'use server';

import fs from 'fs';
import path from 'path';
import db from "@/db/db";
import { menuTreeNodes } from "@/db/schema/menu-v2";
import { eq, and, asc, inArray, isNull } from "drizzle-orm";
import { revalidatePath } from "next/cache";
import type { 
  MenuDomain, 
  MenuTreeNode, 
  MenuTreeAdminResult, 
  MenuTreeActiveResult,
  CreateMenuGroupInput,
  CreateGroupInput,
  UpdateNodeInput,
  ReorderNodeInput,
  DiscoveredMenu
} from "./types";
import { DOMAIN_APP_PATHS } from "./types";

// 도메인별 전체 트리 조회 (관리 화면용)
export async function getMenuTreeForAdmin(domain: MenuDomain): Promise<MenuTreeAdminResult> {
  const nodes = await db.select()
    .from(menuTreeNodes)
    .where(eq(menuTreeNodes.domain, domain))
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  // 트리에 포함될 노드들:
  // - menu_group (최상위 드롭다운)
  // - group (드롭다운 내 그룹)
  // - 배정된 menu (parentId !== null)
  // - 최상위 menu (parentId === null, isActive === true) - 단일 링크
  const treeNodes = nodes.filter(n => 
    n.nodeType === 'menu_group' || 
    n.nodeType === 'group' || 
    (n.nodeType === 'menu' && n.parentId !== null) ||
    (n.nodeType === 'menu' && n.parentId === null && n.isActive)
  ) as MenuTreeNode[];
  
  const tree = buildTree(treeNodes);
  
  // 미배정 메뉴 (parentId가 null이고 isActive가 false인 menu)
  const unassigned = nodes.filter(n => 
    n.nodeType === 'menu' && n.parentId === null && !n.isActive
  ) as MenuTreeNode[];
  
  return { tree, unassigned };
}

// 도메인별 활성 트리 조회 (헤더용)
export async function getActiveMenuTree(domain: MenuDomain): Promise<MenuTreeActiveResult> {
  const nodes = await db.select()
    .from(menuTreeNodes)
    .where(and(
      eq(menuTreeNodes.domain, domain),
      eq(menuTreeNodes.isActive, true)
    ))
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  // 트리에 포함될 노드들:
  // - menu_group (최상위 드롭다운)
  // - group (드롭다운 내 그룹)
  // - 배정된 menu (parentId !== null)
  // - 최상위 menu (parentId === null) - 단일 링크
  const treeNodes = nodes.filter(n => 
    n.nodeType === 'menu_group' || 
    n.nodeType === 'group' || 
    n.nodeType === 'menu'
  ) as MenuTreeNode[];
  
  const tree = buildTree(treeNodes);
  
  return { tree };
}

// 메뉴그룹 생성 (드롭다운)
export async function createMenuGroup(domain: MenuDomain, data: CreateMenuGroupInput) {
  const [result] = await db.insert(menuTreeNodes).values({
    domain,
    parentId: null,
    nodeType: 'menu_group',
    titleKo: data.titleKo,
    titleEn: data.titleEn,
    sortOrder: data.sortOrder ?? 0,
    isActive: true,
  }).returning();
  
  revalidatePath('/evcp/menu-v2');
  return result;
}

// 그룹 생성 (메뉴그룹 하위)
export async function createGroup(domain: MenuDomain, data: CreateGroupInput) {
  const [result] = await db.insert(menuTreeNodes).values({
    domain,
    parentId: data.parentId,
    nodeType: 'group',
    titleKo: data.titleKo,
    titleEn: data.titleEn,
    sortOrder: data.sortOrder ?? 0,
    isActive: true,
  }).returning();
  
  revalidatePath('/evcp/menu-v2');
  return result;
}

// 최상위 메뉴 생성 (단일 링크 - 기존 additional 역할)
export async function createTopLevelMenu(domain: MenuDomain, data: {
  titleKo: string;
  titleEn?: string;
  menuPath: string;
  sortOrder?: number;
}) {
  const [result] = await db.insert(menuTreeNodes).values({
    domain,
    parentId: null,
    nodeType: 'menu',
    titleKo: data.titleKo,
    titleEn: data.titleEn,
    menuPath: data.menuPath,
    sortOrder: data.sortOrder ?? 0,
    isActive: true,
  }).returning();
  
  revalidatePath('/evcp/menu-v2');
  return result;
}

// 노드 이동 (드래그앤드롭)
export async function moveNode(nodeId: number, newParentId: number | null, newSortOrder: number) {
  await db.update(menuTreeNodes)
    .set({ 
      parentId: newParentId, 
      sortOrder: newSortOrder,
      updatedAt: new Date()
    })
    .where(eq(menuTreeNodes.id, nodeId));
  
  revalidatePath('/evcp/menu-v2');
}

// 노드 수정
export async function updateNode(nodeId: number, data: UpdateNodeInput) {
  await db.update(menuTreeNodes)
    .set({ ...data, updatedAt: new Date() })
    .where(eq(menuTreeNodes.id, nodeId));
  
  revalidatePath('/evcp/menu-v2');
}

// 노드 삭제
export async function deleteNode(nodeId: number) {
  const [node] = await db.select().from(menuTreeNodes).where(eq(menuTreeNodes.id, nodeId)).limit(1);
  
  if (!node) return;
  
  if (node.nodeType === 'menu') {
    // 최상위 메뉴(parentId === null)는 직접 삭제 가능
    // 하위 메뉴(parentId !== null)는 미배정으로
    if (node.parentId === null) {
      await db.delete(menuTreeNodes).where(eq(menuTreeNodes.id, nodeId));
    } else {
      await db.update(menuTreeNodes)
        .set({ parentId: null, isActive: false, updatedAt: new Date() })
        .where(eq(menuTreeNodes.id, nodeId));
    }
  } else {
    // 메뉴그룹/그룹 삭제 시, 하위 메뉴는 미배정으로
    const children = await db.select({ id: menuTreeNodes.id, nodeType: menuTreeNodes.nodeType })
      .from(menuTreeNodes)
      .where(eq(menuTreeNodes.parentId, nodeId));
    
    for (const child of children) {
      if (child.nodeType === 'menu') {
        // 메뉴는 미배정으로
        await db.update(menuTreeNodes)
          .set({ parentId: null, isActive: false, updatedAt: new Date() })
          .where(eq(menuTreeNodes.id, child.id));
      } else if (child.nodeType === 'group') {
        // 그룹의 하위 메뉴도 미배정으로
        await db.update(menuTreeNodes)
          .set({ parentId: null, isActive: false, updatedAt: new Date() })
          .where(eq(menuTreeNodes.parentId, child.id));
        
        // 그룹 삭제
        await db.delete(menuTreeNodes).where(eq(menuTreeNodes.id, child.id));
      }
    }
    
    // 본 노드 삭제
    await db.delete(menuTreeNodes).where(eq(menuTreeNodes.id, nodeId));
  }
  
  revalidatePath('/evcp/menu-v2');
}

// 순서 일괄 변경
export async function reorderNodes(updates: ReorderNodeInput[]) {
  for (const { id, sortOrder } of updates) {
    await db.update(menuTreeNodes)
      .set({ sortOrder, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, id));
  }
  revalidatePath('/evcp/menu-v2');
}

// 미배정 메뉴를 특정 그룹에 배정
export async function assignMenuToGroup(menuId: number, groupId: number) {
  await db.update(menuTreeNodes)
    .set({ 
      parentId: groupId, 
      isActive: true,
      updatedAt: new Date() 
    })
    .where(eq(menuTreeNodes.id, menuId));
  
  revalidatePath('/evcp/menu-v2');
}

// 미배정 메뉴를 최상위 메뉴로 활성화
export async function activateAsTopLevelMenu(menuId: number) {
  await db.update(menuTreeNodes)
    .set({ 
      parentId: null, 
      isActive: true,
      updatedAt: new Date() 
    })
    .where(eq(menuTreeNodes.id, menuId));
  
  revalidatePath('/evcp/menu-v2');
}

// 단일 노드 조회
export async function getNodeById(nodeId: number): Promise<MenuTreeNode | null> {
  const [node] = await db.select()
    .from(menuTreeNodes)
    .where(eq(menuTreeNodes.id, nodeId))
    .limit(1);
  
  return node as MenuTreeNode | null;
}

// Helper: Convert flat list to tree
function buildTree(nodes: MenuTreeNode[]): MenuTreeNode[] {
  const nodeMap = new Map<number, MenuTreeNode>();
  const roots: MenuTreeNode[] = [];
  
  nodes.forEach(node => {
    nodeMap.set(node.id, { ...node, children: [] });
  });
  
  nodes.forEach(node => {
    const current = nodeMap.get(node.id)!;
    if (node.parentId === null) {
      roots.push(current);
    } else {
      const parent = nodeMap.get(node.parentId);
      if (parent) {
        if (!parent.children) parent.children = [];
        parent.children.push(current);
      }
    }
  });
  
  const sortChildren = (nodes: MenuTreeNode[]) => {
    nodes.sort((a, b) => a.sortOrder - b.sortOrder);
    nodes.forEach(node => {
      if (node.children?.length) {
        sortChildren(node.children);
      }
    });
  };
  sortChildren(roots);
  
  return roots;
}

// ============================================
// Menu Discovery & Sync (Server Actions)
// ============================================

const DYNAMIC_SEGMENT_PATTERN = /^\[.+\]$/;

/**
 * Discover pages from app router for a specific domain
 */
function discoverMenusFromAppRouter(domain: MenuDomain): DiscoveredMenu[] {
  const { appDir, basePath } = DOMAIN_APP_PATHS[domain];
  const menus: DiscoveredMenu[] = [];
  
  function scanDirectory(dir: string, currentPath: string[], routeGroup: string) {
    const absoluteDir = path.resolve(process.cwd(), dir);
    
    if (!fs.existsSync(absoluteDir)) return;
    
    const entries = fs.readdirSync(absoluteDir, { withFileTypes: true });
    
    for (const entry of entries) {
      const fullPath = path.join(absoluteDir, entry.name);
      
      if (entry.isDirectory()) {
        if (entry.name.startsWith('(') && entry.name.endsWith(')')) {
          scanDirectory(fullPath, currentPath, entry.name);
        }
        else if (DYNAMIC_SEGMENT_PATTERN.test(entry.name)) {
          continue;
        }
        else {
          scanDirectory(fullPath, [...currentPath, entry.name], routeGroup);
        }
      }
      else if (entry.name === 'page.tsx') {
        const menuPath = basePath + (currentPath.length > 0 ? '/' + currentPath.join('/') : '');
        menus.push({
          domain,
          menuPath,
          pageFilePath: fullPath,
          routeGroup
        });
      }
    }
  }
  
  scanDirectory(appDir, [], '');
  return menus;
}

/**
 * Sync discovered menus for a specific domain
 */
export async function syncDiscoveredMenus(domain: MenuDomain): Promise<{ added: number; removed: number }> {
  const discovered = discoverMenusFromAppRouter(domain);
  
  const existing = await db.select({ 
    id: menuTreeNodes.id,
    menuPath: menuTreeNodes.menuPath 
  })
    .from(menuTreeNodes)
    .where(and(
      eq(menuTreeNodes.domain, domain),
      inArray(menuTreeNodes.nodeType, ['menu', 'additional'])
    ));
  
  const existingPaths = new Set(existing.map(e => e.menuPath).filter(Boolean));
  
  const newMenus = discovered.filter(d => !existingPaths.has(d.menuPath));
  let added = 0;
  
  for (const menu of newMenus) {
    const pathSegments = menu.menuPath.split('/').filter(Boolean);
    const lastSegment = pathSegments[pathSegments.length - 1] || 'unknown';
    
    await db.insert(menuTreeNodes).values({
      domain,
      parentId: null,
      nodeType: 'menu',
      sortOrder: 0,
      titleKo: lastSegment,
      titleEn: lastSegment,
      menuPath: menu.menuPath,
      isActive: false,
    });
    added++;
  }
  
  revalidatePath('/evcp/menu-v2');
  return { added, removed: 0 };
}

/**
 * Sync all domains
 */
export async function syncAllDomains(): Promise<Record<MenuDomain, { added: number; removed: number }>> {
  const [evcp, partners] = await Promise.all([
    syncDiscoveredMenus('evcp'),
    syncDiscoveredMenus('partners')
  ]);
  return { evcp, partners };
}

/**
 * Get discovered menus without syncing
 */
export async function getDiscoveredMenus(): Promise<Record<MenuDomain, DiscoveredMenu[]>> {
  return {
    evcp: discoverMenusFromAppRouter('evcp'),
    partners: discoverMenusFromAppRouter('partners')
  };
}

// ============================================
// Move Node Helpers
// ============================================

/**
 * Move node up within same parent (decrease sort order)
 */
export async function moveNodeUp(nodeId: number): Promise<void> {
  const [node] = await db.select()
    .from(menuTreeNodes)
    .where(eq(menuTreeNodes.id, nodeId))
    .limit(1);
  
  if (!node) return;
  
  // Get siblings (nodes with same parent)
  const siblings = await db.select()
    .from(menuTreeNodes)
    .where(node.parentId === null 
      ? and(eq(menuTreeNodes.domain, node.domain), isNull(menuTreeNodes.parentId))
      : eq(menuTreeNodes.parentId, node.parentId)
    )
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  // Find current index
  const currentIndex = siblings.findIndex(s => s.id === nodeId);
  if (currentIndex <= 0) return; // Already at top
  
  // Swap sort orders with previous node
  const prevNode = siblings[currentIndex - 1];
  const prevSortOrder = prevNode.sortOrder;
  const currentSortOrder = node.sortOrder;
  
  // If sort orders are the same, assign unique values
  if (prevSortOrder === currentSortOrder) {
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentIndex - 1, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nodeId));
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentIndex, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, prevNode.id));
  } else {
    await db.update(menuTreeNodes)
      .set({ sortOrder: prevSortOrder, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nodeId));
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentSortOrder, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, prevNode.id));
  }
  
  revalidatePath('/evcp/menu-v2');
}

/**
 * Move node down within same parent (increase sort order)
 */
export async function moveNodeDown(nodeId: number): Promise<void> {
  const [node] = await db.select()
    .from(menuTreeNodes)
    .where(eq(menuTreeNodes.id, nodeId))
    .limit(1);
  
  if (!node) return;
  
  // Get siblings (nodes with same parent)
  const siblings = await db.select()
    .from(menuTreeNodes)
    .where(node.parentId === null 
      ? and(eq(menuTreeNodes.domain, node.domain), isNull(menuTreeNodes.parentId))
      : eq(menuTreeNodes.parentId, node.parentId)
    )
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  // Find current index
  const currentIndex = siblings.findIndex(s => s.id === nodeId);
  if (currentIndex >= siblings.length - 1) return; // Already at bottom
  
  // Swap sort orders with next node
  const nextNode = siblings[currentIndex + 1];
  const nextSortOrder = nextNode.sortOrder;
  const currentSortOrder = node.sortOrder;
  
  // If sort orders are the same, assign unique values
  if (nextSortOrder === currentSortOrder) {
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentIndex + 1, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nodeId));
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentIndex, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nextNode.id));
  } else {
    await db.update(menuTreeNodes)
      .set({ sortOrder: nextSortOrder, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nodeId));
    await db.update(menuTreeNodes)
      .set({ sortOrder: currentSortOrder, updatedAt: new Date() })
      .where(eq(menuTreeNodes.id, nextNode.id));
  }
  
  revalidatePath('/evcp/menu-v2');
}

/**
 * Move node to a different parent
 */
export async function moveNodeToParent(nodeId: number, newParentId: number | null): Promise<void> {
  const [node] = await db.select()
    .from(menuTreeNodes)
    .where(eq(menuTreeNodes.id, nodeId))
    .limit(1);
  
  if (!node) return;
  
  // Get max sort order in new parent
  const siblings = await db.select({ sortOrder: menuTreeNodes.sortOrder })
    .from(menuTreeNodes)
    .where(newParentId === null 
      ? and(eq(menuTreeNodes.domain, node.domain), isNull(menuTreeNodes.parentId))
      : eq(menuTreeNodes.parentId, newParentId)
    )
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  const maxSortOrder = siblings.length > 0 ? Math.max(...siblings.map(s => s.sortOrder)) + 1 : 0;
  
  await db.update(menuTreeNodes)
    .set({ 
      parentId: newParentId, 
      sortOrder: maxSortOrder,
      updatedAt: new Date() 
    })
    .where(eq(menuTreeNodes.id, nodeId));
  
  revalidatePath('/evcp/menu-v2');
}

/**
 * Get all possible parent targets for a node (for Move To dialog)
 * Returns items in tree order (same as Menu Structure display)
 * 
 * Rules:
 * - menu_group: Cannot be moved (always at top level)
 * - group: Can only move to menu_group (not to root or other groups)
 * - menu: Can move to root, menu_group, or group
 */
export async function getAvailableParents(
  nodeId: number, 
  domain: MenuDomain, 
  nodeType: string
): Promise<{ id: number | null; title: string; depth: number }[]> {
  const nodes = await db.select()
    .from(menuTreeNodes)
    .where(and(
      eq(menuTreeNodes.domain, domain),
      inArray(menuTreeNodes.nodeType, ['menu_group', 'group'])
    ))
    .orderBy(asc(menuTreeNodes.sortOrder));
  
  const result: { id: number | null; title: string; depth: number }[] = [];
  
  // For menu nodes, allow moving to root (as top-level menu)
  if (nodeType === 'menu') {
    result.push({ id: null, title: 'Top Level (Root)', depth: 0 });
  }
  
  // Build tree structure
  const nodeMap = new Map(nodes.map(n => [n.id, n]));
  const menuGroups = nodes.filter(n => n.parentId === null && n.nodeType === 'menu_group');
  
  // Helper to check if node is descendant of nodeId (prevent circular reference)
  const isDescendantOf = (checkNode: typeof nodes[0], ancestorId: number): boolean => {
    let parent = checkNode.parentId;
    while (parent !== null) {
      if (parent === ancestorId) return true;
      const parentNode = nodeMap.get(parent);
      parent = parentNode?.parentId ?? null;
    }
    return false;
  };
  
  // Traverse tree in order (menu_group -> its children groups)
  for (const menuGroup of menuGroups) {
    // Skip if it's the node being moved or its descendant
    if (menuGroup.id === nodeId || isDescendantOf(menuGroup, nodeId)) continue;
    
    // Add menu_group
    result.push({ 
      id: menuGroup.id, 
      title: menuGroup.titleKo, 
      depth: 1 
    });
    
    // For group nodes, only menu_groups are valid targets (skip children)
    if (nodeType === 'group') continue;
    
    // Add children groups (sorted by sortOrder)
    const childGroups = nodes
      .filter(n => n.parentId === menuGroup.id && n.nodeType === 'group')
      .sort((a, b) => a.sortOrder - b.sortOrder);
    
    for (const group of childGroups) {
      // Skip if it's the node being moved or its descendant
      if (group.id === nodeId || isDescendantOf(group, nodeId)) continue;
      
      result.push({ 
        id: group.id, 
        title: group.titleKo, 
        depth: 2 
      });
    }
  }
  
  return result;
}