import { apiRequest, listResource } from './api/client'

export type SitemapTargetType = 'page' | 'post' | 'course'

export type SitemapMenuItem = {
  id: string
  label: string
  targetType: SitemapTargetType
  targetId: string
  to: string
  children: SitemapMenuItem[]
}

export type SitemapMenu = {
  id: string
  name: string
  description?: string
  items: SitemapMenuItem[]
  createdAt?: number
  updatedAt?: number
}

export type SitemapSourceOption = {
  id: string
  label: string
  slug?: string
}

export type SitemapSources = {
  pages: SitemapSourceOption[]
  posts: SitemapSourceOption[]
  courses: SitemapSourceOption[]
}

function asString(value: unknown): string {
  return typeof value === 'string' ? value.trim() : ''
}

function asNumber(value: unknown): number | undefined {
  if (typeof value === 'number' && Number.isFinite(value)) return value
  return undefined
}

function normalizeItem(raw: unknown): SitemapMenuItem {
  const source = (raw ?? {}) as Record<string, unknown>
  const children = Array.isArray(source.children) ? source.children.map(normalizeItem) : []

  const targetTypeRaw = asString(source.targetType)
  const targetType: SitemapTargetType = targetTypeRaw === 'post' || targetTypeRaw === 'course' ? targetTypeRaw : 'page'

  return {
    id: asString(source.id),
    label: asString(source.label),
    targetType,
    targetId: asString(source.targetId),
    to: asString(source.to),
    children,
  }
}

export function normalizeSitemapMenu(raw: unknown): SitemapMenu {
  const source = (raw ?? {}) as Record<string, unknown>
  const items = Array.isArray(source.items) ? source.items.map(normalizeItem) : []

  return {
    id: asString(source.id),
    name: asString(source.name),
    description: asString(source.description) || undefined,
    items,
    createdAt: asNumber(source.createdAt),
    updatedAt: asNumber(source.updatedAt),
  }
}

export async function fetchSitemapMenus(): Promise<SitemapMenu[]> {
  const records = await listResource<unknown>('sitemap-menus')
  return records.map(normalizeSitemapMenu).filter(menu => menu.id && menu.name)
}

export async function createSitemapMenu(payload: Pick<SitemapMenu, 'name' | 'description' | 'items'>): Promise<SitemapMenu> {
  const created = await apiRequest<unknown>('/api/sitemap-menus/', {
    method: 'POST',
    body: JSON.stringify(payload),
  })
  return normalizeSitemapMenu(created)
}

export async function updateSitemapMenu(id: string, payload: Pick<SitemapMenu, 'name' | 'description' | 'items'>): Promise<SitemapMenu> {
  const updated = await apiRequest<unknown>(`/api/sitemap-menus/${encodeURIComponent(id)}`, {
    method: 'PATCH',
    body: JSON.stringify(payload),
  })
  return normalizeSitemapMenu(updated)
}

export async function removeSitemapMenu(id: string): Promise<void> {
  await apiRequest<void>(`/api/sitemap-menus/${encodeURIComponent(id)}`, {
    method: 'DELETE',
  })
}

export function buildPathForSource(targetType: SitemapTargetType, option: SitemapSourceOption): string {
  if (targetType === 'page') {
    return '/admin/builder'
  }
  if (targetType === 'post') {
    return option.slug ? `/blog/${option.slug}` : '/blog'
  }
  return option.slug ? `/live-courses/${option.slug}` : '/live-courses'
}

export async function fetchSitemapSources(): Promise<SitemapSources> {
  const [pagesRaw, postsRaw, coursesRaw] = await Promise.all([
    listResource<unknown>('pages'),
    apiRequest<unknown[]>('/api/blog/posts'),
    listResource<unknown>('live-courses'),
  ])

  const pages = pagesRaw
    .map(raw => {
      const source = (raw ?? {}) as Record<string, unknown>
      return {
        id: asString(source.id),
        label: asString(source.name) || asString(source.slug) || asString(source.id),
        slug: asString(source.slug) || undefined,
      }
    })
    .filter(item => item.id && item.label)

  const posts = postsRaw
    .map(raw => {
      const source = (raw ?? {}) as Record<string, unknown>
      return {
        id: asString(source.id),
        label: asString(source.title) || asString(source.slug) || asString(source.id),
        slug: asString(source.slug) || undefined,
      }
    })
    .filter(item => item.id && item.label)

  const courses = coursesRaw
    .map(raw => {
      const source = (raw ?? {}) as Record<string, unknown>
      return {
        id: asString(source.id),
        label: asString(source.title) || asString(source.slug) || asString(source.id),
        slug: asString(source.slug) || undefined,
      }
    })
    .filter(item => item.id && item.label)

  return { pages, posts, courses }
}

export type MenuParentOption = {
  id: string
  label: string
}

export function flattenParentOptions(items: SitemapMenuItem[], depth = 0): MenuParentOption[] {
  const options: MenuParentOption[] = []
  for (const item of items) {
    options.push({ id: item.id, label: `${' '.repeat(depth * 2)}${item.label}`.trimStart() })
    options.push(...flattenParentOptions(item.children, depth + 1))
  }
  return options
}

export function addMenuItem(items: SitemapMenuItem[], parentId: string | null, newItem: SitemapMenuItem): SitemapMenuItem[] {
  if (!parentId) {
    return [...items, newItem]
  }

  return items.map(item => {
    if (item.id === parentId) {
      return { ...item, children: [...item.children, newItem] }
    }
    return { ...item, children: addMenuItem(item.children, parentId, newItem) }
  })
}

export function removeMenuItem(items: SitemapMenuItem[], itemId: string): SitemapMenuItem[] {
  return items
    .filter(item => item.id !== itemId)
    .map(item => ({ ...item, children: removeMenuItem(item.children, itemId) }))
}

function moveWithinSiblings(items: SitemapMenuItem[], itemId: string, direction: 'up' | 'down'): SitemapMenuItem[] {
  const index = items.findIndex(item => item.id === itemId)
  if (index === -1) {
    return items.map(item => ({ ...item, children: moveWithinSiblings(item.children, itemId, direction) }))
  }

  const target = direction === 'up' ? index - 1 : index + 1
  if (target < 0 || target >= items.length) {
    return items
  }

  const next = [...items]
  const [entry] = next.splice(index, 1)
  next.splice(target, 0, entry)
  return next
}

export function moveMenuItem(items: SitemapMenuItem[], itemId: string, direction: 'up' | 'down'): SitemapMenuItem[] {
  return moveWithinSiblings(items, itemId, direction)
}

export function updateMenuItemLabel(items: SitemapMenuItem[], itemId: string, label: string): SitemapMenuItem[] {
  return items.map(item => {
    if (item.id === itemId) {
      return { ...item, label }
    }
    return { ...item, children: updateMenuItemLabel(item.children, itemId, label) }
  })
}

export function toHomeNavItems(items: SitemapMenuItem[]): Array<{ id: string; label: string; to: string }> {
  return items
    .map(item => ({ id: item.id, label: item.label, to: item.to }))
    .filter(item => item.id && item.label && item.to.startsWith('/'))
}