tapdb: add mint asset anchor output idx and universe commitments support

Add a new `assets_output_index` column to the
`asset_minting_batches` table to store the output index of the
asset anchor transaction. Populate this column for existing
entries based on the `change_output_index`.

Introduce a `universe_commitments` flag column to indicate
whether universe commitments are enabled for a minting batch,
defaulting to `FALSE`.

Create the `mint_anchor_uni_commitments` table to associate a
mint batch anchor transaction with its universe commitments,
storing the pre-commitment output index, Taproot internal key,
and asset group pub key.

Author: ffranr

tapdb/migrations.go

@@ -22,7 +22,7 @@ const (
 	// daemon.
 	//
 	// NOTE: This MUST be updated when a new migration is added.
-	LatestMigrationVersion = 29
+	LatestMigrationVersion = 30
 )
 
 // MigrationTarget is a functional option that can be passed to applyMigrations

tapdb/sqlc/assets.sql.go

@@ -0,0 +1,11 @@
+-- Drop the mint_anchor_uni_commitments table and its unique index.
+DROP INDEX IF EXISTS mint_anchor_uni_commitments_unique;
+
+-- Drop the table mint_anchor_uni_commitments.
+DROP TABLE IF EXISTS mint_anchor_uni_commitments;
+
+-- Drop the universe_commitments column from the asset_minting_batches table.
+ALTER TABLE asset_minting_batches DROP COLUMN universe_commitments;
+
+-- Drop the assets output index column from the asset_minting_batches table.
+ALTER TABLE asset_minting_batches DROP COLUMN assets_output_index;

tapdb/sqlc/migrations/000030_mint_anchor_uni_commitments.down.sql

@@ -0,0 +1,44 @@
+-- Add a column to the asset_minting_batches table which stores the output index
+-- of the asset anchor transaction output.
+ALTER TABLE asset_minting_batches ADD COLUMN assets_output_index INTEGER;
+
+-- Existing minting anchor transactions have exactly two outputs: the asset
+-- commitment and the change output. We can therefore infer the asset anchor
+-- output index from the change output index.
+UPDATE asset_minting_batches
+SET assets_output_index = CASE
+    WHEN change_output_index = 1 THEN 0
+    WHEN change_output_index = 0 THEN 1
+    -- If change_output_index is neither 0 nor 1, just set the asset anchor
+    -- output index to NULL.
+    ELSE NULL
+END;
+
+-- Add a flag column which indicates if the universe commitments are enabled for
+-- this minting batch. This should default to false for all existing minting
+-- batches.
+ALTER TABLE asset_minting_batches
+    ADD COLUMN universe_commitments BOOLEAN NOT NULL DEFAULT FALSE;
+
+-- Create a table to relate a mint batch anchor transaction to its universe
+-- commitments.
+CREATE TABLE IF NOT EXISTS mint_anchor_uni_commitments (
+    id INTEGER PRIMARY KEY,
+
+    -- The ID of the minting batch this universe commitment relates to.
+    batch_id INTEGER NOT NULL REFERENCES asset_minting_batches(batch_id),
+
+    -- The index of the mint batch anchor transaction pre-commitment output.
+    tx_output_index INTEGER NOT NULL,
+
+    -- The Taproot output internal key for the pre-commitment output.
+    taproot_internal_key BLOB,
+
+    -- The asset group key associated with the universe commitment.
+    group_key BLOB
+);
+
+-- Create a unique index on the mint_anchor_uni_commitments table to enforce the
+-- uniqueness of (batch_id, tx_output_index) pairs.
+CREATE UNIQUE INDEX mint_anchor_uni_commitments_unique
+    ON mint_anchor_uni_commitments (batch_id, tx_output_index);