<?php

const ROUTER_VERSION = 1;
const ROUTER_MC_KEY = 'ch1p/routes';

$RouterInput = [];
$Routes = [
    'children' => [],
    're_children' => []
];

function router_init(): void {
    global $Routes;
    $mc = MC();

    $from_cache = !is_dev();
    $write_cache = !is_dev();

    if ($from_cache) {
        $cache = $mc->get(ROUTER_MC_KEY);

        if ($cache === false || !isset($cache['version']) || $cache['version'] < ROUTER_VERSION) {
            $from_cache = false;
        } else {
            $Routes = $cache['routes'];
        }
    }

    if (!$from_cache) {
        $routes_table = require_once APP_ROOT.'/routes.php';

        foreach ($routes_table as $controller => $routes) {
            foreach ($routes as $route => $resolve)
                router_add($route, $controller.' '.$resolve);
        }

        if ($write_cache)
            $mc->set(ROUTER_MC_KEY, ['version' => ROUTER_VERSION, 'routes' => $Routes]);
    }
}

function router_add(string $template, string $value): void {
    global $Routes;
    if ($template == '')
        return;

    // expand {enum,erat,ions}
    $templates = [[$template, $value]];
    if (preg_match_all('/\{([\w\d_\-,]+)\}/', $template, $matches)) {
        foreach ($matches[1] as $match_index => $variants) {
            $variants = explode(',', $variants);
            $variants = array_map('trim', $variants);
            $variants = array_filter($variants, function($s) { return $s != ''; });

            for ($i = 0; $i < count($templates); ) {
                list($template, $value) = $templates[$i];
                $new_templates = [];
                foreach ($variants as $variant_index => $variant) {
                    $new_templates[] = [
                        str_replace_once($matches[0][$match_index], $variant, $template),
                        str_replace('${'.($match_index+1).'}', $variant, $value)
                    ];
                }
                array_splice($templates, $i, 1, $new_templates);
                $i += count($new_templates);
            }
        }
    }

    // process all generated routes
    foreach ($templates as $template) {
        list($template, $value) = $template;

        $start_pos = 0;
        $parent = &$Routes;
        $template_len = strlen($template);

        while ($start_pos < $template_len) {
            $slash_pos = strpos($template, '/', $start_pos);
            if ($slash_pos !== false) {
                $part = substr($template, $start_pos, $slash_pos-$start_pos+1);
                $start_pos = $slash_pos+1;
            } else {
                $part = substr($template, $start_pos);
                $start_pos = $template_len;
            }

            $parent = &_router_add($parent, $part,
                $start_pos < $template_len ? null : $value);
        }
    }
}

function &_router_add(&$parent, $part, $value = null) {
    $par_pos = strpos($part, '(');
    $is_regex = $par_pos !== false && ($par_pos == 0 || $part[$par_pos-1] != '\\');

    $children_key = !$is_regex ? 'children' : 're_children';

    if (isset($parent[$children_key][$part])) {
        if (is_null($value)) {
            $parent = &$parent[$children_key][$part];
        } else {
            if (!isset($parent[$children_key][$part]['value'])) {
                $parent[$children_key][$part]['value'] = $value;
            } else {
                trigger_error(__METHOD__.': route is already defined');
            }
        }
        return $parent;
    }

    $child = [
        'children' => [],
        're_children' => []
    ];
    if (!is_null($value))
        $child['value'] = $value;

    $parent[$children_key][$part] = $child;
    return $parent[$children_key][$part];
}

function router_find($uri) {
    global $Routes;
    if ($uri != '/' && $uri[0] == '/')
        $uri = substr($uri, 1);

    $start_pos = 0;
    $parent = &$Routes;
    $uri_len = strlen($uri);
    $matches = [];

    while ($start_pos < $uri_len) {
        $slash_pos = strpos($uri, '/', $start_pos);
        if ($slash_pos !== false) {
            $part = substr($uri, $start_pos, $slash_pos-$start_pos+1);
            $start_pos = $slash_pos+1;
        } else {
            $part = substr($uri, $start_pos);
            $start_pos = $uri_len;
        }

        $found = false;
        if (isset($parent['children'][$part])) {
            $parent = &$parent['children'][$part];
            $found = true;
        } else if (!empty($parent['re_children'])) {
            foreach ($parent['re_children'] as $re => &$child) {
                $exp = '#^'.$re.'$#';
                $re_result = preg_match($exp, $part, $match);
                if ($re_result === false) {
                    logError(__METHOD__.": regex $exp failed");
                    continue;
                }

                if ($re_result) {
                    if (count($match) > 1)
                        $matches = array_merge($matches, array_slice($match, 1));
                    $parent = &$child;
                    $found = true;
                    break;
                }
            }
        }

        if (!$found)
            return null;
    }

    if (!isset($parent['value']))
        return null;

    $value = $parent['value'];
    if (!empty($matches)) {
        foreach ($matches as $i => $match) {
            $needle = '$('.($i+1).')';
            $pos = strpos($value, $needle);
            if ($pos !== false)
                $value = substr_replace($value, $match, $pos, strlen($needle));
        }
    }

    return $value;
}