function ReplaceUnitBJ takes unit whichUnit, integer newUnitId, integer unitStateMethod returns unit
    local unit    oldUnit = whichUnit
    local unit    newUnit
    local boolean wasHidden
    local integer index
    local item    indexItem
    local real    oldRatio

    // If we have bogus data, don't attempt the replace.
    if (oldUnit == null) then
        set bj_lastReplacedUnit = oldUnit
        return oldUnit
    endif

    // Hide the original unit.
    set wasHidden = IsUnitHidden(oldUnit)
    call ShowUnit(oldUnit, false)

    // Create the replacement unit.
    if (newUnitId == 'ugol') then
        set newUnit = CreateBlightedGoldmine(GetOwningPlayer(oldUnit), GetUnitX(oldUnit), GetUnitY(oldUnit), GetUnitFacing(oldUnit))
    else
        set newUnit = CreateUnit(GetOwningPlayer(oldUnit), newUnitId, GetUnitX(oldUnit), GetUnitY(oldUnit), GetUnitFacing(oldUnit))
    endif

    // Set the unit's life and mana according to the requested method.
    if (unitStateMethod == bj_UNIT_STATE_METHOD_RELATIVE) then
        // Set the replacement's current/max life ratio to that of the old unit.
        // If both units have mana, do the same for mana.
        if (GetUnitState(oldUnit, UNIT_STATE_MAX_LIFE) > 0) then
            set oldRatio = GetUnitState(oldUnit, UNIT_STATE_LIFE) / GetUnitState(oldUnit, UNIT_STATE_MAX_LIFE)
            call SetUnitState(newUnit, UNIT_STATE_LIFE, oldRatio * GetUnitState(newUnit, UNIT_STATE_MAX_LIFE))
        endif

        if (GetUnitState(oldUnit, UNIT_STATE_MAX_MANA) > 0) and (GetUnitState(newUnit, UNIT_STATE_MAX_MANA) > 0) then
            set oldRatio = GetUnitState(oldUnit, UNIT_STATE_MANA) / GetUnitState(oldUnit, UNIT_STATE_MAX_MANA)
            call SetUnitState(newUnit, UNIT_STATE_MANA, oldRatio * GetUnitState(newUnit, UNIT_STATE_MAX_MANA))
        endif
    elseif (unitStateMethod == bj_UNIT_STATE_METHOD_ABSOLUTE) then
        // Set the replacement's current life to that of the old unit.
        // If the new unit has mana, do the same for mana.
        call SetUnitState(newUnit, UNIT_STATE_LIFE, GetUnitState(oldUnit, UNIT_STATE_LIFE))
        if (GetUnitState(newUnit, UNIT_STATE_MAX_MANA) > 0) then
            call SetUnitState(newUnit, UNIT_STATE_MANA, GetUnitState(oldUnit, UNIT_STATE_MANA))
        endif
    elseif (unitStateMethod == bj_UNIT_STATE_METHOD_DEFAULTS) then
        // The newly created unit should already have default life and mana.
    elseif (unitStateMethod == bj_UNIT_STATE_METHOD_MAXIMUM) then
        // Use max life and mana.
        call SetUnitState(newUnit, UNIT_STATE_LIFE, GetUnitState(newUnit, UNIT_STATE_MAX_LIFE))
        call SetUnitState(newUnit, UNIT_STATE_MANA, GetUnitState(newUnit, UNIT_STATE_MAX_MANA))
    else
        // Unrecognized unit state method - ignore the request.
    endif

    // Mirror properties of the old unit onto the new unit.
    //call PauseUnit(newUnit, IsUnitPaused(oldUnit))
    call SetResourceAmount(newUnit, GetResourceAmount(oldUnit))

    // If both the old and new units are heroes, handle their hero info.
    if (IsUnitType(oldUnit, UNIT_TYPE_HERO) and IsUnitType(newUnit, UNIT_TYPE_HERO)) then
        call SetHeroXP(newUnit, GetHeroXP(oldUnit), false)

        set index = 0
        loop
            set indexItem = UnitItemInSlot(oldUnit, index)
            if (indexItem != null) then
                call UnitRemoveItem(oldUnit, indexItem)
                call UnitAddItem(newUnit, indexItem)
            endif

            set index = index + 1
            exitwhen index >= bj_MAX_INVENTORY
        endloop
    endif

    // Remove or kill the original unit.  It is sometimes unsafe to remove
    // hidden units, so kill the original unit if it was previously hidden.
    if wasHidden then
        call KillUnit(oldUnit)
        call RemoveUnit(oldUnit)
    else
        call RemoveUnit(oldUnit)
    endif

    set bj_lastReplacedUnit = newUnit
    return newUnit
endfunction