/** @module */
import { split } from '../helpers/split'
import { wrapTokens } from '../helpers/wrap_tokens'
import marpitPlugin from '../plugin'
export const defaultAnchorCallback = (i) => `${i + 1}`
/**
* Marpit slide plugin.
*
* Split markdown-it tokens into the slides by horizontal rule. Each slides
* will be wrapped by section element.
*
* @function slide
* @param {MarkdownIt} md markdown-it instance.
* @param {Object} [opts]
* @param {Object} [opts.attributes] The `<section>` element attributes by
* key-value pairs.
* @param {(boolean|Marpit~AnchorCallback)} [opts.anchor=true] If true, assign
* the anchor with the page number starting from 1. You can customize anchor
* name by passing callback function.
*/
function _slide(md, opts = {}) {
const anchor = opts.anchor === undefined ? true : opts.anchor
const anchorCallback = (() => {
if (typeof anchor === 'function') return anchor
if (anchor) return defaultAnchorCallback
return () => undefined
})()
md.core.ruler.push('marpit_slide', (state) => {
if (state.inlineMode) return
const splittedTokens = split(
state.tokens,
(t) => t.type === 'hr' && t.level === 0,
true
)
const { length: marpitSlideTotal } = splittedTokens
state.tokens = splittedTokens.reduce((arr, slideTokens, marpitSlide) => {
const firstHr =
slideTokens[0] && slideTokens[0].type === 'hr'
? slideTokens[0]
: undefined
const mapTarget = firstHr || slideTokens.find((t) => t.map)
return [
...arr,
...wrapTokens(
state.Token,
'marpit_slide',
{
...(opts.attributes || {}),
tag: 'section',
id: anchorCallback(marpitSlide),
open: {
block: true,
meta: { marpitSlide, marpitSlideTotal, marpitSlideElement: 1 },
map: mapTarget ? mapTarget.map : [0, 1],
},
close: {
block: true,
meta: { marpitSlide, marpitSlideTotal, marpitSlideElement: -1 },
},
},
slideTokens.slice(firstHr ? 1 : 0)
),
]
}, [])
})
}
export const slide = marpitPlugin(_slide)
export default slide