From 5d44fa3a3048b9c7d2fcbbbf8d54e10f63729ad2 Mon Sep 17 00:00:00 2001
From: Alfie Day <azelphur@azelphur.com>
Date: Wed, 21 Aug 2024 17:49:21 +0100
Subject: [PATCH] Tracking Bitcoin Price (#5)

---
 README.md       | 26 ++++++++++++++++++
 sync-bitcoin.js | 71 +++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 97 insertions(+)
 create mode 100644 sync-bitcoin.js

diff --git a/README.md b/README.md
index 5afe4c5..5826f29 100644
--- a/README.md
+++ b/README.md
@@ -11,6 +11,7 @@ This is a collection of useful scripts to help you manage your Actual Budget.
     - [Tracking Home Prices (Zillow's Zestimate)](#tracking-home-prices-zillows-zestimate)
     - [Tracking Car Prices (Kelley Blue Book)](#tracking-car-prices-kelley-blue-book)
     - [Tracking Investment Accounts](#tracking-investment-accounts)
+    - [Tracking Bitcoin Price](#tracking-bitcoin-price)
 
 ## Requirements
 
@@ -50,6 +51,11 @@ INVESTMENT_CATEGORY_NAME="Investment"
 
 # optional, for logging into SimpleFIN
 SIMPLEFIN_CREDENTIALS="<credentials - not the setup token!>"
+
+# optional, for retrieving Bitcoin Price (these default to Kraken USD)
+BITCOIN_PRICE_URL="https://api.kraken.com/0/public/Ticker?pair=xbtusd"
+BITCOIN_PRICE_JSON_PATH="result.XXBTZUSD.c[0]"
+BITCOIN_PAYEE_NAME="Bitcoin Price Change"
 ```
 
 ## Installation
@@ -252,3 +258,23 @@ node track-investments.js
 
 It is recommended to run this script once per month.
 
+### Tracking Bitcoin Price
+
+This script tracks the value of Bitcoin. It adds new transactions to keep the
+account balance equal to the latest value. There is one tag you can set in the
+account notes, BTC:X, where X is the number of Bitcoin you own, eg `BTC:0.01`
+You can optionally change the API endpoint used to retrieve the Bitcoin price,
+an example for retrieving the price in GBP is:
+
+```
+BITCOIN_PRICE_URL="https://api.kraken.com/0/public/Ticker?pair=xbtgbp"
+BITCOIN_PRICE_JSON_PATH=".result.XXBTZGBP.c[0]"
+```
+
+To run:
+
+```console
+node sync-bitcoin.js
+```
+
+It is recommended to run this script once per day or week.
diff --git a/sync-bitcoin.js b/sync-bitcoin.js
new file mode 100644
index 0000000..1ab5a3e
--- /dev/null
+++ b/sync-bitcoin.js
@@ -0,0 +1,71 @@
+const { closeBudget, openBudget, getTransactions, getAccountNote, getAccountBalance, ensurePayee } = require('./utils');
+const api = require('@actual-app/api');
+
+function getValueAtPath(obj, path) {
+    const keys = path.split('.').filter(Boolean);
+    
+    return keys.reduce((acc, key) => {
+        const match = key.match(/^([^\[\]]+)(\[(\d+)\])?$/);
+        
+        if (match) {
+            const property = match[1];
+            const index = match[3];
+
+            acc = acc[property];
+
+            if (index !== undefined) {
+                acc = acc[parseInt(index, 10)];
+            }
+        } else {
+            acc = acc[key];
+        }
+        
+        return acc;
+    }, obj);
+}
+
+async function getBitcoinPrice() {
+  const url = process.env.BITCOIN_PRICE_URL || "https://api.kraken.com/0/public/Ticker?pair=xbtusd"
+  const path = process.env.BITCOIN_PRICE_JSON_PATH || "result.XXBTZUSD.c[0]"
+  try {
+    response = await fetch(url);
+    const json = await response.json();
+    return getValueAtPath(json, path);
+  } catch (error) {
+    return undefined;
+  }
+}
+
+(async () => {
+  const bitcoinPrice = await getBitcoinPrice();
+  if (!bitcoinPrice) {
+    throw new Error("Unable to retrieve Bitcoin price. Check your BITCOIN_PRICE_URL and BITCOIN_PRICE_JSON_PATH environment variables");
+  }
+  await openBudget();
+  const payeeId = await ensurePayee(process.env.BITCOIN_PAYEE_NAME || 'Bitcoin Price Change');
+  const accounts = await api.getAccounts();
+  for (const account of accounts) {
+    if (account.closed) {
+      continue;
+    }
+    const note = await getAccountNote(account);
+    if (!note || note.indexOf("BTC:") === -1) {
+      continue;
+    }
+    const btc_amount = note.split('BTC:')[1].split(' ')[0];
+    const currentBalance = await getAccountBalance(account);
+    const targetBalance = Math.round(bitcoinPrice * btc_amount * 100);
+    const diff = currentBalance - targetBalance;
+    if (diff != 0) {
+      await api.importTransactions(account.id, [{
+        date: new Date(),
+        payee: payeeId,
+        amount: diff,
+        cleared: true,
+        reconciled: true,
+        notes: "Updated Bitcoin Price",
+      }])
+    }
+  }
+  await closeBudget();
+})();