/*
Copyright (C) 2025 QuantumNous

This program is free software: you can redistribute it and/or modify
it under the terms of the GNU Affero General Public License as
published by the Free Software Foundation, either version 3 of the
License, or (at your option) any later version.

This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Affero General Public License for more details.

You should have received a copy of the GNU Affero General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>.

For commercial licensing, please contact support@quantumnous.com
*/

import { useState, useEffect, useRef, useCallback, useMemo } from 'react';
import { API, isAdmin, showError } from '../../helpers';

const PAGE_SIZE = 200;

const isSuccess = (l) =>
  l?.type === 0 || l?.status === 0 || l?.type === 'success';

const sum = (arr, key) =>
  arr.reduce((s, l) => s + (Number(l[key]) || 0), 0);

export const useDashboardData = (userState) => {
  const initialized = useRef(false);
  const [loading, setLoading] = useState(false);
  const [recentLogs, setRecentLogs] = useState([]);
  const [uptimeData, setUptimeData] = useState([]);
  const [uptimeLoading, setUptimeLoading] = useState(false);

  const isAdminUser = isAdmin();
  const user = userState?.user;
  const remaining = Number(user?.quota || 0);
  const used = Number(user?.used_quota || 0);
  const total = remaining + used;

  const loadRecentLogs = useCallback(async () => {
    setLoading(true);
    try {
      const now = Math.floor(Date.now() / 1000);
      const start = now - 30 * 86400;
      const url = isAdminUser
        ? `/api/log/?p=0&page_size=${PAGE_SIZE}&start_timestamp=${start}&end_timestamp=${now}`
        : `/api/log/self/?p=0&page_size=${PAGE_SIZE}&start_timestamp=${start}&end_timestamp=${now}`;
      const res = await API.get(url);
      const { success, message, data } = res.data;
      if (success) {
        setRecentLogs(data?.items || []);
      } else {
        showError(message);
      }
    } catch (err) {
      console.error(err);
    } finally {
      setLoading(false);
    }
  }, [isAdminUser]);

  const loadUptimeData = useCallback(async () => {
    setUptimeLoading(true);
    try {
      const res = await API.get('/api/uptime/status');
      const { success, message, data } = res.data;
      if (success) {
        setUptimeData(data || []);
      } else {
        showError(message);
      }
    } catch (err) {
      console.error(err);
    } finally {
      setUptimeLoading(false);
    }
  }, []);

  useEffect(() => {
    if (!initialized.current) {
      loadRecentLogs();
      loadUptimeData();
      initialized.current = true;
    }
  }, [loadRecentLogs, loadUptimeData]);

  // ========== Today / month metrics ==========
  const metrics = useMemo(() => {
    const now = new Date();
    const startOfDay = new Date(
      now.getFullYear(),
      now.getMonth(),
      now.getDate(),
    ).getTime() / 1000;
    const startOfMonth = new Date(
      now.getFullYear(),
      now.getMonth(),
      1,
    ).getTime() / 1000;

    const todayLogs = recentLogs.filter(
      (l) => (l?.created_at || 0) >= startOfDay && isSuccess(l),
    );
    const monthLogs = recentLogs.filter(
      (l) => (l?.created_at || 0) >= startOfMonth && isSuccess(l),
    );

    const todayLatencies = todayLogs
      .map((l) => Number(l?.use_time) || 0)
      .filter((v) => v > 0);

    return {
      today: {
        requests: todayLogs.length,
        tokens: sum(todayLogs, 'token_used'),
        cost: sum(todayLogs, 'quota'),
        avgLatency:
          todayLatencies.length > 0
            ? Math.round(
                todayLatencies.reduce((s, v) => s + v, 0) /
                  todayLatencies.length,
              )
            : null,
      },
      month: {
        requests: monthLogs.length,
        tokens: sum(monthLogs, 'token_used'),
        cost: sum(monthLogs, 'quota'),
      },
    };
  }, [recentLogs]);

  // ========== N-day daily stats (for sparkline) ==========
  const dailyStats = useMemo(() => {
    const now = new Date();
    const days = [];
    const n = 7;
    for (let i = n - 1; i >= 0; i--) {
      const d = new Date(now.getFullYear(), now.getMonth(), now.getDate() - i);
      const dayStart = Math.floor(d.getTime() / 1000);
      const dayEnd = dayStart + 86400;
      const dayLogs = recentLogs.filter(
        (l) => (l?.created_at || 0) >= dayStart && (l?.created_at || 0) < dayEnd && isSuccess(l),
      );
      days.push({
        date: d,
        count: dayLogs.length,
        cost: sum(dayLogs, 'quota'),
        tokens: sum(dayLogs, 'token_used'),
      });
    }
    return days;
  }, [recentLogs]);

  // ========== MoM delta (this month cost vs last month) ==========
  const monthDelta = useMemo(() => {
    const now = new Date();
    const startOfLastMonth = new Date(
      now.getFullYear(),
      now.getMonth() - 1,
      1,
    ).getTime() / 1000;
    const startOfThisMonth = new Date(
      now.getFullYear(),
      now.getMonth(),
      1,
    ).getTime() / 1000;
    const lastMonthLogs = recentLogs.filter(
      (l) =>
        (l?.created_at || 0) >= startOfLastMonth &&
        (l?.created_at || 0) < startOfThisMonth &&
        isSuccess(l),
    );
    const lastCost = sum(lastMonthLogs, 'quota');
    if (lastCost === 0) return null;
    return ((metrics.month.cost - lastCost) / lastCost) * 100;
  }, [recentLogs, metrics.month.cost]);

  // ========== Monthly forecast (projected end-of-month cost) ==========
  const monthlyForecast = useMemo(() => {
    const now = new Date();
    const daysInMonth = new Date(
      now.getFullYear(),
      now.getMonth() + 1,
      0,
    ).getDate();
    const daysElapsed = now.getDate();
    const spent = metrics.month.cost;
    const dailyAvg = daysElapsed > 0 ? spent / daysElapsed : 0;
    const projected = Math.round(dailyAvg * daysInMonth);

    return {
      spent,
      balance: remaining,
      dailyAvg: Math.round(dailyAvg),
      daysInMonth,
      daysElapsed,
      projected,
      monthDelta,
    };
  }, [metrics.month.cost, remaining, monthDelta]);

  // ========== Days remaining estimate ==========
  const daysRemaining = useMemo(() => {
    const now = new Date();
    const daysElapsed = now.getDate();
    if (metrics.month.cost === 0 || daysElapsed === 0) return null;
    const dailyAvg = metrics.month.cost / daysElapsed;
    if (dailyAvg === 0) return null;
    const days = Math.floor(remaining / dailyAvg);
    return days > 0 ? days : 0;
  }, [metrics.month.cost, remaining]);

  // ========== SLA overview (uptime / error rate / p95 latency) ==========
  const sla = useMemo(() => {
    const totalCalls = recentLogs.length;
    const successCalls = recentLogs.filter((l) => isSuccess(l)).length;
    const errorRate =
      totalCalls > 0 ? ((totalCalls - successCalls) / totalCalls) * 100 : null;

    const latencies = recentLogs
      .map((l) => Number(l?.use_time) || 0)
      .filter((v) => v > 0)
      .sort((a, b) => a - b);
    const p95Latency =
      latencies.length > 0
        ? latencies[Math.min(latencies.length - 1, Math.floor(latencies.length * 0.95))]
        : null;

    const healthyChannels = uptimeData.filter((c) => c?.status === 1).length;
    const uptime =
      uptimeData.length > 0
        ? uptimeData.reduce((s, c) => s + (Number(c?.uptime) || 0), 0) /
          uptimeData.length
        : null;
    const uptimePct =
      uptime != null ? uptime * 100 : healthyChannels / Math.max(uptimeData.length, 1) * 100;

    return {
      uptime: uptime != null ? uptimePct : null,
      errorRate,
      p95Latency,
      totalCalls,
      channelCount: uptimeData.length,
      healthyChannels,
    };
  }, [recentLogs, uptimeData]);

  // ========== Top models ==========
  const topModels = useMemo(() => {
    const m = new Map();
    recentLogs.forEach((l) => {
      const name = l?.model_name || '未知模型';
      m.set(name, (m.get(name) || 0) + 1);
    });
    return Array.from(m.entries())
      .map(([name, count]) => ({ name, count }))
      .sort((a, b) => b.count - a.count)
      .slice(0, 5);
  }, [recentLogs]);

  const refresh = useCallback(async () => {
    await Promise.all([loadRecentLogs(), loadUptimeData()]);
  }, [loadRecentLogs, loadUptimeData]);

  return {
    loading,
    recentLogs,
    uptimeData,
    uptimeLoading,
    metrics,
    dailyStats,
    monthDelta,
    daysRemaining,
    topModels,
    sla,
    monthlyForecast,
    refresh,
    quotaTotal: total,
  };
};