/*
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 */

const { GObject, Gio, GLib, Gtk, Gdk, WebKit2, Pango } = imports.gi
const {
    debug, Obj, formatPrice, base64ToPixbuf, markupEscape,
    linkIsRel, makeLinksButton, sepHeaderFunc, user_agent,
    promptAuthenticate, mimetypeCan,
    downloadWithWebKit, listDir, getFileInfoAsync
} = imports.utils
const { getSubjectAuthority } = imports.schemes
const { PropertiesBox, PropertiesWindow } = imports.properties
const { HdyColumn } = imports.handy
const { Window } = imports.window

const librarySettings = new Gio.Settings({ schema_id: pkg.name + '.library' })

const bookDir = [GLib.get_user_data_dir(), pkg.name, 'books']

class AcquisitionArea {
    constructor(options) {
        this.init(options)
    }
    init(options) {
        const { actionArea, entry, file, canUpdate, dialog, toplevel } = options
        this.actionArea = actionArea
        this.entry = entry
        this.file = file
        this.canUpdate = canUpdate
        this.dialog = dialog
        this.toplevel = toplevel || dialog
        this.downloadToken = {}
    }
    static async launchURI(x) {
        let type
        const isFile = x instanceof Gio.File
        if (isFile) {
            const info = await getFileInfoAsync(x)
            type = info.get_content_type()
        } else type = x.type

        if (mimetypeCan.open(type)) {
            const application = Gio.Application.get_default()
            const file = isFile ? x : Gio.File.new_for_uri(x.href)
            new Window({
                application,
                file,
                modal: true,
                transient_for: application.active_window
            }).present()
        } else {
            const uri = isFile ? x.get_uri() : x.href
            const appInfo = Gio.AppInfo.get_default_for_type(type, true)
            appInfo.launch_uris([uri], null)
        }
    }
    static getFileForId(id) {
        const path = GLib.build_filenamev(bookDir)
        const dir = Gio.File.new_for_path(path)
        for (const name of listDir(dir)) {
            let [fileId, lastUpdated] = name.split('@')
            fileId = decodeURIComponent(fileId)
            lastUpdated = decodeURIComponent(lastUpdated)
            if (fileId === id) return {
                file: dir.get_child(name),
                lastUpdated
            }
        }
    }
    static makeFileForId(id, updated, suggestedName) {
        const encodedId = [id, updated, suggestedName]
            .map(encodeURIComponent)
            .join('@')
        const path = GLib.build_filenamev(bookDir.concat(encodedId))
        return Gio.File.new_for_path(path)
    }
    static makeAcquisitionButton(links, onActivate, rel) {
        if (!rel) rel = links[0].rel.split('/').pop()
        let label = _('Download')
        let icon
        switch (rel) {
            case 'buy': label = _('Buy'); break
            case 'open-access': label = _('Free'); break
            case 'preview': label = _('Preview'); break
            case 'sample': label = _('Sample'); break
            case 'borrow': label = _('Borrow'); break
            case 'subscribe': label = _('Subscribe'); break
            case 'related alternate':
                label = _('More')
                icon = 'view-more-symbolic'
                break
        }
        if (rel !== 'related alternate' && links.length === 1) {
            const link = links[0]

            if (link.price) label = formatPrice(link.price)

            const { title } = link
            const { type, drm } = OpdsClient.getIndirectAcquisition(link)

            let button = new Gtk.Button({
                tooltip_text: title || Gio.content_type_get_description(type)
            })
            if (icon) {
                button.tooltip_text = label
                button.image = new Gtk.Image({
                    icon_name: icon
                })
            } else if (drm) {
                const buttonBox = new Gtk.Box({ spacing: 3 })
                const icon = new Gtk.Image({
                    icon_name: 'emblem-drm-symbolic',
                    tooltip_text: _('Protected by DRM')
                })
                buttonBox.pack_start(new Gtk.Label({ label }), true, true, 0)
                buttonBox.pack_end(icon, false, true, 0)
                button.add(buttonBox)
            } else {
                button.label = label
            }
            button.show_all()
            button.connect('clicked', () => onActivate(link))
            return button
        } else {
            const buttonLinks = links.map(link => {
                if (link instanceof Gtk.Widget) return link
                const { href } = link
                const { type, drm } = OpdsClient.getIndirectAcquisition(link)
                const price = link.price ? ' ' + formatPrice(link.price) : ''
                let title = (link.title || Gio.content_type_get_description(type))
                if (price) title += price
                if (drm) title += _(' (DRM)')
                return {
                    href, type, title,
                    tooltip: type
                }
            })
            const params = { visible: true, label }
            if (icon) {
                params.tooltip_text = label
                params.image = new Gtk.Image({
                    icon_name: icon
                })
            }
            const defaultLink = rel === 'related alternate' ? null : buttonLinks[0]
            const button = makeLinksButton(params, buttonLinks, onActivate, defaultLink)
            return button
        }
    }
    getRelatedLinks() {
        const { links = [] } = this.entry
        return links
            .filter(x => x.rel === 'alternate' || x.rel === 'related')
            .map(x => Object.assign({}, x, { rel: 'related alternate' }))
    }
    makeAcquisitionButtons() {
        const { links = [] } = this.entry
        const map = new Map()

        links.filter(x => x.rel.startsWith('http://opds-spec.org/acquisition'))
            .concat(this.getRelatedLinks())
            .forEach(x => {
                if (!map.has(x.rel)) map.set(x.rel, [x])
                else map.get(x.rel).push(x)
            })

        return Array.from(map.values()).map((links, i) => {
            const button = AcquisitionArea
                .makeAcquisitionButton(links, link => this.handleLink(link))

            if (i === 0) {
                if (button instanceof Gtk.Button)
                    button.get_style_context().add_class('suggested-action')
                else if (button.foreach) button.foreach(child =>
                    child.get_style_context().add_class('suggested-action'))
            }
            return button
        })
    }
    clearActionArea() {
        const actionArea = this.actionArea
        const children = actionArea.get_children()
        children.forEach(child => actionArea.remove(child))
        return actionArea
    }
    packOpenButtons() {
        const actionArea = this.clearActionArea()
        const open = new Gtk.Button({
            visible: true,
            label: _('Open')
        })
        open.connect('clicked', () => AcquisitionArea.launchURI(this.file))
        actionArea.add(open)
        if (this.canUpdate) {
            const update = new Gtk.Button({
                visible: true,
                tooltip_text: _('Update available'),
                label: _('Update')
            })
            update.connect('clicked', () => this.packAcquisitionButtons())
            actionArea.add(update)
        }

        const del = new Gtk.ModelButton({
            visible: true,
            text: _('Delete'),
        })
        del.connect('clicked', () => {
            const msg = new Gtk.MessageDialog({
                text: _('Delete this item?'),
                secondary_text:
                    _('If you delete this item, it will be permanently lost.'),
                message_type: Gtk.MessageType.QUESTION,
                modal: true,
                transient_for: this.toplevel
            })
            msg.add_button(_('Cancel'), Gtk.ResponseType.CANCEL)
            msg.add_button(_('Delete'), Gtk.ResponseType.ACCEPT)
            msg.set_default_response(Gtk.ResponseType.CANCEL)
            msg.get_widget_for_response(Gtk.ResponseType.ACCEPT)
                .get_style_context().add_class('destructive-action')
            const res = msg.run()
            msg.destroy()
            const accept = res === Gtk.ResponseType.ACCEPT
            if (accept) {
                this.file.delete(null)
                this.file = null
                this.packAcquisitionButtons()
            }
        })

        const relatedLinks = this.getRelatedLinks()
        const moreLinks = relatedLinks.length
            ? [del, new Gtk.Separator({ visible: true }), ...relatedLinks]
            : [del]

        const more = AcquisitionArea.makeAcquisitionButton(
            moreLinks,
            link => this.handleLink(link),
            'related alternate')
        actionArea.add(more)

        open.grab_focus()
    }
    packDownloading() {
        const actionArea = this.clearActionArea()
        const downloading = new Gtk.ProgressBar({
            visible: true,
            width_request: 100,
        })
        actionArea.add(downloading)
        return downloading
    }
    packError() {
        const actionArea = this.clearActionArea()
        const icon = new Gtk.Image({
            visible: true,
            icon_name: 'dialog-error-symbolic'
        })
        const label = new Gtk.Label({
            visible: true,
            wrap: true,
            xalign: 0,
            label: _('An error occurred.')
        })
        const button = new Gtk.Button({
            visible: true,
            label: _('OK')
        })
        button.connect('clicked', () => this.packAcquisitionButtons())
        icon.get_style_context().add_class('dim-label')
        label.get_style_context().add_class('dim-label')
        actionArea.add(icon)
        actionArea.add(label)
        actionArea.add(button)
    }
    packAcquisitionButtons() {
        const { id, updated } = this.entry

        if (!this.file && id) {
            const result = AcquisitionArea.getFileForId(id)
            if (result) {
                const { file, lastUpdated } = result
                this.file = file
                this.canUpdate = new Date(updated) > new Date(lastUpdated)
                this.packOpenButtons()
                return
            }
        }

        const actionArea = this.clearActionArea()
        const acquisitionButtons = this.makeAcquisitionButtons()

        if (this.file) {
            const back = new Gtk.Button({
                visible: true,
                tooltip_text: _('Go back'),
                image: new Gtk.Image({
                    visible: true,
                    icon_name: 'go-previous-symbolic'
                })
            })
            back.connect('clicked', () => this.packOpenButtons())
            actionArea.add(back)
        }

        acquisitionButtons.forEach(button => actionArea.add(button))
        if (acquisitionButtons.length) {
            const first =  acquisitionButtons[0]
            if (first instanceof Gtk.Button) first.grab_focus()
            else if (first.get_children) {
                const children = first.get_children()
                if (children.length) children[0].grab_focus()
            }
        }
    }
    handleLink({ type, href, rel }) {
        const canOpen = mimetypeCan.open(type)

        // open samples directly, in "ephemeral" mode
        if (canOpen && rel
        && (rel.endsWith('/sample') || rel.endsWith('/preview'))) {
            const application = Gio.Application.get_default()
            const file = Gio.File.new_for_uri(href)
            new Window({
                application,
                file,
                ephemeral: true,
                modal: true,
                transient_for: application.active_window
            }).present()
            return
        }

        // open OPDS feeds and entries in library window
        if (OpdsClient.typeIsOpds(type)) {
            if (this.dialog) this.dialog.close()
            window.getLibraryWindow().openCatalog(href)
            return
        }

        // open web pages in browser
        if (type === 'text/html' || type === 'application/xml+xhtml') {
            Gtk.show_uri_on_window(null, href, Gdk.CURRENT_TIME)
            return
        }

        const { id, updated } = this.entry

        const action = id && updated
            ? librarySettings.get_string('opds-action') : 'ask'

        if (action === 'ask') {
            const OPEN = 1
            const SAVE = 2
            const msg = new Gtk.MessageDialog({
                text: _('What would you like to do with this file?'),
                secondary_text: _('Format: %s')
                    .format(Gio.content_type_get_description(type)),
                message_type: Gtk.MessageType.QUESTION,
                modal: true,
                transient_for: this.toplevel
            })
            msg.add_button(_('Cancel'), Gtk.ResponseType.CANCEL)
            msg.add_button(_('Open'), OPEN)
            msg.add_button(_('Save'), SAVE)
            msg.set_default_response(SAVE)
            const res = msg.run()
            msg.destroy()

            if (res === OPEN) {
                AcquisitionArea.launchURI({ type, href })
                return true
            } else if (res !== SAVE) return true
        }

        let file
        const downloading = this.packDownloading()

        downloadWithWebKit(href, (download, suggestedName) => {
            if (!suggestedName) suggestedName = ''

            if (action === 'auto') {
                file = AcquisitionArea.makeFileForId(id, updated, suggestedName)
            } else {
                const chooser = new Gtk.FileChooserNative({
                    action: Gtk.FileChooserAction.SAVE,
                    transient_for: this.toplevel,
                    do_overwrite_confirmation: true,
                    create_folders: true,
                })
                chooser.set_current_name(suggestedName)
                if (chooser.run() !== Gtk.ResponseType.ACCEPT) {
                    download.cancel()
                    chooser.destroy()
                    return
                }
                file = chooser.get_file()
                chooser.destroy()
            }

            const mkdirp = GLib.mkdir_with_parents(
                file.get_parent().get_path(), parseInt('0755', 8))

            if (mkdirp !== 0) {
                download.cancel()
                return
            }
            return file.get_uri()
        },
        progress => downloading.fraction = progress,
        this.downloadToken,
        this.toplevel)
            .then(() => {
                if (this.file) this.file.delete(null)
                this.file = file
                this.canUpdate = false
                this.packOpenButtons()
                AcquisitionArea.launchURI(this.file)
            })
            .catch(err => {
                const code = WebKit2.DownloadError.CANCELLED_BY_USER
                if (err.code === code) this.packAcquisitionButtons()
                else this.packError()
            })
    }
}

const htmlPath = pkg.pkgdatadir + '/assets/client.html'
var OpdsClient = class OpdsClient {
    constructor(widget) {
        this._widget = widget
        this._promises = new Map()

        this._webView = new WebKit2.WebView({
            settings: new WebKit2.Settings({
                enable_write_console_messages_to_stdout: true,
                allow_universal_access_from_file_urls: true,
                user_agent
            })
        })
        this._webView.connect('authenticate', this._handleAuth.bind(this))

        const runResource = resource => new Promise((resolve) =>
            this._webView.run_javascript_from_gresource(resource, null, () => resolve()))
        const loadScripts = async () => {
            await runResource('/com/github/johnfactotum/Foliate/web/utils.js')
            await runResource('/com/github/johnfactotum/Foliate/web/opds.js')
        }
        this._webView.connect('load-changed', (webView, event) => {
            if (event == WebKit2.LoadEvent.FINISHED) loadScripts()
        })

        const contentManager = this._webView.get_user_content_manager()
        contentManager.connect('script-message-received::action', (_, jsResult) => {
            const data = jsResult.get_js_value().to_string()
            const { type, payload, token } = JSON.parse(data)
            this._handleAction(type, payload, token)
        })
        contentManager.register_script_message_handler('action')
        this._webView.load_uri(GLib.filename_to_uri(htmlPath, null))
        this._webView.connect('destroy', () => {
            Array.from(this._promises.values()).forEach(({ reject }) =>
                reject(new Error('OPDS: WebView destroyed')))
        })
    }
    _handleAction(type, payload, token) {
        switch (type) {
            case 'ready':
                this._promises.get('ready').resolve()
                break
            case 'error':
                this._promises.get(token).reject(new Error(payload))
                break
            case 'opensearch':
            case 'entry':
            case 'feed': {
                this._promises.get(token).resolve(payload)
                break
            }
            case 'image': {
                const pixbuf = base64ToPixbuf(payload)
                this._promises.get(token).resolve(pixbuf)
                break
            }
            case 'auth': {
                const { username, password } = payload
                this.username = username
                this.password = password
            }
        }
    }
    _run(script) {
        this._webView.run_javascript(script, null, () => {})
    }
    init() {
        return this._makePromise('ready')
    }
    get(uri) {
        debug('OPDS: getting ' + uri)
        const token = this._makeToken()
        this._run(`getFeed(
            decodeURI("${encodeURI(uri)}"),
            decodeURI("${encodeURI(token)}"))`)
        return this._makePromise(token)
    }
    getImage(uri) {
        const token = this._makeToken()
        this._run(`getImage(
            decodeURI("${encodeURI(uri)}"),
            decodeURI("${encodeURI(token)}"))`)
        return this._makePromise(token)
    }
    getOpenSearch(query, uri) {
        const token = this._makeToken()
        this._run(`getOpenSearch(
            "${encodeURIComponent(query)}",
            decodeURI("${encodeURI(uri)}"),
            decodeURI("${encodeURI(token)}"))`)
        return this._makePromise(token)
    }
    _makePromise(token) {
        return new Promise((resolve, reject) =>
            this._promises.set(token, {
                resolve: arg => {
                    resolve(arg)
                    this._promises.delete(token)
                },
                reject: arg => {
                    reject(arg)
                    this._promises.delete(token)
                }
            }))
    }
    _makeToken() {
        return Math.random() + '' + new Date().getTime()
    }
    close() {
        this._webView.destroy()
    }
    _handleAuth(webView, req) {
        const widget = this._widget
        const toplevel = widget instanceof Gtk.Widget
            ? widget.get_toplevel() : null
        return promptAuthenticate(req, this.username, this.password, toplevel)
    }
    static opdsEntryToMetadata(entry, showSummary = true) {
        const {
            title, summary, content, publisher, language, identifiers, rights,
            published, updated, issued, extent,
            authors = [],
            categories = [],
            sources = [],
        } = entry
        return {
            title, publisher, language, identifiers, rights,
            // Translators: this is the punctuation used to join together a list of
            // authors or categories
            creator: authors.map(x => x.name).join(_(', ')),
            categories: categories.map(x => {
                const authority = getSubjectAuthority(x.scheme)
                if (authority) x.authority = authority.key
                return x
            }),
            sources,
            description: showSummary ? summary : content || summary,
            longDescription: showSummary ? content : '',
            pubdate: issued || published,
            modified_date: updated,
            extent
        }
    }
    static isAcquisitionFeed(feed) {
        return feed.entries && feed.entries.some(OpdsClient.isCatalogEntry)
    }
    static isCatalogEntry(entry) {
        return entry.links
            && entry.links.some(link =>
                linkIsRel(link, rel =>
                    rel.startsWith('http://opds-spec.org/acquisition')))
    }
    static typeIsOpds(type) {
        // should probably check "profile=opds-catalog" too/instead
        return type.includes('application/atom+xml')
    }
    static getIndirectAcquisition(link) {
        const types = [link.type]
        while ('indirectAcquisition' in link) {
            link = link.indirectAcquisition
            types.push(link.type)
        }
        return {
            types,
            type: types[types.length - 1],
            drm: types.includes('application/vnd.adobe.adept+xml')
        }
    }
    static getImageLink(entry) {
        // many feeds provide very tiny thumbnails so we have to prefer non-
        // thumbnails otherwise things are just too small/blurry
        const rels = [
            'http://opds-spec.org/image',
            'http://opds-spec.org/cover',
            'http://opds-spec.org/image/thumbnail',
            'http://opds-spec.org/thumbnail',
        ]
        for (const rel of rels) {
            const link = entry.links.find(x => linkIsRel(x, rel))
            if (link) return link
        }
    }
    static getOpdsLink(entry) {
        return entry.links.find(link => OpdsClient.typeIsOpds(link.type)) || entry.links[0]
    }
}

var LoadBox = GObject.registerClass({
    GTypeName: 'FoliateLoadBox'
}, class LoadBox extends Gtk.Stack {
    _init(params, load) {
        super._init(params)
        this.transition_type = Gtk.StackTransitionType.CROSSFADE
        this._load = load

        this._buildLoading()
        this._buildError()

        let loaded
        this.connect('realize', () => {
            if (loaded) return
            loaded = true
            this._loadWidget()
        })
    }
    _buildLoading() {
        const spinner = new Gtk.Spinner({
            visible: true,
            active: true,
            valign: Gtk.Align.CENTER,
            halign: Gtk.Align.CENTER,
            width_request: 64,
            height_request: 64
        })
        this.add_named(spinner, 'loading')
    }
    _buildError() {
        const error = new Gtk.Label({
            visible: true,
            wrap: true,
            label: _('Unable to load OPDS feed')
        })
        error.get_style_context().add_class('dim-label')
        const reload = new Gtk.Button({
            visible: true,
            label: _('Reload'),
            halign: Gtk.Align.CENTER
        })
        reload.connect('clicked', () => this._loadWidget())
        const errorBox = new Gtk.Box({
            visible: true,
            orientation: Gtk.Orientation.VERTICAL,
            spacing: 12,
            valign: Gtk.Align.CENTER
        })
        errorBox.pack_start(error, false, true, 0)
        errorBox.pack_start(reload, false, true, 0)
        this.add_named(errorBox, 'error')
    }
    _loadWidget() {
        this.visible_child_name = 'loading'
        const widget = this._load()
        this.add_named(widget, 'loaded')
        widget.connect('loaded', () => {
            this.visible_child_name = 'loaded'
        })
        widget.connect('error', () => {
            this.visible_child_name = 'error'
        })
    }
})

var OpdsFullEntryBox =  GObject.registerClass({
    GTypeName: 'FoliateOpdsFullEntryBox',
}, class OpdsFullEntryBox extends Gtk.Box {
    _init(params) {
        super._init(params)
        this.orientation = Gtk.Orientation.VERTICAL
    }
    async load(entry) {
        let pixbuf
        const client = new OpdsClient(this)
        await client.init()
        try {
            const thumbnail = OpdsClient.getImageLink(entry)
            if (thumbnail) pixbuf = await client.getImage(thumbnail.href)
        } finally {
            client.close()
        }

        const propertiesBox = new PropertiesBox({
            visible: true,
            border_width: 12
        }, OpdsClient.opdsEntryToMetadata(entry, false), pixbuf)
        this.pack_start(propertiesBox, true, true, 0)

        const actionArea = propertiesBox.actionArea
        const toplevel = this.get_toplevel()
        const aa = new AcquisitionArea({ entry, actionArea, toplevel })
        aa.packAcquisitionButtons()
    }
})

var OpdsFeed = GObject.registerClass({
    GTypeName: 'FoliateOpdsFeed',
    Properties: {
        uri: GObject.ParamSpec.string('uri', 'uri', 'uri',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY, ''),
    },
    Signals: {
        'loaded': { flags: GObject.SignalFlags.RUN_FIRST },
        'error': { flags: GObject.SignalFlags.RUN_FIRST },
    }
}, class OpdsFeed extends Gtk.Bin {
    _init(params) {
        super._init(params)
        if (this.uri) {
            const client = new OpdsClient(this)
            client.init()
                .then(() => client.get(this.uri))
                .then(feed => {
                    this.feed = feed
                    this.emit('loaded')
                })
                .catch(e => {
                    logError(e)
                    this.emit('error')
                })
                .then(() => client.close())
        }
    }
})

const OpdsBoxChild =  GObject.registerClass({
    GTypeName: 'FoliateOpdsBoxChild',
    Template: 'resource:///com/github/johnfactotum/Foliate/ui/opdsBoxChild.ui',
    InternalChildren: [
        'image', 'title'
    ],
    Properties: {
        entry: GObject.ParamSpec.object('entry', 'entry', 'entry',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY, Obj.$gtype),
    }
}, class OpdsBoxChild extends Gtk.FlowBoxChild {
    _init(params) {
        super._init(params)
        const { title } = this.entry.value
        this._title.label = title
        this._coverLoaded = false
    }
    loadCover(pixbuf) {
        this._image.load(pixbuf)
        this._coverLoaded = true
    }
    generateCover() {
        const entry = this.entry.value
        const metadata = OpdsClient.opdsEntryToMetadata(entry)
        if (!OpdsClient.isCatalogEntry(entry) && !metadata.creator) {
            metadata.creator = entry.content
        }
        this._image.generate(metadata)
    }
    get image() {
        return this._image
    }
    get surface() {
        return this._coverLoaded ? this._image.surface : null
    }
})

var OpdsAcquisitionBox = GObject.registerClass({
    GTypeName: 'FoliateOpdsAcquisitionBox',
    Properties: {
        'max-entries':
            GObject.ParamSpec.int('max-entries', 'max-entries', 'max-entries',
                GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT, 0, 2147483647, 0),
    },
    Signals: {
        'loaded': { flags: GObject.SignalFlags.RUN_FIRST },
        'error': { flags: GObject.SignalFlags.RUN_FIRST },
        'image-draw': { flags: GObject.SignalFlags.RUN_FIRST },
        'link-activated': {
            flags: GObject.SignalFlags.RUN_FIRST,
            param_types: [GObject.TYPE_STRING, GObject.TYPE_STRING]
        },
    }
}, class OpdsAcquisitionBox extends Gtk.FlowBox {
    _init(params, sort) {
        super._init(Object.assign({
            valign: Gtk.Align.START,
            row_spacing: 12,
            column_spacing: 12,
            homogeneous: true,
            activate_on_single_click: true,
            selection_mode: Gtk.SelectionMode.NONE
        }, params))
        this.sort = sort

        this.connect('child-activated', this._onChildActivated.bind(this))
    }
    _onChildActivated(flowbox, child) {
        const toplevel = this.get_toplevel()

        const entry = child.entry.value
        if (!OpdsClient.isCatalogEntry(entry)) {
            const { href, type } = OpdsClient.getOpdsLink(entry)
            this.emit('link-activated', href, type)
            return
        }

        const getTitle = child => {
            const index = child.get_index()
            const total = flowbox.get_children().length
            return _('%d of %d').format(index + 1, total)
        }

        const surface = child.surface
        const dialog = new PropertiesWindow({
            modal: true,
            use_header_bar: true,
            transient_for: toplevel
        }, OpdsClient.opdsEntryToMetadata(entry), surface)

        dialog.title = getTitle(child)

        const actionArea = dialog.propertiesBox.actionArea
        const aa = new AcquisitionArea({ dialog, entry, actionArea })
        aa.packAcquisitionButtons()

        const getPrevNext = child => {
            const index = child.get_index()
            const prev = flowbox.get_child_at_index(index - 1)
            const next = flowbox.get_child_at_index(index + 1)
            return [prev, next]
        }

        const buildButton = (child, i) => {
            if (!child) return

            const entry = child.entry.value
            if (!OpdsClient.isCatalogEntry(entry)) return

            const isPrev = i === 0
            const callback = isPrev => {
                dialog.clearButtons()
                const name = dialog.updateProperties(
                    OpdsClient.opdsEntryToMetadata(entry),
                    child.surface)
                dialog.title = getTitle(child)

                if (aa.downloadToken.cancel) aa.downloadToken.cancel()
                const actionArea = dialog.propertiesBox.actionArea
                aa.init({ dialog, entry, actionArea })
                aa.packAcquisitionButtons()

                getPrevNext(child).forEach(buildButton)
                dialog.setVisible(name, isPrev)
            }
            dialog.packButton(isPrev, callback)
        }
        getPrevNext(child).forEach(buildButton)

        dialog.connect('destroy', () => {
            if (aa.downloadToken.cancel) aa.downloadToken.cancel()
        })
        dialog.run()
        dialog.close()
    }
    async load(entries) {
        this.emit('loaded')
        if (!entries) return // TODO: empty placeholder
        let loadCount = 0
        const client = new OpdsClient(this)
        await client.init()
        const list = new Gio.ListStore()
        if (this.sort) entries = this.sort(entries.slice(0))
        if (this.max_entries) entries = entries.slice(0, this.max_entries)
        entries.forEach(entry => list.append(new Obj(entry)))
        this.bind_model(list, entry => {
            const child = new OpdsBoxChild({ entry })
            const thumbnail = OpdsClient.getImageLink(entry.value)
            child.image.connect('draw', () => this.emit('image-draw'))
            child.image.connect('realize', () => {
                if (thumbnail)
                    client.getImage(thumbnail.href)
                        .then(pixbuf => child.loadCover(pixbuf))
                        .catch(() => child.generateCover())
                        .then(() => {
                            loadCount++
                            if (loadCount === entries.length) client.close()
                        })
                else {
                    child.generateCover()
                    loadCount++
                    if (loadCount === entries.length) client.close()
                }
            })
            return child
        })
    }
    error(e) {
        logError(e)
        this.emit('error')
    }
})

const NavigationRow =  GObject.registerClass({
    GTypeName: 'FoliateNavigationRow',
    Template: 'resource:///com/github/johnfactotum/Foliate/ui/navigationRow.ui',
    InternalChildren: ['title', 'content', 'count', 'select'],
    Properties: {
        entry: GObject.ParamSpec.object('entry', 'entry', 'entry',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY, Obj.$gtype),
    }
}, class NavigationRow extends Gtk.ListBoxRow {
    _init(params) {
        super._init(params)
        const { title, content, links } = this.entry.value
        this._title.label = title || ''
        if (content) this._content.label = content
        else this._content.hide()

        const count = links[0].count
        if (typeof count === 'string') this._count.label = count
        else this._count.hide()

        const activeFacet = links[0].activeFacet
        if (activeFacet) this._select.show()
    }
})

var OpdsNavigationBox = GObject.registerClass({
    GTypeName: 'FoliateOpdsNavigationBox',
    Properties: {
        facet: GObject.ParamSpec.boolean('facet', 'facet', 'facet',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY, false),
    },
    Signals: {
        'loaded': { flags: GObject.SignalFlags.RUN_FIRST },
        'error': { flags: GObject.SignalFlags.RUN_FIRST },
        'link-activated': {
            flags: GObject.SignalFlags.RUN_FIRST,
            param_types: [GObject.TYPE_STRING, GObject.TYPE_STRING]
        },
    }
}, class OpdsNavigationBox extends Gtk.ListBox {
    _init(params) {
        super._init(params)
        this.get_style_context().add_class('frame')

        this._map = new Map()

        this.connect('row-activated', (listbox, row) => {
            const entry = this._map.get(row).value
            const { href, type } = OpdsClient.getOpdsLink(entry)
            this.emit('link-activated', href, type)
        })

        if (this.facet) {
            let lastGroup
            this.set_header_func(row => {
                const index = row.get_index()
                const entry = this._map.get(row).value
                const group = entry.links[0].facetGroup
                if (group && group !== lastGroup) {
                    const box = new Gtk.Box({
                        orientation: Gtk.Orientation.VERTICAL,
                    })
                    if (index) box.pack_start(new Gtk.Separator(), false, true, 0)
                    const label = new Gtk.Label({
                        label: `<b>${markupEscape(group)}</b>`,
                        margin_top: index ? 18 : 6,
                        margin_bottom: 6,
                        margin_start: 6,
                        margin_end: 6,
                        use_markup: true,
                        justify: Gtk.Justification.CENTER,
                        ellipsize: Pango.EllipsizeMode.END,
                    })
                    label.get_style_context().add_class('dim-label')
                    box.pack_start(label, false, true, 0)
                    box.pack_start(new Gtk.Separator(), false, true, 0)
                    box.show_all()
                    row.set_header(box)
                } else if (index) row.set_header(new Gtk.Separator())
                lastGroup = group
            })
        } else this.set_header_func(sepHeaderFunc)
    }
    load(entries) {
        this.emit('loaded')
        if (!entries) return // TODO: empty placeholder
        const list = new Gio.ListStore()
        entries.forEach(entry => list.append(new Obj(entry)))
        this.bind_model(list, entry => {
            const row = new NavigationRow({ entry })
            this._map.set(row, entry)
            return row
        })
    }
    error(e) {
        logError(e)
        this.emit('error')
    }
})

var OpdsBox = GObject.registerClass({
    GTypeName: 'FoliateOpdsBox',
    Properties: {
        uri: GObject.ParamSpec.string('uri', 'uri', 'uri',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT_ONLY, ''),
    },
    Signals: {
        'loaded': { flags: GObject.SignalFlags.RUN_FIRST },
        'error': { flags: GObject.SignalFlags.RUN_FIRST },
    }
}, class OpdsBox extends Gtk.Bin {
    _init(params) {
        super._init(params)
        if (this.uri) {
            const client = new OpdsClient(this)
            client.init()
                .then(() => client.get(this.uri))
                .then(this.load.bind(this))
                .catch(this.error.bind(this))
                .then(() => client.close())
        }
    }
    load(feed) {
        this.feed = feed
        const opdsbox = feed.isEntry
            ? new OpdsFullEntryBox({ visible: true, margin: 18 })
            : OpdsClient.isAcquisitionFeed(feed)
                ? new OpdsAcquisitionBox({ visible: true, margin: 18 })
                : new OpdsNavigationBox({ visible: true, margin: 18 })
        if (feed.isEntry) opdsbox.load(feed)
        else opdsbox.load(feed.entries)
        this.add(opdsbox)
        this.emit('loaded')
    }
    error(e) {
        logError(e)
        this.emit('error')
    }
})

const defaultTitle = _('OPDS Catalog')

var OpdsBrowser = GObject.registerClass({
    GTypeName: 'FoliateOpdsBrowser',
    Properties: {
        title: GObject.ParamSpec.string('title', 'title', 'title',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT, defaultTitle),
        subtitle: GObject.ParamSpec.string('subtitle', 'subtitle', 'subtitle',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT, ''),
        searchable: GObject.ParamSpec.boolean('searchable', 'searchable', 'searchable',
            GObject.ParamFlags.READWRITE | GObject.ParamFlags.CONSTRUCT, false),
    }
}, class OpdsBrowser extends Gtk.Box {
    _init(params) {
        super._init(params)

        this.actionGroup = new Gio.SimpleActionGroup()
        const actions = {
            'back': () => this._goBack(),
            'home': () => this._goHome(),
            'reload': () => this._loadOpds(this._uri),
            'location': () => this.showLocationDialog()
        }
        Object.keys(actions).forEach(name => {
            const action = new Gio.SimpleAction({ name })
            action.connect('activate', actions[name])
            this.actionGroup.add_action(action)
        })
        this.reset()
    }
    getCatalog() {
        return {
            title: this.title,
            uri: this._home || this._uri,
            preview: this._uri
        }
    }
    reset() {
        if (this._opdsWidget) this._opdsWidget.destroy()
        this._uri = null
        this._history = []
        this._searchLink = null
        this._updateBack()
        this._home = null
    }
    search(text) {
        if (!this._searchLink) return
        const query = text.trim()
        if (!query) return

        this._opdsWidget.destroy()
        this._opdsWidget = new Gtk.Spinner({
            visible: true,
            active: true,
            valign: Gtk.Align.CENTER,
            halign: Gtk.Align.CENTER,
            width_request: 48,
            height_request: 48
        })
        this.pack_start(this._opdsWidget, true, true, 0)

        const client = new OpdsClient(this)
        client.init()
            .then(() => client.getOpenSearch(query, this._searchLink.href))
            .then(uri => this.loadOpds(uri))
            .catch(e => logError(e))
            .then(() => client.close())
    }
    _updateBack() {
        this.actionGroup.lookup_action('back').enabled = this._history.length
    }
    _goBack() {
        if (!this._history.length) return
        this._loadOpds(this._history.pop())
        this._updateBack()
    }
    _pushHistory(x) {
        if (!x) return
        this._history.push(x)
        this._updateBack()
    }
    _clearHistory() {
        this._history = []
        this._updateBack()
    }
    get _home() {
        return this.__home
    }
    set _home(home) {
        this.__home = home
        this.actionGroup.lookup_action('home').enabled = home && home !== this._uri
    }
    _goHome() {
        if (!this._home) return
        this.loadOpds(this._home)
    }
    showLocationDialog() {
        const top = this.get_toplevel()
        const width = top.get_size()[0]
        const window = new Gtk.Dialog({
            title: _('OPDS URL'),
            modal: true,
            use_header_bar: true,
            transient_for: top,
            default_width: Math.min(500, width * 0.95)
        })
        window.add_button(_('Cancel'), Gtk.ResponseType.CANCEL)
        window.add_button(_('Go'), Gtk.ResponseType.ACCEPT)
        window.set_default_response(Gtk.ResponseType.ACCEPT)

        const entry =  new Gtk.Entry({ text: this._uri })
        entry.connect('activate', () =>
            window.response(Gtk.ResponseType.ACCEPT))

        const container = window.get_content_area()
        container.border_width = 18
        container.pack_start(entry, false, true, 0)
        window.show_all()
        const response = window.run()
        if (response === Gtk.ResponseType.ACCEPT) this.loadOpds(entry.text)
        window.close()
    }
    loadOpds(uri) {
        this._pushHistory(this._uri)
        this._loadOpds(uri).catch(e => logError(e))
    }
    async _loadOpds(uri) {
        this.set_property('title', _('Loading…'))
        this.set_property('subtitle', '')

        this._uri = uri
        if (this._opdsWidget) this._opdsWidget.destroy()

        const handleLink = (href, type) => {
            if (OpdsClient.typeIsOpds(type)) this.loadOpds(href)
            else Gtk.show_uri_on_window(null, href, Gdk.CURRENT_TIME)
        }

        const nb = new Gtk.Notebook({
            visible: true,
            scrollable: true,
            show_border: false
        })
        const updateShowTabs = () => nb.show_tabs = nb.get_n_pages() > 1
        nb.connect('page-added', updateShowTabs)
        nb.connect('page-removed', updateShowTabs)
        this._opdsWidget = nb
        this.pack_start(nb, true, true, 0)

        const makePage = (uri, title, top) => new Promise((resolve, reject) => {
            const label = new Gtk.Label({
                visible: true,
                ellipsize: Pango.EllipsizeMode.END,
                label: title || _('Loading…'),
                tooltip_text: title || null,
                width_chars: 10,
            })

            const column = new HdyColumn({
                visible: true,
                maximum_width: 2000,
                linear_growth_width: 2000
            })
            const box = new Gtk.Box({
                visible: true,
                orientation: Gtk.Orientation.VERTICAL
            })

            const loadbox = new LoadBox({
                visible: true,
                expand: true
            }, () => {
                const widget = new OpdsBox({
                    visible: true,
                    valign: Gtk.Align.START,
                    uri
                })
                widget.connect('loaded', () => {
                    if (top && this._uri !== uri) return reject()

                    const feed = widget.feed
                    if (!title) {
                        const title = feed.title || ''
                        label.label = title
                        label.tooltip_text = title
                    }

                    const buttonBox = new Gtk.Box({
                        visible: true,
                        margin: 18,
                        halign: Gtk.Align.CENTER
                    })
                    buttonBox.get_style_context().add_class('linked')
                    box.pack_end(buttonBox, false, true, 0)

                    const paginationRels = {
                        first: { icon: 'go-first-symbolic', label: _('First') },
                        previous: { icon: 'go-previous-symbolic', label: _('Previous') },
                        next: { icon: 'go-next-symbolic', label: _('Next') },
                        last: { icon: 'go-last-symbolic', label: _('Last') }
                    }
                    Object.keys(paginationRels).forEach(rel => {
                        const link = feed.links.find(link => 'href' in link && linkIsRel(link, rel))
                        if (!link) return
                        const icon_name = paginationRels[rel].icon
                        const label = paginationRels[rel].label
                        const paginationBtton = new Gtk.Button({
                            visible: true,
                            hexpand: true,
                            image: new Gtk.Image({ visible: true, icon_name }),
                            tooltip_text: label
                        })
                        paginationBtton.connect('clicked', () => this.loadOpds(link.href))
                        buttonBox.pack_start(paginationBtton, false, true, 0)
                    })

                    const opdsbox = widget.get_child()
                    if (opdsbox instanceof OpdsFullEntryBox) {
                        column.maximum_width = 600
                    } else {
                        opdsbox.connect('link-activated', (_, href, type) => {
                            handleLink(href, type)
                        })
                    }
                    if (opdsbox instanceof OpdsNavigationBox) {
                        column.maximum_width = 600
                    }

                    resolve(feed)
                })
                widget.connect('error', () => {
                    if (top && this._uri !== uri) return reject()
                    if (!title) label.label = _('Error')
                    reject(new Error())
                })
                return widget
            })
            box.pack_start(loadbox, false, true, 0)
            column.add(box)

            const scrolled = new Gtk.ScrolledWindow({ visible: true })
            scrolled.add(column)
            nb.append_page(scrolled, label)
            nb.child_set_property(scrolled, 'tab-expand', true)
        })

        const related = {
            'related': _('Related'),
            'section': _('Section'),
            'subsection': _('Subsection'),
            'http://opds-spec.org/sort/new': _('New'),
            'http://opds-spec.org/sort/popular': _('Popular'),
            'http://opds-spec.org/featured': _('Featured'),
            'http://opds-spec.org/recommended': _('Recommended')
        }

        makePage(uri, null, true).then(feed => {
            if (feed.title) this.set_property('title', feed.title)
            if (feed.subtitle) this.set_property('subtitle', feed.subtitle)
            const tabs = [].concat(feed.links).filter(link => 'href' in link
                && 'type' in link
                && OpdsClient.typeIsOpds(link.type)
                && 'rel' in link
                && Object.keys(related).some(rel => linkIsRel(link, rel)))

            tabs.forEach(({ title, href, rel }) => {
                makePage(href, title || related[rel])
            })

            const home = feed.links.find(link => linkIsRel(link, 'start'))
            if (home) this._home = home.href

            const facets = feed.links.filter(link => linkIsRel(link, 'http://opds-spec.org/facet'))
            if (facets.length) {
                const opdsbox = new OpdsNavigationBox({
                    visible: true,
                    facet: true,
                    margin: 18,
                    valign: Gtk.Align.START
                })
                opdsbox.load(facets.map(facet => ({
                    title: facet.title,
                    links: [facet]
                })))
                opdsbox.connect('link-activated', (_, href, type) => {
                    handleLink(href, type)
                })

                const label = new Gtk.Label({
                    visible: true,
                    label: _('Filter'),
                })
                const box = new HdyColumn({ visible: true, maximum_width: 700 })
                box.add(opdsbox)
                const scrolled = new Gtk.ScrolledWindow({ visible: true })
                scrolled.add(box)
                nb.insert_page(scrolled, label, 0)
            }

            const search = feed.links.find(link => linkIsRel(link, 'search'))
            this._searchLink = search
            this.set_property('searchable', Boolean(search))
        }).catch(e => {
            if (e) this.set_property('title', _('Error'))
        })
    }
})
