Added initial app with JSON weight extract.

.gitignore

@@ -0,0 +1,16 @@
+.dub
+docs.json
+__dummy.html
+docs/
+/fitbit-extract
+fitbit-extract.so
+fitbit-extract.dylib
+fitbit-extract.dll
+fitbit-extract.a
+fitbit-extract.lib
+fitbit-extract-test-*
+*.exe
+*.pdb
+*.o
+*.obj
+*.lst

dub.json

@@ -0,0 +1,9 @@
+{
+	"authors": [
+		"Andrew Lalis"
+	],
+	"copyright": "Copyright © 2024, Andrew Lalis",
+	"description": "Tools for parsing and extracting data from your FitBit export.",
+	"license": "MIT",
+	"name": "fitbit-extract"
+}

source/app.d

@@ -0,0 +1,58 @@
+import std.stdio;
+import std.json;
+import std.algorithm;
+import std.array;
+import std.csv;
+import std.datetime;
+import std.path;
+import std.file;
+import std.format;
+
+int main(string[] args) {
+	if (args.length < 2) {
+		stderr.writeln("Missing required first argument for FitBit directory.");
+		return 1;
+	}
+	string fitbitDir = args[1];
+	auto w = parseWeight(fitbitDir);
+	writeln("Date, Weight");
+	foreach (e; w) {
+		writefln!"%s, %0.1f"(e.date.toISOExtString, e.weight);
+	}
+	return 0;
+}
+
+struct WeightEntry {
+	Date date;
+	float weight;
+}
+
+WeightEntry[] parseWeight(string fitbitDir) {
+	string exportDataDir = buildPath(fitbitDir, "Global Export Data");
+	Appender!(WeightEntry[]) app;
+	foreach (DirEntry entry; dirEntries(exportDataDir, SpanMode.shallow, false)) {
+		if (startsWith(baseName(entry.name), "weight")) {
+			JSONValue weightArray = parseJSON(cast(string) std.file.read(entry.name));
+			foreach (JSONValue weightObj; weightArray.array) {
+				WeightEntry w;
+				w.weight = weightObj.object["weight"].floating;
+				int day, month, year;
+				formattedRead!"%d/%d/%d"(weightObj.object["date"].str, month, day, year);
+				w.date = Date(year + 2000, month, day);
+
+				bool dateAlreadyExists = false;
+				foreach (WeightEntry existingEntry; app[]) {
+					if (existingEntry.date == w.date) {
+						dateAlreadyExists = true;
+						break;
+					}
+				}
+
+				if (!dateAlreadyExists) app ~= w;
+			}
+		}
+	}
+	return app[]
+		.sort!((a, b) => a.date < b.date)
+		.array;
+}