSON file
     */
    const content = fs.readFileSync(JSON_filename, (err) => {
        if (err) {
            console.error(err);
            return;
        }
    });

    return JSON.parse(content).users;
}

function writeUsersToJSONFile(JSON_filename, users) {
    /*
     ** Overwrite the given JSON_filename with the given
     ** list of users.
     ** JSON_filename: path to the JSON file
     ** users : list of users objects
     */
    const usersJSON = JSON.stringify({ users: users });

    fs.writeFileSync(JSON_filename, usersJSON, (err) => {
        if (err) {
            console.error(err);
            return;
        }
    });
}
function epiTinderWebServer(host, port, filename) {
    const app = express();

    app.use(express.json());
    const users = readUsersFromJSONFile(filename);
    let maxID = 0;

    if (users.length > 0) {
        maxID = Math.max(...users.map((e) => e.id)) + 1;
    }

    app.get("/", (req, res) => {
        res.status(200).send({ message: "Hello World!" });
    });
    app.get("/users", (req, res) => {
        res.status(200).send(users);
    });
    app.post("/users", (req, res) => {
        const new_user = {
            id: maxID++,
            name: req.body.name,
            age: req.body.age,
            description: req.body.description,
        };

        users.push(new_user);
        writeUsersToJSONFile(filename, users);
        res.status(201).send(new_user);
    });
    app.get("/users/:id", (req, res) => {
        const u = users.find((e) => e.id == req.params.id);

        if (u == undefined) {
            res.status(404).send({
                message: `No user with id: ${req.params.id} found`,
            });
        } else {
            res.status(200).send(u);
        }
    });
    app.put("/users/:id", (req, res) => {
        const u = users.findIndex((e) => e.id == req.params.id);

        if (u == -1) {
            res.status(404).send({
                message: `No user with id: ${req.params.id} found`,
            });
        } else {
            users[u].name = req.body.name;
            users[u].age = req.body.age;
            users[u].description = req.body.description;
            writeUsersToJSONFile(filename, users);
            res.status(201).send(users[u]);
        }
    });
    app.delete("/users/:id", (req, res) => {
        const u = users.findIndex((e) => e.id == req.params.id);

        if (u == -1) {
            res.status(404).send({
                message: `No user with id: ${req.params.id} found`,
            });
        } else {
            const usr = users[u];

            users.splice(u, 1);
            writeUsersToJSONFile(filename, users);
            res.status(200).send(usr);
        }
    });
    app.get("*", (req, res) => {
        res.status(404).send({ message: "Not found" });
    });
    return app.listen(port, () => {
        console.log("Server running at http://" + host + ":" + port + "/");
    });
}
module.exports = {
    epiTinderWebServer,
};