// Package api 日志管理 API：审计日志/连接日志的分页、筛选、导出、清理
package api

import (
	"encoding/csv"
	"fmt"
	"strconv"
	"strings"
	"time"

	"github.com/gin-gonic/gin"

	"vpn-platform/backend/internal/model"
	"vpn-platform/backend/internal/store"
)

// ---- 审计日志 ----

// listAuditPaged 分页查询审计日志（支持筛选）
// GET /api/audit-logs?page=1&page_size=20&username=xxx&action=xxx&keyword=xxx&start=2026-01-01&end=2026-12-31
func (s *Server) listAuditPaged(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	if page < 1 {
		page = 1
	}
	if pageSize < 1 || pageSize > 100 {
		pageSize = 20
	}

	q := store.DB.Model(&model.AuditLog{})

	if v := c.Query("username"); v != "" {
		q = q.Where("username = ?", v)
	}
	if v := c.Query("action"); v != "" {
		q = q.Where("action LIKE ?", "%"+v+"%")
	}
	if v := c.Query("keyword"); v != "" {
		q = q.Where("(target LIKE ? OR detail LIKE ?)", "%"+v+"%", "%"+v+"%")
	}
	if v := c.Query("start"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at >= ?", t)
		}
	}
	if v := c.Query("end"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at < ?", t.Add(24*time.Hour))
		}
	}

	var total int64
	q.Count(&total)

	var logs []model.AuditLog
	q.Order("id desc").Offset((page - 1) * pageSize).Limit(pageSize).Find(&logs)

	c.JSON(200, gin.H{
		"items":     logs,
		"total":     total,
		"page":      page,
		"page_size": pageSize,
	})
}

// exportAuditLogs 导出审计日志为 CSV
// GET /api/audit-logs/export?username=xxx&action=xxx&start=xxx&end=xxx
func (s *Server) exportAuditLogs(c *gin.Context) {
	q := store.DB.Model(&model.AuditLog{})
	if v := c.Query("username"); v != "" {
		q = q.Where("username = ?", v)
	}
	if v := c.Query("action"); v != "" {
		q = q.Where("action LIKE ?", "%"+v+"%")
	}
	if v := c.Query("keyword"); v != "" {
		q = q.Where("(target LIKE ? OR detail LIKE ?)", "%"+v+"%", "%"+v+"%")
	}
	if v := c.Query("start"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at >= ?", t)
		}
	}
	if v := c.Query("end"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at < ?", t.Add(24*time.Hour))
		}
	}

	var logs []model.AuditLog
	q.Order("id desc").Limit(10000).Find(&logs)

	filename := fmt.Sprintf("audit-logs-%s.csv", time.Now().Format("20060102-150405"))
	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	c.Writer.Write([]byte{0xEF, 0xBB, 0xBF}) // UTF-8 BOM

	w := csv.NewWriter(c.Writer)
	w.Write([]string{"ID", "时间", "用户", "操作", "目标", "详情"})
	for _, l := range logs {
		w.Write([]string{
			strconv.FormatUint(uint64(l.ID), 10),
			l.CreatedAt.Format("2006-01-02 15:04:05"),
			l.Username,
			l.Action,
			l.Target,
			l.Detail,
		})
	}
	w.Flush()
}

// ---- 连接日志 ----

// listConnectionLogsPaged 分页查询连接日志
// GET /api/connection-logs?page=1&page_size=20&username=xxx&event=xxx&tunnel_id=xxx&start=xxx&end=xxx
func (s *Server) listConnectionLogsPaged(c *gin.Context) {
	page, _ := strconv.Atoi(c.DefaultQuery("page", "1"))
	pageSize, _ := strconv.Atoi(c.DefaultQuery("page_size", "20"))
	if page < 1 {
		page = 1
	}
	if pageSize < 1 || pageSize > 100 {
		pageSize = 20
	}

	q := store.DB.Model(&model.ConnectionLog{})

	if v := c.Query("username"); v != "" {
		q = q.Where("username = ?", v)
	}
	if v := c.Query("event"); v != "" {
		events := strings.Split(v, ",")
		q = q.Where("event IN ?", events)
	}
	if v := c.Query("tunnel_id"); v != "" {
		if tid, err := strconv.Atoi(v); err == nil {
			q = q.Where("tunnel_id = ?", tid)
		}
	}
	if v := c.Query("keyword"); v != "" {
		q = q.Where("(detail LIKE ? OR ip_address LIKE ?)", "%"+v+"%", "%"+v+"%")
	}
	if v := c.Query("start"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at >= ?", t)
		}
	}
	if v := c.Query("end"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at < ?", t.Add(24*time.Hour))
		}
	}

	var total int64
	q.Count(&total)

	var logs []model.ConnectionLog
	q.Order("id desc").Offset((page - 1) * pageSize).Limit(pageSize).Find(&logs)

	c.JSON(200, gin.H{
		"items":     logs,
		"total":     total,
		"page":      page,
		"page_size": pageSize,
	})
}

// exportConnectionLogs 导出连接日志为 CSV
func (s *Server) exportConnectionLogs(c *gin.Context) {
	q := store.DB.Model(&model.ConnectionLog{})
	if v := c.Query("username"); v != "" {
		q = q.Where("username = ?", v)
	}
	if v := c.Query("event"); v != "" {
		events := strings.Split(v, ",")
		q = q.Where("event IN ?", events)
	}
	if v := c.Query("tunnel_id"); v != "" {
		if tid, err := strconv.Atoi(v); err == nil {
			q = q.Where("tunnel_id = ?", tid)
		}
	}
	if v := c.Query("keyword"); v != "" {
		q = q.Where("(detail LIKE ? OR ip_address LIKE ?)", "%"+v+"%", "%"+v+"%")
	}
	if v := c.Query("start"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at >= ?", t)
		}
	}
	if v := c.Query("end"); v != "" {
		if t, err := time.Parse("2006-01-02", v); err == nil {
			q = q.Where("created_at < ?", t.Add(24*time.Hour))
		}
	}

	var logs []model.ConnectionLog
	q.Order("id desc").Limit(10000).Find(&logs)

	filename := fmt.Sprintf("connection-logs-%s.csv", time.Now().Format("20060102-150405"))
	c.Header("Content-Type", "text/csv; charset=utf-8")
	c.Header("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
	c.Writer.Write([]byte{0xEF, 0xBB, 0xBF})

	w := csv.NewWriter(c.Writer)
	w.Write([]string{"ID", "时间", "隧道ID", "用户名", "事件", "IP地址", "详情"})
	for _, l := range logs {
		w.Write([]string{
			strconv.FormatUint(uint64(l.ID), 10),
			l.CreatedAt.Format("2006-01-02 15:04:05"),
			strconv.FormatUint(uint64(l.TunnelID), 10),
			l.Username,
			l.Event,
			l.IPAddress,
			l.Detail,
		})
	}
	w.Flush()
}

// ---- 日志清理 ----

// cleanupLogs 清理过期日志
// POST /api/logs/cleanup  {"days": 30}
func (s *Server) cleanupLogs(c *gin.Context) {
	var req struct {
		Days int `json:"days"`
	}
	if err := c.ShouldBindJSON(&req); err != nil || req.Days < 1 {
		req.Days = 30
	}

	cutoff := time.Now().AddDate(0, 0, -req.Days)

	var auditDeleted, connDeleted, sessionDeleted int64

	store.DB.Where("created_at < ?", cutoff).Delete(&model.AuditLog{}).Count(&auditDeleted)
	store.DB.Where("created_at < ?", cutoff).Delete(&model.ConnectionLog{}).Count(&connDeleted)
	store.DB.Where("connected_at < ? AND status = ?", cutoff, "disconnected").Delete(&model.VPNSession{}).Count(&sessionDeleted)

	store.Audit(c.GetString("username"), "cleanup_logs", "", fmt.Sprintf("清理 %d 天前日志: 审计=%d 连接=%d 会话=%d", req.Days, auditDeleted, connDeleted, sessionDeleted))

	c.JSON(200, gin.H{
		"ok":               true,
		"audit_deleted":    auditDeleted,
		"conn_deleted":     connDeleted,
		"session_deleted":  sessionDeleted,
		"cutoff":           cutoff.Format("2006-01-02"),
	})
}

// logStats 日志统计（各表记录数 + 最早/最新记录时间）
// GET /api/logs/stats
func (s *Server) logStats(c *gin.Context) {
	type stat struct {
		Count  int64  `json:"count"`
		Oldest string `json:"oldest"`
		Newest string `json:"newest"`
	}

	getStat := func(modelName interface{}) stat {
		var st stat
		store.DB.Model(modelName).Count(&st.Count)
		// SQLite 的 MIN/MAX 返回字符串，直接扫 string 更兼容
		store.DB.Model(modelName).Select("COALESCE(MIN(created_at),'')").Scan(&st.Oldest)
		store.DB.Model(modelName).Select("COALESCE(MAX(created_at),'')").Scan(&st.Newest)
		return st
	}

	// vpn_sessions 用 connected_at
	getSessionStat := func() stat {
		var st stat
		store.DB.Model(&model.VPNSession{}).Count(&st.Count)
		store.DB.Model(&model.VPNSession{}).Select("COALESCE(MIN(connected_at),'')").Scan(&st.Oldest)
		store.DB.Model(&model.VPNSession{}).Select("COALESCE(MAX(connected_at),'')").Scan(&st.Newest)
		return st
	}

	c.JSON(200, gin.H{
		"audit":      getStat(&model.AuditLog{}),
		"connection": getStat(&model.ConnectionLog{}),
		"session":    getSessionStat(),
	})
}

// ---- 自动清理（启动时调用）----

// AutoCleanupLogs 自动清理超过 keepDays 天的旧日志（0 = 不清理）
func AutoCleanupLogs(keepDays int) {
	if keepDays <= 0 || store.DB == nil {
		return
	}
	cutoff := time.Now().AddDate(0, 0, -keepDays)
	store.DB.Where("created_at < ?", cutoff).Delete(&model.AuditLog{})
	store.DB.Where("created_at < ?", cutoff).Delete(&model.ConnectionLog{})
	store.DB.Where("connected_at < ? AND status = ?", cutoff, "disconnected").Delete(&model.VPNSession{})
	store.DB.Where("created_at < ?", cutoff).Delete(&model.TrafficSample{}) // 保留最近 30 天流量采样
}