/**
 * 新增庫存頁面（手動入庫）
 */

import { useState, useEffect } from "react";
import { Plus, Trash2, Calendar, ArrowLeft, Save, Boxes } from "lucide-react";
import { Button } from "@/Components/ui/button";
import { Input } from "@/Components/ui/input";
import { Label } from "@/Components/ui/label";
import { Textarea } from "@/Components/ui/textarea";
import { SearchableSelect } from "@/Components/ui/searchable-select";
import {
    Table,
    TableBody,
    TableCell,
    TableHead,
    TableHeader,
    TableRow,
} from "@/Components/ui/table";
import AuthenticatedLayout from "@/Layouts/AuthenticatedLayout";
import { Head, Link, router } from "@inertiajs/react";
import { Warehouse, InboundItem, InboundReason } from "@/types/warehouse";
import { getCurrentDateTime } from "@/utils/format";
import { toast } from "sonner";
import { getInventoryBreadcrumbs } from "@/utils/breadcrumb";

interface Product {
    id: string;
    name: string;
    code: string;
    baseUnit: string;
    largeUnit?: string;
    conversionRate?: number;
}

interface Batch {
    inventoryId: string;
    batchNumber: string;
    originCountry: string;
    expiryDate: string | null;
    quantity: number;
    isDeleted?: boolean;
}

interface Props {
    warehouse: Warehouse;
    products: Product[];
}

const INBOUND_REASONS: InboundReason[] = [
    "期初建檔",
    "盤點調整",
    "實際入庫未走採購流程",
    "生產加工成品入庫",
    "其他",
];

export default function AddInventoryPage({ warehouse, products }: Props) {
    const [inboundDate, setInboundDate] = useState(getCurrentDateTime());
    const [reason, setReason] = useState<InboundReason>("期初建檔");
    const [notes, setNotes] = useState("");
    const [items, setItems] = useState<InboundItem[]>([]);
    const [errors, setErrors] = useState<Record<string, string>>({});
    const [batchesCache, setBatchesCache] = useState<Record<string, { batches: Batch[], nextSequences: Record<string, string> }>>({});

    // 取得商品批號與流水號
    const fetchProductBatches = async (productId: string, originCountry?: string, arrivalDate?: string) => {
        if (!productId) return;

        const country = originCountry || 'TW';
        const date = arrivalDate || inboundDate.split('T')[0];
        const cacheKey = `${country}_${date}`;

        // 如果該商品的批號列表尚未載入，強制載入
        const existingCache = batchesCache[productId];
        const hasBatches = existingCache && existingCache.batches.length >= 0 && existingCache.batches !== undefined;
        const hasThisSequence = existingCache?.nextSequences?.[cacheKey];

        // 若 batches 尚未載入，或特定條件的 sequence 尚未載入，則呼叫 API
        if (!hasBatches || !hasThisSequence) {
            try {
                const response = await fetch(`/api/warehouses/${warehouse.id}/inventory/batches/${productId}?originCountry=${country}&arrivalDate=${date}`);
                const data = await response.json();

                setBatchesCache(prev => {
                    const existingProductCache = prev[productId] || { batches: [], nextSequences: {} };
                    return {
                        ...prev,
                        [productId]: {
                            batches: data.batches,
                            nextSequences: {
                                ...existingProductCache.nextSequences,
                                [cacheKey]: data.nextSequence
                            }
                        }
                    };
                });
            } catch (error) {
                console.error("Failed to fetch batches", error);
            }
        }
    };

    // 當 items 變動、日期變動時，確保資料同步
    useEffect(() => {
        items.forEach(item => {
            if (item.productId) {
                // 無論 batchMode 為何，都要載入批號列表
                // 若使用者切換到 new 模式，則額外傳入 originCountry 以取得正確流水號
                const country = item.batchMode === 'new' ? item.originCountry : undefined;
                fetchProductBatches(item.productId, country, inboundDate.split('T')[0]);
            }
        });
    }, [items, inboundDate]);

    // 新增明細行
    const handleAddItem = () => {
        const defaultProduct = products.length > 0 ? products[0] : { id: "", name: "", code: "", baseUnit: "個" };
        const newItem: InboundItem = {
            tempId: `temp-${Date.now()}-${Math.random().toString(36).substr(2, 9)}`,
            productId: defaultProduct.id,
            productName: defaultProduct.name,
            quantity: 0,
            unit: defaultProduct.baseUnit, // 僅用於顯示當前選擇單位的名稱
            baseUnit: defaultProduct.baseUnit,
            largeUnit: defaultProduct.largeUnit,
            conversionRate: defaultProduct.conversionRate,
            selectedUnit: 'base',
            batchMode: 'existing', // 預設選擇現有批號
            originCountry: 'TW',
        };
        setItems([...items, newItem]);
    };

    // 刪除明細行
    const handleRemoveItem = (tempId: string) => {
        setItems(items.filter((item) => item.tempId !== tempId));
    };

    // 更新明細行
    const handleUpdateItem = (tempId: string, updates: Partial<InboundItem>) => {
        setItems(
            items.map((item) =>
                item.tempId === tempId ? { ...item, ...updates } : item
            )
        );
    };

    // 處理商品變更
    const handleProductChange = (tempId: string, productId: string) => {
        const product = products.find((p) => p.id === productId);

        if (product) {
            handleUpdateItem(tempId, {
                productId,
                productName: product.name,
                unit: product.baseUnit,
                baseUnit: product.baseUnit,
                largeUnit: product.largeUnit,
                conversionRate: product.conversionRate,
                selectedUnit: 'base',
                batchMode: 'existing',
                inventoryId: undefined, // 清除已選擇的批號
                expiryDate: undefined,
            });
        }
    };

    // 驗證表單
    const validateForm = (): boolean => {
        const newErrors: Record<string, string> = {};

        if (!reason) {
            newErrors.reason = "請選擇入庫原因";
        }

        if (reason === "其他" && !notes.trim()) {
            newErrors.notes = "原因為「其他」時，備註為必填";
        }

        if (items.length === 0) {
            newErrors.items = "請至少新增一筆庫存明細";
        }

        items.forEach((item, index) => {
            if (!item.productId) {
                newErrors[`item-${index}-product`] = "請選擇商品";
            }
            if (item.quantity <= 0) {
                newErrors[`item-${index}-quantity`] = "數量必須大於 0";
            }
            if (item.batchMode === 'existing' && !item.inventoryId) {
                newErrors[`item-${index}-batch`] = "請選擇批號";
            }
            if (item.batchMode === 'new' && !item.originCountry) {
                newErrors[`item-${index}-country`] = "新批號必須輸入產地";
            }
        });

        setErrors(newErrors);
        return Object.keys(newErrors).length === 0;
    };

    // 處理儲存
    const handleSave = () => {
        if (!validateForm()) {
            toast.error("請檢查表單內容");
            return;
        }

        router.post(`/warehouses/${warehouse.id}/inventory`, {
            inboundDate,
            reason,
            notes,
            items: items.map(item => {
                // 如果選擇大單位，則換算為基本單位數量
                const finalQuantity = item.selectedUnit === 'large' && item.conversionRate
                    ? item.quantity * item.conversionRate
                    : item.quantity;

                return {
                    productId: item.productId,
                    quantity: finalQuantity,
                    batchMode: item.batchMode,
                    inventoryId: item.inventoryId,
                    originCountry: item.originCountry,
                    expiryDate: item.expiryDate
                };
            })
        }, {
            onSuccess: () => {
                toast.success("庫存記錄已儲存");
                router.get(`/warehouses/${warehouse.id}/inventory`);
            },
            onError: (err) => {
                toast.error("儲存失敗，請檢查輸入內容");
                console.error(err);
            }
        });
    };

    // 生成批號預覽
    const getBatchPreview = (productId: string | undefined, productCode: string | undefined, country: string, dateStr: string) => {
        if (!productCode || !productId) return "--";
        try {
            // 直接字串處理，避免時區問題且確保與 fetchProductBatches 的 key 一致
            const datePart = dateStr.includes('T') ? dateStr.split('T')[0] : dateStr;
            const [yyyy, mm, dd] = datePart.split('-');
            const dateFormatted = `${yyyy}${mm}${dd}`;

            const cacheKey = `${country}_${datePart}`;
            const seq = batchesCache[productId]?.nextSequences?.[cacheKey] || "XX";

            return `${productCode}-${country}-${dateFormatted}-${seq}`;
        } catch (e) {
            return "--";
        }
    };

    return (
        <AuthenticatedLayout breadcrumbs={getInventoryBreadcrumbs(warehouse.id, warehouse.name, "手動入庫")}>
            <Head title={`新增庫存 - ${warehouse.name}`} />
            <div className="container mx-auto p-6 max-w-7xl">
                {/* 頁面標題與導航 - 已於先前任務優化 */}
                <div className="mb-6">
                    <div className="mb-6">
                        <Link href={`/warehouses/${warehouse.id}/inventory`}>
                            <Button
                                variant="outline"
                                className="gap-2 button-outlined-primary"
                            >
                                <ArrowLeft className="h-4 w-4" />
                                返回庫存管理
                            </Button>
                        </Link>
                    </div>

                    <div className="flex items-center justify-between">
                        <div>
                            <h1 className="text-2xl font-bold text-grey-0 flex items-center gap-2">
                                <Boxes className="h-6 w-6 text-primary-main" />
                                新增庫存（手動入庫）
                            </h1>
                            <p className="text-gray-500 mt-1">
                                為 <span className="font-semibold text-gray-900">{warehouse.name}</span> 新增庫存記錄
                            </p>
                        </div>
                        <Button
                            onClick={handleSave}
                            className="button-filled-primary"
                        >
                            <Save className="mr-2 h-4 w-4" />
                            儲存
                        </Button>
                    </div>
                </div>

                {/* 表單內容 */}
                <div className="space-y-6">
                    {/* 基本資訊區塊 */}
                    <div className="bg-white rounded-lg shadow-sm border p-6 space-y-4">
                        <h3 className="font-semibold text-lg border-b pb-2">基本資訊</h3>
                        <div className="grid grid-cols-1 md:grid-cols-2 gap-6">
                            {/* 倉庫 */}
                            <div className="space-y-2">
                                <Label className="text-gray-700">倉庫</Label>
                                <Input
                                    value={warehouse.name}
                                    disabled
                                    className="bg-gray-50 border-gray-200"
                                />
                            </div>

                            {/* 入庫日期 */}
                            <div className="space-y-2">
                                <Label htmlFor="inbound-date" className="text-gray-700">
                                    入庫日期 <span className="text-red-500">*</span>
                                </Label>
                                <div className="relative">
                                    <Calendar className="absolute left-2.5 top-2.5 h-4 w-4 text-gray-400 pointer-events-none" />
                                    <Input
                                        id="inbound-date"
                                        type="datetime-local"
                                        value={inboundDate}
                                        onChange={(e) => setInboundDate(e.target.value)}
                                        className="border-gray-300 pl-9"
                                    />
                                </div>
                            </div>

                            {/* 入庫原因 */}
                            <div className="space-y-2">
                                <Label htmlFor="reason" className="text-gray-700">
                                    入庫原因 <span className="text-red-500">*</span>
                                </Label>
                                <SearchableSelect
                                    value={reason}
                                    onValueChange={(value) => setReason(value as InboundReason)}
                                    options={INBOUND_REASONS.map((r) => ({ label: r, value: r }))}
                                    placeholder="選擇入庫原因"
                                    className="border-gray-300"
                                />
                                {errors.reason && (
                                    <p className="text-sm text-red-500">{errors.reason}</p>
                                )}
                            </div>

                            {/* 備註 */}
                            <div className="space-y-2 md:col-span-2">
                                <Label htmlFor="notes" className="text-gray-700">
                                    備註 {reason === "其他" && <span className="text-red-500">*</span>}
                                </Label>
                                <Textarea
                                    id="notes"
                                    value={notes}
                                    onChange={(e) => setNotes(e.target.value)}
                                    placeholder="請輸入備註說明..."
                                    className="border-gray-300 resize-none min-h-[100px]"
                                />
                                {errors.notes && (
                                    <p className="text-sm text-red-500">{errors.notes}</p>
                                )}
                            </div>
                        </div>
                    </div>

                    {/* 庫存明細區塊 */}
                    <div className="bg-white rounded-lg shadow-sm border p-6 space-y-4">
                        <div className="flex items-center justify-between">
                            <div>
                                <h3 className="font-semibold text-lg">庫存明細</h3>
                                <p className="text-sm text-gray-500">
                                    請新增要入庫的商品明細
                                </p>
                            </div>
                            <Button
                                type="button"
                                onClick={handleAddItem}
                                variant="outline"
                                className="button-outlined-primary"
                            >
                                <Plus className="mr-2 h-4 w-4" />
                                新增明細
                            </Button>
                        </div>

                        {errors.items && (
                            <p className="text-sm text-red-500">{errors.items}</p>
                        )}

                        {items.length > 0 ? (
                            <div className="border rounded-lg overflow-hidden">
                                <Table>
                                    <TableHeader>
                                        <TableRow className="bg-gray-50/50">
                                            <TableHead className="w-[180px]">
                                                商品 <span className="text-red-500">*</span>
                                            </TableHead>
                                            <TableHead className="w-[220px]">
                                                批號 <span className="text-red-500">*</span>
                                            </TableHead>
                                            <TableHead className="w-[100px]">
                                                數量 <span className="text-red-500">*</span>
                                            </TableHead>
                                            <TableHead className="w-[90px]">單位</TableHead>
                                            <TableHead className="w-[100px]">轉換數量</TableHead>
                                            <TableHead className="w-[140px]">效期</TableHead>
                                            <TableHead className="w-[50px]"></TableHead>
                                        </TableRow>
                                    </TableHeader>
                                    <TableBody>
                                        {items.map((item, index) => {
                                            // 計算轉換數量
                                            const convertedQuantity = item.selectedUnit === 'large' && item.conversionRate
                                                ? item.quantity * item.conversionRate
                                                : item.quantity;

                                            // Find product code
                                            const product = products.find(p => p.id === item.productId);

                                            return (
                                                <TableRow key={item.tempId}>
                                                    {/* 商品 */}
                                                    <TableCell>
                                                        <SearchableSelect
                                                            value={item.productId}
                                                            onValueChange={(value) =>
                                                                handleProductChange(item.tempId, value)
                                                            }
                                                            options={products.map((p) => ({ label: p.name, value: p.id }))}
                                                            placeholder="選擇商品"
                                                            searchPlaceholder="搜尋商品..."
                                                            className="border-gray-300"
                                                        />
                                                        {errors[`item-${index}-product`] && (
                                                            <p className="text-xs text-red-500 mt-1">
                                                                {errors[`item-${index}-product`]}
                                                            </p>
                                                        )}
                                                    </TableCell>

                                                    {/* 批號與產地控制 */}
                                                    <TableCell>
                                                        <div className="space-y-2">
                                                            <SearchableSelect
                                                                value={item.batchMode === 'new' ? 'new_batch' : (item.inventoryId || "")}
                                                                onValueChange={(value) => {
                                                                    if (value === 'new_batch') {
                                                                        handleUpdateItem(item.tempId, {
                                                                            batchMode: 'new',
                                                                            inventoryId: undefined,
                                                                            originCountry: 'TW',
                                                                            expiryDate: undefined
                                                                        });
                                                                    } else {
                                                                        const selectedBatch = (batchesCache[item.productId]?.batches || []).find(b => b.inventoryId === value);
                                                                        handleUpdateItem(item.tempId, {
                                                                            batchMode: 'existing',
                                                                            inventoryId: value,
                                                                            originCountry: selectedBatch?.originCountry,
                                                                            expiryDate: selectedBatch?.expiryDate || undefined
                                                                        });
                                                                    }
                                                                }}
                                                                options={[
                                                                    { label: "+ 建立新批號", value: "new_batch" },
                                                                    ...(batchesCache[item.productId]?.batches || []).map(b => ({
                                                                        label: `${b.batchNumber} - 庫存: ${b.quantity}`,
                                                                        value: b.inventoryId
                                                                    }))
                                                                ]}
                                                                placeholder="選擇或新增批號"
                                                                className="border-gray-300"
                                                            />
                                                            {errors[`item-${index}-batch`] && (
                                                                <p className="text-xs text-red-500">
                                                                    {errors[`item-${index}-batch`]}
                                                                </p>
                                                            )}

                                                            {item.batchMode === 'new' && (
                                                                <div className="flex items-center gap-2 mt-2">
                                                                    <div className="flex-1">
                                                                        <Input
                                                                            value={item.originCountry || ""}
                                                                            onChange={(e) => {
                                                                                const val = e.target.value.toUpperCase().slice(0, 2);
                                                                                handleUpdateItem(item.tempId, { originCountry: val });
                                                                            }}
                                                                            maxLength={2}
                                                                            placeholder="產地"
                                                                            className="h-8 text-xs text-center border-gray-300"
                                                                        />
                                                                    </div>
                                                                    <div className="flex-[3] text-xs bg-primary-50/50 text-primary-main px-2 py-1 rounded border border-primary-200/50 font-mono overflow-hidden whitespace-nowrap">
                                                                        {getBatchPreview(item.productId, product?.code, item.originCountry || 'TW', inboundDate)}
                                                                    </div>
                                                                </div>
                                                            )}

                                                            {item.batchMode === 'existing' && item.inventoryId && (
                                                                <div className="text-xs text-gray-500 px-2 font-mono">
                                                                    效期: {item.expiryDate || '未設定'}
                                                                </div>
                                                            )}
                                                        </div>
                                                    </TableCell>

                                                    {/* 數量 */}
                                                    <TableCell>
                                                        <Input
                                                            type="number"
                                                            min="1"
                                                            value={item.quantity || ""}
                                                            onChange={(e) =>
                                                                handleUpdateItem(item.tempId, {
                                                                    quantity: parseFloat(e.target.value) || 0,
                                                                })
                                                            }
                                                            className="border-gray-300"
                                                        />
                                                        {errors[`item-${index}-quantity`] && (
                                                            <p className="text-xs text-red-500 mt-1">
                                                                {errors[`item-${index}-quantity`]}
                                                            </p>
                                                        )}
                                                    </TableCell>

                                                    {/* 單位 */}
                                                    <TableCell>
                                                        {item.largeUnit ? (
                                                            <SearchableSelect
                                                                value={item.selectedUnit || ""}
                                                                onValueChange={(value) =>
                                                                    handleUpdateItem(item.tempId, {
                                                                        selectedUnit: value as 'base' | 'large',
                                                                        unit: value === 'base' ? item.baseUnit : item.largeUnit
                                                                    })
                                                                }
                                                                options={[
                                                                    { label: item.baseUnit || "個", value: "base" },
                                                                    { label: item.largeUnit || "", value: "large" }
                                                                ]}
                                                                className="border-gray-300"
                                                            />
                                                        ) : (
                                                            <Input
                                                                value={item.baseUnit || "個"}
                                                                disabled
                                                                className="bg-gray-50 border-gray-200"
                                                            />
                                                        )}
                                                    </TableCell>

                                                    {/* 轉換數量 */}
                                                    <TableCell>
                                                        <div className="flex items-center text-gray-700 font-medium bg-gray-50 px-3 py-2 rounded-md border border-gray-200">
                                                            <span>{convertedQuantity}</span>
                                                            <span className="ml-1 text-gray-500 text-sm">{item.baseUnit || "個"}</span>
                                                        </div>
                                                    </TableCell>

                                                    {/* 效期 */}
                                                    <TableCell>
                                                        <div className="relative">
                                                            <Calendar className="absolute left-2.5 top-2.5 h-4 w-4 text-gray-400 pointer-events-none" />
                                                            <Input
                                                                type="date"
                                                                value={item.expiryDate || ""}
                                                                onChange={(e) =>
                                                                    handleUpdateItem(item.tempId, {
                                                                        expiryDate: e.target.value,
                                                                    })
                                                                }
                                                                disabled={item.batchMode === 'existing'}
                                                                className={`border-gray-300 pl-9 ${item.batchMode === 'existing' ? 'bg-gray-50' : ''}`}
                                                            />
                                                        </div>
                                                    </TableCell>

                                                    {/* 刪除按鈕 */}
                                                    <TableCell>
                                                        <Button
                                                            type="button"
                                                            variant="ghost"
                                                            size="icon"
                                                            onClick={() => handleRemoveItem(item.tempId)}
                                                            className="hover:bg-red-50 hover:text-red-600 h-8 w-8"
                                                        >
                                                            <Trash2 className="h-4 w-4" />
                                                        </Button>
                                                    </TableCell>
                                                </TableRow>
                                            );
                                        })}
                                    </TableBody>
                                </Table>
                            </div>
                        ) : (
                            <div className="border border-dashed rounded-lg p-12 text-center text-gray-500 bg-gray-50/30">
                                <p className="text-base font-medium">尚無明細</p>
                                <p className="text-sm mt-1">請點擊右上方「新增明細」按鈕加入商品</p>
                            </div>
                        )}
                    </div>
                </div>
            </div>
        </AuthenticatedLayout>
    );
}