import { setStyles, srtToVtt, vttToBlob, getExt } from './utils';
import assToVtt from './utils/assToVtt';

export default class Subtitle {
    constructor(art) {
        this.art = art;
        this.state = true;
        this.isInit = false;
        const { url } = this.art.option.subtitle;
        if (url) {
            this.init(url);
        }
    }

    get url() {
        const { $track } = this.art.template;
        if ($track) {
            return $track.src;
        }
        return '';
    }

    switch(url) {
        const { i18n, notice } = this.art;
        return this.init(url).then(blobUrl => {
            notice.show(i18n.get('Switch subtitle'));
            return blobUrl;
        });
    }

    init(url) {
        return new Promise(resolve => {
            const {
                events: { proxy },
                option: { subtitle },
                template: { $video, $subtitle, $track },
            } = this.art;

            setStyles($subtitle, subtitle.style || {});

            if (!$track) {
                const $newTrack = document.createElement('track');
                $newTrack.default = true;
                $newTrack.kind = 'metadata';
                $video.appendChild($newTrack);
                this.art.template.$track = $newTrack;
            }

            this.load(url).then(blobUrl => {
                $subtitle.innerHTML = '';
                const { $track } = this.art.template;
                const lastUrl = $track.src;
                if (lastUrl === blobUrl) return;
                URL.revokeObjectURL(lastUrl);
                $track.src = blobUrl;

                if ($video.textTracks && $video.textTracks[0]) {
                    const [track] = $video.textTracks;
                    // eslint-disable-next-line no-inner-declarations
                    function updateSubtitle() {
                        const [cue] = track.activeCues;
                        $subtitle.innerHTML = '';
                        if (cue) {
                            $subtitle.innerHTML = cue.text
                                .split(/\r?\n/)
                                .map(item => `<p>${item}</p>`)
                                .join('');
                        }
                        this.art.emit('subtitle:update', $subtitle);
                    }

                    if (!this.isInit) {
                        this.isInit = true;
                        proxy(track, 'cuechange', updateSubtitle.bind(this));
                    }

                    this.art.on('artplayerPluginSubtitleOffset', updateSubtitle.bind(this));
                }

                resolve(blobUrl);
            });
        });
    }

    load(url) {
        const { notice } = this.art;
        return fetch(url)
            .then(response => {
                return response.text();
            })
            .then(text => {
                switch (getExt(url)) {
                    case 'srt':
                        return vttToBlob(srtToVtt(text));
                    case 'ass':
                        return vttToBlob(assToVtt(text));
                    case 'vtt':
                        return vttToBlob(text);
                    default:
                        return url;
                }
            })
            .catch(err => {
                notice.show(err);
                throw err;
            });
    }

    set show(value) {
        const { $player } = this.art.template;
        if (value) {
            this.state = true;
            $player.classList.remove('artplayer-subtitle-hide');
            this.art.emit('subtitle:show');
        } else {
            this.state = false;
            $player.classList.add('artplayer-subtitle-hide');
            this.art.emit('subtitle:hide');
        }
    }

    toggle() {
        this.show = !this.state;
    }
}