Ngrammy

import ngrammy from 'ngrammy'
import { flatten, pick, pipe, values } from 'rambda'
import { writable } from 'svelte/store'
import { flattenTree } from '../api/categories'
import { isCategory } from '../api/helpers'

const allCategories = writable({})

// 1. Create an index of bigrams with newline as the sentinel
//
// The default normalisation function (3rd parameter) will collapse
// all whitespace into single space characters, so newline is a
// safe (and default) choice for sentinel.
const index = new ngrammy.Index(2, '\n')

function prepareIndex () {
    if (index.size() > 0) {
        console.debug('index exists already')
    } else {
        console.debug('preparing index')
        browser.bookmarks.getTree().then((bookmarks) => {
            const filterCategories = pipe(flattenTree, filter(isCategory))
            const categories = filterCategories(bookmarks)

            // 2. Add terms to index
            for (category of categories) {
                index.add(category.title, category.id)
                allCategories[category.id] = category
            }
        })
    }
}

function categorySearch (query) {
    // 3. Search the index (index.locations would also return positions)
    const ids = index.search(query)

    const result = pick(ids, allCategories) // allCategories is an object
    const sorted = sortByTitleCaseInsensitive(values(result))

    return sorted
}