<?php

// SPDX-FileCopyrightText: 2018 Icinga GmbH <https://icinga.com>
// SPDX-License-Identifier: GPL-3.0-or-later

namespace Icinga\Web;

use Icinga\Application\Logger;
use Icinga\Util\LessParser;
use Less_Exception_Parser;

/**
 * Compile LESS into CSS
 *
 * Comments will be removed always. lessc is messing them up.
 */
class LessCompiler
{
    /**
     * lessphp compiler
     *
     * @var LessParser
     */
    protected $lessc;

    /**
     * Array of LESS files
     *
     * @var string[]
     */
    protected $lessFiles = array();

    /**
     * Array of module LESS files indexed by module names
     *
     * @var array[]
     */
    protected $moduleLessFiles = array();

    /**
     * LESS source
     *
     * @var string
     */
    protected $source;

    /**
     * Path of the LESS theme
     *
     * @var string
     */
    protected $theme;

    /**
     * Path of the LESS theme mode
     *
     * @var string
     */
    protected $themeMode;

    /**
     * Create a new LESS compiler
     */
    public function __construct()
    {
        $this->lessc = new LessParser();
    }

    /**
     * Add a Web 2 LESS file
     *
     * @param   string  $lessFile   Path to the LESS file
     *
     * @return  $this
     */
    public function addLessFile($lessFile)
    {
        $this->lessFiles[] = realpath($lessFile);
        return $this;
    }

    /**
     * Add a module LESS file
     *
     * @param   string  $moduleName Name of the module
     * @param   string  $lessFile   Path to the LESS file
     *
     * @return  $this
     */
    public function addModuleLessFile($moduleName, $lessFile)
    {
        if (! isset($this->moduleLessFiles[$moduleName])) {
            $this->moduleLessFiles[$moduleName] = array();
        }
        $this->moduleLessFiles[$moduleName][] = realpath($lessFile);
        return $this;
    }

    /**
     * Get the list of LESS files added to the compiler
     *
     * @return string[]
     */
    public function getLessFiles()
    {
        $lessFiles = $this->lessFiles;

        foreach ($this->moduleLessFiles as $moduleLessFiles) {
            $lessFiles = array_merge($lessFiles, $moduleLessFiles);
        }

        if ($this->theme !== null) {
            $lessFiles[] = $this->theme;
        }

        if ($this->themeMode !== null) {
            $lessFiles[] = $this->themeMode;
        }

        return $lessFiles;
    }

    /**
     * Set the path to the LESS theme
     *
     * @param   ?string  $theme  Path to the LESS theme
     *
     * @return  $this
     */
    public function setTheme($theme)
    {
        if ($theme === null || (is_file($theme) && is_readable($theme))) {
            $this->theme = $theme;
        } else {
            Logger::error('Can\t load theme %s. Make sure that the theme exists and is readable', $theme);
        }
        return $this;
    }

    /**
     * Set the path to the LESS theme mode
     *
     * @param   string  $themeMode  Path to the LESS theme mode
     *
     * @return  $this
     */
    public function setThemeMode($themeMode)
    {
        if (is_file($themeMode) && is_readable($themeMode)) {
            $this->themeMode = $themeMode;
        } else {
            Logger::error('Can\t load theme mode %s. Make sure that the theme mode exists and is readable', $themeMode);
        }
        return $this;
    }

    /**
     * Instruct the compiler to minify CSS
     *
     * @return  $this
     */
    public function compress()
    {
        $this->lessc->setFormatter('compressed');
        return $this;
    }

    /**
     * Render to CSS
     *
     * @return  string
     */
    public function render()
    {
        foreach ($this->lessFiles as $lessFile) {
            $this->source .= file_get_contents($lessFile);
        }

        $moduleCss = '';
        $exportedVars = [];
        foreach ($this->moduleLessFiles as $moduleName => $moduleLessFiles) {
            $moduleCss .= '.icinga-module.module-' . $moduleName . ' {';

            foreach ($moduleLessFiles as $moduleLessFile) {
                $content = file_get_contents($moduleLessFile);

                $pattern = '/^@exports:\s*{((?:\s*@[^:}]+:[^;]*;\s+)+)};$/m';
                if (preg_match_all($pattern, $content, $matches, PREG_SET_ORDER)) {
                    foreach ($matches as $match) {
                        $content = str_replace($match[0], '', $content);
                        foreach (explode("\n", trim($match[1])) as $line) {
                            list($name, $value) = explode(':', $line, 2);
                            $exportedVars[trim($name)] = trim($value, ' ;');
                        }
                    }
                }

                $moduleCss .= $content;
            }

            $moduleCss .= '}';
        }

        $this->source .= $moduleCss;

        $varExports = '';
        foreach ($exportedVars as $name => $value) {
            $varExports .= sprintf("%s: %s;\n", $name, $value);
        }

        // exported vars are injected at the beginning to avoid that they are
        // able to override other variables, that's what themes are for
        $this->source = $varExports . "\n\n" . $this->source;

        if ($this->theme !== null) {
            $this->source .= file_get_contents($this->theme);
        }

        if ($this->themeMode !== null) {
            $this->source .= file_get_contents($this->themeMode);
        }

        try {
            return preg_replace(
                '/(\.icinga-module\.module-[^\s]+) (#layout\.[^\s]+)/m',
                '\2 \1',
                $this->lessc->compile($this->source)
            );
        } catch (Less_Exception_Parser $e) {
            $excerpt = substr($this->source, $e->index - 500, 1000);

            $lines = [];
            $found = false;
            $pos = $e->index - 500;
            foreach (explode("\n", $excerpt) as $i => $line) {
                if ($i === 0) {
                    $pos += strlen($line);
                    $lines[] = '.. ' . $line;
                } else {
                    $pos += strlen($line) + 1;
                    $sep = '   ';
                    if (! $found && $pos > $e->index) {
                        $found = true;
                        $sep = '!! ';
                    }

                    $lines[] = $sep . $line;
                }
            }

            $lines[] = '..';
            $excerpt = join("\n", $lines);

            return sprintf("%s\n%s\n\n\n%s", $e->getMessage(), $e->getTraceAsString(), $excerpt);
        }
    }
}
