1 files changed, 111 insertions, 0 deletions
diff --git a/internal/vocab/reader.go b/internal/vocab/reader.go
new file mode 100644
index 0000000..f1506ba
--- /dev/null
+++ b/internal/vocab/reader.go
@@ -0,0 +1,111 @@
+// Package vocab reads language-agnostic vocabulary files.
+package vocab
+
+import (
+	"fmt"
+	"os"
+	"strings"
+)
+
+// CardType identifies the semantic shape of a vocabulary entry.
+type CardType string
+
+const (
+	// CardTypeTranslation marks a standard word-to-translation entry.
+	CardTypeTranslation CardType = "translation"
+	// CardTypeDefinition marks a same-language word-to-definition entry.
+	CardTypeDefinition CardType = "definition"
+)
+
+// WordEntry represents a vocabulary entry with an optional translation.
+type WordEntry struct {
+	Word             string
+	Translation      string
+	NeedsTranslation bool
+	CardType         CardType
+}
+
+// ReadVocabularyFile reads vocabulary entries from a file and returns the parsed slice.
+func ReadVocabularyFile(filename string) ([]WordEntry, error) {
+	content, err := os.ReadFile(filename)
+	if err != nil {
+		return nil, fmt.Errorf("read vocabulary file: %w", err)
+	}
+
+	normalized := strings.ReplaceAll(string(content), "\r\n", "\n")
+	lines := strings.Split(normalized, "\n")
+	entries := make([]WordEntry, 0, len(lines))
+	for _, line := range lines {
+		if entry := parseLine(line); entry != nil {
+			entries = append(entries, *entry)
+		}
+	}
+
+	if len(entries) == 0 {
+		return nil, nil
+	}
+
+	return entries, nil
+}
+
+func parseLine(line string) *WordEntry {
+	trimmed := strings.TrimSpace(line)
+	if trimmed == "" {
+		return nil
+	}
+
+	if strings.Contains(trimmed, "==") {
+		parts := strings.SplitN(trimmed, "==", 2)
+		if len(parts) != 2 {
+			return nil
+		}
+
+		word := strings.TrimSpace(parts[0])
+		translation := strings.TrimSpace(parts[1])
+		if word == "" || translation == "" {
+			return nil
+		}
+
+		return &WordEntry{
+			Word:             word,
+			Translation:      translation,
+			NeedsTranslation: false,
+			CardType:         CardTypeDefinition,
+		}
+	}
+
+	if strings.Contains(trimmed, "=") {
+		parts := strings.SplitN(trimmed, "=", 2)
+		if len(parts) != 2 {
+			return nil
+		}
+
+		word := strings.TrimSpace(parts[0])
+		translation := strings.TrimSpace(parts[1])
+		if word == "" && translation != "" {
+			return &WordEntry{
+				Word:             "",
+				Translation:      translation,
+				NeedsTranslation: true,
+				CardType:         CardTypeTranslation,
+			}
+		}
+		if word != "" && translation != "" {
+			return &WordEntry{
+				Word:             word,
+				Translation:      translation,
+				NeedsTranslation: false,
+				CardType:         CardTypeTranslation,
+			}
+		}
+
+		return nil
+	}
+
+	return &WordEntry{
+		Word:             trimmed,
+		Translation:      "",
+		NeedsTranslation: false,
+		CardType:         CardTypeTranslation,
+	}
+}