index.js

import process from 'process';
import fs from 'fs'

function list(taskStatus) {
        try {
            const data = fs.readFileSync('tasks.json', 'utf8');
            const tasks = JSON.parse(data);

            if (taskStatus === "todo"){
                const taskstate = tasks.filter(t => t.status === "todo")
                if (taskstate.length === 0){
                    console.log("This task status does not exisit")
                }
                taskstate.forEach(task => {
                    console.log([task.id], task.description, "--", task.status)
                });
            } else if (taskStatus === "in-progress"){
                const taskstate = tasks.filter(t => t.status === "in-progress")
                if (taskstate.length === 0){
                    console.log("This task status does not exisit")
                }
                taskstate.forEach(task => {
                    console.log([task.id], task.description, "--", task.status)
                });
            } else if (taskStatus === "done"){
                const taskstate = tasks.filter(t => t.status === "done")
                if (taskstate.length === 0){
                    console.log("This task status does not exisit")
                }
                taskstate.forEach(task => {
                    console.log([task.id], task.description, "--", task.status)
                });
            } else {
                tasks.forEach(task => {
                console.log([task.id], task.description, "--", task.status);
                });
            }

            if (tasks.length === 0){
                console.log("There are no tasks available to list. Use 'add' followed by your task description to create a new task entry!");
            }

        } catch (error) {
            console.error("There is an error:", error.message);
            process.exit(1);
        }
}

function add(addDescription) {
    if (!addDescription || !addDescription.trim()){
        console.log("To add a task, please enter a description!");
        process.exit(1);
    }

    const data = fs.readFileSync('tasks.json', 'utf8');
    const tasks = JSON.parse(data);

    if (tasks){
        try {

        let createdAt = new Date().toISOString();
        const updatedAt = new Date().toISOString();

        if (tasks.length === 0){

            const newTask = {
                "id": 1,
                "description": addDescription,
                "status": "todo",
                "createdAt": createdAt,
                "updatedAt": updatedAt
            }


            tasks.push(newTask);
            fs.writeFileSync('./tasks.json', JSON.stringify(tasks, null, 2));
            console.log("Task added successfully:", newTask);

        }
        
        if (tasks.length > 0) {
            const largestId = Math.max(...tasks?.map(t => t.id))

            const addNewId = largestId + 1
            const newTask = { 
                "id": addNewId,
                "description": addDescription,
                "status": "todo",
                "createdAt": createdAt,
                "updatedAt": updatedAt
            }

            tasks.push(newTask);
            fs.writeFileSync('./tasks.json', JSON.stringify(tasks, null, 2));
            console.log("Task added successfully:", newTask);
        }

        } catch (error) {
            console.error("There is an error:", error.message);
        }

    }
}

function update({id, updateDescription}) {

    if (!id) {
        console.log("\nProvide the 'id' of the task you would like to update followed by the new task 'description'\n")
        return list();
    }

    if (!updateDescription) {
        console.log("\nProvide the 'description' of the new task\n")
        return list();
    }

    try {
        const data = fs.readFileSync('tasks.json', 'utf8');
        const tasks = JSON.parse(data);

        const index = tasks.findIndex((t => t.id === id))

        if (id && index === -1 ){
            console.log("This task id has not been found")
            return list();
        }
        
        const updatedTask = {
            id: tasks[index].id,
            description: updateDescription,
            status: tasks[index].status,
            createdAt: tasks[index].createdAt,
            updatedAt: new Date().toISOString()
        }

        tasks[index] = updatedTask
        
        fs.writeFileSync('./tasks.json', JSON.stringify(tasks, null, 2));
        console.log("Task updated successfully:", updatedTask);

    } catch(error) {
        console.error("There is an error:", error.message);
    }

}

function updateStatus(id){

    if (!id) {
        console.log("Please provide the 'id' to update the status from the following tasks");
        return list();
    }

    try {

        const data = fs.readFileSync('tasks.json', 'utf8');
        const tasks = JSON.parse(data);

        const index = tasks.findIndex((t => t.id === id))

        if (id && index === -1 ){
            console.log("This task id has not been found")
            return list();
        }

        const statusChange = command.slice(5);
        
        const updatedStatus = {
            id: tasks[index].id,
            description: tasks[index].description,
            status: statusChange,
            createdAt: tasks[index].createdAt,
            updatedAt: new Date().toISOString()
        }

        tasks[index] = updatedStatus

        fs.writeFileSync('./tasks.json', JSON.stringify(tasks, null, 2));
        console.log("Task updated successfully:", updatedStatus);

    } catch(error){
        console.error(error.message)
    }

}

function deleteTask(id) {

    if (!id){
        console.log("Please provide an id of the task you would like to delete")
        list();
        process.exit(1);
    }

    try {

    const data = fs.readFileSync('tasks.json', 'utf8');
    const tasks = JSON.parse(data);

    const index = tasks.findIndex((t => t.id === id))
    
    if (id && index === -1 ){
        console.log("This task id has not been found, select from exisiting one")
        return list();
    }
    
    const updatedTask = tasks.filter(t => t.id !==id)

    fs.writeFileSync('./tasks.json', JSON.stringify(updatedTask, null, 2));
    console.log("Task deleted successfully");

    } catch(error) {
        console.log("There is an error:", error.message)
    }
}


const argumentList = process.argv.slice(2)
const command = argumentList[0]
const id = Number(argumentList[1])
const addDescription = argumentList.slice(1).join(" ")
const updateDescription = argumentList.slice(2).join(" ")
const taskStatus = argumentList.slice(1).join(" ")

if (command === "add"){
    add(addDescription);
} else if (command === "list"){
    list(taskStatus);
} else if (command === "update"){
    update({ id,  updateDescription });
} else if (command === "mark-in-progress" || command === "mark-done" || command === "mark-todo"){
    updateStatus(id);
} else if (command === "delete") {
    deleteTask(id);
} else if (command === "--help") {
    console.log(" Your Task Manager:",`\n`, `\n`,"Please select the following commands:",`\n`,"-'list' (to list all)" ,`\n`, "-'list mark-[status]' (to can sort and change by the following status: 'todo', 'in-progess', 'done')",`\n`,"-'add' (provide a descriprion) ", `\n`,"-'update' (provide the exisiting id and new description) ", `\n`,"-'delete' (provide the id)" )
} else {
    console.log(" Your Task Manager:",`\n`, `\n`,"Please select the following commands:",`\n`,"-'list' (to list all)" ,`\n`, "-'list mark-[status]' (to can sort and change by the following status: 'todo', 'in-progess', 'done')",`\n`,"-'add' (provide a descriprion) ", `\n`,"-'update' (provide the exisiting id and new description) ", `\n`,"-'delete' (provide the id)" )
}