view.js

import * as CFI from './epubcfi.js'
import { TOCProgress, SectionProgress } from './progress.js'
import { Overlayer } from './overlayer.js'
import { textWalker } from './text-walker.js'

const SEARCH_PREFIX = 'foliate-search:'

class History extends EventTarget {
    #arr = []
    #index = -1
    pushState(x) {
        const last = this.#arr[this.#index]
        if (last === x || last?.fraction && last.fraction === x.fraction) return
        this.#arr[++this.#index] = x
        this.#arr.length = this.#index + 1
        this.dispatchEvent(new Event('index-change'))
    }
    replaceState(x) {
        const index = this.#index
        this.#arr[index] = x
    }
    back() {
        const index = this.#index
        if (index <= 0) return
        const detail = { state: this.#arr[index - 1] }
        this.#index = index - 1
        this.dispatchEvent(new CustomEvent('popstate', { detail }))
        this.dispatchEvent(new Event('index-change'))
    }
    forward() {
        const index = this.#index
        if (index >= this.#arr.length - 1) return
        const detail = { state: this.#arr[index + 1] }
        this.#index = index + 1
        this.dispatchEvent(new CustomEvent('popstate', { detail }))
        this.dispatchEvent(new Event('index-change'))
    }
    get canGoBack() {
        return this.#index > 0
    }
    get canGoForward() {
        return this.#index < this.#arr.length - 1
    }
    clear() {
        this.#arr = []
        this.#index = -1
    }
}

const languageInfo = lang => {
    if (!lang) return {}
    try {
        const canonical = Intl.getCanonicalLocales(lang)[0]
        const locale = new Intl.Locale(canonical)
        const isCJK = ['zh', 'ja', 'kr'].includes(locale.language)
        const direction = (locale.getTextInfo?.() ?? locale.textInfo)?.direction
        return { canonical, locale, isCJK, direction }
    } catch (e) {
        console.warn(e)
        return {}
    }
}

export class View extends HTMLElement {
    #root = this.attachShadow({ mode: 'open' })
    #sectionProgress
    #tocProgress
    #pageProgress
    #searchResults = new Map()
    isFixedLayout = false
    lastLocation
    history = new History()
    constructor() {
        super()
        this.history.addEventListener('popstate', ({ detail }) => {
            const resolved = this.resolveNavigation(detail.state)
            this.renderer.goTo(resolved)
        })
    }
    async open(book) {
        this.book = book
        this.language = languageInfo(book.metadata?.language)

        if (book.splitTOCHref && book.getTOCFragment) {
            const ids = book.sections.map(s => s.id)
            this.#sectionProgress = new SectionProgress(book.sections, 1500, 1600)
            const splitHref = book.splitTOCHref.bind(book)
            const getFragment = book.getTOCFragment.bind(book)
            this.#tocProgress = new TOCProgress()
            await this.#tocProgress.init({
                toc: book.toc ?? [], ids, splitHref, getFragment })
            this.#pageProgress = new TOCProgress()
            await this.#pageProgress.init({
                toc: book.pageList ?? [], ids, splitHref, getFragment })
        }

        this.isFixedLayout = this.book.rendition?.layout === 'pre-paginated'
        if (this.isFixedLayout) {
            await import('./fixed-layout.js')
            this.renderer = document.createElement('foliate-fxl')
        } else {
            await import('./paginator.js')
            this.renderer = document.createElement('foliate-paginator')
        }
        this.renderer.setAttribute('exportparts', 'head,foot,filter')
        this.renderer.addEventListener('load', e => this.#onLoad(e.detail))
        this.renderer.addEventListener('relocate', e => this.#onRelocate(e.detail))
        this.renderer.addEventListener('create-overlayer', e =>
            e.detail.attach(this.#createOverlayer(e.detail)))
        this.renderer.open(book)
        this.#root.append(this.renderer)

        if (book.sections.some(section => section.mediaOverlay)) {
            book.media.activeClass ||= '-epub-media-overlay-active'
            const activeClass = book.media.activeClass
            this.mediaOverlay = book.getMediaOverlay()
            let lastActive
            this.mediaOverlay.addEventListener('highlight', e => {
                const resolved = this.resolveNavigation(e.detail.text)
                this.renderer.goTo(resolved)
                    .then(() => {
                        const { doc } = this.renderer.getContents()
                            .find(x => x.index = resolved.index)
                        const el = resolved.anchor(doc)
                        el.classList.add(activeClass)
                        lastActive = new WeakRef(el)
                    })
            })
            this.mediaOverlay.addEventListener('unhighlight', () => {
                lastActive?.deref()?.classList?.remove(activeClass)
            })
        }
    }
    close() {
        this.renderer?.destroy()
        this.renderer?.remove()
        this.#sectionProgress = null
        this.#tocProgress = null
        this.#pageProgress = null
        this.#searchResults = new Map()
        this.lastLocation = null
        this.history.clear()
        this.tts = null
        this.mediaOverlay = null
    }
    goToTextStart() {
        return this.goTo(this.book.landmarks
            ?.find(m => m.type.includes('bodymatter') || m.type.includes('text'))
            ?.href ?? this.book.sections.findIndex(s => s.linear !== 'no'))
    }
    async init({ lastLocation, showTextStart }) {
        const resolved = lastLocation ? this.resolveNavigation(lastLocation) : null
        if (resolved) {
            await this.renderer.goTo(resolved)
            this.history.pushState(lastLocation)
        }
        else if (showTextStart) await this.goToTextStart()
        else {
            this.history.pushState(0)
            await this.next()
        }
    }
    #emit(name, detail, cancelable) {
        return this.dispatchEvent(new CustomEvent(name, { detail, cancelable }))
    }
    #onRelocate({ reason, range, index, fraction, size }) {
        const progress = this.#sectionProgress?.getProgress(index, fraction, size) ?? {}
        const tocItem = this.#tocProgress?.getProgress(index, range)
        const pageItem = this.#pageProgress?.getProgress(index, range)
        const cfi = this.getCFI(index, range)
        this.lastLocation = { ...progress, tocItem, pageItem, cfi, range }
        if (reason === 'snap' || reason === 'page' || reason === 'scroll')
            this.history.replaceState(cfi)
        this.#emit('relocate', this.lastLocation)
    }
    #onLoad({ doc, index }) {
        // set language and dir if not already set
        doc.documentElement.lang ||= this.language.canonical ?? ''
        if (!this.language.isCJK)
            doc.documentElement.dir ||= this.language.direction ?? ''

        this.#handleLinks(doc, index)

        this.#emit('load', { doc, index })
    }
    #handleLinks(doc, index) {
        const { book } = this
        const section = book.sections[index]
        for (const a of doc.querySelectorAll('a[href]'))
            a.addEventListener('click', e => {
                e.preventDefault()
                const href_ = a.getAttribute('href')
                const href = section?.resolveHref?.(href_) ?? href_
                if (book?.isExternal?.(href))
                    Promise.resolve(this.#emit('external-link', { a, href }, true))
                        .then(x => x ? globalThis.open(href, '_blank') : null)
                        .catch(e => console.error(e))
                else Promise.resolve(this.#emit('link', { a, href }, true))
                    .then(x => x ? this.goTo(href) : null)
                    .catch(e => console.error(e))
            })
    }
    async addAnnotation(annotation, remove) {
        const { value } = annotation
        if (value.startsWith(SEARCH_PREFIX)) {
            const cfi = value.replace(SEARCH_PREFIX, '')
            const { index, anchor } = await this.resolveNavigation(cfi)
            const obj = this.#getOverlayer(index)
            if (obj) {
                const { overlayer, doc } = obj
                if (remove) {
                    overlayer.remove(value)
                    return
                }
                const range = doc ? anchor(doc) : anchor
                overlayer.add(value, range, Overlayer.outline)
            }
            return
        }
        const { index, anchor } = await this.resolveNavigation(value)
        const obj = this.#getOverlayer(index)
        if (obj) {
            const { overlayer, doc } = obj
            overlayer.remove(value)
            if (!remove) {
                const range = doc ? anchor(doc) : anchor
                const draw = (func, opts) => overlayer.add(value, range, func, opts)
                this.#emit('draw-annotation', { draw, annotation, doc, range })
            }
        }
        const label = this.#tocProgress.getProgress(index)?.label ?? ''
        return { index, label }
    }
    deleteAnnotation(annotation) {
        return this.addAnnotation(annotation, true)
    }
    #getOverlayer(index) {
        return this.renderer.getContents()
            .find(x => x.index === index && x.overlayer)
    }
    #createOverlayer({ doc, index }) {
        const overlayer = new Overlayer()
        doc.addEventListener('click', e => {
            const [value, range] = overlayer.hitTest(e)
            if (value && !value.startsWith(SEARCH_PREFIX)) {
                this.#emit('show-annotation', { value, index, range })
            }
        }, false)

        const list = this.#searchResults.get(index)
        if (list) for (const item of list) this.addAnnotation(item)

        this.#emit('create-overlay', { index })
        return overlayer
    }
    async showAnnotation(annotation) {
        const { value } = annotation
        const resolved = await this.goTo(value)
        if (resolved) {
            const { index, anchor } = resolved
            const { doc } =  this.#getOverlayer(index)
            const range = anchor(doc)
            this.#emit('show-annotation', { value, index, range })
        }
    }
    getCFI(index, range) {
        const baseCFI = this.book.sections[index].cfi ?? CFI.fake.fromIndex(index)
        if (!range) return baseCFI
        return CFI.joinIndir(baseCFI, CFI.fromRange(range))
    }
    resolveCFI(cfi) {
        if (this.book.resolveCFI)
            return this.book.resolveCFI(cfi)
        else {
            const parts = CFI.parse(cfi)
            const index = CFI.fake.toIndex((parts.parent ?? parts).shift())
            const anchor = doc => CFI.toRange(doc, parts)
            return { index, anchor }
        }
    }
    resolveNavigation(target) {
        try {
            if (typeof target === 'number') return { index: target }
            if (typeof target.fraction === 'number') {
                const [index, anchor] = this.#sectionProgress.getSection(target.fraction)
                return { index, anchor }
            }
            if (CFI.isCFI.test(target)) return this.resolveCFI(target)
            return this.book.resolveHref(target)
        } catch (e) {
            console.error(e)
            console.error(`Could not resolve target ${target}`)
        }
    }
    async goTo(target) {
        const resolved = this.resolveNavigation(target)
        try {
            await this.renderer.goTo(resolved)
            this.history.pushState(target)
            return resolved
        } catch(e) {
            console.error(e)
            console.error(`Could not go to ${target}`)
        }
    }
    async goToFraction(frac) {
        const [index, anchor] = this.#sectionProgress.getSection(frac)
        await this.renderer.goTo({ index, anchor })
        this.history.pushState({ fraction: frac })
    }
    async select(target) {
        try {
            const obj = await this.resolveNavigation(target)
            await this.renderer.goTo({ ...obj, select: true })
            this.history.pushState(target)
        } catch(e) {
            console.error(e)
            console.error(`Could not go to ${target}`)
        }
    }
    deselect() {
        for (const { doc } of this.renderer.getContents())
            doc.defaultView.getSelection().removeAllRanges()
    }
    getSectionFractions() {
        return (this.#sectionProgress?.sectionFractions ?? [])
            .map(x => x + Number.EPSILON)
    }
    getProgressOf(index, range) {
        const tocItem = this.#tocProgress?.getProgress(index, range)
        const pageItem = this.#pageProgress?.getProgress(index, range)
        return { tocItem, pageItem }
    }
    async getTOCItemOf(target) {
        try {
            const { index, anchor } = await this.resolveNavigation(target)
            const doc = await this.book.sections[index].createDocument()
            const frag = anchor(doc)
            const isRange = frag instanceof Range
            const range = isRange ? frag : doc.createRange()
            if (!isRange) range.selectNodeContents(frag)
            return this.#tocProgress.getProgress(index, range)
        } catch(e) {
            console.error(e)
            console.error(`Could not get ${target}`)
        }
    }
    async prev(distance) {
        await this.renderer.prev(distance)
    }
    async next(distance) {
        await this.renderer.next(distance)
    }
    goLeft() {
        return this.book.dir === 'rtl' ? this.next() : this.prev()
    }
    goRight() {
        return this.book.dir === 'rtl' ? this.prev() : this.next()
    }
    async * #searchSection(matcher, query, index) {
        const doc = await this.book.sections[index].createDocument()
        for (const { range, excerpt } of matcher(doc, query))
            yield { cfi: this.getCFI(index, range), excerpt }
    }
    async * #searchBook(matcher, query) {
        const { sections } = this.book
        for (const [index, { createDocument }] of sections.entries()) {
            if (!createDocument) continue
            const doc = await createDocument()
            const subitems = Array.from(matcher(doc, query), ({ range, excerpt }) =>
                ({ cfi: this.getCFI(index, range), excerpt }))
            const progress = (index + 1) / sections.length
            yield { progress }
            if (subitems.length) yield { index, subitems }
        }
    }
    async * search(opts) {
        this.clearSearch()
        const { searchMatcher } = await import('./search.js')
        const { query, index } = opts
        const matcher = searchMatcher(textWalker,
            { defaultLocale: this.language, ...opts })
        const iter = index != null
            ? this.#searchSection(matcher, query, index)
            : this.#searchBook(matcher, query)

        const list = []
        this.#searchResults.set(index, list)

        for await (const result of iter) {
            if (result.subitems){
                const list = result.subitems
                    .map(({ cfi }) => ({ value: SEARCH_PREFIX + cfi }))
                this.#searchResults.set(result.index, list)
                for (const item of list) this.addAnnotation(item)
                yield {
                    label: this.#tocProgress.getProgress(result.index)?.label ?? '',
                    subitems: result.subitems,
                }
            }
            else {
                if (result.cfi) {
                    const item = { value: SEARCH_PREFIX + result.cfi }
                    list.push(item)
                    this.addAnnotation(item)
                }
                yield result
            }
        }
        yield 'done'
    }
    clearSearch() {
        for (const list of this.#searchResults.values())
            for (const item of list) this.deleteAnnotation(item)
        this.#searchResults.clear()
    }
    async initTTS() {
        const doc = this.renderer.getContents()[0].doc
        if (this.tts && this.tts.doc === doc) return
        const { TTS } = await import('./tts.js')
        this.tts = new TTS(doc, textWalker, range =>
            this.renderer.scrollToAnchor(range, true))
    }
    startMediaOverlay() {
        const { index } = this.renderer.getContents()[0]
        return this.mediaOverlay.start(index)
    }
}

customElements.define('foliate-view', View)