"use client";

import React, { useCallback, useEffect, useMemo, useState } from "react";
import { post } from "@/api/request";

/** 接口请求与返回类型定义 */
interface ConsumptionItem {
    /** 项目名称 */
    project_name: string;
    /** 总消耗（字符串数字） */
    total_consumption: string;
}

interface ConsumptionResponseData {
    consumption_list: ConsumptionItem[];
    page: number;
    page_size: number;
    total: number;
    period_days: 7 | 30 | 90;
}

interface ApiResponse<T = any> {
    code: number;
    message: string;
    data: T;
    successful: boolean;
}

type PeriodDays = 7 | 30 | 90;

/**
 * Credit 使用详情页
 * - 周期切换：7 / 30 / 90
 * - 分页：上一页/下一页（固定每页20）
 * - 表格展示：项目名、总消耗；不展示项目ID
 * - 空/错误状态：使用 “-” 显示
 */
const UsageView: React.FC = () => {
    const [days, setDays] = useState<PeriodDays>(7);
    const [page, setPage] = useState<number>(1);
    const pageSize = 20;

    const [loading, setLoading] = useState<boolean>(false);
    const [error, setError] = useState<string>("");
    const [items, setItems] = useState<ConsumptionItem[]>([]);
    const [total, setTotal] = useState<number>(0);
    const [serverPeriodDays, setServerPeriodDays] = useState<PeriodDays>(90);

    /** 读取 user_id（参考 dashboard/page.tsx） */
    const userId = useMemo(() => {
        try {
            const raw = localStorage.getItem("currentUser") || "{}";
            const u = JSON.parse(raw);
            return String(u?.id || "");
        } catch {
            return "";
        }
    }, []);

    const canPrev = page > 1;
    const canNext = useMemo(() => {
        if (total <= 0) return false;
        const maxPage = Math.ceil(total / pageSize);
        return page < maxPage;
    }, [page, total]);

    const loadData = useCallback(async () => {
        if (!userId) {
            setItems([]);
            setTotal(0);
            setError("no-user");
            return;
        }
        setLoading(true);
        setError("");
        try {
            const body = {
                user_id: userId,
                page,
                page_size: pageSize,
                days,
            };
            const res = await post<ApiResponse<ConsumptionResponseData>>(
                "/api/token/consumption",
                body
            );
            if (res && res.successful && res.code === 0) {
                setItems(res.data?.consumption_list || []);
                setTotal(res.data?.total || 0);
                setServerPeriodDays(res.data?.period_days || days);
            } else {
                setItems([]);
                setTotal(0);
                setError("api-error");
            }
        } catch {
            setItems([]);
            setTotal(0);
            setError("api-error");
        } finally {
            setLoading(false);
        }
    }, [userId, page, pageSize, days]);

    useEffect(() => {
        loadData();
    }, [loadData]);

    const handleChangeDays = useCallback((d: PeriodDays) => {
        setDays(d);
        setPage(1);
    }, []);

    const handlePrev = useCallback(() => {
        if (canPrev) setPage((p) => p - 1);
    }, [canPrev]);

    const handleNext = useCallback(() => {
        if (canNext) setPage((p) => p + 1);
    }, [canNext]);

    const periodLabel = useMemo(() => serverPeriodDays || days, [serverPeriodDays, days]);

    return (
        <div data-alt="usage-view-container" className="mx-auto max-w-5xl p-6">
            <div data-alt="header" className="mb-6 flex items-center justify-between">
                <h2 className="text-xl font-semibold text-white">Credit Usage Details</h2>
                <div data-alt="period-switch" className="inline-flex rounded-lg bg-white/5 p-1">
                    {([7, 30, 90] as PeriodDays[]).map((d) => (
                        <button
                            key={d}
                            type="button"
                            data-alt={`period-${d}`}
                            onClick={() => handleChangeDays(d)}
                            className={
                                `px-3 py-1.5 text-sm rounded-md transition-colors ` +
                                (days === d
                                    ? "bg-[#C039F6] text-white"
                                    : "text-white/80 hover:bg-white/10")
                            }
                        >
                            {d}d
                        </button>
                    ))}
                </div>
            </div>

            <div data-alt="meta" className="mb-3 text-sm text-white/70">
                <span data-alt="meta-period">Period: {periodLabel || "-"} days</span>
            </div>

            <div data-alt="table-wrapper" className="overflow-hidden rounded-lg border border-white/10">
                <table data-alt="table" className="min-w-full table-fixed">
                    <thead className="bg-white/5">
                        <tr>
                            <th className="w-2/3 px-4 py-2 text-left text-sm font-medium text-white">Project Name</th>
                            <th className="w-1/3 px-4 py-2 text-right text-sm font-medium text-white">Total Consumption</th>
                        </tr>
                    </thead>
                    <tbody className="divide-y divide-white/10">
                        {loading ? (
                            <tr>
                                <td className="px-4 py-3 text-white/70" colSpan={2} data-alt="row-loading">Loading...</td>
                            </tr>
                        ) : error ? (
                            <tr>
                                <td className="px-4 py-3 text-white/70" data-alt="row-error">-</td>
                                <td className="px-4 py-3 text-right text-white/70">-</td>
                            </tr>
                        ) : items.length === 0 ? (
                            <tr>
                                <td className="px-4 py-3 text-white/70" data-alt="row-empty">-</td>
                                <td className="px-4 py-3 text-right text-white/70">-</td>
                            </tr>
                        ) : (
                            items.map((it, idx) => (
                                <tr key={`${it.project_name}-${idx}`}>
                                    <td className="truncate px-4 py-2 text-white/90" data-alt="cell-project-name">
                                        {it?.project_name || "-"}
                                    </td>
                                    <td className="px-4 py-2 text-right text-white" data-alt="cell-total-consumption">
                                        {it?.total_consumption ?? "-"}
                                    </td>
                                </tr>
                            ))
                        )}
                    </tbody>
                </table>
            </div>

            <div data-alt="pagination" className="mt-4 flex items-center justify-between text-sm text-white/80">
                <div data-alt="total-info">
                    Total {Number.isFinite(total) ? total : 0}
                </div>
                <div data-alt="pager" className="inline-flex gap-2">
                    <button
                        type="button"
                        onClick={handlePrev}
                        disabled={!canPrev}
                        className={
                            "rounded-md px-3 py-1.5 transition-colors " +
                            (canPrev ? "bg-white/10 hover:bg-white/20" : "bg-white/5 text-white/40 cursor-not-allowed")
                        }
                        data-alt="prev-page"
                    >
                        Previous
                    </button>
                    <span data-alt="page-indicator" className="px-1 py-1.5">Page {page}</span>
                    <button
                        type="button"
                        onClick={handleNext}
                        disabled={!canNext}
                        className={
                            "rounded-md px-3 py-1.5 transition-colors " +
                            (canNext ? "bg-white/10 hover:bg-white/20" : "bg-white/5 text-white/40 cursor-not-allowed")
                        }
                        data-alt="next-page"
                    >
                        Next
                    </button>
                </div>
            </div>
        </div>
    );
};

export default React.memo(UsageView);