<?php

declare(strict_types=1);

namespace flight\template;

use Exception;

/**
 * The View class represents output to be displayed. It provides
 * methods for managing view data and inserts the data into
 * view templates upon rendering.
 *
 * @license [MIT](https://docs.flightphp.com/license)
 * @copyright 2011 [Mike Cao](https://mikecao.com)
 */
class View
{
    /** Location of view templates */
    public string $path;

    /** File extension */
    public string $extension = '.php';

    public bool $preserveVars = true;

    /** @var array<string, mixed> View variables */
    protected array $vars = [];

    /** @param string $path Path to templates directory */
    public function __construct(string $path = '.')
    {
        $this->path = $path;
    }

    /**
     * Gets a template variable
     * @return mixed Variable value or `null` if doesn't exists
     */
    public function get(string $key)
    {
        return $this->vars[$key] ?? null;
    }

    /**
     * Sets a template variable
     * @param string|array<string, mixed> $key
     * @param mixed $value Value
     * @return $this
     */
    public function set($key, $value = null)
    {
        if (is_array($key)) {
            foreach ($key as $k => $v) {
                $this->vars[$k] = $v;
            }
        } else {
            $this->vars[$key] = $value;
        }

        return $this;
    }

    /**
     * Checks if a template variable is set
     * @return bool If key exists
     */
    public function has(string $key): bool
    {
        return isset($this->vars[$key]);
    }

    /**
     * Unsets a template variable. If no key is passed in, clear all variables
     * @return $this
     */
    public function clear(?string $key = null)
    {
        if ($key === null) {
            $this->vars = [];
        } else {
            unset($this->vars[$key]);
        }

        return $this;
    }

    /**
     * Renders a template
     * @param string $file Template file
     * @param ?array<string, mixed> $templateData Template data
     * @throws Exception If template not found
     */
    public function render(string $file, ?array $templateData = null): void
    {
        $template = $this->getTemplate($file);

        if (!$this->exists($file)) {
            $normalized_path = $this::normalizePath($template);

            throw new Exception("Template file not found: $normalized_path.");
        }

        extract($this->vars);

        if (is_array($templateData)) {
            extract($templateData);

            if ($this->preserveVars) {
                $this->vars += $templateData;
            }
        }

        include $template;
    }

    /**
     * Gets the output of a template
     * @param string $file Template file
     * @param ?array<string, mixed> $data Template data
     * @return string Output of template
     */
    public function fetch(string $file, ?array $data = null): string
    {
        \ob_start();

        $this->render($file, $data);

        return \ob_get_clean();
    }

    /**
     * Checks if a template file exists
     * @param string $file Template file
     * @return bool Template file exists
     */
    public function exists(string $file): bool
    {
        return \file_exists($this->getTemplate($file));
    }

    /**
     * Gets the full path to a template file
     * @param string $file Template file
     * @return string Template file location
     */
    public function getTemplate(string $file): string
    {
        if (!empty($this->extension) && (substr($file, -1 * strlen($this->extension)) !== $this->extension)) {
            $file .= $this->extension;
        }

        $is_windows = strtoupper(substr(PHP_OS, 0, 3)) === 'WIN';

        if ((substr($file, 0, 1) === '/') || ($is_windows && substr($file, 1, 1) === ':')) {
            return $file;
        }

        return $this->path . DIRECTORY_SEPARATOR . $file;
    }

    /**
     * Displays escaped output
     * @param string $str String to escape
     * @return string Escaped string
     */
    public function e(string $str): string
    {
        $value = \htmlentities($str);
        echo $value;
        return $value;
    }

    protected static function normalizePath(string $path, string $separator = DIRECTORY_SEPARATOR): string
    {
        return \str_replace(['\\', '/'], $separator, $path);
    }
}