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package moe.nea.ledger.database
import java.sql.Connection
import java.sql.PreparedStatement
import java.sql.ResultSet
import java.time.Instant
interface DBSchema {
val tables: List<Table>
}
interface DBType<T> {
val dbType: String
fun get(result: ResultSet, index: Int): T
fun set(stmt: PreparedStatement, index: Int, value: T)
fun getName(): String = javaClass.simpleName
}
object DBString : DBType<String> {
override val dbType: String
get() = "TEXT"
override fun get(result: ResultSet, index: Int): String {
return result.getString(index)
}
override fun set(stmt: PreparedStatement, index: Int, value: String) {
stmt.setString(index, value)
}
}
object DBInt : DBType<Long> {
override val dbType: String
get() = "INTEGER"
override fun get(result: ResultSet, index: Int): Long {
return result.getLong(index)
}
override fun set(stmt: PreparedStatement, index: Int, value: Long) {
stmt.setLong(index, value)
}
}
object DBInstant : DBType<Instant> {
override val dbType: String
get() = "INTEGER"
override fun set(stmt: PreparedStatement, index: Int, value: Instant) {
stmt.setLong(index, value.toEpochMilli())
}
override fun get(result: ResultSet, index: Int): Instant {
return Instant.ofEpochMilli(result.getLong(index))
}
}
// TODO: add table
class Column<T> @Deprecated("Use Table.column instead") constructor(val name: String, val type: DBType<T>) {
val sqlName get() = "`$name`"
}
interface Constraint {
fun asSQL(): String
}
class UniqueConstraint(val columns: List<Column<*>>) : Constraint {
init {
require(columns.isNotEmpty())
}
override fun asSQL(): String {
return "UNIQUE (${columns.joinToString() { it.sqlName }})"
}
}
abstract class Table(val name: String) {
val sqlName get() = "`$name`"
protected val _mutable_columns: MutableList<Column<*>> = mutableListOf()
protected val _mutable_constraints: MutableList<Constraint> = mutableListOf()
val columns: List<Column<*>> get() = _mutable_columns
val constraints get() = _mutable_constraints
protected fun unique(vararg columns: Column<*>) {
_mutable_constraints.add(UniqueConstraint(columns.toList()))
}
protected fun <T> column(name: String, type: DBType<T>): Column<T> {
@Suppress("DEPRECATION") val column = Column(name, type)
_mutable_columns.add(column)
return column
}
fun debugSchema() {
val nameWidth = columns.maxOf { it.name.length }
val typeWidth = columns.maxOf { it.type.getName().length }
val totalWidth = maxOf(2 + nameWidth + 3 + typeWidth + 2, name.length + 4)
val adjustedTypeWidth = totalWidth - nameWidth - 2 - 3 - 2
var string = "\n"
string += ("+" + "-".repeat(totalWidth - 2) + "+\n")
string += ("| $name${" ".repeat(totalWidth - 4 - name.length)} |\n")
string += ("+" + "-".repeat(totalWidth - 2) + "+\n")
for (column in columns) {
string += ("| ${column.name}${" ".repeat(nameWidth - column.name.length)} |")
string += (" ${column.type.getName()}" +
"${" ".repeat(adjustedTypeWidth - column.type.getName().length)} |\n")
}
string += ("+" + "-".repeat(totalWidth - 2) + "+")
println(string)
}
fun createIfNotExists(connection: Connection) {
val properties = mutableListOf<String>()
for (column in columns) {
properties.add("${column.sqlName} ${column.type.dbType}")
}
for (constraint in constraints) {
properties.add(constraint.asSQL())
}
connection.prepareAndLog("CREATE TABLE IF NOT EXISTS `$name` (" + properties.joinToString() + ")")
.execute()
}
fun selectAll(connection: Connection): Query {
return Query(connection, columns, this)
}
}
fun Connection.prepareAndLog(statement: String): PreparedStatement {
println("Preparing to execute $statement")
return prepareStatement(statement)
}
class Query(
val connection: Connection,
val selectedColumns: List<Column<*>>,
var table: Table,
var limit: UInt? = null,
var skip: UInt? = null,
// var order: OrderClause?= null,
// val condition: List<SqlCondition>
) : Iterable<ResultRow> {
fun skip(skip: UInt): Query {
require(limit != null)
this.skip = skip
return this
}
fun limit(limit: UInt): Query {
this.limit = limit
return this
}
override fun iterator(): Iterator<ResultRow> {
val columnSelections = selectedColumns.joinToString { it.sqlName }
var query = "SELECT $columnSelections FROM ${table.sqlName} "
if (limit != null) {
query += "LIMIT $limit "
if (skip != null) {
query += "OFFSET $skip "
}
}
val prepared = connection.prepareAndLog(query)
val results = prepared.executeQuery()
return object : Iterator<ResultRow> {
var hasAdvanced = false
var hasEnded = false
override fun hasNext(): Boolean {
if (hasEnded) return false
if (hasAdvanced) return true
if (results.next()) {
hasAdvanced = true
return true
} else {
hasEnded = true
return false
}
}
override fun next(): ResultRow {
if (!hasNext()) {
throw NoSuchElementException()
}
hasAdvanced = false
return ResultRow(selectedColumns.withIndex().associate {
it.value to it.value.type.get(results, it.index + 1)
})
}
}
}
}
class ResultRow(val columnValues: Map<Column<*>, *>) {
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
}
}
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