proposed changes to BookLearning_ISReadABook.lua

--Additions to give skill XP when reading
BookLearning = {};

--Addition for skill configuration via lua, so it can be set from outside of this mod. You can make a simple list of items like "Farming", "Cooking" and such here
BookLearning.allowedSkills = BookLearning.allowedSkills or {};

--Add skill XP gain to book reading timed action
BOOKLEARNING_ISReadABook_update = ISReadABook.update
function ISReadABook:update()
    BOOKLEARNING_ISReadABook_update(self)
    local checkSuccess;
    local canLearn;
    checkSuccess, canLearn = pcall(BookLearning.checkIfCanLearn, self);

    if (checkSuccess and canLearn) then
        BookLearning.gainXP(self);
    end
end

--Sets o to true if the player can learn from this book
BookLearning.checkIfCanLearn = function(self)
    local o = true;

    if (not (SkillBook[self.item:getSkillTrained()] ~= nil))
        or self.item:getLvlSkillTrained() > self.character:getPerkLevel(SkillBook[self.item:getSkillTrained()].perk) + 1
        or self.character:HasTrait("Illiterate")
        or self.item:getMaxLevelTrained() < self.character:getPerkLevel(SkillBook[self.item:getSkillTrained()].perk) + 1
    then
        o = false;
    end

    return o;
end

--Provides player XP for every page read.
BookLearning.gainXP = function(self)
    local trainedStuff = SkillBook[self.item:getSkillTrained()];

    if trainedStuff then
        -- check if allowedSkills list exists, if so check if this is allowed
        if #BookLearning.allowedSkills > 0 then
            local isAllowed = false;

            for _,skill in ipairs(BookLearning.allowedSkills) do
                if tostring(trainedStuff.perk) == skill then
                    isAllowed = true;
                    break;
                end
            end

            if not isAllowed then
                return;
            end
        end
        -- end check

        local readPercent = (self.item:getAlreadyReadPages() / self.item:getNumberOfPages()) * 100;
        if readPercent > 100 then
            readPercent = 100;
        end

        local targetSkillLevel = self.item:getLvlSkillTrained() + self.item:getNumLevelsTrained() - 1;
        local bookMaxXP = 0;
        for i=1,targetSkillLevel do
            bookMaxXP = (bookMaxXP + BookLearning.xpByLevel[i]);
        end
        local targetXP = bookMaxXP * (readPercent / 100);
        local xpGained = math.ceil(targetXP - self.character:getXp():getXP(trainedStuff.perk));

        --Fix rounding error for XP on last page
        if readPercent == 100 then
            xpGained = xpGained + 0.1;
        end

        if xpGained > 0 then
            self.character:getXp():AddXP(trainedStuff.perk, xpGained);
        end
    end
end

--XP per skill level as of 41.50
BookLearning.xpByLevel = {};
BookLearning.xpByLevel[0] = 0;
BookLearning.xpByLevel[1] = 75;
BookLearning.xpByLevel[2] = 150;
BookLearning.xpByLevel[3] = 300;
BookLearning.xpByLevel[4] = 750;
BookLearning.xpByLevel[5] = 1500;
BookLearning.xpByLevel[6] = 3000;
BookLearning.xpByLevel[7] = 4500;
BookLearning.xpByLevel[8] = 6000;
BookLearning.xpByLevel[9] = 7500;
BookLearning.xpByLevel[10] = 9000;