task-cli

#!/usr/bin/env python3

import json
import os
import sys
from datetime import datetime, timezone


TASKS_FILE = "tasks.json"


def get_now_iso() -> str:
    return datetime.now(timezone.utc).isoformat()


def load_tasks() -> list:
    if not os.path.exists(TASKS_FILE):
        return []
    try:
        with open(TASKS_FILE, "r", encoding="utf-8") as f:
            content = f.read().strip()
            if not content:
                return []
            data = json.loads(content)
            if isinstance(data, list):
                return data
            return []
    except (json.JSONDecodeError, OSError):
        print("Error: Failed to read tasks.json. The file may be corrupted.")
        sys.exit(1)


def save_tasks(tasks: list) -> None:
    try:
        with open(TASKS_FILE, "w", encoding="utf-8") as f:
            json.dump(tasks, f, indent=2, ensure_ascii=False)
    except OSError:
        print("Error: Failed to write tasks.json.")
        sys.exit(1)


def generate_next_id(tasks: list) -> int:
    max_id = 0
    for task in tasks:
        try:
            tid = int(task.get("id", 0))
            if tid > max_id:
                max_id = tid
        except (TypeError, ValueError):
            continue
    return max_id + 1


def find_task(tasks: list, task_id: int):
    for task in tasks:
        if task.get("id") == task_id:
            return task
    return None


def print_usage() -> None:
    usage = (
        "Usage:\n"
        "  task-cli add <description>\n"
        "  task-cli update <id> <new-description>\n"
        "  task-cli delete <id>\n"
        "  task-cli mark-in-progress <id>\n"
        "  task-cli mark-done <id>\n"
        "  task-cli list [todo|in-progress|done]\n"
    )
    print(usage, end="")


def cmd_add(args: list) -> None:
    if len(args) < 1:
        print("Error: Description is required for add.")
        print_usage()
        sys.exit(1)
    description = " ".join(args).strip()
    if not description:
        print("Error: Description cannot be empty.")
        sys.exit(1)

    tasks = load_tasks()
    new_id = generate_next_id(tasks)
    now = get_now_iso()
    new_task = {
        "id": new_id,
        "description": description,
        "status": "todo",
        "createdAt": now,
        "updatedAt": now,
    }
    tasks.append(new_task)
    save_tasks(tasks)
    print(f"Task added successfully (ID: {new_id})")


def cmd_update(args: list) -> None:
    if len(args) < 2:
        print("Error: update requires <id> and <new-description>.")
        print_usage()
        sys.exit(1)
    try:
        task_id = int(args[0])
    except ValueError:
        print("Error: <id> must be a number.")
        sys.exit(1)
    new_desc = " ".join(args[1:]).strip()
    if not new_desc:
        print("Error: New description cannot be empty.")
        sys.exit(1)

    tasks = load_tasks()
    task = find_task(tasks, task_id)
    if not task:
        print(f"Error: Task with ID {task_id} not found.")
        sys.exit(1)
    task["description"] = new_desc
    task["updatedAt"] = get_now_iso()
    save_tasks(tasks)
    print(f"Task {task_id} updated successfully")


def cmd_delete(args: list) -> None:
    if len(args) != 1:
        print("Error: delete requires exactly one <id> argument.")
        print_usage()
        sys.exit(1)
    try:
        task_id = int(args[0])
    except ValueError:
        print("Error: <id> must be a number.")
        sys.exit(1)

    tasks = load_tasks()
    before = len(tasks)
    tasks = [t for t in tasks if t.get("id") != task_id]
    if len(tasks) == before:
        print(f"Error: Task with ID {task_id} not found.")
        sys.exit(1)
    save_tasks(tasks)
    print(f"Task {task_id} deleted successfully")


def cmd_mark_status(args: list, new_status: str) -> None:
    if len(args) != 1:
        print(f"Error: command requires exactly one <id> argument.")
        print_usage()
        sys.exit(1)
    try:
        task_id = int(args[0])
    except ValueError:
        print("Error: <id> must be a number.")
        sys.exit(1)

    tasks = load_tasks()
    task = find_task(tasks, task_id)
    if not task:
        print(f"Error: Task with ID {task_id} not found.")
        sys.exit(1)
    task["status"] = new_status
    task["updatedAt"] = get_now_iso()
    save_tasks(tasks)
    print(f"Task {task_id} marked as {new_status}")


def format_task_line(task: dict) -> str:
    tid = task.get("id")
    status = task.get("status")
    desc = task.get("description", "")
    created_at = task.get("createdAt", "")
    updated_at = task.get("updatedAt", "")
    return f"{tid:>3} | [{status}] {desc} | created: {created_at} | updated: {updated_at}"


def cmd_list(args: list) -> None:
    allowed_statuses = {"todo", "in-progress", "done"}
    filter_status = None
    if len(args) == 1:
        if args[0] not in allowed_statuses:
            print("Error: Invalid status. Use one of: todo, in-progress, done.")
            sys.exit(1)
        filter_status = args[0]
    elif len(args) > 1:
        print("Error: list accepts at most one optional status.")
        print_usage()
        sys.exit(1)

    tasks = load_tasks()
    if filter_status:
        tasks = [t for t in tasks if t.get("status") == filter_status]

    if not tasks:
        if filter_status:
            print(f"No tasks with status '{filter_status}'.")
        else:
            print("No tasks found.")
        return

    for task in sorted(tasks, key=lambda t: int(t.get("id", 0))):
        print(format_task_line(task))


def main(argv: list) -> None:
    if len(argv) < 2:
        print_usage()
        sys.exit(1)

    command = argv[1]
    args = argv[2:]

    if command == "add":
        cmd_add(args)
    elif command == "update":
        cmd_update(args)
    elif command == "delete":
        cmd_delete(args)
    elif command == "mark-in-progress":
        cmd_mark_status(args, "in-progress")
    elif command == "mark-done":
        cmd_mark_status(args, "done")
    elif command == "list":
        cmd_list(args)
    else:
        print(f"Error: Unknown command '{command}'.")
        print_usage()
        sys.exit(1)


if __name__ == "__main__":
    main(sys.argv)