import * as ast from '@quenk/jcon/lib/ast';

import { basename, normalize } from 'path';

import { Future, pure, doFuture } from '@quenk/noni/lib/control/monad/future';
import {Path} from '@quenk/noni/lib/io/file';

import { Context } from './context';
import { getAllDirectives } from './util';

/**
 * addProperties adds special properties useful for module configuration.
 *
 * Currently these are:
 *
 * 1. id (uses the module basename if not provided)
 * 2. app.dirs.self
 */
export const addProperties = (ctx: Context, f: ast.File): ast.File => {

    let id = f.directives.reduce((prev, prop) =>
        ((prop instanceof ast.Property) && (prop.path[0].value === 'id')) ?
            (<ast.StringLiteral>prop.value).value : prev, basename(ctx.path));

    let idProp = new ast.Property(
        [new ast.Identifier('id', {})],
        new ast.StringLiteral(id, {}), {});

    let selfProp = new ast.Property(
        [
            new ast.Identifier('app', {}),
            new ast.Identifier('dirs', {}),
            new ast.Identifier('self', {}),
        ],
        new ast.StringLiteral(getRelPath(ctx.root, ctx.path), {}), {});

    return new ast.File(f.includes, [idProp, selfProp, ...f.directives], {});

}

const getRelPath = (root: Path, dir: Path) => {

    let path = normalize(dir.split(root).join(''));
    return (path === '') ? '/' : path;

}

/**
 * flattenDirectives loads the directives of all the includes and makes them
 * available to the root File.
 */
export const flattenDirectives =
    (ctx: Context, f: ast.File): Future<ast.File> =>
        doFuture<ast.File>(function*() {

            let dirs = yield getAllDirectives(ctx, f);

            return pure(new ast.File(f.includes, dirs, f.location));

        });

/**
 * transformTree applies all the transforms to the AST in one go.
 */
export const transformTree = (ctx: Context, f: ast.File): Future<ast.File> =>
    doFuture<ast.File>(function*() {

        let file = yield flattenDirectives(ctx, f);

        return pure(addProperties(ctx, file));

    });