[libeufin] 02/02: implement history API

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ms pushed a commit to branch master
in repository libeufin.

commit 225bc67cbecee0f031bf3dfb4d1288235d0720da
Author: ms <ms@taler.net>
AuthorDate: Sun Jan 9 16:15:47 2022 +0100

    implement history API
---
 .../src/main/kotlin/tech/libeufin/sandbox/DB.kt    | 19 ++++++++++++
 .../src/main/kotlin/tech/libeufin/sandbox/Main.kt  | 36 +++++++++++++++++-----
 2 files changed, 48 insertions(+), 7 deletions(-)

diff --git a/sandbox/src/main/kotlin/tech/libeufin/sandbox/DB.kt 
b/sandbox/src/main/kotlin/tech/libeufin/sandbox/DB.kt
index 6e86b844..caf82ad5 100644
--- a/sandbox/src/main/kotlin/tech/libeufin/sandbox/DB.kt
+++ b/sandbox/src/main/kotlin/tech/libeufin/sandbox/DB.kt
@@ -338,10 +338,21 @@ object BankAccountTransactionsTable : LongIdTable() {
 class BankAccountTransactionEntity(id: EntityID<Long>) : LongEntity(id) {
     companion object : 
LongEntityClass<BankAccountTransactionEntity>(BankAccountTransactionsTable) {
         override fun new(init: BankAccountTransactionEntity.() -> Unit): 
BankAccountTransactionEntity {
+            /**
+             * Fresh transactions are those that wait to be included in a
+             * "history" report, likely a Camt.5x message.  The "fresh 
transactions"
+             * table keeps a list of such transactions.
+             */
             val freshTx = super.new(init)
             BankAccountFreshTransactionsTable.insert {
                 it[transactionRef] = freshTx.id
             }
+            /**
+             * The bank account involved in this transaction points to
+             * it as the "last known" transaction, to make it easier to
+             * build histories that depend on such record.
+             */
+            freshTx.account.lastTransaction = freshTx
             return freshTx
         }
     }
@@ -384,6 +395,13 @@ object BankAccountsTable : IntIdTable() {
     val owner = text("owner")
     val isPublic = bool("isPublic").default(false)
     val demoBank = reference("demoBank", DemobankConfigsTable)
+
+    /**
+     * Point to the last transaction related to this account, regardless
+     * of it being credit or debit.  This reference helps to construct
+     * history results that start from / depend on the last transaction.
+     */
+    val lastTransaction = reference("lastTransaction", 
BankAccountTransactionsTable).nullable()
 }
 
 class BankAccountEntity(id: EntityID<Int>) : IntEntity(id) {
@@ -395,6 +413,7 @@ class BankAccountEntity(id: EntityID<Int>) : IntEntity(id) {
     var owner by BankAccountsTable.owner
     var isPublic by BankAccountsTable.isPublic
     var demoBank by DemobankConfigEntity referencedOn 
BankAccountsTable.demoBank
+    var lastTransaction by BankAccountTransactionEntity optionalReferencedOn 
BankAccountsTable.lastTransaction
 }
 
 object BankAccountStatementsTable : IntIdTable() {
diff --git a/sandbox/src/main/kotlin/tech/libeufin/sandbox/Main.kt 
b/sandbox/src/main/kotlin/tech/libeufin/sandbox/Main.kt
index e3212e27..a74fd970 100644
--- a/sandbox/src/main/kotlin/tech/libeufin/sandbox/Main.kt
+++ b/sandbox/src/main/kotlin/tech/libeufin/sandbox/Main.kt
@@ -1279,8 +1279,7 @@ val sandboxApp: Application.() -> Unit = {
                     })
                     return@get
                 }
-                // This endpoint is being called "GET /transaction" in the 
docs.
-                get("/accounts/{account_name}/history") {
+                get("/accounts/{account_name}/transactions") {
                     val demobank = ensureDemobank(call)
                     val bankAccount = getBankAccountFromLabel(
                         call.getUriComponent("account_name"),
@@ -1290,13 +1289,36 @@ val sandboxApp: Application.() -> Unit = {
                     if (!authOk && (call.request.basicAuth() != 
bankAccount.owner)) throw forbidden(
                         "Cannot access bank account ${bankAccount.label}"
                     )
+
+                    val page: Int = 
Integer.decode(call.request.queryParameters["page"] ?: "1")
+                    val size: Int = 
Integer.decode(call.request.queryParameters["size"] ?: "5")
+
                     val ret = mutableListOf<RawPayment>()
+                    /**
+                     * Case where page number wasn't given,
+                     * therefore the results starts from the last transaction. 
*/
                     transaction {
-                        BankAccountTransactionEntity.find {
-                            BankAccountTransactionsTable.account eq 
bankAccount.id
-                            // FIXME: more criteria to come.
-                        }.forEach {
-                            ret.add(getHistoryElementFromTransactionRow(it))
+                        /**
+                         * Get a history page - from the calling bank account 
- having
+                         * 'firstElementId' as the latest transaction in it.  
*/
+                        fun getPage(firstElementId: Long): 
Iterable<BankAccountTransactionEntity> {
+                            return BankAccountTransactionEntity.find {
+                                (BankAccountTransactionsTable.id lessEq 
firstElementId) and
+                                        (BankAccountTransactionsTable.account 
eq bankAccount.id)
+                            }.take(size)
+                        }
+                        val lt: BankAccountTransactionEntity? = 
bankAccount.lastTransaction
+                        if (lt == null) return@transaction
+                        var firstElement: BankAccountTransactionEntity = lt
+                        /**
+                         * This loop fetches (and discards) pages until the
+                         * desired one is found.  */
+                        for (i in 0..(page)) {
+                            val pageBuf = getPage(firstElement.id.value)
+                            firstElement = pageBuf.last()
+                            if (i == page) pageBuf.forEach {
+                                
ret.add(getHistoryElementFromTransactionRow(it))
+                            }
                         }
                     }
                     call.respond(ret)

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