// The manual.
//
// Panama's docs/ directory is engineering artifacts: design specs, plans, an
// upstream ledger. None of it is written for the person using the desktop,
// and the person using the desktop is the one with questions.
//
// So the manual is prose, in chapters, rendered here rather than opened in a
// browser. Keeping it in Settings means it is reachable from the same place
// as everything else it talks about, and a link to a settings page can just
// be a settings page -- see onLinkActivated below, where that stopped being a
// figure of speech.
//
// The chapter list and the chapter titles both come from ManualChapters, which
// reads each file's own first heading. This page used to carry a hand-written
// copy of those titles under a comment claiming they were read from the files.
//
// One Text per chapter, never the whole manual at once: Text has an implicit
// texture size limit, and a document long enough to hit it fails by going
// blank rather than by complaining.

import Quickshell
import Quickshell.Io
import QtQuick
import qs.config
import qs.services

SettingsPage {
    id: root

    title: "Manual"
    lede: "How this desktop works, for the person using it."

    readonly property var chapters: contents.titled

    property int current: 0

    // A deep link picks the chapter once and then lets go, so arriving at a
    // chapter does not pin you to it. Same consume-once idiom ShellState uses
    // for settings sections.
    Component.onCompleted: {
        const section = ShellState.takeSettingsSection();
        for (let index = 0; index < root.chapters.length; index++) {
            if (root.chapters[index].file.indexOf(section) >= 0 && section !== "") {
                root.current = index;
                break;
            }
        }
    }

    ManualChapters { id: contents }

    SettingsTabs {
        tabs: root.chapters.map((chapter, index) => ({
            value: String(index),
            label: chapter.title
        }))
        current: String(root.current)
        onSelected: value => root.current = parseInt(value, 10)
    }

    SettingsCard {
        FileView {
            id: chapterFile
            path: Quickshell.shellDir + "/manual/" + root.chapters[root.current].file
            printErrors: false
            onLoaded: body.text = this.text()
            onLoadFailed: body.text =
                "This chapter could not be read.\n\nIt should be at `"
                + chapterFile.path + "`."
        }

        Text {
            id: body

            width: parent.width
            textFormat: Text.MarkdownText
            wrapMode: Text.WordWrap
            color: Theme.fgDim
            linkColor: Theme.accent
            font.family: Theme.fontFamily
            font.pixelSize: Theme.fontSize
            // Markdown's own line height is tight for a wall of prose at this
            // size; a document read once needs to be easy on the first pass.
            lineHeight: 1.35

            // A link that names a settings page opens that page instead of a
            // browser, which is the whole reason the manual lives inside
            // Settings. Anything else -- a project URL, a wiki -- still leaves
            // the desktop.
            //
            // The scheme is Panama's own, so a chapter can never accidentally
            // hand an http link to openSettings, and an unknown page cannot be
            // smuggled in either: SettingsRoutes.resolve turns anything it does
            // not recognize into Home rather than a blank loader. A fragment,
            // where there is one, is the section within the page.
            onLinkActivated: link => {
                const target = String(link ?? "");
                const scheme = "panama://settings/";
                if (target.indexOf(scheme) !== 0) {
                    Qt.openUrlExternally(target);
                    return;
                }
                const rest = target.slice(scheme.length);
                const hash = rest.indexOf("#");
                if (hash < 0)
                    ShellState.openSettings(rest);
                else
                    ShellState.openSettingsSection(rest.slice(0, hash), rest.slice(hash + 1));
            }
        }
    }
}