4dkankan-components/docs/.vitepress/vitepress/composables/page-nav.ts

import { computed } from 'vue'
import { useData } from 'vitepress'
import { ensureStartingSlash, isArray, removeExtention as removeExtension } from '../utils'
import { useLang } from './lang'
import { getFlatSideBarLinks, getSidebarConfig } from './sidebar'

export function usePageNav() {
    const { page, theme } = useData()
    const lang = useLang()

    const path = computed(() => {
        return removeExtension(ensureStartingSlash(page.value.relativePath))
    })

    const candidates = computed(() => {
        const config = getSidebarConfig(theme.value.sidebars, path.value, lang.value)
        return isArray(config) ? getFlatSideBarLinks(config) : []
    })

    const index = computed(() => {
        return candidates.value.findIndex(item => {
            return item.link === path.value
        })
    })
    const next = computed(() => {
        if (theme.value.nextLinks !== false && index.value > -1 && index.value < candidates.value.length - 1) {
            return candidates.value[index.value + 1]
        }

        return null
    })

    const prev = computed(() => {
        if (theme.value.prevLinks !== false && index.value > 0) {
            return candidates.value[index.value - 1]
        }
        return null
    })

    const hasLinks = computed(() => !!next.value || !!prev.value)
    return {
        next,
        prev,
        hasLinks,
    }
}