SQLite.kt

package kore.sqlite

import android.content.Context
import android.database.Cursor
import android.database.sqlite.SQLiteDatabase
import android.database.sqlite.SQLiteStatement
import java.io.File

class SQLite(
    private val context: Context,
    private val fileName:String? = null
){
    private var _db: SQLiteDatabase? = null
    private val db:SQLiteDatabase get() = _db ?: run{
        val dbFile = File(context.getDatabasePath(fileName), "$fileName.sqlite")
        dbFile.parentFile?.mkdirs()
        SQLiteDatabase.openOrCreateDatabase(dbFile, null).also{_db = it}
    }
    private fun fillResult(cursor: Cursor, container: ArrayList<Map<String, Any?>>) {
        val colCount = cursor.columnCount
        val colNames = cursor.columnNames
        while (cursor.moveToNext()) {
            val row = mutableMapOf<String, Any?>()
            for (i in 0 until colCount) {
                row[colNames[i]] = when (cursor.getType(i)) {
                    Cursor.FIELD_TYPE_NULL    -> null
                    Cursor.FIELD_TYPE_INTEGER -> cursor.getLong(i)
                    Cursor.FIELD_TYPE_FLOAT   -> cursor.getDouble(i)
                    Cursor.FIELD_TYPE_STRING  -> cursor.getString(i)
                    Cursor.FIELD_TYPE_BLOB    -> cursor.getBlob(i)
                    else -> null
                }
            }
            container.add(row)
        }
    }
    fun close() {
        if(db.isOpen) db.close()
    }
    fun exec(sql: String):Boolean
    = try{
        db.execSQL(sql)
        true
    }catch(_:Exception){
        false
    }
    fun select(sql:String):ArrayList<Map<String, Any?>>?
    = try{
        db.rawQuery(sql, null).use {cursor->
            val result = arrayListOf<Map<String, Any?>>()
            fillResult(cursor, result)
            result
        }
    }catch(_:Exception){
        null
    }
    fun execPrepared(sql: String, block:(SQLiteStatement)->Unit):Int
    = try{
        db.compileStatement(sql).use{
            block(it)
            it.executeUpdateDelete()
        }
    }catch(_:Exception){
        -1
    }
    fun selectPrepared(sql: String, vararg args: String): ArrayList<Map<String, Any?>> {
        val result = arrayListOf<Map<String, Any?>>()
        db.rawQuery(sql, args).use { cursor ->
            fillResult(cursor, result)
            return result
        }
    }
}