pragma Singleton

// Snapshots of the settings store.
//
// The whole desktop configuration is one JSON file, so a backup is a copy and a
// restore is an overwrite. Worth exposing now that the settings app changes
// real things -- compositor geometry, idle timeouts, the dock -- because being
// able to return to a known-good state is what makes experimenting feel safe.
//
// Restoring rewrites the file underneath the running shell, so the store is
// told to re-read afterwards rather than waiting for the next change.

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

Singleton {
    id: root

    readonly property string helperPath: Quickshell.shellDir + "/scripts/panama-settings-backup"

    property var snapshots: []
    property string lastError: ""
    property string lastAction: ""

    readonly property bool busy: listQuery.running || actionRun.running

    Process {
        id: listQuery
        command: [root.helperPath, "list"]
        stdout: StdioCollector {
            onStreamFinished: {
                try {
                    const parsed = JSON.parse(this.text);
                    root.snapshots = Array.isArray(parsed) ? parsed : [];
                    root.lastError = "";
                } catch (error) {
                    root.lastError = "Could not read the list of snapshots.";
                }
            }
        }
    }

    Process {
        id: actionRun
        property bool restoring: false
        onExited: (exitCode, exitStatus) => {
            if (exitCode !== 0) {
                root.lastError = actionRun.restoring
                    ? "That snapshot could not be restored."
                    : "The settings could not be backed up.";
                return;
            }
            root.lastError = "";
            root.lastAction = actionRun.restoring ? "restored" : "saved";
            if (actionRun.restoring)
                DesktopPreferences.reload();
            root.refresh();
        }
    }

    Component.onCompleted: root.refresh()

    function refresh(): void {
        if (!listQuery.running)
            listQuery.running = true;
    }

    function save(): void {
        if (actionRun.running)
            return;
        actionRun.restoring = false;
        actionRun.exec([root.helperPath, "save"]);
    }

    // The name is matched against the snapshot list rather than trusted, so no
    // caller-supplied path reaches the helper even though it validates as well.
    function restore(name: string): bool {
        if (actionRun.running)
            return false;
        if (!root.snapshots.some(snapshot => snapshot.name === name)) {
            root.lastError = "That snapshot is not in the list.";
            return false;
        }
        actionRun.restoring = true;
        actionRun.exec([root.helperPath, "restore", name]);
        return true;
    }
}