Add hypothetical rank endpoint (#38)

app/start.go

@@ -102,6 +102,7 @@ func Start(dbO *sqlx.DB) *fhr.Router {
 		r.Method("/api/v1/scores", v1.ScoresGET)
 		r.Method("/api/v1/beatmaps/rank_requests/status", v1.BeatmapRankRequestsStatusGET)
 		r.Method("/api/v1/countries", v1.CountriesGET)
+		r.Method("/api/v1/hypothetical-rank", v1.HypotheticalRankGET)
 
 		// ReadConfidential privilege required
 		r.Method("/api/v1/friends", v1.FriendsGET, common.PrivilegeReadConfidential)

app/v1/rank.go

@@ -0,0 +1,77 @@
+package v1
+
+import (
+	"fmt"
+	"strconv"
+
+	"github.com/osuAkatsuki/akatsuki-api/common"
+	redis "gopkg.in/redis.v5"
+)
+
+type hypotheticalRankResponse struct {
+	common.ResponseBase
+	Rank int `json:"rank"`
+}
+
+func HypotheticalRankGET(md common.MethodData) common.CodeMessager {
+	modeInt, err := strconv.Atoi(md.Query("mode"))
+	if err != nil || modeInt > 3 || modeInt < 0 {
+		return common.SimpleResponse(400, "invalid mode")
+	}
+
+	mode := modesToReadable[modeInt]
+
+	rx, err := strconv.Atoi(md.Query("rx"))
+	if err != nil || rx > 2 || rx < 0 {
+		return common.SimpleResponse(400, "invalid relax int")
+	}
+
+	performancePoints, err := strconv.Atoi(md.Query("pp"))
+	if err != nil || performancePoints < 0 {
+		return common.SimpleResponse(400, "invalid performance points")
+	}
+
+	var rank int
+	var rankErr error
+	if rx == 0 {
+		rank, rankErr = rankAtPerformancePoints(md.R, mode, performancePoints)
+	} else if rx == 1 {
+		rank, rankErr = relaxRankAtPerformancePoints(md.R, mode, performancePoints)
+	} else if rx == 2 {
+		rank, rankErr = autopilotRankAtPerformancePoints(md.R, mode, performancePoints)
+	}
+
+	if rankErr != nil {
+		md.Err(err)
+		return common.SimpleResponse(500, "failed to calculate hypothetical rank")
+	}
+
+	resp := hypotheticalRankResponse{
+		Rank: rank,
+	}
+	resp.Code = 200
+	return resp
+}
+
+func rankAtPerformancePoints(r *redis.Client, mode string, performancePoints int) (int, error) {
+	return _rankAtPerformancePoints(r, "ripple:leaderboard:"+mode, performancePoints)
+}
+
+func relaxRankAtPerformancePoints(r *redis.Client, mode string, performancePoints int) (int, error) {
+	return _rankAtPerformancePoints(r, "ripple:relaxboard:"+mode, performancePoints)
+}
+
+func autopilotRankAtPerformancePoints(r *redis.Client, mode string, performancePoints int) (int, error) {
+	return _rankAtPerformancePoints(r, "ripple:autoboard:"+mode, performancePoints)
+}
+
+func _rankAtPerformancePoints(r *redis.Client, key string, performancePoints int) (int, error) {
+	res := r.ZCount(key, fmt.Sprintf("(%d", performancePoints), "inf")
+	err := res.Err()
+	if err != nil {
+		return -1, err
+	}
+
+	x := int(res.Val()) + 1
+	return x, nil
+}