From e53bfa3aeb134ae3a00c28446d2b18eda5ffdbf4 Mon Sep 17 00:00:00 2001
From: Martin Polden <mpolden@mpolden.no>
Date: Tue, 21 Sep 2021 21:24:47 +0200
Subject: parser: Support episode numbers using roman numerals

---
 parser/parser.go      | 78 +++++++++++++++++++++++++++++++++++++++++++++++++--
 parser/parser_test.go | 48 +++++++++++++++++++++++++++++++
 2 files changed, 123 insertions(+), 3 deletions(-)

diff --git a/parser/parser.go b/parser/parser.go
index 1404542..a2087bf 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -17,7 +17,7 @@ var (
 		regexp.MustCompile(`^(?P<name>.+?)\.S(?P<season>\d{2})(?:E(?P<episode>\d{2}))?`), // S01, S01E04
 		regexp.MustCompile(`^(?P<name>.+?)\.E(?P<episode>\d{2})`),                        // E04
 		regexp.MustCompile(`^(?P<name>.+?)\.(?P<season>\d{1,2})x(?P<episode>\d{2})`),     // 1x04, 01x04
-		regexp.MustCompile(`^(?P<name>.+?)\.Part\.?(?P<episode>\d{1,2})`),                // Part4, Part11, Part.4, Part.11
+		regexp.MustCompile(`^(?P<name>.+?)\.P(?:ar)?t\.?(?P<episode>([^.]+))`),           // P(ar)t(.)11, Pt(.)XI
 	}
 	splitPattern = regexp.MustCompile(`[-_.]`)
 )
@@ -114,12 +114,15 @@ func Show(s string) (Media, error) {
 			case "season":
 				season, err = strconv.Atoi(group)
 				if err != nil {
-					return Media{}, fmt.Errorf("invalid input: %q: %s", s, err)
+					return Media{}, fmt.Errorf("invalid input: %q: %w", s, err)
 				}
 			case "episode":
 				episode, err = strconv.Atoi(group)
 				if err != nil {
-					return Media{}, fmt.Errorf("invalid input: %q: %s", s, err)
+					episode, err = rtoi(group)
+					if err != nil {
+						return Media{}, fmt.Errorf("invalid input: %q: %w", s, err)
+					}
 				}
 			}
 		}
@@ -165,3 +168,72 @@ func codec(s string) string {
 		return false
 	})
 }
+
+var numerals = []numeral{
+	// units
+	{"IX", 9},
+	{"VIII", 8},
+	{"VII", 7},
+	{"VI", 6},
+	{"IV", 4},
+	{"III", 3},
+	{"II", 2},
+	{"V", 5},
+	{"I", 1},
+	// tens
+	{"XC", 90},
+	{"LXXX", 80},
+	{"LXX", 70},
+	{"LX", 60},
+	{"XL", 40},
+	{"XXX", 30},
+	{"XX", 20},
+	{"L", 50},
+	{"X", 10},
+	// hundreds
+	{"CM", 900},
+	{"DCCC", 800},
+	{"DCC", 700},
+	{"DC", 600},
+	{"CD", 400},
+	{"CCC", 300},
+	{"CC", 200},
+	{"D", 500},
+	{"C", 100},
+	// thousands
+	{"MMM", 3000},
+	{"MM", 2000},
+	{"M", 1000},
+}
+
+type numeral struct {
+	s string
+	n int
+}
+
+func (n numeral) parse(s string, lastIndex int) (string, int, int) {
+	i := strings.LastIndex(s, n.s)
+	if i > -1 && i < lastIndex {
+		rest := s[:i] + s[i+len(n.s):]
+		return rest, i, n.n
+	}
+	return s, lastIndex, 0
+}
+
+func rtoi(s string) (int, error) {
+	// needlessly complete parsing of roman numerals
+	sum := 0
+	lastIndex := len(s)
+	for _, num := range numerals {
+		var n int
+		s, lastIndex, n = num.parse(s, lastIndex)
+		sum += n
+		if s == "" {
+			break
+		}
+	}
+	if s != "" {
+		return 0, fmt.Errorf("invalid roman numeral: %q", s)
+	}
+	return sum, nil
+}
diff --git a/parser/parser_test.go b/parser/parser_test.go
index caa8a02..cb6c3d7 100644
--- a/parser/parser_test.go
+++ b/parser/parser_test.go
@@ -172,6 +172,15 @@ func TestShow(t *testing.T) {
 				Episode: 16,
 				Codec:   "xvid",
 			}},
+		{"Generation.Kill.Pt.VII.Bomb.in.the.Garden.720p.Bluray.X264-DIMENSION",
+			Media{
+				Release:    "Generation.Kill.Pt.VII.Bomb.in.the.Garden.720p.Bluray.X264-DIMENSION",
+				Name:       "Generation.Kill",
+				Season:     1,
+				Episode:    7,
+				Resolution: "720p",
+				Codec:      "x264",
+			}},
 	}
 	for _, tt := range tests {
 		got, err := Show(tt.in)
@@ -200,3 +209,42 @@ func TestReplaceName(t *testing.T) {
 		t.Errorf("Expected %q, got %q", want, m.Name)
 	}
 }
+
+func TestRtoi(t *testing.T) {
+	assertRtoiErr(t, "foo")
+	assertRtoiErr(t, "VIM")
+	assertRtoiErr(t, "DMVI")
+
+	assertRtoi(t, "XXXIX", 39)
+	assertRtoi(t, "CCXLVI", 246)
+	assertRtoi(t, "DCCLXXXIX", 789)
+	assertRtoi(t, "MMCDXXI", 2421)
+
+	assertRtoi(t, "CLX", 160)
+	assertRtoi(t, "CCVII", 207)
+	assertRtoi(t, "MIX", 1009)
+	assertRtoi(t, "MLXVI", 1066)
+
+	assertRtoi(t, "MDCCLXXVI", 1776)
+	assertRtoi(t, "MCMXVIII", 1918)
+	assertRtoi(t, "MCMLIV", 1954)
+	assertRtoi(t, "MMXIV", 2014)
+
+	assertRtoi(t, "MMMCMXCIX", 3999)
+}
+
+func assertRtoiErr(t *testing.T, rnum string) {
+	if n, err := rtoi(rnum); err == nil {
+		t.Fatalf("rtoi(%q) = (%d, %v), want error", rnum, n, err)
+	}
+}
+
+func assertRtoi(t *testing.T, rnum string, expected int) {
+	n, err := rtoi(rnum)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if n != expected {
+		t.Errorf("rtoi(%q) = %d, want %d", rnum, n, expected)
+	}
+}
-- 
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