From 0ee116a416bf1868ed6ed3e7c040b24e13fdb549 Mon Sep 17 00:00:00 2001
From: siddharth <s@ricketyspace.net>
Date: Sun, 28 Nov 2021 17:23:55 -0500
Subject: db: add FernDB.Exists

---
 db/db.go      | 14 ++++++++++++++
 db/db_test.go | 43 +++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 57 insertions(+)

diff --git a/db/db.go b/db/db.go
index 6bc6d04..6dfda22 100644
--- a/db/db.go
+++ b/db/db.go
@@ -68,3 +68,17 @@ func Open() (*FernDB, error) {
 	}
 	return db, nil
 }
+
+func (fdb *FernDB) Exists(feed, entry string) bool {
+	if _, ok := fdb.downloaded[feed]; !ok {
+		return false
+	}
+	for _, e := range fdb.downloaded[feed] {
+		if e == entry {
+			return true
+		}
+	}
+	return false
+
+}
+
diff --git a/db/db_test.go b/db/db_test.go
index 37ec6ca..9a8642a 100644
--- a/db/db_test.go
+++ b/db/db_test.go
@@ -139,3 +139,46 @@ func TestOpenExistingDB(t *testing.T) {
 		}
 	}
 }
+
+func TestExists(t *testing.T) {
+	// Set custom path for db.
+	dbPath = path.Join(os.TempDir(), "fern-db.json")
+	defer os.Remove(dbPath)
+
+	// Write a sample test db to fern-db.json
+	testDBJSON := []byte(`{"npr":["william-prince","joy-oladokun","lucy-ducas"]}`)
+	dbFile, err := os.Create(dbPath)
+	defer dbFile.Close()
+	if err != nil {
+		t.Errorf("Unable to create fern-db.json: %v", err.Error())
+		return
+	}
+	n, err := dbFile.Write(testDBJSON)
+	if len(testDBJSON) != n {
+		t.Errorf("Write to fern-db.json failed: %v", err.Error())
+		return
+	}
+
+	// Open the db.
+	db, err := Open()
+	if err != nil {
+		t.Errorf("db.Open failed: %v", err.Error())
+		return
+	}
+
+	// Test Exists.
+	if db.Exists("mkbhd", "v-raptor") {
+		t.Errorf("db.Exists failed: mkbhd does not exist in db")
+		return
+	}
+	if db.Exists("npr", "julien-baker") {
+		t.Errorf("db.Exists failed: (%s, %s) does not exist in db",
+			"npr", "julien-baker")
+		return
+	}
+	if !db.Exists("npr", "joy-oladokun") {
+		t.Errorf("db.Exists failed: (%s, %s) exists in db",
+			"npr", "joy-oladokun")
+		return
+	}
+}
-- 
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