import type { LayoutMenuItem } from './menu'
import { mdiHome } from '@mdi/js'
import { defineStore } from 'pinia'
import { computed, ref } from 'vue'

export interface BreadcrumbItem {
  title: string
  to?: string
  disabled?: boolean
  icon?: string
}

interface BreadcrumbPayload {
  path: string
  menuItems: LayoutMenuItem[]
  favoriteItems?: LayoutMenuItem[]
  fallbackTitle?: string | null
  homeLabel?: string
  homeIcon?: string
}

function buildTrail(items: LayoutMenuItem[], targetPath: string): LayoutMenuItem[] | null {
  const walk = (nodes: LayoutMenuItem[], trail: LayoutMenuItem[]): LayoutMenuItem[] | null => {
    for (const node of nodes) {
      const nextTrail = [...trail, node]
      if (node.path && node.path === targetPath) return nextTrail
      if (node.subItems?.length) {
        const found = walk(node.subItems, nextTrail)
        if (found) return found
      }
    }
    return null
  }

  return walk(items || [], [])
}

function toBreadcrumbItems(
  trail: LayoutMenuItem[],
  homeLabel: string,
  homeIcon: string
): BreadcrumbItem[] {
  const isHomePath = (path?: string) => path === '/' || path === ''
  const startsWithHome = trail.length > 0 && isHomePath(trail[0]?.path)
  const crumbs: BreadcrumbItem[] = []

  if (!startsWithHome) {
    crumbs.push({
      title: homeLabel,
      to: '/',
      icon: homeIcon,
    })
  }

  for (const [index, node] of trail.entries()) {
    const isLast = index === trail.length - 1
    crumbs.push({
      title: node.title,
      to: isLast ? undefined : node.path,
      icon: startsWithHome && index === 0 ? homeIcon : undefined,
    })
  }

  return crumbs
}

export const useBreadcrumbStore = defineStore('breadcrumbs', () => {
  const items = ref<BreadcrumbItem[]>([])
  const homeLabel = ref('首頁')
  const homeIcon = ref(mdiHome)

  const setBreadcrumbs = (payload: BreadcrumbPayload) => {
    if (!payload?.path) return

    homeLabel.value = payload.homeLabel ?? homeLabel.value
    homeIcon.value = payload.homeIcon ?? homeIcon.value

    const trailFromMenu = buildTrail(payload.menuItems || [], payload.path)
    const trailFromFavorite = payload.favoriteItems?.length
      ? buildTrail(payload.favoriteItems, payload.path)
      : null
    const trail = trailFromMenu || trailFromFavorite

    if (trail?.length) {
      items.value = toBreadcrumbItems(trail, homeLabel.value, homeIcon.value)
      return
    }

    if (payload.fallbackTitle && payload.fallbackTitle !== homeLabel.value) {
      items.value = [
        {
          title: homeLabel.value,
          to: '/',
          icon: homeIcon.value,
        },
        {
          title: payload.fallbackTitle,
        },
      ]
      return
    }

    items.value = [
      {
        title: homeLabel.value,
        to: '/',
        icon: homeIcon.value,
      },
    ]
  }

  const reset = () => {
    items.value = []
  }

  const breadcrumbItems = computed(() => items.value)

  return {
    items,
    breadcrumbItems,
    setBreadcrumbs,
    reset,
  }
})