com.lightningkite.lightningdb.UpdateRestrictions.kt Maven / Gradle / Ivy

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A set of tools to fill in/replace what Ktor is lacking in.
The newest version!
package com.lightningkite.lightningdb

import kotlinx.serialization.Serializable

/**
 * Permission rules regarding updating items per-field.
 */
@Serializable
data class UpdateRestrictions(
    /**
     * If the modification matches paths, then the condition is applied to the update
     */
    val fields: List> = listOf()
) {
    @Serializable
    data class Part(val path: DataClassPathPartial, val limitedIf: Condition, val limitedTo: Condition)

    operator fun invoke(on: Modification): Condition {
        val totalConditions = ArrayList>()
        for(field in fields) {
            if(on.affects(field.path)) {
                totalConditions.add(field.limitedIf)
                if(field.limitedTo !is Condition.Always) {
                    if(!field.limitedTo.guaranteedAfter(on)) return Condition.Never()
                }
            }
        }
        return when(totalConditions.size) {
            0 -> Condition.Always()
            1 -> totalConditions[0]
            else -> Condition.And(totalConditions)
        }
    }

    class Builder(
        val fields: ArrayList> = ArrayList()
    ) {
        val it = path()
        /**
         * Makes a field unmodifiable.
         */
        fun DataClassPath.cannotBeModified() {
            fields.add(Part(this, Condition.Never(), Condition.Always()))
        }
        /**
         * Makes a field only modifiable if the item matches the [condition].
         */
        infix fun DataClassPath.requires(condition: Condition) {
            fields.add(Part(this, condition, Condition.Always()))
        }
        /**
         * Makes a field only modifiable if the item matches the [condition].
         * In addition, the value it is being changed to must match [valueMust].
         */
        fun  DataClassPath.requires(requires: Condition, valueMust: (DataClassPath)->Condition) {
            fields.add(Part(this, requires, this.condition(valueMust)))
        }
        /**
         * The value is only allowed to change to a value that matches [valueMust].
         */
        fun  DataClassPath.mustBe(valueMust: (DataClassPath)->Condition) {
            fields.add(Part(this, Condition.Always(), this.condition(valueMust)))
        }
        fun build() = UpdateRestrictions(fields)
        fun include(mask: UpdateRestrictions) { fields.addAll(mask.fields) }
    }
}

/**
 * DSL for defining [UpdateRestrictions]
 */
inline fun  updateRestrictions(builder: UpdateRestrictions.Builder.()->Unit): UpdateRestrictions {
    return UpdateRestrictions.Builder().apply(builder).build()
}