<?php

namespace Icinga\Application\Modules;

use Icinga\Application\ApplicationBootstrap;
use Icinga\Data\ArrayDatasource;
use Icinga\Web\Notification;
use Icinga\Exception\ConfigurationError;

// TODO: show whether enabling/disabling modules is allowed by checking enableDir
//       perms

class Manager
{
    protected $installedBaseDirs;
    protected $enabledDirs       = array();
    protected $loadedModules     = array();
    protected $index;
    protected $app;

    protected $enableDir;

    public function __construct(ApplicationBootstrap $app)
    {
        $this->app = $app;
        $this->prepareEssentials();
        $this->detectEnabledModules();
    }

    protected function prepareEssentials()
    {
        $this->enableDir = $this->app->getConfig()->getConfigDir()
                         . '/enabledModules';

        if (! file_exists($this->enableDir) || ! is_dir($this->enableDir)) {
            throw new ProgrammingError(
                sprintf(
                    'Missing module directory: %s',
                    $this->enableDir
                )
            );
        }
    }

    protected function detectEnabledModules()
    {
        $fh = opendir($this->enableDir);

        while (false !== ($file = readdir($fh))) {

            if ($file[0] === '.') {
                continue;
            }

            $link = $this->enableDir . '/' . $file;
            if (! is_link($link)) {
                continue;
            }

            $dir = realpath($link);
            if (! file_exists($dir) || ! is_dir($dir)) {
                continue;
            }

            $this->enabledDirs[$file] = $dir;
        }
    }

    public function loadEnabledModules()
    {
        foreach ($this->listEnabledModules() as $name) {
            $this->loadModule($name);
        }
        return $this;
    }

    public function loadModule($name)
    {
        if ($this->hasLoaded($name)) {
            return $this;
        }
        $module = new Module($this->app, $name, $this->getModuleDir($name));
        $module->register();
        $this->loadedModules[$name] = $module;
        return $this;
    }

    public function enableModule($name)
    {
        if (! $this->hasInstalled($name)) {
            throw new ConfigurationError(
                sprintf(
                    "Cannot enable module '%s' as it isn't installed",
                    $name
                )
            );
            return $this;
        }
        $target = $this->installedBaseDirs[$name];
        $link = $this->enableDir . '/' . $name;
        if (! is_writable($this->enableDir)) {
            Notification::error("I do not have permissions to enable modules");
            return $this;
        }
        if (@symlink($target, $link)) {
            Notification::success("The module $name has been enabled");
        } else {
            Notification::error("Enabling module $name failed");
        }
        return $this;
    }

    public function disableModule($name)
    {
        if (! $this->hasEnabled($name)) {
            return $this;
        }
        if (! is_writable($this->enableDir)) {
            Notification::error("I do not have permissions to disable modules");
            return $this;
        }
        $link = $this->enableDir . '/' . $name;
        if (file_exists($link) && is_link($link)) {
            if (@unlink($link)) {
                Notification::success("The module $name has been disabled");
            } else {
                Notification::error("Disabling module $name failed");
            }
        }
        return $this;
    }

    public function getModuleConfigDir($name)
    {
        return $this->getModuleDir($name, '/config');
    }

    public function getModuleDir($name, $subdir = '')
    {
        if ($this->hasEnabled($name)) {
            return $this->enabledDirs[$name]. $subdir;
        }

        if ($this->hasInstalled($name)) {
            return $this->installedBaseDirs[$name] . $subdir;
        }

        throw new ProgrammingError(
            sprintf(
                'Trying to access uninstalled module dir: %s',
                $name
            )
        );
    }

    public function hasInstalled($name)
    {
        if ($this->installedBaseDirs === null) {
            $this->detectInstalledModules();
        }
        return array_key_exists($name, $this->installedBaseDirs);
    }

    public function hasEnabled($name)
    {
        return array_key_exists($name, $this->enabledDirs);
    }

    public function hasLoaded($name)
    {
        return array_key_exists($name, $this->loadedModules);
    }

    public function getLoadedModules()
    {
        return $this->loadedModules;
    }

    public function getModule($name)
    {
        if (! $this->hasLoaded($name)) {
            throw new ProgrammingError(
                sprintf(
                    'Cannot access module %s as it hasn\'t been loaded',
                    $name
                )
            );
        }
        return $this->loadedModules[$name];
    }

    public function getModuleInfo()
    {
        $installed = $this->listInstalledModules();
        $info = array();
        foreach ($installed as $name) {
            $info[] = (object) array(
                'name'    => $name,
                'path'    => $this->installedBaseDirs[$name],
                'enabled' => $this->hasEnabled($name),
                'loaded'  => $this->hasLoaded($name)
            );
        }
        return $info;
    }

    public function select()
    {
        $ds = new ArrayDatasource($this->getModuleInfo());
        return $ds->select();
    }

    public function listEnabledModules()
    {
        return array_keys($this->enabledDirs);
    }

    public function listLoadedModules()
    {
        return array_keys($this->loadedModules);
    }

    public function listInstalledModules()
    {
        if ($this->installedBaseDirs === null) {
            $this->detectInstalledModules();
        }
        return array_keys($this->installedBaseDirs);
    }

    public function detectInstalledModules()
    {
        // TODO: Allow multiple paths for installed modules (e.g. web vs pkg)
        $basedir = realpath(ICINGA_APPDIR . '/../modules');
        $fh = @opendir($basedir);
        if ($fh === false) {
            return $this;
        }

        while ($name = readdir($fh)) {
            if ($name[0] === '.') {
                continue;
            }
            if (is_dir($basedir . '/' . $name)) {
                $this->installedBaseDirs[$name] = $basedir . '/' . $name;
            }
        }
    }
}