--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/src/core/anime_db.cpp	Sun Sep 10 03:59:16 2023 -0400
@@ -0,0 +1,78 @@
+#include "core/anime_db.h"
+#include "core/anime.h"
+
+namespace Anime {
+
+int Database::GetTotalAnimeAmount() {
+	int total = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.IsInUserList())
+			total++;
+	}
+	return total;
+}
+
+int Database::GetTotalEpisodeAmount() {
+	int total = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.IsInUserList()) {
+			total += anime.GetUserRewatchedTimes() * anime.GetEpisodes();
+			total += anime.GetUserProgress();
+		}
+	}
+	return total;
+}
+
+/* Returns the total watched amount in minutes. */
+int Database::GetTotalWatchedAmount() {
+	int total = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.IsInUserList()) {
+			total += anime.GetDuration() * anime.GetUserProgress();
+			total += anime.GetEpisodes() * anime.GetDuration() * anime.GetUserRewatchedTimes();
+		}
+	}
+	return total;
+}
+
+/* Returns the total planned amount in minutes.
+   Note that we should probably limit progress to the
+   amount of episodes, as AniList will let you
+   set episode counts up to 32768. But that should
+   rather be handled elsewhere. */
+int Database::GetTotalPlannedAmount() {
+	int total = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.IsInUserList())
+			total += anime.GetDuration() * (anime.GetEpisodes() - anime.GetUserProgress());
+	}
+	return total;
+}
+
+/* I'm sure many will appreciate this being called an
+   "average" instead of a "mean" */
+double Database::GetAverageScore() {
+	double avg = 0;
+	int amt = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.IsInUserList() && anime.GetUserScore()) {
+			avg += anime.GetUserScore();
+			amt++;
+		}
+	}
+	return avg / amt;
+}
+
+double Database::GetScoreDeviation() {
+	double squares_sum = 0, avg = GetAverageScore();
+	int amt = 0;
+	for (const auto& [id, anime] : items) {
+		if (anime.GetUserScore()) {
+			squares_sum += std::pow((double)anime.GetUserScore() - avg, 2);
+			amt++;
+		}
+	}
+	return (amt > 0) ? std::sqrt(squares_sum / amt) : 0;
+}
+
+} // namespace Anime
\ No newline at end of file