WIP: random utxo selector

ARCH.md

@@ -85,7 +85,8 @@ Error conditions:
 ## Needed Extensions
 - Invoice generator that asks for addresses on behalf of ships and tracks whether they've made payments. `wallet-hook` could probably be renamed to `wallet-manager` and extended for this purpose.
 - `btc-provider` should push out address state in each block
-- `btc-wallet-store` should watch the next ~20 addresses in each wallet account, so that it can detect BTC sent to the wallet if the wallet is also managed/generates addresses in an outside-Urbit program.
+- `btc-wallet-store` should watch the next ~20 addresses in each wallet account, so that it can detect BTC sent to the wallet if the wallet is also manageed/generates addresses in an outside-Urbit program.
+- use Branch-and-Bound UTXO selection algo
 
 ## Possible Improvements/Changes
 - Do away with `btc-wallet-hook` altogether in its current form, and instead make `btc-provider` both a server (as it is now) and also a client. Pros: less between-agent data. Cons: complicates the otherwise simple provider module. PrA better solution might be to split just the connectivity parts of `btc-wallet-hook` into a local provider

WALLET.scratch.md

@@ -1,11 +1,7 @@
 # btc-wallet-* Scratch Code
 
 ## xpub
-Mnemonic
-```
-absurd sick rose mask magnet know slide spell rent casual someone grant giant inhale toward
-```
-
+xpub1 is from mnemonic from PRIVATE.scratch
 ```
 =xpub1 'zpub6r8dKyWJ31XF6n69KKeEwLjVC5ruqAbiJ4QCqLsrV36Mvx9WEjUaiPNPGFLHNCCqgCdy6iZC8ZgHsm6a1AUTVBMVbKGemNcWFcwBGSjJKbD'
 =xpub2 'xpub6D7yaZieZEeG617UcKXDhbsDeso6bmxSAiGWkvkASoiwcjaRtrH5HeNRnDT25s7zmxYzj6MtFe32dVqcf9YcBKKgn9THHjwn2uSjkvobK4e'
@@ -81,6 +77,8 @@ Uses `btc-wallet-hook`, with max-gap=3
 ## scrys
 ```
 .^((list @t) %gx /=btc-wallet-store=/scanned/noun)
+
+.^(@ud %gx /=btc-wallet-store=/balance/[xpub]/noun)
 ```
 
 ## Algos

app/btc-wallet-hook.hoon

@@ -25,8 +25,8 @@
       provider=(unit [host=ship connected=?])
       =btc-state
       def-wallet=(unit xpub)
-      padr=pend-addr
-      ptxb=pend-txbu
+      =pend-addr
+      =pend-txbu
       =piym
       =poym
       =piym-watch
@@ -141,10 +141,13 @@
     ==
     ::
       %pay-address
+    :: TODO: update poym
+    :: send tx request out for poym
+    ::  TODO: ask wallet to generate tbxu for poym
     `state
     ::
       %force-retry
-    [(retry padr) state]
+    [(retry pend-addr) state]
   ==
 ::  if status is %connected, retry all pending address lookups
 ::
@@ -156,7 +159,7 @@
   ?-  -.s
       %connected
     ::  only retry if previously disconnected
-    :-  ?:(connected.u.provider ~ (retry padr))
+    :-  ?:(connected.u.provider ~ (retry pend-addr))
     %=  state
         provider  `[host.u.provider %.y]
         btc-state  [blockcount.s fee.s now.bowl]
@@ -171,9 +174,9 @@
   ?.  ?=(%& -.update)  `state
   ?-  -.body.p.update
       %address-info
-    =/  ureq  (~(get by padr) req-id.p.update)
+    =/  ureq  (~(get by pend-addr) req-id.p.update)
     ?~  ureq  `state
-    :_  state(padr (~(del by padr) req-id.p.update))
+    :_  state(pend-addr (~(del by pend-addr) req-id.p.update))
     :~  %+  poke-wallet-store  /
         :*  %address-info  xpub.u.ureq  chyg.u.ureq  idx.u.ureq
             utxos.body.p.update  used.body.p.update  blockcount.body.p.update
@@ -187,7 +190,7 @@
   ?-  -.req
       %scan-address
     =/  ri=req-id:bp  (mk-req-id (hash-xpub:bwsl +>.req))
-    :_  state(padr (~(put by padr) ri req))
+    :_  state(pend-addr (~(put by pend-addr) ri req))
     ?~  provider  ~
     ?:  provider-connected
       ~[(get-address-info ri host.u.provider a.req)]
@@ -214,12 +217,13 @@
     state(piym (~(add ja piym) fam [address.upd payer value]))
     ::
       %scan-done
-    :: TODO: update def-wallet if none set
+    ?~  def-wallet
+      `state(def-wallet `xpub.upd)
     `state
   ==
 ::
 ++  retry
-  |=  p=pend-addr
+  |=  p=^pend-addr
   ^-  (list card)
   ?~  provider  ~|("provider not set" !!)
   %+  turn  ~(tap by p)

app/btc-wallet-store.hoon

@@ -7,6 +7,10 @@
 ::    - /requests: to request data about addresses
 ::    - /updates: new data about one of our addresses
 ::
+::  Scrys
+::  x/scanned: (list xpub) of all scanned wallets
+::  x/balance/xpub: balance (in sats) of wallet
+::
 /-  *btc-wallet-store
 /+  dbug, default-agent, *btc-wallet-store, btc, bip32
 |%
@@ -85,6 +89,9 @@
   ?+  pax  (on-peek:def pax)
       [%x %scanned ~]
     ``noun+!>(scanned-wallets)
+    ::
+      [%x %balance @ ~]
+    ``noun+!>((balance:hc (xpub:btc +>-.pax)))
   ==
 ++  on-leave  on-leave:def
 ++  on-agent  on-agent:def
@@ -154,7 +161,8 @@
     [(sy (gulf 0 endpoint)) endpoint %.n]
   :-  (weld (req-scan ~[/requests] b xpub %0) (req-scan ~[/requests] b xpub %1))
   state(scans (insert-batches xpub b b))
-::  if the batch is done but the wallet isn't done scanning, returns new address requests and updated batch
+::  if the batch is done but the wallet isn't done scanning,
+::  returns new address requests and updated batch
 ::
 ++  bump-batch
   |=  [=xpub =chyg]
@@ -236,4 +244,43 @@
   |=  [=xpub:btc w=walt]
   ^-  (unit xpub:btc)
   ?:  scanned.w  `xpub  ~
+::
+++  balance
+  |=  =xpub:btc
+  ^-  sats:btc
+  =/  w  (~(get by walts) xpub)
+  ?~  w  ~|("btc-wallet-store: non-existent xpub" !!)
+  =/  values=(list sats:btc)
+    %+  turn  ~(val by wach.u.w)
+    |=  =addi  ^-  sats:btc
+    %+  roll
+      %+  turn  ~(tap by utxos.addi)
+      |=(=utxo:btc value.utxo)
+    add
+  (roll values add)
+::  Uses naive random selection. Should switch to branch-and-bound later
+::
+++  select-utxos
+  |=  [target=sats w=walt]
+  ^-  (unit (list input))
+  =/  is=(list input)
+    %-  zing
+    %+  turn  ~(val by wach.w)
+    |=  =addi
+    %+  turn  ~(tap in utxos.addi)
+      |=(=utxo:btc [utxo chyg.addi idx.addi])
+  (single-random-draw target is)
+::
+++  single-random-draw
+  |=  [target=sats is=(list input)]
+  ^-  (unit (list input))
+  =|  [selected=(list input) total=sats:btc]
+  =/  rng  ~(. og eny.bowl)
+  |-  ?~  is  ~
+  =^  n  rng  (rads:rng (lent is))
+  =/  i  (snag n ((list input) is))
+  =/  new-total  (add total value.utxo.i)
+  ?:  (gth new-total target)
+    `[i selected]
+  $(is t.is, total new-total, selected [i selected])
 --

sur/btc-wallet-store.hoon

@@ -39,6 +39,9 @@
       max-gap=@ud
       confs=@ud
   ==
+::  input: utxo for a transaction
+::
++$  input  [=utxo =chyg =idx]
 ::  todo: Set of indices; empty it out until none are left--means scanning of that batch is done
 ::  start:     index this batch started scanning from
 ::