import { Accordion, AccordionContent, AccordionItem, AccordionTrigger } from "@/Components/ui/accordion";
import { Button } from "@/Components/ui/button";
import { Checkbox } from "@/Components/ui/checkbox";
import { Input } from "@/Components/ui/input";
import { cn } from "@/lib/utils";
import { useState, useEffect, useMemo } from "react";
import { ChevronsDown, ChevronsUp } from "lucide-react";

export interface Permission {
    id: number;
    name: string;
    display_name?: string;
}

export interface GroupedPermission {
    key: string;
    name: string;
    permissions: Permission[];
}

interface PermissionSelectorProps {
    groupedPermissions: GroupedPermission[];
    selectedPermissions: string[];
    onChange: (permissions: string[]) => void;
}

export default function PermissionSelector({ groupedPermissions, selectedPermissions, onChange }: PermissionSelectorProps) {

    // 翻譯權限後綴
    const translateAction = (permissionName: string) => {
        const parts = permissionName.split('.');
        if (parts.length < 2) return permissionName;
        const action = parts[parts.length - 1];

        const map: Record<string, string> = {
            'view': '檢視',
            'create': '新增',
            'edit': '編輯',
            'delete': '刪除',

            'adjust': '調整',
            'transfer': '調撥',
            'count': '盤點',
            'safety_stock': '安全庫存設定',
            'export': '匯出',
            'complete': '完成',
            'view_cost': '檢視成本',
            'view_logs': '檢視日誌',
            'activate': '啟用/停用',
            'approve': '核准/退回',
            'cancel': '取消',
        };

        const actionText = map[action] || action;

        // 處理多段式權限 (例如 inventory_count.view) 
        if (parts.length >= 2) {
            const middleKey = parts[parts.length - 2];
            // 如果中間那段有翻譯且不等於動作本身，則顯示為 "標籤: 動作"
            if (map[middleKey] && middleKey !== action) {
                return `${map[middleKey]}: ${actionText}`;
            }
        }

        return actionText;
    };

    const togglePermission = (name: string) => {
        if (selectedPermissions.includes(name)) {
            onChange(selectedPermissions.filter(p => p !== name));
        } else {
            onChange([...selectedPermissions, name]);
        }
    };

    const toggleGroup = (groupPermissions: Permission[]) => {
        const groupNames = groupPermissions.map(p => p.name);
        const allSelected = groupNames.every(name => selectedPermissions.includes(name));

        if (allSelected) {
            // Unselect all
            onChange(selectedPermissions.filter(p => !groupNames.includes(p)));
        } else {
            // Select all
            const newPermissions = [...selectedPermissions];
            groupNames.forEach(name => {
                if (!newPermissions.includes(name)) newPermissions.push(name);
            });
            onChange(newPermissions);
        }
    };

    // State for controlling accordion items
    const [openItems, setOpenItems] = useState<string[]>([]);
    const [searchQuery, setSearchQuery] = useState("");

    // Memoize filtered groups to prevent infinite loops in useEffect
    const filteredGroups = useMemo(() => {
        return groupedPermissions.map(group => {
            // If search is empty, return group as is
            if (!searchQuery.trim()) return group;

            // Check if group name matches
            const groupNameMatch = group.name.toLowerCase().includes(searchQuery.toLowerCase());

            // Filter permissions that match
            const matchingPermissions = group.permissions.filter(p => {
                const translatedName = p.display_name || translateAction(p.name);
                return translatedName.includes(searchQuery) ||
                    p.name.toLowerCase().includes(searchQuery.toLowerCase());
            });

            // If group name matches, show all permissions. Otherwise show only matching permissions.
            if (groupNameMatch) {
                return group;
            }

            return {
                ...group,
                permissions: matchingPermissions
            };
        }).filter(group => group.permissions.length > 0);
    }, [groupedPermissions, searchQuery]);

    const currentDisplayKeys = useMemo(() => filteredGroups.map(g => g.key), [filteredGroups]);

    const onExpandAll = () => setOpenItems(currentDisplayKeys);
    const onCollapseAll = () => setOpenItems([]);

    // Auto-expand groups when searching
    useEffect(() => {
        if (searchQuery.trim()) {
            const filteredKeys = filteredGroups.map(g => g.key);
            setOpenItems(prev => {
                const next = new Set([...prev, ...filteredKeys]);
                return Array.from(next);
            });
        }
        // removing the 'else' block which forced collapse on empty search
        // We let the user manually collapse if they want, or we could reset only when search is cleared explicitly?
        // User behavior: if I finish searching, I might want to see my previous state, but "Expand All" failing was the main issue.
        // The issue was the effect running on every render resetting state.
    }, [searchQuery]); // Only run when query changes. We actually depend on filteredGroups result but only when query changes matters most for "auto" trigger.
    // Actually, correctly: if filteredGroups changes due to search change, we expand. 

    // Better interaction: When search query *changes* and is not empty, we expand matches.

    return (
        <div className="space-y-4">
            <div className="flex flex-col sm:flex-row sm:items-center justify-between gap-4 mb-2">
                <div className="relative flex-1 max-w-sm">
                    <Input
                        placeholder="搜尋權限名稱..."
                        value={searchQuery}
                        onChange={(e) => setSearchQuery(e.target.value)}
                        className="pl-8"
                    />
                    <div className="absolute left-2.5 top-2.5 text-gray-400">
                        <svg xmlns="http://www.w3.org/2000/svg" width="16" height="16" viewBox="0 0 24 24" fill="none" stroke="currentColor" strokeWidth="2" strokeLinecap="round" strokeLinejoin="round"><circle cx="11" cy="11" r="8" /><path d="m21 21-4.3-4.3" /></svg>
                    </div>
                </div>

                <div className="flex items-center justify-between sm:justify-end gap-4 w-full sm:w-auto">
                    <div className="text-sm text-gray-500 whitespace-nowrap">
                        已選擇 {selectedPermissions.length} 項
                    </div>
                    <div className="flex items-center gap-1">
                        <Button
                            type="button"
                            variant="ghost"
                            size="sm"
                            onClick={onExpandAll}
                            className="h-8 text-xs text-gray-600 hover:text-primary-main gap-1.5"
                        >
                            <ChevronsDown className="h-3.5 w-3.5" />
                            展開全部
                        </Button>
                        <div className="h-4 w-px bg-gray-200" />
                        <Button
                            type="button"
                            variant="ghost"
                            size="sm"
                            onClick={onCollapseAll}
                            className="h-8 text-xs text-gray-600 hover:text-primary-main gap-1.5"
                        >
                            <ChevronsUp className="h-3.5 w-3.5" />
                            收合全部
                        </Button>
                    </div>
                </div>
            </div>

            <Accordion
                type="multiple"
                value={openItems}
                onValueChange={setOpenItems}
                className="w-full space-y-2"
            >
                {filteredGroups.length === 0 ? (
                    <div className="text-center py-8 text-gray-500 bg-gray-50 rounded-lg border border-dashed">
                        沒有符合「{searchQuery}」的權限項目
                    </div>
                ) : (
                    filteredGroups.map((group) => {
                        const selectedCount = group.permissions.filter(p => selectedPermissions.includes(p.name)).length;
                        const totalCount = group.permissions.length;
                        const isAllSelected = selectedCount === totalCount;

                        // 將權限分為「基本操作」與「狀態/進階操作」
                        const statusActions = ['approve', 'cancel', 'complete', 'activate'];
                        const normalPermissions = group.permissions.filter(p => !statusActions.includes(p.name.split('.').pop() || ''));
                        const specialPermissions = group.permissions.filter(p => statusActions.includes(p.name.split('.').pop() || ''));

                        return (
                            <AccordionItem
                                key={group.key}
                                value={group.key}
                                className="bg-white border rounded-lg px-2 data-[state=open]:bg-gray-50/50 last:border-b"
                            >
                                <div className="flex items-center w-full">
                                    <div className="flex items-center pl-2 pr-1">
                                        <Checkbox
                                            id={`group-select-${group.key}`}
                                            checked={isAllSelected}
                                            onCheckedChange={() => toggleGroup(group.permissions)}
                                            className="data-[state=checked]:bg-primary-main"
                                        />
                                    </div>

                                    <AccordionTrigger className="px-2 hover:no-underline hover:bg-gray-50 rounded-lg group flex-1 py-3">
                                        <div className="flex items-center gap-3">
                                            <span className={cn(
                                                "font-medium",
                                                selectedCount > 0 ? "text-primary-main" : "text-gray-700"
                                            )}>
                                                {group.name}
                                            </span>
                                            <span className="text-xs text-gray-400 bg-gray-100 px-2 py-0.5 rounded-full font-mono">
                                                {selectedCount} / {totalCount}
                                            </span>
                                        </div>
                                    </AccordionTrigger>
                                </div>
                                <AccordionContent className="px-2 pb-4">
                                    <div className="pl-10 space-y-6 pt-1">
                                        {/* 基本操作 */}
                                        {normalPermissions.length > 0 && (
                                            <div className="space-y-3">
                                                <div className="text-xs font-semibold text-gray-400 uppercase tracking-wider">
                                                    基本功能權限
                                                </div>
                                                <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-y-3 gap-x-4">
                                                    {normalPermissions.map((permission) => (
                                                        <PermissionItem
                                                            key={permission.id}
                                                            permission={permission}
                                                            selectedPermissions={selectedPermissions}
                                                            onToggle={togglePermission}
                                                            translate={translateAction}
                                                        />
                                                    ))}
                                                </div>
                                            </div>
                                        )}

                                        {/* 狀態操作/進階權限 */}
                                        {specialPermissions.length > 0 && (
                                            <div className="space-y-3 pt-2 border-t border-gray-100 italic">
                                                <div className="text-xs font-semibold text-amber-600/70 uppercase tracking-wider flex items-center gap-1">
                                                    <span className="w-1 h-3 bg-amber-500 rounded-full" />
                                                    單據狀態與進階操作權限
                                                </div>
                                                <div className="grid grid-cols-1 sm:grid-cols-2 md:grid-cols-3 gap-y-3 gap-x-4">
                                                    {specialPermissions.map((permission) => (
                                                        <PermissionItem
                                                            key={permission.id}
                                                            permission={permission}
                                                            selectedPermissions={selectedPermissions}
                                                            onToggle={togglePermission}
                                                            translate={translateAction}
                                                        />
                                                    ))}
                                                </div>
                                            </div>
                                        )}
                                    </div>
                                </AccordionContent>
                            </AccordionItem>
                        );
                    })
                )}
            </Accordion>
        </div>
    );
}

function PermissionItem({ permission, selectedPermissions, onToggle, translate }: any) {
    return (
        <div className="flex items-start space-x-3">
            <Checkbox
                id={permission.name}
                checked={selectedPermissions.includes(permission.name)}
                onCheckedChange={() => onToggle(permission.name)}
            />
            <div className="grid gap-1.5 leading-none">
                <label
                    htmlFor={permission.name}
                    className="text-sm leading-none peer-disabled:cursor-not-allowed peer-disabled:opacity-70 cursor-pointer text-gray-700 hover:text-primary-main transition-colors"
                >
                    {permission.display_name || translate(permission.name)}
                </label>
                <p className="text-[10px] text-gray-400 font-mono">
                    {permission.name}
                </p>
            </div>
        </div>
    );
}
