Initial commit

2 files changed, 122 insertions, 0 deletions

diff --git a/api/minecraft/minecraft.go b/api/minecraft/minecraft.go
new file mode 100644
index 0000000..16cc0f3
--- /dev/null
+++ b/api/minecraft/minecraft.go
@@ -0,0 +1,82 @@
+package minecraft
+
+import (
+	"encoding/json"
+	"io"
+	"log"
+	"net/http"
+	"regexp"
+	"strconv"
+	"strings"
+	"time"
+
+	"penguins.lan/adapters/rcon"
+	"penguins.lan/api/types"
+	"penguins.lan/database"
+)
+
+const (
+	queryTimeout = 3 * time.Second
+	// staleAfter marks the cache offline if the scheduler stopped refreshing it.
+	staleAfter = 30 * time.Second
+)
+
+type Status struct {
+	Online  bool     `json:"online"`
+	Count   int      `json:"count"`
+	Max     int      `json:"max"`
+	Players []string `json:"players"`
+}
+
+var listPattern = regexp.MustCompile(`There are (\d+) of a max of (\d+) players online:?\s*(.*)`)
+
+// Query runs "list" over RCON. The scheduler calls this; requests read the cache.
+func Query(address, password string) (Status, error) {
+	client, err := rcon.Dial(address, password, queryTimeout)
+	if err != nil {
+		return Status{}, err
+	}
+	defer client.Close()
+
+	out, err := client.Execute("list")
+	if err != nil {
+		return Status{}, err
+	}
+	return parseList(out), nil
+}
+
+func parseList(out string) Status {
+	m := listPattern.FindStringSubmatch(strings.TrimSpace(out))
+	if m == nil {
+		return Status{Online: true}
+	}
+
+	count, _ := strconv.Atoi(m[1])
+	max, _ := strconv.Atoi(m[2])
+
+	players := []string{}
+	for _, p := range strings.Split(m[3], ",") {
+		if p = strings.TrimSpace(p); p != "" {
+			players = append(players, p)
+		}
+	}
+	return Status{Online: true, Count: count, Max: max, Players: players}
+}
+
+func StatusContinuation(context *types.RequestContext, req *http.Request, resp http.ResponseWriter) types.ContinuationChain {
+	return func(success types.Continuation, _failure types.Continuation) types.ContinuationChain {
+		resp.Header().Set("Content-Type", "application/json")
+
+		cached, updatedAt, err := database.GetMinecraftStatus(context.DBConn)
+		if err != nil {
+			log.Println("minecraft: read cache failed:", err)
+		}
+
+		if cached == "" || time.Since(updatedAt) > staleAfter {
+			json.NewEncoder(resp).Encode(Status{Online: false})
+		} else {
+			io.WriteString(resp, cached)
+		}
+		return success(context, req, resp)
+	}
+}
diff --git a/api/minecraft/minecraft_test.go b/api/minecraft/minecraft_test.go
new file mode 100644
index 0000000..0c89fc5
--- /dev/null
+++ b/api/minecraft/minecraft_test.go
@@ -0,0 +1,40 @@
+package minecraft
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestParseList(t *testing.T) {
+	cases := []struct {
+		out  string
+		want Status
+	}{
+		{
+			"There are 2 of a max of 20 players online: Alice, Bob",
+			Status{Online: true, Count: 2, Max: 20, Players: []string{"Alice", "Bob"}},
+		},
+		{
+			"There are 0 of a max of 20 players online:",
+			Status{Online: true, Count: 0, Max: 20, Players: []string{}},
+		},
+		{
+			"There are 1 of a max of 20 players online: Steve\n",
+			Status{Online: true, Count: 1, Max: 20, Players: []string{"Steve"}},
+		},
+		{
+			"some unexpected response",
+			Status{Online: true, Count: 0, Max: 0, Players: []string{}},
+		},
+	}
+
+	for _, c := range cases {
+		got := parseList(c.out)
+		if got.Players == nil {
+			got.Players = []string{}
+		}
+		if !reflect.DeepEqual(got, c.want) {
+			t.Errorf("parseList(%q) = %+v, want %+v", c.out, got, c.want)
+		}
+	}
+}