basic web app

This commit is contained in:
Matthew Frost 2023-11-18 15:57:24 +01:00
parent 4da54d788e
commit 8721646b29
2 changed files with 111 additions and 87 deletions

157
main.go
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@ -1,60 +1,125 @@
package main
import (
"encoding/json"
"fmt"
"net/http"
"time"
"log"
"fmt"
"github.com/kenshaw/escpos"
"math"
"net/http"
"os"
"time"
)
// RequestData represents the JSON request body structure
type RequestData struct {
Date string `json:"date"`
Nickname string `json:"nickname"`
const ESC = byte(27)
func pageWidth(widht int) []byte {
return []byte{escpos.GS, 87, byte(widht), 0}
}
func pageMargin(margin int) []byte {
return []byte{escpos.GS, 76, byte(margin), 0}
}
func pageMode() []byte {
return []byte{ESC, 'L'}
}
func pageDirection(direction uint8) []byte {
// https://www.epson-biz.com/modules/ref_escpos/index.php?content_id=55
return []byte{ESC, 'T', direction}
}
func pagePrintArea(x, y, width, height int) []byte {
return []byte{ESC, 'W',
byte(x & 255), byte(x >> 8 & 255),
byte(y & 255), byte(y >> 8 & 255),
byte(width & 255), byte(width >> 8 & 255),
byte(height & 255), byte(height >> 8 & 255)}
}
func offsetY(offset int) []byte {
// A positive number specifies movement downward, and a negative number specifies movement upward.
// The horizontal or vertical motion unit is used for the print direction set by ESC T.
// When the starting position is set to the upper left or lower right of the print area using ESC T, the vertical motion unit is used.
// When the starting position is set to the upper right or lower left of the print area using ESC T, the horizontal motion unit is used.
return []byte{escpos.GS, '\\', byte(offset & 255), byte(offset >> 8 & 255)}
}
func offsetX(offset int) []byte {
// A positive number specifies movement to the right, and a negative number specifies movement to the left.
// When Standard mode is selected, the horizontal motion unit is used.
// when Page mode is selected, the horizontal or vertical motion unit is used for the print direction set by ESC T.
// When the starting position is set to the upper left or lower right of the print area using ESC T, the horizontal motion unit is used.
// When the starting position is set to the upper right or lower left of the print area using ESC T, the vertical motion unit is used.
return []byte{ESC, '\\', byte(offset & 255), byte(offset >> 8 & 255)}
}
func invert(n int) []byte {
//When the LSB of n is 0, white/black reverse print mode is turned off.
//n = 0 255
return []byte{escpos.GS, byte('B'), byte(n)}
}
func disableSensors() []byte {
return []byte{ESC, 'c', '3', 0}
}
func printSpeed(m int) []byte {
// m = 0 9, 48 57 : slowest - fastest
// [Default] 0 = Setting value of GS ( E <Function 5> customize value (a = 6)
// m = 0
//Slower print speed seems to retain a bit more quality in dithered images. pure B/W images do not have a noticable difference
return []byte{escpos.GS, '(', 'K', 2, 0, 50, byte(m & 255), byte(m >> 8 & 255)}
}
func main() {
// Set the output to unbuffered
log.SetOutput(os.Stdout)
f, err := os.OpenFile("/dev/usb/lp0", os.O_WRONLY|os.O_CREATE, 0)
if err != nil {
panic(err)
}
defer f.Close()
http.HandleFunc("/print/dnh-label", func(w http.ResponseWriter, r *http.Request) {
// Only handle POST requests
if r.Method != http.MethodPost {
http.Error(w, "Invalid request method", http.StatusMethodNotAllowed)
return
}
ep := escpos.New(f)
ep.Init()
// Parse JSON request body
var requestData RequestData
decoder := json.NewDecoder(r.Body)
if err := decoder.Decode(&requestData); err != nil {
http.Error(w, "Invalid JSON request body", http.StatusBadRequest)
return
}
http.HandleFunc("/create_label", func(w http.ResponseWriter, r *http.Request) {
createDnhLabelHandler(w, r, ep)
})
// Validate the date format
_, err := time.Parse("2006-01-02", requestData.Date)
if err != nil {
http.Error(w, "Invalid date format. Please use yyyy-mm-dd", http.StatusBadRequest)
return
}
// Process the request
response := fmt.Sprintf("Received Date: %s, Nickname: %s", requestData.Date, requestData.Nickname)
// Send a JSON response
w.Header().Set("Content-Type", "application/json")
w.WriteHeader(http.StatusOK)
json.NewEncoder(w).Encode(map[string]string{"message": response})
// Force immediate output to the console
log.Println(response)
})
// Start the server
fmt.Println("Server is running on :8080")
http.ListenAndServe(":8080", nil)
fmt.Println("Server starting on port 8080")
if err := http.ListenAndServe(":8080", nil); err != nil {
panic(err)
}
}
func createDnhLabelHandler(w http.ResponseWriter, r *http.Request, ep *escpos.Escpos) {
if r.Method != http.MethodPost {
http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
return
}
name := r.FormValue("name")
date := r.FormValue("date")
// Check if name is blank
if name == "" {
http.Error(w, "Name cannot be blank", http.StatusBadRequest)
return
}
// Set date to today if not defined
if date == "" {
date = time.Now().Format("2006-01-02")
}
// Here you can add the logic for creating a label using the POST data
text := fmt.Sprintf("%s - %s \n", name, date)
ep.Init()
ep.WriteRaw(pageMode())
ep.WriteRaw(pageDirection(1))
ep.WriteRaw(pagePrintArea(0, 0, int(math.Round((29.0/80.0)*512)), 850))
ep.WriteRaw(offsetY(30))
ep.SetFontSize(1, 1)
ep.Write("Technologia Incognita\n")
ep.WriteRaw(offsetY(35))
ep.SetFontSize(3, 2)
ep.SetEmphasize(1)
ep.Write("Do Not Hack\n")
ep.SetEmphasize(0)
ep.WriteRaw(offsetY(15))
ep.SetFontSize(1, 1)
ep.Write(text)
ep.WriteRaw([]byte{12}) // FF: in Page mode, prints all the data in the print buffer collectively and switches from Page mode to Standard mode.
ep.Cut()
ep.End()
}

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@ -1,41 +0,0 @@
package main
import (
"fmt"
"net/http"
"time"
)
func main() {
http.HandleFunc("/create_label", createLabelHandler)
fmt.Println("Server starting on port 8080")
if err := http.ListenAndServe(":8080", nil); err != nil {
panic(err)
}
}
func createLabelHandler(w http.ResponseWriter, r *http.Request) {
if r.Method != http.MethodPost {
http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
return
}
name := r.FormValue("name")
date := r.FormValue("date")
// Check if name is blank
if name == "" {
http.Error(w, "Name cannot be blank", http.StatusBadRequest)
return
}
// Set date to today if not defined
if date == "" {
date = time.Now().Format("2006-01-02")
}
// Here you can add the logic for creating a label using the POST data
fmt.Fprintf(w, "Label created! Name: %s, Date: %s", name, date)
}