feat: Add basic server implementation

7 files changed, 87 insertions, 13 deletions

diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/Column.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/Column.kt
index d1294f7..33727de 100644
--- a/database/core/src/main/kotlin/moe/nea/ledger/database/Column.kt
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/Column.kt
@@ -1,10 +1,31 @@
 package moe.nea.ledger.database
 
+import moe.nea.ledger.database.sql.IntoSelectable
+import moe.nea.ledger.database.sql.Selectable
+import java.sql.PreparedStatement
+
 class Column<T> @Deprecated("Use Table.column instead") constructor(
 	val table: Table,
 	val name: String,
 	val type: DBType<T>
-) {
+) : IntoSelectable<T> {
+	override fun asSelectable() = object : Selectable<T> {
+		override fun asSql(): String {
+			return qualifiedSqlName
+		}
+
+		override val dbType: DBType<T>
+			get() = this@Column.type
+
+		override fun guessColumn(): Column<T>? {
+			return this@Column
+		}
+
+		override fun appendToStatement(stmt: PreparedStatement, startIndex: Int): Int {
+			return startIndex
+		}
+	}
+
 	val sqlName get() = "`$name`"
 	val qualifiedSqlName get() = table.sqlName + "." + sqlName
 }
\ No newline at end of file
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/Query.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/Query.kt
index 7829fbb..e58eef4 100644
--- a/database/core/src/main/kotlin/moe/nea/ledger/database/Query.kt
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/Query.kt
@@ -3,19 +3,22 @@ package moe.nea.ledger.database
 import moe.nea.ledger.database.sql.ANDExpression
 import moe.nea.ledger.database.sql.BooleanExpression
 import moe.nea.ledger.database.sql.Clause
+import moe.nea.ledger.database.sql.IntoSelectable
 import moe.nea.ledger.database.sql.Join
 import moe.nea.ledger.database.sql.SQLQueryComponent
 import moe.nea.ledger.database.sql.SQLQueryGenerator.concatToFilledPreparedStatement
+import moe.nea.ledger.database.sql.Selectable
 import java.sql.Connection
 
 class Query(
 	val connection: Connection,
-	val selectedColumns: MutableList<Column<*>>,
+	val selectedColumns: MutableList<Selectable<*>>,
 	var table: Table,
 	var limit: UInt? = null,
 	var skip: UInt? = null,
 	val joins: MutableList<Join> = mutableListOf(),
 	val conditions: MutableList<BooleanExpression> = mutableListOf(),
+	var distinct: Boolean = false,
 //	var order: OrderClause?= null,
 ) : Iterable<ResultRow> {
 	fun join(table: Table, on: Clause): Query {
@@ -28,8 +31,10 @@ class Query(
 		return this
 	}
 
-	fun select(vararg columns: Column<*>): Query {
-		selectedColumns.addAll(columns)
+	fun select(vararg columns: IntoSelectable<*>): Query {
+		for (column in columns) {
+			this.selectedColumns.add(column.asSelectable())
+		}
 		return this
 	}
 
@@ -39,16 +44,29 @@ class Query(
 		return this
 	}
 
+	fun distinct(): Query {
+		this.distinct = true
+		return this
+	}
+
 	fun limit(limit: UInt): Query {
 		this.limit = limit
 		return this
 	}
 
 	override fun iterator(): Iterator<ResultRow> {
-		val columnSelections = selectedColumns.joinToString { it.qualifiedSqlName }
 		val elements = mutableListOf(
-			SQLQueryComponent.standalone("SELECT $columnSelections FROM ${table.sqlName}"),
+			SQLQueryComponent.standalone("SELECT"),
 		)
+		if (distinct)
+			elements.add(SQLQueryComponent.standalone("DISTINCT"))
+		selectedColumns.forEachIndexed { idx, it ->
+			elements.add(it)
+			if (idx != selectedColumns.lastIndex) {
+				elements.add(SQLQueryComponent.standalone(","))
+			}
+		}
+		elements.add(SQLQueryComponent.standalone("FROM ${table.sqlName}"))
 		elements.addAll(joins)
 		if (conditions.any()) {
 			elements.add(SQLQueryComponent.standalone("WHERE"))
@@ -84,7 +102,7 @@ class Query(
 				}
 				hasAdvanced = false
 				return ResultRow(selectedColumns.withIndex().associate {
-					it.value to it.value.type.get(results, it.index + 1)
+					it.value to it.value.dbType.get(results, it.index + 1)
 				})
 			}
 
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/ResultRow.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/ResultRow.kt
index d92f913..6715f27 100644
--- a/database/core/src/main/kotlin/moe/nea/ledger/database/ResultRow.kt
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/ResultRow.kt
@@ -1,9 +1,22 @@
 package moe.nea.ledger.database
 
-class ResultRow(val columnValues: Map<Column<*>, *>) {
+import moe.nea.ledger.database.sql.Selectable
+
+class ResultRow(val selectableValues: Map<Selectable<*>, *>) {
+	val columnValues = selectableValues.mapNotNull {
+		val col = it.key.guessColumn() ?: return@mapNotNull null
+		col to it.value
+	}.toMap()
+
 	operator fun <T> get(column: Column<T>): T {
 		val value = columnValues[column]
 			?: error("Invalid column ${column.name}. Only ${columnValues.keys.joinToString { it.name }} are available.")
 		return value as T
 	}
+
+	operator fun <T> get(column: Selectable<T>): T {
+		val value = selectableValues[column]
+			?: error("Invalid selectable ${column}. Only ${selectableValues.keys} are available.")
+		return value as T
+	}
 }
\ No newline at end of file
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/Table.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/Table.kt
index c136f48..61dc8f0 100644
--- a/database/core/src/main/kotlin/moe/nea/ledger/database/Table.kt
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/Table.kt
@@ -98,6 +98,6 @@ abstract class Table(val name: String) {
 	}
 
 	fun selectAll(connection: Connection): Query {
-		return Query(connection, columns.toMutableList(), this)
+		return Query(connection, columns.mapTo(mutableListOf()) { it.asSelectable() }, this)
 	}
 }
\ No newline at end of file
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/sql/IntoSelectable.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/IntoSelectable.kt
new file mode 100644
index 0000000..0068f6b
--- /dev/null
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/IntoSelectable.kt
@@ -0,0 +1,5 @@
+package moe.nea.ledger.database.sql
+
+interface IntoSelectable<T> {
+	fun asSelectable(): Selectable<T>
+}
\ No newline at end of file
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/sql/SQLQueryGenerator.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/SQLQueryGenerator.kt
index be81ff2..2eb54fd 100644
--- a/database/core/src/main/kotlin/moe/nea/ledger/database/sql/SQLQueryGenerator.kt
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/SQLQueryGenerator.kt
@@ -6,14 +6,14 @@ import java.sql.PreparedStatement
 
 object SQLQueryGenerator {
 	fun List<SQLQueryComponent>.concatToFilledPreparedStatement(connection: Connection): PreparedStatement {
-		var query = ""
+		val query = StringBuilder()
 		for (element in this) {
 			if (query.isNotEmpty()) {
-				query += " "
+				query.append(" ")
 			}
-			query += element.asSql()
+			query.append(element.asSql())
 		}
-		val statement = connection.prepareAndLog(query)
+		val statement = connection.prepareAndLog(query.toString())
 		var index = 1
 		for (element in this) {
 			val nextIndex = element.appendToStatement(statement, index)
diff --git a/database/core/src/main/kotlin/moe/nea/ledger/database/sql/Selectable.kt b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/Selectable.kt
new file mode 100644
index 0000000..a95b66b
--- /dev/null
+++ b/database/core/src/main/kotlin/moe/nea/ledger/database/sql/Selectable.kt
@@ -0,0 +1,17 @@
+package moe.nea.ledger.database.sql
+
+import moe.nea.ledger.database.Column
+import moe.nea.ledger.database.DBType
+
+/**
+ * Something that can be selected. Like a column, or an expression thereof
+ */
+interface Selectable<T> : SQLQueryComponent, IntoSelectable<T> {
+	override fun asSelectable(): Selectable<T> {
+		return this
+	}
+
+	val dbType: DBType<T>
+	fun guessColumn(): Column<T>?
+}
+