Api/Sources/src/main/kotlin/allin/data/postgres/PostgresFriendDataSource.kt

package allin.data.postgres

import allin.data.FriendDataSource
import allin.data.postgres.entities.FriendEntity
import allin.data.postgres.entities.friends
import allin.data.postgres.entities.users
import allin.dto.UserDTO
import allin.ext.length
import allin.ext.levenshteinLessEq
import allin.ext.toLowerCase
import allin.model.FriendStatus
import org.ktorm.database.Database
import org.ktorm.dsl.and
import org.ktorm.dsl.div
import org.ktorm.dsl.eq
import org.ktorm.dsl.notEq
import org.ktorm.entity.*

class PostgresFriendDataSource(private val database: Database) : FriendDataSource {
    override fun addFriend(sender: String, receiver: String) {
        database.friends.add(
            FriendEntity {
                this.sender = sender
                this.receiver = receiver
            }
        )
    }

    override fun getFriendFromUserId(id: String): List<UserDTO> {
        return database.friends.map { it.toFriend() }
            .filter { it.sender == id }
            .mapNotNull { friend ->
                val receiverUser = database.users.find { usr ->
                    usr.id eq friend.receiver
                }
                receiverUser?.toUserDTO(
                    database,
                    friendStatus = if (isFriend(friend.receiver, id)) {
                        FriendStatus.FRIEND
                    } else FriendStatus.REQUESTED
                )
            }
    }


    override fun getFriendRequestsFromUserId(id: String): List<UserDTO> {
        return database.friends
            .filter { it.receiver eq id }
            .mapNotNull {
                if (isFriend(firstUser = id, secondUser = it.sender)) {
                    null
                } else {
                    database.users.find { usr ->
                        usr.id eq it.sender
                    }?.toUserDTO(database, friendStatus = FriendStatus.NOT_FRIEND)
                }
            }
    }


    override fun deleteFriend(senderId: String, receiverId: String): Boolean {
        val result = database.friends.removeIf { (it.sender eq receiverId) and (it.receiver eq senderId) } +
                database.friends.removeIf { (it.sender eq senderId) and (it.receiver eq receiverId) }

        return result > 0
    }

    override fun isFriend(firstUser: String, secondUser: String) =
        database.friends.any { (it.sender eq firstUser) and (it.receiver eq secondUser) }

    override fun filterUsersByUsername(fromUserId: String, search: String): List<UserDTO> {
        return database.users
            .filter { (it.id notEq fromUserId) }
            .mapColumns {
                tupleOf(
                    it.id,
                    it.username,
                    it.username.toLowerCase().levenshteinLessEq(
                        search.lowercase(),
                        (it.username.length() / 2)
                    )
                )
            }
            .filter { (_, username, distance) ->
                val maxSize = ((username?.length ?: 0) / 2)
                distance?.let { it <= maxSize } ?: false
            }
            .sortedBy { it.second }
            .mapNotNull { (id, _, _) ->
                id?.let {
                    val user = database.users.find { it.id eq id }
                    user?.toUserDTO(database, friendStatus = getFriendStatus(fromUserId, user.id))
                }
            }
    }

}