<?php
namespace Sasae;

use InvalidArgumentException;
use Stringable;
use Twig\TemplateWrapper as TwigTemplateWrapper;

/**
 * Provides a wrapper of Twig\TemplateWrapper.
 */
class SasaeContext implements Stringable {
    /**
     * @internal
     * @param array<string, mixed> $vars
     */
    public function __construct(
        private TwigTemplateWrapper $wrapper,
        private array $vars = []
    ) {}

    /**
     * Returns the underlying wrapper instance.
     *
     * @return TwigTemplateWrapper
     */
    public function getWrapper(): TwigTemplateWrapper {
        return $this->wrapper;
    }

    /**
     * Sets a local variable.
     *
     * $path is evaluated to allow accessing deeper layer arrays without overwriting it entirely.
     *
     * @param string $path Array path to the variable.
     * @param mixed $value Desired value.
     */
    public function setVar(string $path, mixed $value): void {
        $path = explode('.', $path);
        $target = &$this->vars;
        $targetName = array_pop($path);

        if(!empty($path)) {
            $path = array_reverse($path);
            while(($name = array_pop($path)) !== null) {
                if(!is_array($target))
                    throw new InvalidArgumentException('The $path you\'re attempting to write to conflicts with a non-array type.');

                if(!array_key_exists($name, $target))
                    $target[$name] = [];
                $target = &$target[$name];
            }
        }

        if(!is_array($target))
            throw new InvalidArgumentException('The $path you\'re attempting to write to conflicts with a non-array type.');

        $target[$targetName] = $value;
    }

    /**
     * Merges a set of variables into the local variable set.
     *
     * @param array<string, mixed> $vars Variables to apply to the set.
     */
    public function setVars(array $vars): void {
        $this->vars = array_merge($this->vars, $vars);
    }

    /**
     * Renders the template to a string, taking additional variables that are not commit to local set.
     *
     * @param ?array<string, mixed> $vars Additional local variables, nullable to avoid additional function calls.
     * @return string Rendered template.
     */
    public function render(?array $vars = null): string {
        return $this->wrapper->render(
            $vars === null ? $this->vars : array_merge($this->vars, $vars)
        );
    }

    /**
     * Renders the template to a string.
     *
     * @return string Rendered template.
     */
    public function __toString(): string {
        return $this->render();
    }
}