Make find command print satpoints instead of outpoints (#57)

README.md

@@ -72,14 +72,17 @@ If the coinbase transaction underpays the block subsidy or fees, those
 satoshis, along with their ordinal numbers, are destroyed and taken out of
 circulation.
 
-The `find` command, as of yet unfinished, gives the current outpoint containing
+The `find` command, as of yet unfinished, gives the current satpoint containing
 the satoshi with a given ordinal at a given height:
 
 ```
 $ ord find --blocksdir ~/.bicoin/blocks 0 0
-4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0
+4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0:0
 ```
 
+A satpoint is an outpoint, that is to say a transaction ID and output index,
+followed by the offset into the output itself, and gives the position of the
+satoshi within a particular output.
 
 ## Traits
 

src/command/find.rs

@@ -5,19 +5,17 @@ pub(crate) fn run(blocksdir: Option<&Path>, ordinal: Ordinal, at_height: u64) ->
 
   let height = ordinal.height().n();
   assert!(height < 100);
-  assert!(at_height == height);
+  assert!(height == at_height);
 
   let block = index.block(height)?;
 
-  let position = ordinal.subsidy_position();
-
-  let mut ordinal = 0;
-  for (i, output) in block.txdata[0].output.iter().enumerate() {
-    if ordinal + output.value >= position {
-      println!("{}:{}", block.txdata[0].txid(), i);
+  let mut offset = ordinal.subsidy_position();
+  for (index, output) in block.txdata[0].output.iter().enumerate() {
+    if output.value > offset {
+      println!("{}:{index}:{offset}", block.txdata[0].txid());
       break;
     }
-    ordinal += output.value;
+    offset -= output.value;
   }
 
   Ok(())

tests/find.rs

@@ -4,14 +4,22 @@ use super::*;
 fn first_satoshi() -> Result {
   Test::new()?
     .args(&["find", "--blocksdir", "blocks", "0", "0"])
-    .expected_stdout("4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0\n")
+    .expected_stdout("4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0:0\n")
+    .run()
+}
+
+#[test]
+fn second_satoshi() -> Result {
+  Test::new()?
+    .args(&["find", "--blocksdir", "blocks", "1", "0"])
+    .expected_stdout("4a5e1e4baab89f3a32518a88c31bc87f618f76673e2cc77ab2127b7afdeda33b:0:1\n")
     .run()
 }
 
 #[test]
 fn first_satoshi_of_second_block() -> Result {
   Test::new()?
     .args(&["find", "--blocksdir", "blocks", "5000000000", "1"])
-    .expected_stdout("e5fb252959bdc7727c80296dbc53e1583121503bb2e266a609ebc49cf2a74c1d:0\n")
+    .expected_stdout("e5fb252959bdc7727c80296dbc53e1583121503bb2e266a609ebc49cf2a74c1d:0:0\n")
     .run()
 }