package handler

import (
	"context"
	"fmt"
	"net/http"
	"os"
	"time"

	"bj_power_mes/common/httpx"
	"bj_power_mes/internal/svc"

	"github.com/zeromicro/go-zero/core/logx"
)

// diskStatusView 磁盘空间状态视图（附件中心顶部提示 + 定时告警共用）。
type diskStatusView struct {
	RootDir     string `json:"rootDir"`
	UsedPercent int    `json:"usedPercent"`
	FreeBytes   uint64 `json:"freeBytes"`
	TotalBytes  uint64 `json:"totalBytes"`
	WarnPercent int    `json:"warnPercent"`
	CritPercent int    `json:"critPercent"`
	Level       string `json:"level"` // ok / warn / critical / unknown
	Message     string `json:"message"`
	CheckedAt   int64  `json:"checkedAt"`
}

// diskStatus 读取附件根目录所在磁盘剩余空间并给出告警级别。
// 剩余 < DiskCriticalPercent → critical（提示执行备份归档清理）；< DiskWarnPercent → warn。
func diskStatus(svcCtx *svc.ServiceContext) diskStatusView {
	cfg := svcCtx.Config.Upload
	root := cfg.Dir
	if root == "" {
		root = "uploads"
	}
	v := diskStatusView{
		RootDir: root, WarnPercent: cfg.DiskWarnPercent, CritPercent: cfg.DiskCriticalPercent,
		Level: "ok", Message: "磁盘空间正常", CheckedAt: time.Now().Unix(),
	}
	used, free, total, err := diskUsage(root)
	if err != nil {
		_ = os.MkdirAll(root, 0o755)
		used, free, total, err = diskUsage(root)
	}
	if err != nil {
		v.Level = "unknown"
		v.Message = "磁盘空间检测失败：" + err.Error()
		return v
	}
	v.UsedPercent, v.FreeBytes, v.TotalBytes = used, free, total
	freePercent := 100 - used
	switch {
	case freePercent < cfg.DiskCriticalPercent:
		v.Level = "critical"
		v.Message = fmt.Sprintf("磁盘剩余空间仅 %d%%，低于 %d%%，请立即执行备份归档清理（附件中心可一键归档）", freePercent, cfg.DiskCriticalPercent)
	case freePercent < cfg.DiskWarnPercent:
		v.Level = "warn"
		v.Message = fmt.Sprintf("磁盘剩余空间 %d%%，低于 %d%% 告警线，请及时清理", freePercent, cfg.DiskWarnPercent)
	}
	return v
}

// DiskStatusHandler GET /attachment/disk-status
func DiskStatusHandler(svcCtx *svc.ServiceContext) http.HandlerFunc {
	return func(w http.ResponseWriter, r *http.Request) {
		httpx.Ok(w, diskStatus(svcCtx))
	}
}

// StartDiskMonitor 启动磁盘空间监控：每天 DiskCheckHour(默认 7 点) 检测一次，
// 剩余 <20% 告警、<10% 提示清理（写服务日志 + 操作日志，附件中心顶部同步展示）。
func StartDiskMonitor(svcCtx *svc.ServiceContext) {
	go func() {
		hour := svcCtx.Config.Upload.DiskCheckHour
		if hour < 0 || hour > 23 {
			hour = 7
		}
		for {
			now := time.Now()
			next := time.Date(now.Year(), now.Month(), now.Day(), hour, 0, 0, 0, time.Local)
			if !next.After(now) {
				next = next.Add(24 * time.Hour)
			}
			time.Sleep(time.Until(next))
			checkDiskOnce(svcCtx)
		}
	}()
}

func checkDiskOnce(svcCtx *svc.ServiceContext) {
	st := diskStatus(svcCtx)
	switch st.Level {
	case "critical":
		logx.Errorf("[磁盘监控] %s（已用 %d%%，剩余 %d%%）", st.Message, st.UsedPercent, 100-st.UsedPercent)
		svcCtx.EventLog.Write(context.Background(), "system.disk", "", "system", "attachment", "disk", st.Message,
			map[string]any{"usedPercent": st.UsedPercent, "freeBytes": st.FreeBytes})
	case "warn":
		logx.Alert("[磁盘监控] " + st.Message)
		svcCtx.EventLog.Write(context.Background(), "system.disk", "", "system", "attachment", "disk", st.Message,
			map[string]any{"usedPercent": st.UsedPercent, "freeBytes": st.FreeBytes})
	default:
		logx.Infof("[磁盘监控] 正常：剩余 %d%%（%s）", 100-st.UsedPercent, st.RootDir)
	}
}