Add ability to search by arbitrary metadata

Example:

~/git/git-bug/git-bug ls --metadata github-url=https://github.com/author/myproject/issues/42

or

~/git/git-bug/git-bug ls metadata:github-url:\"https://github.com/author/myproject/issues/42\"

Fixes the cmdline part of <https://github.com/MichaelMure/git-bug/issues/567>.

5 files changed, 85 insertions, 8 deletions

diff --git a/query/lexer.go b/query/lexer.go
index 5ca700c7..45f657df 100644
--- a/query/lexer.go
+++ b/query/lexer.go
@@ -11,16 +11,20 @@ type tokenKind int
 const (
 	_ tokenKind = iota
 	tokenKindKV
+	tokenKindKVV
 	tokenKindSearch
 )
 
 type token struct {
 	kind tokenKind
 
-	// KV
+	// KV and KVV
 	qualifier string
 	value     string
 
+	// KVV only
+	subQualifier string
+
 	// Search
 	term string
 }
@@ -33,6 +37,15 @@ func newTokenKV(qualifier, value string) token {
 	}
 }
 
+func newTokenKVV(qualifier, subQualifier, value string) token {
+	return token{
+		kind:      tokenKindKVV,
+		qualifier: qualifier,
+		subQualifier: subQualifier,
+		value:     value,
+	}
+}
+
 func newTokenSearch(term string) token {
 	return token{
 		kind: tokenKindSearch,
@@ -50,7 +63,23 @@ func tokenize(query string) ([]token, error) {
 
 	var tokens []token
 	for _, field := range fields {
-		split := strings.Split(field, ":")
+		// Split using ':' as separator, but separators inside '"' don't count.
+		quoted := false
+		split := strings.FieldsFunc(field, func(r rune) bool {
+			if r == '"' {
+				quoted = !quoted
+			}
+			return !quoted && r == ':'
+		})
+		if (strings.HasPrefix(field, ":")) {
+			split = append([]string{""}, split...)
+		}
+		if (strings.HasSuffix(field, ":")) {
+			split = append(split, "")
+		}
+		if (quoted) {
+			return nil, fmt.Errorf("can't tokenize \"%s\": unmatched quote", field)
+		}
 
 		// full text search
 		if len(split) == 1 {
@@ -58,18 +87,31 @@ func tokenize(query string) ([]token, error) {
 			continue
 		}
 
-		if len(split) != 2 {
-			return nil, fmt.Errorf("can't tokenize \"%s\"", field)
+		if len(split) > 3 {
+			return nil, fmt.Errorf("can't tokenize \"%s\": too many separators", field)
 		}
 
 		if len(split[0]) == 0 {
 			return nil, fmt.Errorf("can't tokenize \"%s\": empty qualifier", field)
 		}
-		if len(split[1]) == 0 {
-			return nil, fmt.Errorf("empty value for qualifier \"%s\"", split[0])
-		}
 
-		tokens = append(tokens, newTokenKV(split[0], removeQuote(split[1])))
+		if len(split) == 2 {
+			if len(split[1]) == 0 {
+				return nil, fmt.Errorf("empty value for qualifier \"%s\"", split[0])
+			}
+
+			tokens = append(tokens, newTokenKV(split[0], removeQuote(split[1])))
+		} else {
+			if len(split[1]) == 0 {
+				return nil, fmt.Errorf("empty sub-qualifier for qualifier \"%s\"", split[0])
+			}
+
+			if len(split[2]) == 0 {
+				return nil, fmt.Errorf("empty value for qualifier \"%s:%s\"", split[0], split[1])
+			}
+
+			tokens = append(tokens, newTokenKVV(split[0], removeQuote(split[1]), removeQuote(split[2])))
+		}
 	}
 	return tokens, nil
 }
diff --git a/query/lexer_test.go b/query/lexer_test.go
index 59f17dec..4ffb35a0 100644
--- a/query/lexer_test.go
+++ b/query/lexer_test.go
@@ -37,6 +37,14 @@ func TestTokenize(t *testing.T) {
 		{`key:'value value`, nil},
 		{`key:value value'`, nil},
 
+		// sub-qualifier posive testing
+		{`key:subkey:"value:value"`, []token{newTokenKVV("key", "subkey", "value:value")}},
+
+		// sub-qualifier negative testing
+		{`key:subkey:value:value`, nil},
+		{`key:subkey:`, nil},
+		{`key:subkey:"value`, nil},
+
 		// full text search
 		{"search", []token{newTokenSearch("search")}},
 		{"search more terms", []token{
diff --git a/query/parser.go b/query/parser.go
index 762a47e5..e820c629 100644
--- a/query/parser.go
+++ b/query/parser.go
@@ -67,6 +67,21 @@ func Parse(query string) (*Query, error) {
 			default:
 				return nil, fmt.Errorf("unknown qualifier \"%s\"", t.qualifier)
 			}
+
+		case tokenKindKVV:
+			switch t.qualifier {
+			case "metadata":
+				if len(t.subQualifier) == 0 {
+					return nil, fmt.Errorf("empty value for sub-qualifier \"metadata:%s\"", t.subQualifier)
+				}
+				var pair StringPair
+				pair.Key = t.subQualifier
+				pair.Value = t.value
+				q.Metadata = append(q.Metadata, pair)
+
+			default:
+				return nil, fmt.Errorf("unknown qualifier \"%s:%s\"", t.qualifier, t.subQualifier)
+			}
 		}
 	}
 	return q, nil
diff --git a/query/parser_test.go b/query/parser_test.go
index 87dd870a..6d91d6cc 100644
--- a/query/parser_test.go
+++ b/query/parser_test.go
@@ -84,6 +84,11 @@ func TestParse(t *testing.T) {
 				OrderDirection: OrderDescending,
 			},
 		},
+
+		// Metadata
+		{`metadata:key:"https://www.example.com/"`, &Query{
+			Filters: Filters{Metadata: []StringPair{{"key", "https://www.example.com/"}}},
+		}},
 	}
 
 	for _, tc := range tests {
diff --git a/query/query.go b/query/query.go
index 816d6414..3a2321cf 100644
--- a/query/query.go
+++ b/query/query.go
@@ -23,10 +23,17 @@ func NewQuery() *Query {
 
 type Search []string
 
+// Used for key-value pairs when filtering based on metadata
+type StringPair struct {
+	Key string
+	Value string
+}
+
 // Filters is a collection of Filter that implement a complex filter
 type Filters struct {
 	Status      []bug.Status
 	Author      []string
+	Metadata    []StringPair
 	Actor       []string
 	Participant []string
 	Label       []string