<?php

/*
 *  Copyright (C) 2001 Kai Blaschke <webmaster@thw-theorie.de>
 *
 *  The included "THW Thema" templates, logos and the Q&A catalog are protected
 *  by copyright laws, and must not be used without the written permission
 *  of the
 *
 *  Bundesanstalt Technisches Hilfswerk
 *  Provinzialstraße 93
 *  D-53127 Bonn
 *  Germany
 *  E-Mail: redaktion@thw.de
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */

/************************************************************
 * Template class
 *
 * This class is capable of replacing variables with text,
 * including other templates, and it can parse dynamic blocks
 * which can be nested inside other blocks.
 *
 * Predefined template variables:
 *
 * - {templatePath} Contains the template path
 * - {templateLang} Contains the country code, if set
 *
 * If you don't need them, remove them immediately after
 * creating the class instance or setting a new template path.
 *
 **************************************************************/
class Template
{
    /**
     * @var array Contains all template filenames
     */
    private array $templateFiles = array();

    /**
     * @var array Contains all template data
     */
    private array $templateData = array();

    /**
     * @var array Already loaded templates.
     */
    private array $loadedTemplates = array();

    /**
     * @var array Array of variable/value pairs stored as $LOADED[HANDLE]=>true
     */
    private array $parserVariables = array();

    /**
     * @var array Handles which contain parsed templates to be replaced in templates
     */
    private array $templateHandles = array();

    /**
     * @var array Array with dynamic block data
     */
    private array $templateBlocks = array();

    /**
     * @var array Parsed block data
     */
    private array $parsedBlocks = array();

    /**
     * @var string Path to template files. Filename: $templateDirectory/filename[.$languageCode].tpl
     */
    private string $templateDirectory;

    /**
     * @var string Country code (en, de, fr, ...)
     */
    private string $languageCode;

    /**
     * @var string Filename extension (default is .tpl)
     */
    private string $templateExtension;

    /**
     * @var bool Safely replaces curly braces with HTML entities in variable values if set to true.
     */
    public bool $replaceBraces = true;

    /**
     * @var bool Set to "true" on Windows systems, if you encounter problems with paths.
     */
    public bool $useWindowsPathSeparator = false;

    /**
     * @var bool If set to true, die() is called in error
     */
    public bool $dieOnError = true;

    /**
     * constructor.
     * @param string $tpldir The template base directory.
     * @param string $lang The browser language code.
     * @param string $tplext Optional. The template file extension.
     */
    function __construct(string $tpldir,
                         string $lang = "",
                         string $tplext = "tpl")
    {
        $this->setPath($tpldir);
        $this->languageCode = strtolower($lang);
        $this->templateExtension = $tplext;

        $this->addVars("templateLang", $this->languageCode);
    }

    /**
     * Sets or changes the template search path
     * @param string $path New template base directory.
     * @return bool true if the path was set correctly, false if an error occurred.
     */
    function setPath(string $path): bool
    {
        if ($this->useWindowsPathSeparator) {
            if (ord(substr($path, -1)) != 92) {
                $path .= chr(92);
            }
        } else {
            if (ord(substr($path, -1)) != 47) {
                $path .= chr(47);
            }
        }

        if (is_dir($path)) {
            $this->templateDirectory = $path;

            // Add a path variable for use in templates
            $this->addVars("templatePath", $path);

            return true;
        } else {
            echo "[TEMPLATE ENGINE] The specified template path "
                . "'<b>" . $path . "</b>' is invalid!<br />";

            $this->templateDirectory = "";

            if ($this->dieOnError) {
                die();
            }
            return false;
        }
    }

    /**
     * Get dynamic blocks recursively to enable nested blocks.
     * @param string $tplFilename Template base filename.
     * @param string $contents Content to search for dynamic blocks.
     * @return void
     */
    function getDynamicBlocks(string $tplFilename,
                              string $contents): void
    {
        preg_match_all("/(\{\|([a-zA-Z0-9]+)})(.*?)\\1/s", $contents, $blocks);

        if (empty($blocks[0])) {
            return;
        }

        // Go through all blocks and save them in $this->BLOCKS
        for ($I = 0; $I < count($blocks[0]); $I++) {
            $blockparts = array();

            preg_match_all("/(\{\|" . $blocks[2][$I] . "\*([a-zA-Z0-9]+)})(.*?)\\1/s", $blocks[3][$I], $blockparts);

            for ($J = 0; $J < count($blockparts[0]); $J++) {
                // Get nested blocks
                $this->getDynamicBlocks($tplFilename, $blockparts[3][$J]);

                // Replace block data with placeholders
                $blockparts[3][$J] = preg_replace("/(\{\|([a-zA-Z0-9]+)})(.*?)\\1/s", "\\1", $blockparts[3][$J]);

                // Save block data
                $this->templateBlocks[$tplFilename][$blocks[2][$I]][$blockparts[2][$J]] = $blockparts[3][$J];

            }
        }
    }

    /**
     * Loads a template, runs some checks and extracts dynamic blocks.
     * @param string $tplFilename Template base filename.
     * @return bool true if the template is loaded, false if an error occurred.
     */
    function loadTemplate(string $tplFilename): bool
    {
        // Template already loaded?
        if (isset($this->loadedTemplates[$tplFilename])) {
            return true;
        }

        // Has the path been set?
        if (empty($this->templateDirectory)) {
            echo "[TEMPLATE ENGINE] Template path not set or invalid!<br />";

            if ($this->dieOnError) {
                die();
            }

            return false;
        }

        // Is a user-defined county code set?
        if (!empty($this->languageCode)) {
            // Yes. Try to find template with the specified CC
            if (file_exists($this->templateDirectory . $this->templateFiles[$tplFilename] . "." . $this->languageCode . "." . $this->templateExtension)) {
                $filename = $this->templateDirectory . $this->templateFiles[$tplFilename] . "." . $this->languageCode . "." . $this->templateExtension;
            } else {
                // Otherwise, use template filename without CC
                if (file_exists($this->templateDirectory . $this->templateFiles[$tplFilename] . "." . $this->templateExtension)) {
                    $filename = $this->templateDirectory . $this->templateFiles[$tplFilename] . "."
                        . $this->templateExtension;
                } else {
                    echo "[TEMPLATE ENGINE] Can't find template " . "'" . $tplFilename . "'!<br />";

                    if ($this->dieOnError) {
                        die();
                    }

                    return false;
                }
            }
        } else {
            // No. Use template filename without CC
            if (file_exists($this->templateDirectory . $this->templateFiles[$tplFilename] . "." . $this->templateExtension)) {
                $filename = $this->templateDirectory . $this->templateFiles[$tplFilename] . "." . $this->templateExtension;
            } else {
                echo "[TEMPLATE ENGINE] Can't find template " . "'" . $tplFilename . "'!<br />";

                if ($this->dieOnError) {
                    die();
                }

                return false;
            }
        }

        // Load template file
        $contents = implode("", (@file($filename)));

        if (empty($contents)) {
            echo "[TEMPLATE ENGINE] Can't load template '" . $tplFilename . "'!<br />";

            if ($this->dieOnError) {
                die();
            }

            return false;
        }

        // Parse dynamic blocks recursively
        $this->getDynamicBlocks($tplFilename, $contents);

        // Replace all block data with placeholders
        $contents = preg_replace("/(\{\|([a-zA-Z0-9]+)})(.*?)\\1/s", "\\1", $contents);

        $this->templateData[$tplFilename] = $contents;
        $this->loadedTemplates[$tplFilename] = 1;

        return true;

    }

    /**
     * Parses a template and loads it if necessary.
     * The result is assigned or concatenated to the specified handle.
     * @param string $handle Result handle to store the parsed template in.
     * @param string $file Template file to parse.
     * @param bool $append true to append the parsed template to the given handle, false replaces the contents.
     * @param bool $delunused true to delete unused variable placeholders, false to keep them for later processing.
     * @return bool true if the file was parsed correctly, false if an error occurred.
     */
    function parse(string $handle = "",
                   string $file = "",
                   bool   $append = false,
                   bool   $delunused = false): bool
    {
        // Check if all prerequisites are met
        if (empty($handle) || empty($file)) {
            return false;
        }

        if (!isset($this->templateFiles[$file])) {
            return false;
        }

        if (!isset($this->loadedTemplates[$file]) && !$this->loadTemplate($file)) {
            return false;
        }

        $templateCopy = $this->templateData[$file];

        // Reset array pointers
        reset($this->templateHandles);
        reset($this->parserVariables);

        // Replace blocks
        if (isset($this->parsedBlocks[$file])) {
            reset($this->parsedBlocks[$file]);

            foreach ($this->parsedBlocks[$file] as $varname => $value) {
                $templateCopy = preg_replace("/\{\|" . $varname . "}/i",
                    $value, $templateCopy);
            }
        }

        // Replace variables
        foreach ($this->parserVariables as $varname => $value) {
            $templateCopy = preg_replace("/\{" . $varname . "}/i",
                $value, $templateCopy);
        }

        // Replace {~name} placeholders with already parsed handle of
        // the same name
        foreach ($this->templateHandles as $varname => $value) {
            $templateCopy = preg_replace("/\{~" . $varname . "}/i",
                $value, $templateCopy);
        }

        // Delete unused variables and placeholders
        if ($delunused) {
            $templateCopy = preg_replace("/\{[~|]?(\w*?)}/", "", $templateCopy);
        }

        // Assign to handle
        if ($append && isset($this->templateHandles[$handle])) {
            $this->templateHandles[$handle] .= $templateCopy;
        } else {
            $this->templateHandles[$handle] = $templateCopy;
        }

        return true;
    }


    /**
     * Parses multiple templates.
     *
     * $list is an associative array of the type "handle"=>"template".
     * Note that concatenation is not possible. Use the parse() method instead.
     * @param array $list Associative array with handles as key and files as values.
     * @return bool true if all templates were parsed correctly, false if an error occurred.
     */
    function multiParse(array $list): bool
    {
        foreach ($list as $handle => $file) {
            if (!$this->parse($handle, $file)) return false;
        }

        return true;
    }

    /**
     * Parses a template and prints the result.
     * @param string $handle Result handle to store the parsed template in.
     * @param string $file Template base filename to parse.
     * @param bool $append true to append the parsed template to the given handle, false replaces the contents.
     * @return bool true if the template was parsed correctly, false if an error occurred.
     */
    function printParse(string $handle = "",
                        string $file = "",
                        bool   $append = false): bool
    {
        if ($this->parse($handle, $file, $append)) {
            $this->printHandle($handle);
            return true;
        }

        return false;
    }

    /**
     * Parses a block and replaces or appends the result to the block handle.
     *
     * Note: First argument is the template file name containing the blocks,
     * not a handle name!
     *
     * Note: This function has no effect on any template handle.
     * Parsed block data is inserted into the template handle in the
     * parse() method.
     * @param string $file Template base filename to parse.
     * @param string $block Block name to parse.
     * @param string $blockpart Block part to parse.
     * @param bool $append true appends the parsed data to the block contents, false replaces it.
     * @param bool $delunused true removes unused variable placeholders, false keeps them for later processing.
     * @return bool true if the bock was parsed successfully, false if an error occurred.
     */
    function parseBlock(string $file = "",
                        string $block = "",
                        string $blockpart = "",
                        bool   $append = false,
                        bool   $delunused = false): bool
    {
        if (empty($file) || empty($block) || empty($blockpart))
            return false;

        if (!isset($this->templateFiles[$file]))
            return false;

        if (!isset($this->loadedTemplates[$file]) && !$this->loadTemplate($file))
            return false;

        $blockCopy = $this->templateBlocks[$file][$block][$blockpart];

        // Reset array pointers
        reset($this->parsedBlocks);
        reset($this->parserVariables);

        // Replace blocks
        if (isset($this->parsedBlocks[$file])) {
            reset($this->parsedBlocks[$file]);

            foreach ($this->parsedBlocks[$file] as $varname => $value) {
                $blockCopy = preg_replace("/\{\|" . $varname . "}/i",
                    $value, $blockCopy);
            }
        }

        // Replace variables
        foreach ($this->parserVariables as $varname => $value) {
            $blockCopy = preg_replace("/\{" . $varname . "}/i",
                $value, $blockCopy);
        }

        // Replace {~name} placeholders with already parsed handle of
        // the same name
        foreach ($this->templateHandles as $varname => $value) {
            $blockCopy = preg_replace("/\{~" . $varname . "}/i",
                $value, $blockCopy);
        }

        // Delete unused variables and placeholders
        if ($delunused) {
            $blockCopy = preg_replace("/\{[~|]?(\w*?)}/", "", $blockCopy);
        }

        // Assign to handle
        if ($append && isset($this->parsedBlocks[$file][$block])) {
            $this->parsedBlocks[$file][$block] .= $blockCopy;
        } else {
            $this->parsedBlocks[$file][$block] = $blockCopy;
        }

        return true;
    }

    /**
     * Deletes all block handles.
     * @return void
     */
    function clearBlockHandles(): void
    {
        if (!empty($this->parsedBlocks)) {
            reset($this->parsedBlocks);
            foreach ($this->parsedBlocks as $ref => $val) {
                unset($this->parsedBlocks[$ref]);
            }
        }
    }

    /**
     * Deletes the specified block handle
     * @param string $file The template base file the block is found ion.
     * @param string $block The block name to delete.
     * @return void
     */
    function delBlockHandle(string $file,
                            string $block): void
    {
        if (!empty($file) && !empty($block)) {
            if (isset($this->parsedBlocks[$file][$block])) {
                unset($this->parsedBlocks[$file][$block]);
            }
        }
    }

    /**
     * Adds one or more templates
     * You can pass one associative array with $handle=>$filename pairs,
     * or two strings ($handle, $filename) to this function.
     * @param mixed $tplList A template handle or an associative array with template handles as keys and filenames as values.
     * @param string $tplFilename A template base filename. Only used if $tplList is a single string.
     * @return void
     */
    function addTemplates(mixed  $tplList,
                          string $tplFilename = ""): void
    {
        if (is_array($tplList)) {
            reset($tplList);
            foreach ($tplList as $handle => $filename) {
                // Add handle to list
                $this->templateFiles[$handle] = $filename;
                // Delete loaded flag if set
                unset($this->loadedTemplates[$handle]);
            }
        } else {
            $this->templateFiles[$tplList] = $tplFilename;
            unset($this->loadedTemplates[$tplList]);
        }
    }

    /**
     * Deletes all template handles
     * @return void
     */
    function clearHandles(): void
    {
        if (!empty($this->templateHandles)) {
            reset($this->templateHandles);
            foreach ($this->templateHandles as $ref => $val) {
                unset($this->templateHandles[$ref]);
            }
        }
    }

    /**
     * Deletes the specified template handle
     * @param string $handleName Template handle to delete.
     * @return void
     */
    function delHandle(string $handleName = ""): void
    {
        if (!empty($handleName)) {
            if (isset($this->templateHandles[$handleName])) {
                unset($this->templateHandles[$handleName]);
            }
        }
    }

    /**
     * Returns the contents of the specified template handle.
     * @param string $handleName The handle to return the contents for.
     * @return bool|string false if the handle doesn't exist, or a string with the contents.
     */
    function getHandle(string $handleName = ""): bool|string
    {
        if (empty($handleName))
            return false;

        if (isset($this->templateHandles[$handleName]))
            return $this->templateHandles[$handleName];

        return false;
    }

    /**
     * Prints a parsed template handle to the output stream.
     * @param string $handleName The handle to print.
     * @return bool false if the handle doesn't exist, true if the handle was printed.
     */
    function printHandle(string $handleName = ""): bool
    {
        if (empty($handleName)) return false;

        // Remove all remaining placeholders
        $this->templateHandles[$handleName] = preg_replace("/\{[~|]?(\w*?)}/",
            "", $this->templateHandles[$handleName]);

        if (isset($this->templateHandles[$handleName])) {
            echo $this->templateHandles[$handleName];
            return true;
        }

        return false;
    }

    /**
     * Deletes all variables set with the addVars() method.
     * @return void
     */
    function clearVars(): void
    {
        if (!empty($this->parserVariables)) {
            reset($this->parserVariables);
            foreach ($this->parserVariables as $ref => $val) {
                unset($this->parserVariables[$ref]);
            }
        }
    }

    /**
     * Adds one or more variables.
     * You can pass one associative array with $varname=>$value pairs
     * or two strings ($varname, $value) to this function.
     * @param mixed $varList Either an associative array with variable names as keys and values as values, or a string with the variable name.
     * @param string $varValue the value to insert for this variable. Only used if $varList is a string with the name of the variable.
     * @return void
     */
    function addVars(mixed  $varList,
                     string $varValue = ""): void
    {
        if (is_array($varList)) {
            reset($varList);
            foreach ($varList as $varname => $value) {
                // Replace curly braces
                if ($this->replaceBraces == true) {
                    $value = preg_replace(array("/(\{)/", "/(})/"),
                        array("&#123;", "&#125;"),
                        $value);
                }

                // Add/replace variable
                if (!preg_match("/[^0-9a-z\-_]/i", $varname))
                    $this->parserVariables[$varname] = $value;
            }
        } else {
            // Replace curly braces
            if ($this->replaceBraces == true) {
                $varValue = preg_replace(array("/(\{)/", "/(})/"),
                    array("&#123;", "&#125;"),
                    $varValue);
            }

            // Add/replace variable
            if (!preg_match("/[^0-9a-z\-_]/i", $varList))
                $this->parserVariables[$varList] = $varValue;
        }
    }

    /**
     * Returns a value set by the addVars() method.
     * @param string $varName The variable to return the value of.
     * @return bool|string false, if the variable didn't exist, or a string with the contents.
     */
    function getVar(string $varName = ""): bool|string
    {
        if (empty($varName)) {
            return false;
        }

        if (isset($this->parserVariables[$varName])) {
            return $this->parserVariables[$varName];
        }

        return false;
    }

}