import QtQuick 2.0
import Sailfish.Silica 1.0
import Sailfish.WebView 1.0
import harbour.calibreweb 1.0

Page {
    id: page

    property string epubPath: ""
    property int bookId: 0
    property string bookFormat: "epub"

    property int currentChapter: 0
    property double chapterFraction: 0.0
    property bool restoring: false
    property int saveCounter: 0
    property int syncCounter: 0
    property string errorMessage: ""

    allowedOrientations: Orientation.All

    EpubBook {
        id: book
    }

    SilicaFlickable {
        anchors.top: parent.top
        anchors.left: parent.left
        anchors.right: parent.right
        anchors.bottom: toolbar.top
        contentHeight: parent.height
        WebView {
            id: web
            anchors.fill: parent
            active: true
            onLoadedChanged: {
                if (!loaded)
                    return
                if (page.restoring)
                    page.restoring = false
                else
                    restorePosition()
                page.ready = true
            }
        }
    }

    BusyIndicator {
        anchors.centerIn: parent
        running: !page.ready
        size: BusyIndicatorSize.Large
    }

    Label {
        anchors.centerIn: parent
        text: page.errorMessage
        color: Theme.errorColor
        visible: page.errorMessage.length > 0
    }

    // ---- barra di controllo ----
    Rectangle {
        id: toolbar
        anchors.left: parent.left
        anchors.right: parent.right
        anchors.bottom: parent.bottom
        height: Theme.itemSizeMedium
        color: Theme.rgba(Theme.primaryColor, 0.08)

        IconButton {
            id: prevBtn
            anchors.left: parent.left
            anchors.verticalCenter: parent.verticalCenter
            icon.source: "image://theme/icon-m-left"
            enabled: page.currentChapter > 0
            onClicked: gotoChapter(page.currentChapter - 1)
        }

        Label {
            id: chapterLabel
            anchors.left: prevBtn.right
            anchors.right: nextBtn.left
            anchors.verticalCenter: parent.verticalCenter
            text: (book.chapterCount > 0)
                  ? (page.currentChapter + 1) + "/" + book.chapterCount
                    + " · " + book.chapterTitle(page.currentChapter)
                    + " · " + Math.round(page.overallProgress() * 100) + "%"
                  : "…"
            truncationMode: TruncationMode.Elide
            color: Theme.primaryColor
            horizontalAlignment: Text.AlignHCenter
            font.pixelSize: Theme.fontSizeSmall
        }

        IconButton {
            id: nextBtn
            anchors.right: parent.right
            anchors.verticalCenter: parent.verticalCenter
            icon.source: "image://theme/icon-m-right"
            enabled: page.currentChapter < book.chapterCount - 1
            onClicked: gotoChapter(page.currentChapter + 1)
        }

        ProgressBar {
            anchors.left: parent.left
            anchors.right: parent.right
            anchors.bottom: parent.bottom
            height: 6
            value: page.overallProgress()
            minimumValue: 0
            maximumValue: 1
        }
    }

    PullDownMenu {
        MenuItem {
            text: "Indice capitoli"
            onClicked: showChapterList()
        }
        MenuItem {
            text: "Aggiorna posizione sul server"
            onClicked: syncNow()
        }
    }

    // ---- timer di tracciamento ----
    Timer {
        id: trackTimer
        interval: 2000
        running: page.ready
        repeat: true
        onTriggered: readScrollPosition()
    }

    function overallProgress() {
        if (book.chapterCount <= 0)
            return 0
        return (page.currentChapter + page.chapterFraction) / book.chapterCount
    }

    function readScrollPosition() {
        if (!web.loaded)
            return
        web.runJavaScript(
            "window.scrollY / Math.max(1, document.documentElement.scrollHeight - window.innerHeight)",
            function(f) {
                var v = Math.max(0, Math.min(1, f))
                if (Math.abs(v - page.chapterFraction) > 0.005) {
                    page.chapterFraction = v
                    maybeSave(true)
                }
            })
    }

    function maybeSave(force) {
        if (bookId <= 0)
            return
        page.saveCounter++
        // salva locale ogni ~10 s, sync server ogni ~30 s
        if (force || page.saveCounter % 5 === 0) {
            appSettings.setBookmarkKey(page.bookId, page.bookFormat,
                                       book.makeBookmarkKey(page.currentChapter, page.chapterFraction))
        }
        if (force || page.syncCounter++ % 15 === 0)
            syncNow()
    }

    function syncNow() {
        if (bookId <= 0)
            return
        apiClient.postBookmark(page.bookId, page.bookFormat,
                               book.makeBookmarkKey(page.currentChapter, page.chapterFraction))
    }

    function gotoChapter(index) {
        if (index < 0 || index >= book.chapterCount)
            return
        if (index !== page.currentChapter) {
            maybeSave(true)
            page.chapterFraction = 0
        }
        page.currentChapter = index
        page.restoring = true
        page.ready = false
        web.url = "file://" + book.chapterFilePath(index)
    }

    function restorePosition() {
        if (page.chapterFraction > 0.01) {
            web.runJavaScript(
                "window.scrollTo(0, " + page.chapterFraction
                + " * Math.max(1, document.documentElement.scrollHeight - window.innerHeight)); true",
                function() { })
        }
    }

    function showChapterList() {
        var dialog = pageStack.push(Qt.resolvedUrl("ChapterListDialog.qml"),
                                    { model: book.chapterList() })
        dialog.accepted.connect(function() {
            gotoChapter(dialog.selectedIndex)
        })
    }

    Component.onCompleted: {
        page.ready = false
        if (!book.open(page.epubPath)) {
            page.errorMessage = "Impossibile aprire il libro EPUB"
            page.ready = true
            return
        }
        // ripristina il segno locale
        var key = appSettings.bookmarkKey(page.bookId, page.bookFormat)
        var ch = 0
        var fr = 0.0
        if (key.length > 0 && book.parseBookmarkKey(key, ch, fr)) {
            page.currentChapter = Math.max(0, Math.min(ch, book.chapterCount - 1))
            page.chapterFraction = fr
        }
        web.url = "file://" + book.chapterFilePath(page.currentChapter)
    }

    onStatusChanged: {
        if (status === PageStatus.Inactive)
            maybeSave(true)
    }
}