extension.ts

import * as vscode from "vscode";

const EXTN_QUALIFIER = 'go-to-character-position';
const COMMANDS = Object.seal({
    go_to_character_position: `${EXTN_QUALIFIER }.go-to-character-position`
})

let cachedInput : any = undefined;
let statusbar : vscode.StatusBarItem;
let indexing: string = getEnumConfiguration('defaultIndex', 'zero based', ['zero based', 'one based']);

/**
 * @param {vscode.ExtensionContext} context
 */
export function activate(context: vscode.ExtensionContext) {

    console.log('"go-to-character-position" is active');

    context.subscriptions.push(
        statusbar,

        vscode.window.onDidChangeTextEditorSelection(updateStatusBarItem),

        vscode.workspace.onDidChangeConfiguration((e: vscode.ConfigurationChangeEvent) => {
            if (e.affectsConfiguration(`${EXTN_QUALIFIER}.defaultIndex`))
                indexing = getEnumConfiguration('defaultIndex', 'zero based', ['zero based', 'one based']);

            if (e.affectsConfiguration(`${EXTN_QUALIFIER}.statusbar`))
                updateStatusBarItemPriority(getConfiguration(`statusbar.priority`, 101));
        }),

        vscode.commands.registerTextEditorCommand(COMMANDS.go_to_character_position, async function (editor) {
            const indexing = getEnumConfiguration('defaultIndex', 'zero based', ['zero based', 'one based']);

            const input = await vscode.window.showInputBox({
                ignoreFocusOut: true,
                prompt: `Your current index setting is ${indexing} and there are ${new Intl.NumberFormat().format(editor.document.getText().length)} characters in this text body`,
                title: "Jump to an absolute character index in the active editor",
                value: cachedInput === undefined ? '' : cachedInput,
                validateInput: (value) => {
                    if (!value.match(/^\d+$/m))
                        return "Invalid input. Please enter a valid positive whole number"

                    return null;
                }
            });

            if (input === undefined) return

            let index = clamp(+input, 0);
            cachedInput = index;

            if (indexing === 'one based') index = clamp(index - 1, 0)

            let target = editor.document.positionAt(index);
            target = editor.document.validatePosition(target);

            editor.revealRange(new vscode.Range(target, target), getRevealType());
            editor.selection = new vscode.Selection(target, target);
        })
    );

    updateStatusBarItemPriority(101);
}

// this method is called when your extension is deactivated
export function deactivate() { }

function getRevealType() {
    const revealType = getEnumConfiguration('revealType', 'top', ['top', 'center', 'default', 'centerifoutsidetheviewport']);

    switch (revealType) {
        case 'default':
            return vscode.TextEditorRevealType.Default
        case 'center':
            return vscode.TextEditorRevealType.InCenter
        case 'centerifoutsidetheviewport':
            return vscode.TextEditorRevealType.InCenterIfOutsideViewport
        default:
            return vscode.TextEditorRevealType.AtTop
    }
}

function getConfiguration(identifier: string, defalt: any): any {
    return vscode.workspace.getConfiguration(EXTN_QUALIFIER).get(identifier, defalt);
}

function getEnumConfiguration(identifier: string, defaultConfig: string, possibles : string[] = []) {
    let enumType = vscode.workspace.getConfiguration(EXTN_QUALIFIER).get(identifier) as string;
    enumType = possibles.includes(enumType.toLowerCase()) ? enumType.toLowerCase() : defaultConfig.toLowerCase();

    return enumType
}

function clamp(val: any, min: any, max = Infinity) {
    if (val < min) return min;
    if (val > max) return max;

    return val
}

function updateStatusBarItemPriority(priority: number) {
    if (statusbar) statusbar.dispose();

    statusbar = vscode.window.createStatusBarItem(vscode.StatusBarAlignment.Right, priority);
    statusbar.name = '↷ Go To Character Index';
    statusbar.tooltip = `↷ Current Index${indexing === 'one based' ? '¹' : 'º'}`;
    statusbar.command = COMMANDS.go_to_character_position;
    statusbar.show();
}

function updateStatusBarItem(e: vscode.TextEditorSelectionChangeEvent) {
    const index = e.textEditor.document.offsetAt(e.textEditor.selection.active) + +(indexing === 'one based');

    statusbar.text = `↷ ${index.toLocaleString()}${indexing === 'one based' ? '¹' : 'º'}`;
}