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package main
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import (
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  "encoding/json"
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  "fmt"
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  "net"
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  "net/http"
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  "os"
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  "strings"
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  "time"
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  "github.com/gin-gonic/gin"
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)
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// LoginRequest defines the expected JSON structure
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type LoginRequest struct {
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  Username  string `json:"username" binding:"required"`
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  Password  string `json:"password" binding:"required"`
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  Timestamp int64  `json:"timestamp" binding:"required"`
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  UUID      string `json:"uuid" binding:"required"`
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}
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const fixedAuthBase64 = "mysecretkey"
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// isMobileUA detects mobile devices based on User-Agent
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func isMobileUA(ua string) bool {
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  ua = strings.ToLower(ua)
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  mobileKeywords := []string{"android", "iphone", "ipod", "ipad", "windows phone", "mobile"}
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  for _, kw := range mobileKeywords {
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    if strings.Contains(ua, kw) {
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      return true
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    }
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  }
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  return false
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}
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func main() {
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  r := gin.Default()
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  r.LoadHTMLGlob("templates/*")
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  r.GET("/page/:uuid", func(c *gin.Context) {
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    uuid := c.Param("uuid")
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    userAgent := c.Request.UserAgent()
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    isMobile := isMobileUA(userAgent)
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    templateName := "desktop.html"
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    if isMobile {
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      templateName = "mobile.html"
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    }
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    c.HTML(http.StatusOK, templateName, gin.H{"UUID": uuid})
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  })
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  r.POST("/api/user", loginHandler)
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  r.Run(":30494")
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}
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func loginHandler(c *gin.Context) {
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  // 1. Auth Header Validation
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  if c.GetHeader("Auth") != fixedAuthBase64 {
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    c.JSON(http.StatusUnauthorized, gin.H{"code": 401, "message": "Unauthorized"})
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    return
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  }
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  // 2. Parse Request Body
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  var req LoginRequest
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  if err := c.ShouldBindJSON(&req); err != nil {
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    c.JSON(http.StatusBadRequest, gin.H{"code": 400, "message": "Invalid Body"})
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    return
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  }
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  // 3. Metadata Collection
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  clientIP := getClientIP(c.Request)
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  userAgent := c.Request.UserAgent()
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  serverTime := time.Now().Format(time.RFC3339)
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  // 4. Log Construction
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  requestBody, _ := json.MarshalIndent(req, "", "  ")
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  logEntry := fmt.Sprintf(
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    "===== Request Log =====\nIP: %s\nUA: %s\nTime: %s\nBody:%s\n========================\n\n",
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    clientIP, userAgent, serverTime, string(requestBody),
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  )
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  // 5. File Persistence
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  _ = appendToLogFile("./api_logs.txt", logEntry)
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  c.JSON(http.StatusOK, gin.H{"code": 200, "message": "Logged successfully"})
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}
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func getClientIP(r *http.Request) string {
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  forwardedFor := r.Header.Get("X-Forwarded-For")
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  if forwardedFor != "" {
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    ips := strings.Split(forwardedFor, ",")
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    return strings.TrimSpace(ips[0])
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  }
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  ip, _, _ := net.SplitHostPort(r.RemoteAddr)
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  return ip
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}
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func appendToLogFile(filePath, content string) error {
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  file, err := os.OpenFile(filePath, os.O_APPEND|os.O_CREATE|os.O_WRONLY, 0644)
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  if err != nil {
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    return err
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  }
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  defer file.Close()
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  _, err = file.WriteString(content)
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  return err
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}
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}