<?php

namespace App\Http\Controllers\Api;

use App\Models\NavItem;
use App\Models\RoleNavItem;
use App\Models\Role;
use App\Services\NavbarService;
use Illuminate\Support\Facades\DB;
use Symfony\Component\HttpFoundation\Response;

class NavBuilderController extends BaseApiController
{
    protected NavItem $items;
    protected RoleNavItem $maps;
    protected NavbarService $service;
    protected Role $role;

    public function __construct()
    {
        parent::__construct();
        $this->items = model(NavItem::class);
        $this->maps = model(RoleNavItem::class);
        $this->service = app(NavbarService::class);
        $this->role = model(Role::class);
    }

    /**
     * Check if user has admin access to nav-builder
     */
    protected function ensureAdmin(): void
    {
        $user = $this->getCurrentUser();
        if (!$user) {
            throw new \Symfony\Component\HttpKernel\Exception\UnauthorizedHttpException('', 'Authentication required');
        }

        $roleNames = $user->roles ?? [];
        if (empty($roleNames)) {
            throw new \Symfony\Component\HttpKernel\Exception\ForbiddenHttpException('Access denied');
        }

        // Map role names -> ids
        $roleIdRows = DB::table('roles')
            ->select('id')
            ->whereIn('name', $roleNames)
            ->get()
            ->toArray();

        $roleIds = array_map('intval', array_column($roleIdRows, 'id'));

        if (empty($roleIds)) {
            throw new \Symfony\Component\HttpKernel\Exception\ForbiddenHttpException('Access denied');
        }

        // Is this route allowed for any of the user's roles?
        $allowed = DB::table('role_nav_items AS rni')
            ->select('1')
            ->join('nav_items AS ni', 'ni.id', '=', 'rni.nav_item_id')
            ->where('ni.url', 'nav-builder')
            ->whereIn('rni.role_id', $roleIds)
            ->first();

        if (!$allowed) {
            throw new \Symfony\Component\HttpKernel\Exception\ForbiddenHttpException('Access denied');
        }
    }

    /**
     * GET /api/v1/nav-builder/data
     * Get navigation builder data (items, roles, parent options)
     */
    public function data()
    {
        try {
            $this->ensureAdmin();
            $payload = $this->buildNavPayload();
            return $this->success($payload, 'Navigation data retrieved successfully');
        } catch (\Symfony\Component\HttpKernel\Exception\HttpException $e) {
            return $this->respondError($e->getMessage(), $e->getStatusCode());
        } catch (\Throwable $e) {
            log_message('error', 'Nav builder data error: ' . $e->getMessage());
            return $this->respondError('Failed to retrieve navigation data', Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * POST /api/v1/nav-builder
     * Save or update a navigation item
     */
    public function save()
    {
        try {
            $this->ensureAdmin();

            $payload = $this->payloadData();
            $id = (int) ($payload['id'] ?? 0);

            // Accept either "menu_parent_id" or "parent_id" from the form
            $menuParentRaw = $payload['menu_parent_id'] ?? $payload['parent_id'] ?? null;
            $menuParentId = ($menuParentRaw === '' || $menuParentRaw === null) ? null : (int) $menuParentRaw;

            if ($id && $menuParentId === $id) {
                // item cannot be its own parent
                $menuParentId = null;
            }

            // Validate parent exists (optional but helpful)
            if ($menuParentId !== null) {
                $parent = $this->items->find($menuParentId);
                if (!$parent) {
                    return $this->respondError('Selected parent does not exist.', Response::HTTP_BAD_REQUEST);
                }
            }

            $data = [
                'menu_parent_id' => $menuParentId,
                'label' => trim((string) ($payload['label'] ?? '')),
                'url' => trim((string) ($payload['url'] ?? '')) ?: null,
                'icon_class' => trim((string) ($payload['icon_class'] ?? '')) ?: null,
                'target' => trim((string) ($payload['target'] ?? '')) ?: null,
                'sort_order' => (int) ($payload['sort_order'] ?? 0),
                'is_enabled' => (int) (($payload['is_enabled'] ?? false) ? 1 : 0),
            ];

            // Save (force insert to return ID)
            if ($id) {
                $this->items->update($id, $data);
            } else {
                $id = (int) $this->items->insert($data, true); // ensure insertID is returned
            }

            // Roles
            $roleIds = array_values(array_unique(array_filter(
                array_map('intval', (array) ($payload['roles'] ?? [])),
                fn ($v) => $v > 0
            )));

            $this->maps->where('nav_item_id', $id)->delete();

            foreach ($roleIds as $rid) {
                $this->maps->insert(['role_id' => $rid, 'nav_item_id' => $id]);
            }

            $this->service->clearCache();

            return $this->success([
                'id' => $id,
                'message' => 'Menu saved successfully',
            ], 'Menu saved successfully');
        } catch (\Symfony\Component\HttpKernel\Exception\HttpException $e) {
            return $this->respondError($e->getMessage(), $e->getStatusCode());
        } catch (\Throwable $e) {
            log_message('error', 'Nav builder save error: ' . $e->getMessage());
            return $this->respondError('Failed to save menu item: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * DELETE /api/v1/nav-builder/{id}
     * Delete a navigation item
     */
    public function delete($id)
    {
        try {
            $this->ensureAdmin();

            $id = (int) $id;
            $this->items->delete($id); // children handled by FK (SET NULL on parent)

            $this->service->clearCache();

            return $this->success([
                'id' => $id,
                'message' => 'Menu item deleted successfully',
            ], 'Menu item deleted successfully');
        } catch (\Symfony\Component\HttpKernel\Exception\HttpException $e) {
            return $this->respondError($e->getMessage(), $e->getStatusCode());
        } catch (\Throwable $e) {
            log_message('error', 'Nav builder delete error: ' . $e->getMessage());
            return $this->respondError('Failed to delete menu item: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * POST /api/v1/nav-builder/reorder
     * Reorder navigation items
     */
    public function reorder()
    {
        try {
            $this->ensureAdmin();

            $payload = $this->payloadData();
            $orders = $payload['orders'] ?? [];

            foreach ($orders as $id => $order) {
                $this->items->update((int) $id, ['sort_order' => (int) $order]);
            }

            $this->service->clearCache();

            return $this->success(['ok' => true], 'Navigation items reordered successfully');
        } catch (\Symfony\Component\HttpKernel\Exception\HttpException $e) {
            return $this->respondError($e->getMessage(), $e->getStatusCode());
        } catch (\Throwable $e) {
            log_message('error', 'Nav builder reorder error: ' . $e->getMessage());
            return $this->respondError('Failed to reorder navigation items: ' . $e->getMessage(), Response::HTTP_INTERNAL_SERVER_ERROR);
        }
    }

    /**
     * Get distinct roles
     */
    protected function distinctRoles(): array
    {
        return DB::table('roles')
            ->select('id', 'name')
            ->orderBy('name')
            ->get()
            ->toArray();
    }

    /**
     * Build navigation payload
     */
    private function buildNavPayload(): array
    {
        $all = $this->items
            ->orderBy('menu_parent_id', 'ASC')
            ->orderBy('label', 'ASC')
            ->orderBy('id', 'ASC')
            ->findAll();

        $byId = [];
        foreach ($all as $a) {
            $a['children'] = [];
            $byId[$a['id']] = $a;
        }

        $tree = [];
        foreach ($byId as $id => &$node) {
            $pid = $node['menu_parent_id'] ?: null;
            if ($pid && isset($byId[$pid])) {
                $byId[$pid]['children'][] = &$node;
            } else {
                $tree[] = &$node;
            }
        }
        unset($node);

        $this->sortTreeAlpha($tree);

        $flatAlpha = $all;
        usort($flatAlpha, fn($a, $b) => strnatcasecmp(
            $this->labelKey($a['label'] ?? ''),
            $this->labelKey($b['label'] ?? '')
        ));

        $roleAssignments = [];
        $roleRows = $this->maps
            ->select('role_nav_items.nav_item_id, roles.id AS role_id, roles.name AS role_name')
            ->join('roles', 'roles.id', '=', 'role_nav_items.role_id', 'left')
            ->findAll();

        foreach ($roleRows as $row) {
            $navId = (int) ($row['nav_item_id'] ?? 0);
            if ($navId <= 0) continue;

            $roleId = (int) ($row['role_id'] ?? 0);
            $roleName = $row['role_name'] ?? ($roleId ? ('#' . $roleId) : null);

            if ($roleId > 0) {
                $roleAssignments[$navId]['ids'][] = $roleId;
            }
            if ($roleName !== null) {
                $roleAssignments[$navId]['names'][] = $roleName;
            }
        }

        $flattened = $this->flattenTreeForResponse($tree, $roleAssignments);

        $parentOptions = array_map(static function ($row) {
            return [
                'id' => (int) ($row['id'] ?? 0),
                'label' => (string) ($row['label'] ?? ''),
            ];
        }, $flatAlpha);

        $roles = array_map(static function ($role) {
            return [
                'id' => (int) ($role['id'] ?? 0),
                'name' => (string) ($role['name'] ?? ''),
            ];
        }, $this->distinctRoles());

        return [
            'items' => $flattened,
            'roles' => $roles,
            'parentOptions' => $parentOptions,
        ];
    }

    /**
     * Case-insensitive, natural sort; ignores leading punctuation & articles ("a/an/the")
     */
    private function labelKey(string $s): string
    {
        $s = trim(preg_replace('/\s+/', ' ', $s));
        $s = preg_replace('/^[^[:alnum:]]+/u', '', $s);      // strip leading punctuation
        $s = preg_replace('/^(?i)(the|an|a)\s+/', '', $s);   // drop leading articles
        return mb_strtolower($s, 'UTF-8');
    }

    /**
     * Sort tree alphabetically
     */
    private function sortTreeAlpha(array &$nodes): void
    {
        usort($nodes, fn($a, $b) => strnatcasecmp(
            $this->labelKey($a['label'] ?? ''),
            $this->labelKey($b['label'] ?? '')
        ));

        foreach ($nodes as &$n) {
            if (!empty($n['children'])) {
                $this->sortTreeAlpha($n['children']);
            }
        }
        unset($n);
    }

    /**
     * Flatten tree for response
     */
    private function flattenTreeForResponse(array $nodes, array $roleAssignments, ?string $parentLabel = null, int $depth = 0, array &$rows = []): array
    {
        foreach ($nodes as $node) {
            $raw = $node;
            unset($raw['children']);

            $navId = (int) ($raw['id'] ?? 0);
            $roles = $roleAssignments[$navId] ?? ['ids' => [], 'names' => []];

            $rows[] = [
                'id' => $navId,
                'label' => (string) ($raw['label'] ?? ''),
                'url' => $raw['url'] ?? null,
                'parent_label' => $parentLabel ?? '—',
                'parent_id' => isset($raw['menu_parent_id']) && (int) $raw['menu_parent_id'] !== 0
                    ? (int) $raw['menu_parent_id']
                    : null,
                'order' => (int) ($raw['sort_order'] ?? 0),
                'enabled' => (int) ($raw['is_enabled'] ?? 0) === 1,
                'target' => $raw['target'] ?? null,
                'depth' => $depth,
                'roles' => [
                    'ids' => array_values(array_unique($roles['ids'] ?? [])),
                    'names' => array_values(array_unique($roles['names'] ?? [])),
                ],
                'raw' => $raw,
            ];

            if (!empty($node['children'])) {
                $this->flattenTreeForResponse(
                    $node['children'],
                    $roleAssignments,
                    (string) ($raw['label'] ?? ''),
                    $depth + 1,
                    $rows
                );
            }
        }

        return $rows;
    }
}