/* BSD 2-Clause License - see OPAL/LICENSE for details. */
package org.opalj
package tac
package fpcf
package analyses

import org.opalj.collection.immutable.IntTrieSet
import org.opalj.collection.immutable.EmptyIntTrieSet
import org.opalj.value.ValueInformation
import org.opalj.br.PCs
import org.opalj.ai.ValueOrigin
import org.opalj.ai.pcOfImmediateVMException
import org.opalj.ai.pcOfMethodExternalException
import org.opalj.ai.ValueOriginForImmediateVMException
import org.opalj.ai.ValueOriginForMethodExternalException
import org.opalj.ai.MethodExternalExceptionsOriginOffset
import org.opalj.ai.ImmediateVMExceptionsOriginOffset
import org.opalj.ai.isMethodExternalExceptionOrigin
import org.opalj.ai.isImmediateVMException

package object cg {

    type V = DUVar[ValueInformation]

    /**
     * A persistent representation (using pcs instead of TAC value origins) for a UVar.
     */
    final def persistentUVar(
        value: V
    )(
        implicit
        stmts: Array[Stmt[V]]
    ): Some[(ValueInformation, IntTrieSet)] = {
        Some((value.value, value.definedBy.map(pcOfDefSite _)))
    }

    final def pcOfDefSite(valueOrigin: ValueOrigin)(implicit stmts: Array[Stmt[V]]): Int = {
        if (valueOrigin >= 0)
            stmts(valueOrigin).pc
        else if (valueOrigin > ImmediateVMExceptionsOriginOffset)
            valueOrigin // <- it is a parameter!
        else if (valueOrigin > MethodExternalExceptionsOriginOffset)
            ValueOriginForImmediateVMException(stmts(pcOfImmediateVMException(valueOrigin)).pc)
        else
            ValueOriginForMethodExternalException(
                stmts(pcOfMethodExternalException(valueOrigin)).pc
            )
    }

    final def valueOriginsOfPCs(pcs: PCs, pcToIndex: Array[Int]): IntTrieSet = {
        pcs.foldLeft(EmptyIntTrieSet: IntTrieSet) { (origins, pc) =>
            if (ai.underlyingPC(pc) < 0)
                origins + pc // parameter
            else if (pc >= 0 && pcToIndex(pc) >= 0)
                origins + pcToIndex(pc) // local
            else if (isImmediateVMException(pc) && pcToIndex(pcOfImmediateVMException(pc)) >= 0)
                origins + ValueOriginForImmediateVMException(pcToIndex(pcOfImmediateVMException(pc)))
            else if (isMethodExternalExceptionOrigin(pc) && pcToIndex(pcOfMethodExternalException(pc)) >= 0)
                origins + ValueOriginForMethodExternalException(pcToIndex(pcOfMethodExternalException(pc)))
            else
                origins // as is
        }
    }

    final def uVarForDefSites(
        defSites:  (ValueInformation, IntTrieSet),
        pcToIndex: Array[Int]
    ): V = {
        UVar(defSites._1, valueOriginsOfPCs(defSites._2, pcToIndex))
    }
}