/**
 * Kanban-specific types with discriminated unions
 * Ensures type safety for Epic, Story, and Task cards
 */

import { WorkItemStatus, WorkItemPriority } from './project';

// Base Kanban item interface with common properties
interface BaseKanbanItem {
  id: string;
  projectId: string;
  status: WorkItemStatus;
  priority: WorkItemPriority;
  description?: string;
  estimatedHours?: number;
  actualHours?: number;
  assigneeId?: string;
  tenantId: string;
  createdAt: string;
  updatedAt: string;
}

// Epic as Kanban item - discriminated by 'type' field
export interface KanbanEpic extends BaseKanbanItem {
  type: 'Epic';
  name: string;  // Epic uses 'name' instead of 'title'
  createdBy: string;
  childCount?: number;  // Number of stories in this epic
  epicId?: never;  // Epic doesn't have epicId
  storyId?: never;  // Epic doesn't have storyId
  title?: never;  // Epic uses 'name', not 'title'
}

// Story as Kanban item - discriminated by 'type' field
export interface KanbanStory extends BaseKanbanItem {
  type: 'Story';
  title: string;  // Story uses 'title'
  epicId: string;  // Story always has epicId
  childCount?: number;  // Number of tasks in this story
  storyId?: never;  // Story doesn't have storyId
  name?: never;  // Story uses 'title', not 'name'
}

// Task as Kanban item - discriminated by 'type' field
export interface KanbanTask extends BaseKanbanItem {
  type: 'Task';
  title: string;  // Task uses 'title'
  storyId: string;  // Task always has storyId
  epicId?: never;  // Task doesn't have epicId (only through story)
  childCount?: never;  // Task doesn't have children
  name?: never;  // Task uses 'title', not 'name'
}

// Discriminated union type for Kanban items
// TypeScript can narrow the type based on the 'type' field
export type KanbanItem = KanbanEpic | KanbanStory | KanbanTask;

// Type guards for runtime type checking
export function isKanbanEpic(item: KanbanItem): item is KanbanEpic {
  return item.type === 'Epic';
}

export function isKanbanStory(item: KanbanItem): item is KanbanStory {
  return item.type === 'Story';
}

export function isKanbanTask(item: KanbanItem): item is KanbanTask {
  return item.type === 'Task';
}

// Helper to get display title regardless of type
export function getKanbanItemTitle(item: KanbanItem): string {
  if (isKanbanEpic(item)) {
    return item.name;
  }
  return item.title;
}

// Kanban column type
export interface KanbanColumn {
  id: WorkItemStatus;
  title: string;
  items: KanbanItem[];
}

// Kanban board type
export interface KanbanBoard {
  projectId: string;
  projectName: string;
  columns: KanbanColumn[];
}

// ==================== Legacy Types (for backward compatibility) ====================
export interface TaskCard {
  id: string;
  title: string;
  description: string;
  priority: string;
  assigneeId?: string;
  estimatedHours?: number;
  actualHours?: number;
}

// Legacy KanbanColumn type for backward compatibility
export interface LegacyKanbanColumn {
  status: string;
  title: string;
  tasks: TaskCard[];
}

// Legacy KanbanBoard type
export interface LegacyKanbanBoard {
  projectId: string;
  projectName: string;
  columns: LegacyKanbanColumn[];
}