Proper IsSpellInRange

[Wopak]

-- Courtesy of Wopak - [url]http://www.ownedcore.com/forums/members/309249-wopak.html[/url]
-- This function doesn't require any PLUA unlocker or any other kind of hack
-- ARGUMENTS
---- name - Name of a spell (string)
---- unit - A unit to target with the spell (string, [url=http://wowprogramming.com/docs/api_types#unitID]API Meta-Types - World of Warcraft Programming: A Guide and Reference for Creating WoW Addons[/url])
---- unit will default to target if left empty
-- RETURN VALUES
---- 1 if the player is near enough to cast the spell on the unit; 0 if not in range; nil if the unit is not a valid target for the spell (1nil)
function fawIsSpellInRange(spell, unit)
    if spell == nil then return nil; end
    if unit == nil then unit = "target"; end

    -- Using WoW's standard API first, because Tricks of the Trade is bugged when passing it's spell index
    -- So only going further down the function the spell's that returns nil
    -- I this returns nil is if the unit is not a valid target for the spell (or you have no target selected)
    local inRange = IsSpellInRange(spell, unit);

    -- Collecting the Spell GLOBAL SpellID, not to be confused with the SpellID
    -- Matching the Spell Name and the GLOBAL SpellID will give us the Spellbook index of the Spell
    -- With the Spellbook index, we can then proceed to do a proper IsSpellInRange with the index.
    if inRange == nil then
        local myIndex = nil;
        local name, texture, offset, numSpells, isGuild = GetSpellTabInfo(2);
        local booktype = "spell";
        for index = offset+1, numSpells+offset do
            -- Get the Global Spell ID from the Player's spellbook
            local spellID = select(2, GetSpellBookItemInfo(index, booktype));
            if spellID and spell == GetSpellBookItemName(index, booktype) then
                myIndex = index;
                break; -- Breaking out of the for/do loop, because we have a match
            end
        end

        -- If the Spell wasn't found, we're checking if we have a Pet Spellbook
        -- If a Pet Spellbook is found, do the same as above and try to get an Index on the Spell
        local numPetSpells = HasPetSpells();
        if myIndex == 0 and numPetSpells then
            booktype = "pet";
            for index = 1, numPetSpells do
                -- Get the Global Spell ID from the Pet's spellbook
                local spellID = select(2, GetSpellBookItemInfo(index, booktype));
                if spellID and spell == GetSpellBookItemName(index, booktype) then
                    myIndex = index;
                    break; -- Breaking out of the for/do loop, because we have a match
                end
            end
        end

        if myIndex then
            return IsSpellInRange(myIndex, booktype, unit);
        end
        return inRange;
    end
    return inRange;
end