LMS-APIs/src/main/kotlin/service/PatronService.kt

package codes.kalar.service

import codes.kalar.exception.DbElementNotFoundException
import codes.kalar.model.NewPatron
import codes.kalar.model.Patron
import java.sql.*

class PatronService(private val connection: Connection) {

    companion object {
        private const val SELECT_PATRON_BY_ID = "SELECT * FROM patron WHERE id = ?"
        private const val SELECT_PATRON_BY_LOGIN_USERNAME = "SELECT * From patron where login_username = ?"
        private const val INSERT_PATRON =
            "INSERT INTO patron (name, has_good_standing, fee_total, is_archived, login_username, last_login, password) VALUES (?, ?, ?, ?, ?, ?, ?)"
        private const val UPDATE_PATRON_BY_ID =
            "UPDATE patron SET name = ?, has_good_standing = ?, fee_total = ?, is_archived = ?, login_username = ?, " +
                    "last_login = ?, password = ? WHERE id = ?"

        // In the event  are "deleted" erroneously, having a flag set instead of actually removing the entry allows
        // for quick reversal.
        private const val ARCHIVE_PATRON_BY_ID = "UPDATE patron set is_archived = true WHERE id = ?"
    }

    fun create(newPatron: NewPatron): Long {
        val statement = connection.prepareStatement(INSERT_PATRON, Statement.RETURN_GENERATED_KEYS)
        statement.setString(1, newPatron.name)
        statement.setBoolean(2, true)
        statement.setLong(3, 0)
        statement.setBoolean(4, false)
        statement.setString(5, newPatron.loginUsername)
        statement.setDate(6, Date(System.currentTimeMillis()))
        statement.setString(7, newPatron.password)
        statement.execute()
        try {
            val key = statement.generatedKeys
            if (key.next()) {
                return key.getLong(1)
            }
            return -1
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Couldn't insert patron ${newPatron.name} into database. ${cause.message}")
        }
    }

    fun readPatronById(id: Long): Patron {
        try {
            val statement = connection.prepareStatement(SELECT_PATRON_BY_ID, Statement.RETURN_GENERATED_KEYS)
            statement.setLong(1, id)
            val resultSet = statement.executeQuery()
            if (resultSet.next()) {
                val patron = createPatronFromResults(resultSet)
                return patron
            } else {
                throw DbElementNotFoundException("Patron with ID $id not found")
            }
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Patron with ID $id is not found")
        }
    }

    fun readPatronByLoginUsername(username: String): Patron {
        try {
            val statement = connection.prepareStatement(SELECT_PATRON_BY_LOGIN_USERNAME)
            statement.setString(1, username)
            val resultSet = statement.executeQuery()
            if (resultSet.next()) {
                val patron = createPatronFromResults(resultSet)
                return patron
            } else {
                throw SQLException()
            }
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Could not find username or password")
        }
    }

    fun loginPatronByLoginUsername(username: String, password: String): Boolean {
        try {
            val statement = connection.prepareStatement(SELECT_PATRON_BY_LOGIN_USERNAME)
            statement.setString(1, username)
            val resultSet = statement.executeQuery()
            return if (resultSet.next()) {
                resultSet.getString("password") == password && !resultSet.getBoolean("is_archived")
            } else {
                throw SQLException()
            }
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Could not find username or password")
        }
    }

    fun update(patron: Patron): Boolean {
        val statement = connection.prepareStatement(UPDATE_PATRON_BY_ID)
        statement.setString(1, patron.name)
        statement.setBoolean(2, patron.hasGoodStanding)
        statement.setLong(3, patron.feeTotal)
        statement.setBoolean(4, patron.isArchived)
        statement.setString(5, patron.loginUsername)
        statement.setString(6, patron.lastLogin)
        statement.setString(7, patron.password)
        statement.setLong(8, patron.id)
        try {
            return !statement.execute()
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Patron with ID ${patron.id} not found.")
        }
    }

    fun delete(id: Long) {
        val statement = connection.prepareStatement(ARCHIVE_PATRON_BY_ID)
        statement.setLong(1, id)
        try {
            statement.execute()
        } catch (cause: SQLException) {
            throw DbElementNotFoundException("Patron with ID $id not found.")
        }
    }

    fun createPatronFromResults(resultSet: ResultSet): Patron {
        return Patron(
            id = resultSet.getLong("id"),
            name = resultSet.getString("name"),
            hasGoodStanding = resultSet.getBoolean("has_good_standing"),
            feeTotal = resultSet.getLong("fee_total"),
            isArchived = resultSet.getBoolean("is_archived"),
            lastLogin = resultSet.getString("last_login"),
            password = "", // For security reasons...
            loginUsername = resultSet.getString("login_username")
        )
    }
}