core: convert EnvelopeBuilder to kotin

Co-authored-by: Younes Khoudli <younes.khoudli@epita.fr>
Signed-off-by: Loup Federico <16464925+Sh099078@users.noreply.github.com>

Author: Sh099078

core/envelope-sim/src/main/java/fr/sncf/osrd/envelope/EnvelopeBuilder.java

@@ -0,0 +1,51 @@
+package fr.sncf.osrd.envelope
+
+import fr.sncf.osrd.envelope.part.EnvelopePart
+
+/** Creates an envelope by concatenating envelope parts. Envelope parts must not overlap.  */
+class EnvelopeBuilder {
+    private var parts: MutableList<EnvelopePart>? = mutableListOf()
+
+    /** Adds a part to the envelope  */
+    fun addPart(part: EnvelopePart) {
+        checkNotNull(parts) { "build() was already called" }
+        parts!!.add(part)
+    }
+
+    /** Adds a list of parts  */
+    fun addParts(parts: Array<EnvelopePart>) {
+        for (part in parts) addPart(part)
+    }
+
+    /** Adds all parts of an envelope  */
+    fun addEnvelope(envelope: Envelope) {
+        for (part in envelope) addPart(part)
+    }
+
+    /** Reverses the order of the parts  */
+    fun reverse() {
+        checkNotNull(parts) { "build() was already called" }
+        for (i in 0..<parts!!.size / 2) {
+            val tmp = parts!![i]
+            parts!![i] = parts!![parts!!.size - i - 1]
+            parts!![parts!!.size - i - 1] = tmp
+        }
+    }
+
+    /** Creates a new Envelope  */
+    fun build(): Envelope {
+        checkNotNull(parts) { "build() was already called" }
+        val envelope = Envelope.make(*parts!!.toTypedArray())
+        parts = null
+        return envelope
+    }
+
+    companion object {
+        /** Concatenates multiple envelopes together  */
+        fun concatenate(vararg envelopes: Envelope): Envelope {
+            val res = EnvelopeBuilder()
+            for (envelope in envelopes) res.addEnvelope(envelope)
+            return res.build()
+        }
+    }
+}