"use server";

import { revalidatePath } from "next/cache";

import { prisma } from "@/lib/db";
import { requireUserId } from "@/lib/auth-helpers";
import { boardPath, categoryAccessFilter } from "@/lib/access";
import { TodoDetailsSchema, TodoTitleSchema } from "@/lib/validation/todo";
import type { TodoDTO } from "@/types/board";

export async function createTodo(
  groupId: string,
  title: string,
  details?: string
): Promise<TodoDTO> {
  const userId = await requireUserId();
  const parsedTitle = TodoTitleSchema.parse(title);
  const parsedDetails = details ? TodoDetailsSchema.parse(details) : undefined;

  const group = await prisma.group.findFirst({
    where: { id: groupId, category: categoryAccessFilter(userId) },
    select: { id: true, category: { select: { projectId: true } } },
  });
  if (!group) throw new Error("Group not found");

  const count = await prisma.todo.count({ where: { groupId } });

  const todo = await prisma.todo.create({
    data: { title: parsedTitle, details: parsedDetails ?? null, order: count, groupId },
  });

  revalidatePath(boardPath(group.category.projectId));
  return {
    id: todo.id,
    title: todo.title,
    details: todo.details,
    completed: todo.completed,
    order: todo.order,
    groupId: todo.groupId,
    createdAt: todo.createdAt.toISOString(),
    updatedAt: todo.updatedAt.toISOString(),
    completedAt: todo.completedAt?.toISOString() ?? null,
  };
}

/**
 * Bulk-inserts several to-dos in one transaction, e.g. from the "Add
 * using AI" interview. Unlike calling `createTodo` in a loop, `order` is
 * computed once up front and assigned sequentially within the same
 * transaction, so concurrent items in this batch never race each other's
 * `prisma.todo.count` read.
 */
export async function createTodos(
  groupId: string,
  todos: { title: string; details?: string }[]
): Promise<TodoDTO[]> {
  const userId = await requireUserId();
  const parsed = todos.map((t) => ({
    title: TodoTitleSchema.parse(t.title),
    details: t.details ? TodoDetailsSchema.parse(t.details) : undefined,
  }));

  const group = await prisma.group.findFirst({
    where: { id: groupId, category: categoryAccessFilter(userId) },
    select: { id: true, category: { select: { projectId: true } } },
  });
  if (!group) throw new Error("Group not found");

  const count = await prisma.todo.count({ where: { groupId } });

  const created = await prisma.$transaction(
    parsed.map((t, index) =>
      prisma.todo.create({
        data: { title: t.title, details: t.details ?? null, order: count + index, groupId },
      })
    )
  );

  revalidatePath(boardPath(group.category.projectId));
  return created.map((todo) => ({
    id: todo.id,
    title: todo.title,
    details: todo.details,
    completed: todo.completed,
    order: todo.order,
    groupId: todo.groupId,
    createdAt: todo.createdAt.toISOString(),
    updatedAt: todo.updatedAt.toISOString(),
    completedAt: todo.completedAt?.toISOString() ?? null,
  }));
}

export async function updateTodo(
  todoId: string,
  data: { title?: string; details?: string | null }
): Promise<void> {
  const userId = await requireUserId();

  const update: { title?: string; details?: string | null } = {};
  if (data.title !== undefined) update.title = TodoTitleSchema.parse(data.title);
  if (data.details !== undefined) {
    update.details = data.details ? TodoDetailsSchema.parse(data.details) : null;
  }

  const todo = await prisma.todo.findFirst({
    where: { id: todoId, group: { category: categoryAccessFilter(userId) } },
    select: { group: { select: { category: { select: { projectId: true } } } } },
  });
  if (!todo) throw new Error("To-do not found");

  await prisma.todo.update({ where: { id: todoId }, data: update });

  revalidatePath(boardPath(todo.group.category.projectId));
}

export async function toggleTodo(todoId: string, completed: boolean): Promise<void> {
  const userId = await requireUserId();

  const todo = await prisma.todo.findFirst({
    where: { id: todoId, group: { category: categoryAccessFilter(userId) } },
    select: { group: { select: { category: { select: { projectId: true } } } } },
  });
  if (!todo) throw new Error("To-do not found");

  await prisma.todo.update({
    where: { id: todoId },
    data: { completed, completedAt: completed ? new Date() : null },
  });

  revalidatePath(boardPath(todo.group.category.projectId));
}

export async function deleteTodo(todoId: string): Promise<void> {
  const userId = await requireUserId();

  const todo = await prisma.todo.findFirst({
    where: { id: todoId, group: { category: categoryAccessFilter(userId) } },
    select: { group: { select: { category: { select: { projectId: true } } } } },
  });
  if (!todo) throw new Error("To-do not found");

  await prisma.todo.delete({ where: { id: todoId } });

  revalidatePath(boardPath(todo.group.category.projectId));
}

/** Persists a new to-do order within a single group. */
export async function reorderTodos(groupId: string, orderedTodoIds: string[]): Promise<void> {
  const userId = await requireUserId();

  const group = await prisma.group.findFirst({
    where: { id: groupId, category: categoryAccessFilter(userId) },
    include: {
      todos: { select: { id: true } },
      category: { select: { projectId: true } },
    },
  });
  if (!group) throw new Error("Group not found");

  const ownedIds = new Set(group.todos.map((t) => t.id));
  if (
    orderedTodoIds.length !== ownedIds.size ||
    !orderedTodoIds.every((id) => ownedIds.has(id))
  ) {
    throw new Error("To-do list does not match this group's to-dos");
  }

  await prisma.$transaction(
    orderedTodoIds.map((id, index) =>
      prisma.todo.update({ where: { id }, data: { order: index } })
    )
  );

  revalidatePath(boardPath(group.category.projectId));
}