From b112b12a3fac204152cc60be4000dc53fe3def92 Mon Sep 17 00:00:00 2001
From: Justin Hawkins <justin@hawkins.id.au>
Date: Sun, 26 Sep 2021 21:15:04 +0930
Subject: [PATCH] Add version package

---
 version/version.go | 79 ++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 79 insertions(+)
 create mode 100644 version/version.go

diff --git a/version/version.go b/version/version.go
new file mode 100644
index 0000000..f2c5dd5
--- /dev/null
+++ b/version/version.go
@@ -0,0 +1,79 @@
+// Package version deals with versioning of the software
+package version
+
+import (
+	"encoding/json"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"net/http"
+
+	"golang.org/x/mod/semver"
+)
+
+type Info struct {
+	CurrentVersion       string `json:"current_version"`
+	GithubVersion        string `json:"github_version"`
+	UpgradeAvailable     bool   `json:"upgrade_available"`
+	GithubVersionFetched bool   `json:"-"`
+}
+
+func (i *Info) UpdateGitHubVersion() error {
+	i.GithubVersionFetched = false
+	versionUrl := "https://api.github.com/repos/tardisx/gropple/releases"
+	resp, err := http.Get(versionUrl)
+	if err != nil {
+		log.Fatal("Error getting response. ", err)
+	}
+	defer resp.Body.Close()
+
+	b, err := io.ReadAll(resp.Body)
+	if err != nil {
+		return fmt.Errorf("failed to read body: %v", err)
+	}
+
+	type release struct {
+		HTMLUrl string `json:"html_url"`
+		TagName string `json:"tag_name"`
+		Name    string `json:"name"`
+	}
+
+	var releases []release
+
+	err = json.Unmarshal(b, &releases)
+	if err != nil {
+		return fmt.Errorf("failed to read unmarshal: %v", err)
+	}
+	if len(releases) == 0 {
+		log.Printf("found no releases on github?")
+		return errors.New("no releases found")
+	}
+
+	i.GithubVersion = releases[0].Name
+
+	i.GithubVersionFetched = true
+	i.UpgradeAvailable = i.canUpgrade()
+	return nil
+}
+
+func (i *Info) canUpgrade() bool {
+	if !i.GithubVersionFetched {
+		return false
+	}
+
+	log.Printf("We are %s, github is %s", i.CurrentVersion, i.GithubVersion)
+
+	if !semver.IsValid(i.CurrentVersion) {
+		log.Fatalf("current version %s is invalid", i.CurrentVersion)
+	}
+
+	if !semver.IsValid(i.GithubVersion) {
+		log.Fatalf("github version %s is invalid", i.GithubVersion)
+	}
+
+	if semver.Compare(i.CurrentVersion, i.GithubVersion) == -1 {
+		return true
+	}
+	return false
+}