import { writable } from "svelte/store";

export type TodoItem = { id: number; text: string; done: boolean };
export type TodoListMeta = { id: string; label: string };

const initialTodoListMeta: TodoListMeta[] = [
  { id: "todos/today", label: "Today" },
  { id: "todos/scheduled", label: "Scheduled" },
  { id: "todos/completed", label: "Completed" }
];
export const todoListsStore = writable<TodoListMeta[]>(initialTodoListMeta);

export const todosStore = writable<Record<string, TodoItem[]>>({
  "todos/today": [
    { id: 1, text: "Finalize journal sidebar interactions", done: false },
    { id: 2, text: "Review fragment taxonomy updates", done: false },
    { id: 3, text: "Capture daily notes summary", done: false }
  ],
  "todos/scheduled": [
    { id: 4, text: "Tuesday: sync settings to backend store", done: false },
    { id: 5, text: "Thursday: polish editor keyboard shortcuts", done: false },
    { id: 6, text: "Friday: QA fragment and todo workflows", done: false }
  ],
  "todos/completed": [
    { id: 7, text: "Replaced navbar profile with settings shortcut", done: true },
    { id: 8, text: "Centered modal presentation", done: true },
    { id: 9, text: "Added fragment creation form mode", done: true }
  ]
});

export function serializeTodoList(title: string, todos: TodoItem[]): string {
  const heading = title?.trim() ? `# ${title}` : "# To-Do List";
  const lines = todos.map((todo) => `- [${todo.done ? "x" : " "}] ${todo.text}`);
  return `${heading}\n\n${lines.join("\n")}`;
}

export function createTodoId(): number {
  return Date.now() + Math.floor(Math.random() * 1000);
}

export function parseTodoList(content: string): TodoItem[] {
  const lines = content.replace(/\r\n/g, "\n").split("\n");
  const parsed: TodoItem[] = [];
  for (const line of lines) {
    const match = line.match(/^- \[( |x)\]\s+(.+)$/i);
    if (!match) continue;
    parsed.push({
      id: createTodoId(),
      text: match[2].trim(),
      done: match[1].toLowerCase() === "x"
    });
  }
  return parsed;
}

export function getOrCreateTodoList(
  lists: Record<string, TodoItem[]>,
  documentId: string,
  fallbackContent: string
): { lists: Record<string, TodoItem[]>; todos: TodoItem[] } {
  const existing = lists[documentId];
  if (existing) {
    return { lists, todos: existing };
  }
  const parsed = parseTodoList(fallbackContent);
  return { lists: { ...lists, [documentId]: parsed }, todos: parsed };
}

export function setTodoList(
  lists: Record<string, TodoItem[]>,
  documentId: string,
  todos: TodoItem[]
): Record<string, TodoItem[]> {
  return { ...lists, [documentId]: todos };
}

export function addTodoItem(todos: TodoItem[], text: string): TodoItem[] {
  return [{ id: createTodoId(), text: text.trim(), done: false }, ...todos];
}

export function toggleTodoItem(todos: TodoItem[], id: number): TodoItem[] {
  return todos.map((todo) => (todo.id === id ? { ...todo, done: !todo.done } : todo));
}

export function updateTodoItemText(todos: TodoItem[], id: number, text: string): TodoItem[] {
  return todos.map((todo) => (todo.id === id ? { ...todo, text: text.trim() } : todo));
}

export function removeTodoItem(todos: TodoItem[], id: number): TodoItem[] {
  return todos.filter((todo) => todo.id !== id);
}

export function createTodoListDraft(): { meta: TodoListMeta; items: TodoItem[] } {
  const id = `todos/list-${Date.now()}`;
  return {
    meta: { id, label: "New List" },
    items: []
  };
}