p/garmin.go

package main

import (
	"encoding/json"
	"fmt"
	"io"
	"log"
	"net/http"
	"net/url"
	"strings"
)

type garminClient struct {
	c          *http.Client
	mapshareID string
}

type garminResponse struct {
	Success bool `json:"success"`
	Error   *struct {
		Code int    `json:"code"`
		Msg  string `json:"msg"`
	} `json:"error"`
}

func newGarminClient(mapshareID string) *garminClient {
	return &garminClient{
		c:          &http.Client{},
		mapshareID: mapshareID,
	}
}

func (gc *garminClient) sendMessage(deviceIDs []string, sender, msg string) error {
	for _, deviceID := range deviceIDs {
		err := gc.sendToDevice(deviceID, sender, msg)
		if err != nil {
			return fmt.Errorf("device %s: %w", deviceID, err)
		}
	}
	return nil
}

func (gc *garminClient) sendToDevice(deviceID, sender, msg string) error {
	data := url.Values{}
	data.Set("deviceIds", deviceID)
	data.Set("messageText", msg)
	data.Set("fromAddr", sender)

	endpoint := fmt.Sprintf("https://share.garmin.com/%s/Map/SendMessageToDevices", gc.mapshareID)

	log.Printf("[->garmin] %s %s", endpoint, data.Encode())

	req, err := http.NewRequest("POST", endpoint, strings.NewReader(data.Encode()))
	if err != nil {
		return err
	}

	req.Header.Set("Content-Type", "application/x-www-form-urlencoded; charset=UTF-8")
	req.Header.Set("Accept", "application/json, text/javascript, */*; q=0.01")
	req.Header.Set("Origin", "https://share.garmin.com")
	req.Header.Set("Referer", fmt.Sprintf("https://share.garmin.com/%s", gc.mapshareID))
	req.Header.Set("X-Requested-With", "XMLHttpRequest")
	req.Header.Set("User-Agent", "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/605.1.15 (KHTML, like Gecko) Version/26.0 Safari/605.1.15")

	resp, err := gc.c.Do(req)
	if err != nil {
		return err
	}

	defer resp.Body.Close()
	body, _ := io.ReadAll(resp.Body)

	log.Printf("[<-garmin] %d %s", resp.StatusCode, string(body))

	if resp.StatusCode != 200 {
		return fmt.Errorf("HTTP %d: %s", resp.StatusCode, string(body))
	}

	var grResp garminResponse
	err = json.Unmarshal(body, &grResp)
	if err != nil {
		return fmt.Errorf("parse response: %w", err)
	}

	if !grResp.Success {
		if grResp.Error != nil {
			return fmt.Errorf("garmin error %d: %s", grResp.Error.Code, grResp.Error.Msg)
		}
		return fmt.Errorf("garmin returned success=false")
	}

	return nil
}