import { TodoRepository } from '@/repositories/TodoRepository';
import { ProjectMemberRepository } from '@/repositories/ProjectMemberRepository';
import { NotificationService } from '@/services/NotificationService';
import { ActivityLogService } from '@/services/ActivityLogService';
import { AttachmentService } from '@/services/AttachmentService';
import { SseHub } from '@/lib/sse/hub';
import type { SqliteDatabase } from '@/lib/db/sqlite';
import { ForbiddenError, NotFoundError, ValidationError } from '@/lib/errors';
import type {
  AttachmentView,
  TodoColumn,
  TodoItem,
  TodoPriority,
} from '@/lib/types';

const STANDARD_COLUMNS = ['Backlog', 'To Do', 'In Progress', 'Review', 'Done'];
const VALID_PRIORITIES: TodoPriority[] = ['low', 'normal', 'high'];

export interface CreateItemInput {
  title: string;
  columnId: number;
  description?: string;
  assigneeId?: number | null;
  priority?: TodoPriority;
  startDate?: string | null;
  dueDate?: string | null;
  tags?: string | null;
  fileIds?: number[];
}

export interface UpdateItemRequest {
  title?: string;
  description?: string | null;
  assigneeId?: number | null;
  priority?: TodoPriority;
  startDate?: string | null;
  dueDate?: string | null;
  tags?: string | null;
  columnId?: number;
  orderIndex?: number;
  milestoneId?: number | null;
  fileIds?: number[];
}

/**
 * ToDo/Kanbanの業務ロジックを担うService。
 * 標準カラム初期生成、権限チェック、タスクCRUD/移動/完了、
 * 担当者割当時の通知(todo_assigned)とアクティビティログ(todo_*)、
 * 添付ファイル紐付け、SSE配信を行う。
 */
export class TodoService {
  constructor(
    private readonly todoRepository: TodoRepository,
    private readonly projectMemberRepository: ProjectMemberRepository,
    private readonly notificationService: NotificationService,
    private readonly activityLogService: ActivityLogService,
    private readonly sseHub: SseHub,
    private readonly attachmentService: AttachmentService,
    private readonly db: SqliteDatabase
  ) {}

  getColumns(actorId: number, projectId: number): TodoColumn[] {
    this.requireMember(projectId, actorId);
    let columns = this.todoRepository.findColumns(projectId);
    if (columns.length === 0) {
      // 標準カラム初期生成
      STANDARD_COLUMNS.forEach((name, idx) => {
        this.todoRepository.createColumn({
          projectId,
          name,
          orderIndex: idx,
        });
      });
      columns = this.todoRepository.findColumns(projectId);
    }
    return columns;
  }

  getItems(actorId: number, projectId: number): TodoItem[] {
    this.requireMember(projectId, actorId);
    return this.todoRepository.findItemsByProject(projectId);
  }

  createColumn(
    actorId: number,
    projectId: number,
    name: string,
    orderIndex?: number
  ): TodoColumn {
    this.requireMember(projectId, actorId);
    if (!name.trim()) {
      throw new ValidationError('カラム名を入力してください', 'name');
    }
    const idx = orderIndex ?? this.todoRepository.findColumns(projectId).length;
    return this.todoRepository.createColumn({
      projectId,
      name,
      orderIndex: idx,
    });
  }

  updateColumn(
    actorId: number,
    columnId: number,
    input: { name?: string; orderIndex?: number }
  ): TodoColumn {
    const column = this.todoRepository.findColumnById(columnId);
    if (!column) throw new NotFoundError('TodoColumn', columnId);
    this.requireMember(column.projectId, actorId);
    const updated = this.todoRepository.updateColumn(columnId, input);
    if (!updated) throw new NotFoundError('TodoColumn', columnId);
    return updated;
  }

  deleteColumn(actorId: number, columnId: number): void {
    const column = this.todoRepository.findColumnById(columnId);
    if (!column) throw new NotFoundError('TodoColumn', columnId);
    this.requireAdmin(column.projectId, actorId);
    this.todoRepository.deleteColumn(columnId);
  }

  createItem(
    actorId: number,
    projectId: number,
    input: CreateItemInput
  ): TodoItem {
    this.requireMember(projectId, actorId);
    if (!input.title.trim()) {
      throw new ValidationError('タイトルを入力してください', 'title');
    }
    const column = this.todoRepository.findColumnById(input.columnId);
    if (!column || column.projectId !== projectId) {
      throw new NotFoundError('TodoColumn', input.columnId);
    }
    if (input.priority && !VALID_PRIORITIES.includes(input.priority)) {
      throw new ValidationError('無効な優先度です', 'priority');
    }
    // タスク本体と添付紐付けはトランザクション内で一貫保存する
    const item = this.db.transaction(() => {
      const orderIndex =
        this.todoRepository.maxItemOrderIndex(input.columnId) + 1;
      const created = this.todoRepository.createItem({
        projectId,
        columnId: input.columnId,
        title: input.title,
        creatorId: actorId,
        description: input.description ?? null,
        assigneeId: input.assigneeId ?? null,
        priority: input.priority,
        startDate: input.startDate ?? null,
        dueDate: input.dueDate ?? null,
        tags: input.tags ?? null,
        orderIndex,
      });
      if (input.fileIds && input.fileIds.length > 0) {
        this.attachmentService.attach(
          actorId,
          projectId,
          'todo_item',
          created.id,
          input.fileIds
        );
      }
      return created;
    });

    if (input.assigneeId && input.assigneeId !== actorId) {
      this.notifyAssigned(projectId, input.assigneeId, item.title);
    }
    this.logTodo(projectId, actorId, 'todo_created', item.id);
    this.broadcastTodo(projectId);
    return item;
  }

  updateItem(
    actorId: number,
    itemId: number,
    input: UpdateItemRequest
  ): TodoItem {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    if (input.priority && !VALID_PRIORITIES.includes(input.priority)) {
      throw new ValidationError('無効な優先度です', 'priority');
    }
    const previousAssignee = item.assigneeId;
    const updated = this.db.transaction(() => {
      const u = this.todoRepository.updateItem(itemId, input);
      if (u && input.fileIds && input.fileIds.length > 0) {
        this.attachmentService.attach(
          actorId,
          item.projectId,
          'todo_item',
          itemId,
          input.fileIds
        );
      }
      return u;
    });
    if (!updated) throw new NotFoundError('TodoItem', itemId);

    if (
      input.assigneeId !== undefined &&
      input.assigneeId !== previousAssignee &&
      input.assigneeId !== null &&
      input.assigneeId !== actorId
    ) {
      this.notifyAssigned(item.projectId, input.assigneeId, updated.title);
    }
    this.logTodo(item.projectId, actorId, 'todo_updated', itemId);
    this.broadcastTodo(item.projectId);
    return updated;
  }

  moveItem(
    actorId: number,
    itemId: number,
    columnId: number,
    orderIndex: number
  ): TodoItem {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    const column = this.todoRepository.findColumnById(columnId);
    if (!column || column.projectId !== item.projectId) {
      throw new NotFoundError('TodoColumn', columnId);
    }
    const updated = this.todoRepository.updateItem(itemId, {
      columnId,
      orderIndex,
    });
    if (!updated) throw new NotFoundError('TodoItem', itemId);
    this.logTodo(item.projectId, actorId, 'todo_updated', itemId);
    this.broadcastTodo(item.projectId);
    return updated;
  }

  /**
   * 指定カラム内のアイテム順序を itemIds の順で再採番する。
   * 同一カラムの並べ替えだけでなく、別カラムからの移動(対象カラムへの挿入)にも使う。
   * すべて同一プロジェクト内であることを検証し、1トランザクションで更新する。
   */
  reorderItems(
    actorId: number,
    projectId: number,
    columnId: number,
    itemIds: number[]
  ): TodoItem[] {
    this.requireMember(projectId, actorId);
    const column = this.todoRepository.findColumnById(columnId);
    if (!column || column.projectId !== projectId) {
      throw new NotFoundError('TodoColumn', columnId);
    }
    const ids = Array.isArray(itemIds) ? itemIds : [];
    if (ids.length === 0) {
      // 空の並べ替えは何も変更せず、SSE/ログも出さない
      return this.todoRepository
        .findItemsByProject(projectId)
        .filter((i) => i.columnId === columnId);
    }
    this.db.transaction(() => {
      ids.forEach((id, idx) => {
        const item = this.todoRepository.findItemById(id);
        if (!item || item.projectId !== projectId) {
          throw new NotFoundError('TodoItem', id);
        }
        this.todoRepository.updateItem(id, { columnId, orderIndex: idx });
      });
    });
    this.logTodo(projectId, actorId, 'todo_updated', ids[0]);
    this.broadcastTodo(projectId);
    return this.todoRepository
      .findItemsByProject(projectId)
      .filter((i) => i.columnId === columnId);
  }

  toggleComplete(actorId: number, itemId: number): TodoItem {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    const now = item.completedAt === null ? new Date().toISOString() : null;
    const updated = this.todoRepository.updateItem(itemId, {
      completedAt: now,
    });
    if (!updated) throw new NotFoundError('TodoItem', itemId);
    if (now) {
      this.logTodo(item.projectId, actorId, 'todo_completed', itemId);
    } else {
      this.logTodo(item.projectId, actorId, 'todo_updated', itemId);
    }
    this.broadcastTodo(item.projectId);
    return updated;
  }

  deleteItem(actorId: number, itemId: number): void {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    const role = this.projectMemberRepository.getRole(item.projectId, actorId);
    if (item.creatorId !== actorId && role !== 'admin') {
      throw new ForbiddenError('作成者または管理者のみ削除できます');
    }
    this.db.transaction(() => {
      this.attachmentService.detach('todo_item', itemId);
      this.todoRepository.deleteItem(itemId);
    });
    this.broadcastTodo(item.projectId);
  }

  /** 単一のToDoアイテムを取得(メンバーシップチェック付き)。 */
  getItem(actorId: number, itemId: number): TodoItem {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    return item;
  }

  /** ToDoに紐付く添付ファイル一覧を取得(メンバーシップチェック付き)。 */
  getItemAttachments(actorId: number, itemId: number): AttachmentView[] {
    const item = this.todoRepository.findItemById(itemId);
    if (!item) throw new NotFoundError('TodoItem', itemId);
    this.requireMember(item.projectId, actorId);
    return this.attachmentService.listViews('todo_item', itemId);
  }

  private requireMember(projectId: number, actorId: number): void {
    if (!this.projectMemberRepository.isMember(projectId, actorId)) {
      throw new ForbiddenError('プロジェクトに参加していません');
    }
  }

  private requireAdmin(projectId: number, actorId: number): void {
    this.requireMember(projectId, actorId);
    if (this.projectMemberRepository.getRole(projectId, actorId) !== 'admin') {
      throw new ForbiddenError('プロジェクト管理者権限が必要です');
    }
  }

  private notifyAssigned(
    projectId: number,
    assigneeId: number,
    title: string
  ): void {
    this.notificationService.notifyOnEvent({
      type: 'todo_assigned',
      projectId,
      title: `ToDo「${title}」の担当者に割り当てられました`,
      body: title,
      assigneeId,
    });
  }

  private logTodo(
    projectId: number,
    actorId: number,
    action: string,
    targetId: number
  ): void {
    this.activityLogService.logActivity({
      projectId,
      actorId,
      action,
      targetType: 'todo',
      targetId,
    });
  }

  private broadcastTodo(projectId: number): void {
    this.sseHub.broadcast(projectId, {
      type: 'todo.updated',
      data: { projectId },
    });
  }
}