Cashlink: simplify state detection

Also now in theory more resilient to very long cashlink tx histories
that can not be retrieved entirely from nodes such that knownFundingTx
is not included anymore. In this case the detection is now able to at
least reach CHARGED or CLAIMING (which is also displayed in the ui
similarly to CLAIMED) states.

src/lib/Cashlink.ts

@@ -139,10 +139,9 @@ class Cashlink {
     }
 
     /**
-     * Cashlink balance in luna
+     * Cashlink balance in luna, with pending outgoing transactions subtracted
      */
     public balance: number | null = null;
-    public state: CashlinkState;
 
     private _getNetwork: () => Promise<NetworkClient>;
     private _networkClientResolver!: (client: NetworkClient) => void;
@@ -160,7 +159,7 @@ class Cashlink {
         value?: number,
         fee?: number,
         message?: string,
-        state: CashlinkState = CashlinkState.UNCHARGED,
+        public state: CashlinkState = CashlinkState.UNCHARGED,
         theme?: CashlinkTheme,
         public timestamp: number = Math.floor(Date.now() / 1000),
         public contactName?: string, /** unused for now */
@@ -175,7 +174,6 @@ class Cashlink {
         if (fee) this.fee = fee;
         if (message) this.message = message;
         if (theme) this.theme = theme;
-        this.state = state;
 
         this._immutable = !!(value || message || theme);
 
@@ -205,7 +203,7 @@ class Cashlink {
     public async detectState() {
         await this._awaitConsensus();
 
-        const balance = await this._awaitBalance();
+        const balance = await this._awaitBalance(); // balance with pending outgoing transactions subtracted by nano-api
         const pendingTransactions = [
             ...(await this._getNetwork()).pendingTransactions,
             ...(await this._getNetwork()).relayedTransactions,
@@ -229,50 +227,25 @@ class Cashlink {
         );
         this._knownTransactions = this._knownTransactions.concat(transactionHistory.newTransactions);
 
-        let newState: CashlinkState = this.state;
-
         const knownFundingTx = this._knownTransactions.find(
             (tx) => tx.recipient === address);
-        const knownClaimingTx = this._knownTransactions.find(
-            (tx) => tx.sender === address);
 
-        switch (this.state) {
-            case CashlinkState.UNKNOWN:
-                if (!pendingFundingTx && !knownFundingTx) {
-                    newState = CashlinkState.UNCHARGED;
-                    break;
-                }
-            case CashlinkState.UNCHARGED:
-                if (pendingFundingTx) {
-                    newState = CashlinkState.CHARGING;
-                }
-            case CashlinkState.CHARGING:
-                if (!balance && !pendingFundingTx) {
-                    // Handle expired/replaced funding tx
-                    newState = CashlinkState.UNCHARGED;
-                    // Not break;ing here, because we need to see if the cashlink is already CLAIMED.
-                }
-                if (knownFundingTx) {
-                    newState = CashlinkState.UNCLAIMED;
-                } else break; // If no known transactions are found, no further checks are necessary
-            case CashlinkState.UNCLAIMED:
-                if (pendingClaimingTx) {
-                    newState = CashlinkState.CLAIMING;
-                }
-            case CashlinkState.CLAIMING:
-                if (balance) {
-                    // Handle recharged/reused cashlink
-                    if (!pendingClaimingTx) newState = CashlinkState.UNCLAIMED;
-                    break; // If a balance is detected on the cashlink, it cannot be in CLAIMED state.
-                }
-                if (knownClaimingTx) {
-                    newState = CashlinkState.CLAIMED;
-                }
-            case CashlinkState.CLAIMED:
-                // Detect cashlink re-use and chain rebranches
-                if (pendingFundingTx) newState = CashlinkState.CHARGING;
-                if (balance) newState = CashlinkState.UNCLAIMED;
-                if (pendingClaimingTx) newState = CashlinkState.CLAIMING;
+        // Detect new state by a sequence of checks from UNCHARGED, CHARGING, UNCLAIMED, CLAIMING to CLAIMED states.
+        // Note that cashlinks that already reached a later state in a previous detectState, can also go back to earlier
+        // states again, e.g. by pending funding/claiming txs expiring, blockchain rebranching or cashlink recharging.
+        let newState: CashlinkState = CashlinkState.UNCHARGED;
+        if (pendingFundingTx) {
+            newState = CashlinkState.CHARGING;
+        }
+        if (balance) {
+            newState = CashlinkState.UNCLAIMED;
+        }
+        if (pendingClaimingTx) {
+            newState = CashlinkState.CLAIMING;
+        }
+        if (knownFundingTx && !balance && !pendingFundingTx && !pendingClaimingTx) {
+            // Cashlink had been funded but no funds are left and it's not being recharged or still being claimed.
+            newState = CashlinkState.CLAIMED;
         }
 
         if (newState !== this.state) this._updateState(newState);