<?php
/*
 * Name: Simple Wiki
 * Author: Shish <webmaster@shishnet.org>
 * License: GPLv2
 * Description: A simple wiki, for those who don't want the hugeness of mediawiki
 * Documentation:
 *  Standard formatting APIs are used (This will be BBCode by default)
 */

class WikiUpdateEvent extends Event
{
    /** @var User  */
    public $user;
    /** @var WikiPage  */
    public $wikipage;

    public function __construct(User $user, WikiPage $wikipage)
    {
        $this->user = $user;
        $this->wikipage = $wikipage;
    }
}

class WikiUpdateException extends SCoreException
{
}

class WikiPage
{
    /** @var int|string */
    public $id;

    /** @var int */
    public $owner_id;

    /** @var string */
    public $owner_ip;

    /** @var string */
    public $date;

    /** @var string */
    public $title;

    /** @var int */
    public $revision;

    /** @var bool */
    public $locked;

    /** @var string */
    public $body;

    public function __construct(array $row=null)
    {
        //assert(!empty($row));

        if (!is_null($row)) {
            $this->id = $row['id'];
            $this->owner_id = $row['owner_id'];
            $this->owner_ip = $row['owner_ip'];
            $this->date = $row['date'];
            $this->title = $row['title'];
            $this->revision = $row['revision'];
            $this->locked = ($row['locked'] == 'Y');
            $this->body = $row['body'];
        }
    }

    public function get_owner(): User
    {
        return User::by_id($this->owner_id);
    }

    public function is_locked(): bool
    {
        return $this->locked;
    }
}

class Wiki extends Extension
{
    public function onInitExt(InitExtEvent $event)
    {
        global $database, $config;

        if ($config->get_int("ext_wiki_version", 0) < 1) {
            $database->create_table("wiki_pages", "
				id SCORE_AIPK,
				owner_id INTEGER NOT NULL,
				owner_ip SCORE_INET NOT NULL,
				date SCORE_DATETIME DEFAULT NULL,
				title VARCHAR(255) NOT NULL,
				revision INTEGER NOT NULL DEFAULT 1,
				locked SCORE_BOOL NOT NULL DEFAULT SCORE_BOOL_N,
				body TEXT NOT NULL,
				UNIQUE (title, revision),
				FOREIGN KEY (owner_id) REFERENCES users(id) ON DELETE RESTRICT
			");
            $config->set_int("ext_wiki_version", 2);
        }
        if ($config->get_int("ext_wiki_version") < 2) {
            $database->Execute("ALTER TABLE wiki_pages ADD COLUMN
				locked ENUM('Y', 'N') DEFAULT 'N' NOT NULL AFTER REVISION");
            $config->set_int("ext_wiki_version", 2);
        }
    }

    public function onPageRequest(PageRequestEvent $event)
    {
        global $page, $user;
        if ($event->page_matches("wiki")) {
            if (is_null($event->get_arg(0)) || strlen(trim($event->get_arg(0))) === 0) {
                $title = "Index";
            } else {
                $title = $event->get_arg(0);
            }

            $content = $this->get_page($title);
            $this->theme->display_page($page, $content, $this->get_page("wiki:sidebar"));
        } elseif ($event->page_matches("wiki_admin/edit")) {
            $content = $this->get_page($_POST['title']);
            $this->theme->display_page_editor($page, $content);
        } elseif ($event->page_matches("wiki_admin/save")) {
            $title = $_POST['title'];
            $rev = int_escape($_POST['revision']);
            $body = $_POST['body'];
            $lock = $user->is_admin() && isset($_POST['lock']) && ($_POST['lock'] == "on");

            if ($this->can_edit($user, $this->get_page($title))) {
                $wikipage = $this->get_page($title);
                $wikipage->revision = $rev;
                $wikipage->body = $body;
                $wikipage->locked = $lock;
                try {
                    send_event(new WikiUpdateEvent($user, $wikipage));

                    $u_title = url_escape($title);
                    $page->set_mode(PageMode::REDIRECT);
                    $page->set_redirect(make_link("wiki/$u_title"));
                } catch (WikiUpdateException $e) {
                    $original = $this->get_page($title);
                    // @ because arr_diff is full of warnings
                    $original->body = @$this->arr_diff(
                        explode("\n", $original->body),
                        explode("\n", $wikipage->body)
                    );
                    $this->theme->display_page_editor($page, $original);
                }
            } else {
                $this->theme->display_permission_denied();
            }
        } elseif ($event->page_matches("wiki_admin/delete_revision")) {
            if ($user->is_admin()) {
                global $database;
                $database->Execute(
                    "DELETE FROM wiki_pages WHERE title=:title AND revision=:rev",
                    ["title"=>$_POST["title"], "rev"=>$_POST["revision"]]
                );
                $u_title = url_escape($_POST["title"]);
                $page->set_mode(PageMode::REDIRECT);
                $page->set_redirect(make_link("wiki/$u_title"));
            }
        } elseif ($event->page_matches("wiki_admin/delete_all")) {
            if ($user->is_admin()) {
                global $database;
                $database->Execute(
                    "DELETE FROM wiki_pages WHERE title=:title",
                    ["title"=>$_POST["title"]]
                );
                $u_title = url_escape($_POST["title"]);
                $page->set_mode(PageMode::REDIRECT);
                $page->set_redirect(make_link("wiki/$u_title"));
            }
        }
    }

    public function onWikiUpdate(WikiUpdateEvent $event)
    {
        global $database;
        $wpage = $event->wikipage;
        try {
            $database->Execute("
				INSERT INTO wiki_pages(owner_id, owner_ip, date, title, revision, locked, body)
				VALUES (?, ?, now(), ?, ?, ?, ?)", [$event->user->id, $_SERVER['REMOTE_ADDR'],
                $wpage->title, $wpage->revision, $wpage->locked?'Y':'N', $wpage->body]);
        } catch (Exception $e) {
            throw new WikiUpdateException("Somebody else edited that page at the same time :-(");
        }
    }

    /**
     * See if the given user is allowed to edit the given page.
     */
    public static function can_edit(User $user, WikiPage $page): bool
    {
        // admins can edit everything
        if ($user->is_admin()) {
            return true;
        }

        // anon / user can't ever edit locked pages
        if ($page->is_locked()) {
            return false;
        }

        // anon / user can edit if allowed by config
        if ($user->can("edit_wiki_page")) {
            return true;
        }

        return false;
    }

    private function get_page(string $title, int $revision=-1): WikiPage
    {
        global $database;
        // first try and get the actual page
        $row = $database->get_row(
            $database->scoreql_to_sql("
				SELECT *
				FROM wiki_pages
				WHERE SCORE_STRNORM(title) LIKE SCORE_STRNORM(:title)
				ORDER BY revision DESC"),
            ["title"=>$title]
        );

        // fall back to wiki:default
        if (empty($row)) {
            $row = $database->get_row("
					SELECT *
					FROM wiki_pages
					WHERE title LIKE :title
					ORDER BY revision DESC", ["title"=>"wiki:default"]);

            // fall further back to manual
            if (empty($row)) {
                $row = [
                    "id" => -1,
                    "owner_ip" => "0.0.0.0",
                    "date" => "",
                    "revision" => 0,
                    "locked" => false,
                    "body" => "This is a default page for when a page is empty, ".
                        "it can be edited by editing [[wiki:default]].",
                ];
            }

            // correct the default
            global $config;
            $row["title"] = $title;
            $row["owner_id"] = $config->get_int("anon_id", 0);
        }

        assert(!empty($row));

        return new WikiPage($row);
    }

    // php-diff {{{
    /**
        Diff implemented in pure php, written from scratch.
        Copyright (C) 2003  Daniel Unterberger <diff.phpnet@holomind.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.

        http://www.gnu.org/licenses/gpl.html

        About:
        I searched a function to compare arrays and the array_diff()
        was not specific enough. It ignores the order of the array-values.
        So I reimplemented the diff-function which is found on unix-systems
        but this you can use directly in your code and adopt for your needs.
        Simply adopt the formatline-function. with the third-parameter of arr_diff()
        you can hide matching lines. Hope someone has use for this.

        Contact: d.u.diff@holomind.de <daniel unterberger>
    **/

    private function arr_diff($f1, $f2, $show_equal = 0)
    {
        $c1         = 0 ;                   # current line of left
        $c2         = 0 ;                   # current line of right
        $max1       = count($f1) ;        # maximal lines of left
        $max2       = count($f2) ;        # maximal lines of right
        $outcount   = 0;                    # output counter
        $hit1       = "" ;                  # hit in left
        $hit2       = "" ;                  # hit in right
        $stop       = 0;
        $out        = "";

        while (
                $c1 < $max1                 # have next line in left
                and
                $c2 < $max2                 # have next line in right
                and
                ($stop++) < 1000            # don-t have more then 1000 ( loop-stopper )
                and
                $outcount < 20              # output count is less then 20
              ) {
            /**
            *   is the trimmed line of the current left and current right line
            *   the same ? then this is a hit (no difference)
            */
            if (trim($f1[$c1]) == trim($f2[$c2])) {
                /**
                *   add to output-string, if "show_equal" is enabled
                */
                $out    .= ($show_equal==1)
                         ?  formatline(($c1), ($c2), "=", $f1[ $c1 ])
                         : "" ;
                /**
                *   increase the out-putcounter, if "show_equal" is enabled
                *   this ist more for demonstration purpose
                */
                if ($show_equal == 1) {
                    $outcount++ ;
                }
                 
                /**
                *   move the current-pointer in the left and right side
                */
                $c1 ++;
                $c2 ++;
            }

            /**
            *   the current lines are different so we search in parallel
            *   on each side for the next matching pair, we walk on both
            *   sided at the same time comparing with the current-lines
            *   this should be most probable to find the next matching pair
            *   we only search in a distance of 10 lines, because then it
            *   is not the same function most of the time. other algos
            *   would be very complicated, to detect 'real' block movements.
            */
            else {
                $b      = "" ;
                $s1     = 0  ;      # search on left
                $s2     = 0  ;      # search on right
                $found  = 0  ;      # flag, found a matching pair
                $b1     = "" ;
                $b2     = "" ;
                $fstop  = 0  ;      # distance of maximum search

                #fast search in on both sides for next match.
                while (
                        $found == 0             # search until we find a pair
                        and
                        ($c1 + $s1 <= $max1)  # and we are inside of the left lines
                        and
                        ($c2 + $s2 <= $max2)  # and we are inside of the right lines
                        and
                        $fstop++  < 10          # and the distance is lower than 10 lines
                      ) {

                    /**
                    *   test the left side for a hit
                    *
                    *   comparing current line with the searching line on the left
                    *   b1 is a buffer, which collects the line which not match, to
                    *   show the differences later, if one line hits, this buffer will
                    *   be used, else it will be discarded later
                    */
                    #hit
                    if (trim($f1[$c1+$s1]) == trim($f2[$c2])) {
                        $found  = 1   ;     # set flag to stop further search
                        $s2     = 0   ;     # reset right side search-pointer
                        $c2--         ;     # move back the current right, so next loop hits
                        $b      = $b1 ;     # set b=output (b)uffer
                    }
                    #no hit: move on
                    else {
                        /**
                        *   prevent finding a line again, which would show wrong results
                        *
                        *   add the current line to leftbuffer, if this will be the hit
                        */
                        if ($hit1[ ($c1 + $s1) . "_" . ($c2) ] != 1) {
                            /**
                            *   add current search-line to diffence-buffer
                            */
                            $b1  .= $this->formatline(($c1 + $s1), ($c2), "-", $f1[ $c1+$s1 ]);

                            /**
                            *   mark this line as 'searched' to prevent doubles.
                            */
                            $hit1[ ($c1 + $s1) . "_" . $c2 ] = 1 ;
                        }
                    }


                    /**
                    *   test the right side for a hit
                    *
                    *   comparing current line with the searching line on the right
                    */
                    if (trim($f1[$c1]) == trim($f2[$c2+$s2])) {
                        $found  = 1   ;     # flag to stop search
                        $s1     = 0   ;     # reset pointer for search
                        $c1--         ;     # move current line back, so we hit next loop
                        $b      = $b2 ;     # get the buffered difference
                    } else {
                        /**
                        *   prevent to find line again
                        */
                        if ($hit2[ ($c1) . "_" . ($c2 + $s2) ] != 1) {
                            /**
                            *   add current searchline to buffer
                            */
                            $b2   .= $this->formatline(($c1), ($c2 + $s2), "+", $f2[ $c2+$s2 ]);

                            /**
                            *   mark current line to prevent double-hits
                            */
                            $hit2[ ($c1) . "_" . ($c2 + $s2) ] = 1;
                        }
                    }

                    /**
                    *   search in bigger distance
                    *
                    *   increase the search-pointers (satelites) and try again
                    */
                    $s1++ ;     # increase left  search-pointer
                    $s2++ ;     # increase right search-pointer
                }

                /**
                *   add line as different on both arrays (no match found)
                */
                if ($found == 0) {
                    $b  .= $this->formatline(($c1), ($c2), "-", $f1[ $c1 ]);
                    $b  .= $this->formatline(($c1), ($c2), "+", $f2[ $c2 ]);
                }

                /**
                *   add current buffer to outputstring
                */
                $out        .= $b;
                $outcount++ ;       #increase outcounter

                $c1++  ;    #move currentline forward
                $c2++  ;    #move currentline forward

                /**
                *   comment the lines are tested quite fast, because
                *   the current line always moves forward
                */
            } /*endif*/
        }/*endwhile*/

        return $out;
    }/*end func*/

    /**
     *   callback function to format the diffence-lines with your 'style'
     */
    private function formatline(int $nr1, int $nr2, string $stat, &$value): string
    { #change to $value if problems
        if (trim($value) == "") {
            return "";
        }

        switch ($stat) {
            case "=":
                // return $nr1. " : $nr2 : = ".htmlentities( $value )  ."<br>";
                return "$value\n";
                break;

            case "+":
                //return $nr1. " : $nr2 : + <font color='blue' >".htmlentities( $value )  ."</font><br>";
                return "+++ $value\n";
                break;

            case "-":
                //return $nr1. " : $nr2 : - <font color='red' >".htmlentities( $value )  ."</font><br>";
                return "--- $value\n";
                break;

            default:
                throw new Exception("stat needs to be =, + or -");
        }
    }
    // }}}
}