-------------------------------------------------------------------
-- Main Table
-------------------------------------------------------------------
local LoadingScreensInfo = {
    -- Vanilla
    [1]  = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Third Church of Marika
    [2]  = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: View of the Erdtree
    [3]  = { weight = 10, requiredEventFlag = "0" },           -- Stormveil: Throneroom Statue of Godfrey
    [4]  = { weight = 10, requiredEventFlag = "0" },           -- Farum Azula: Maliketh Bossroom
    [5]  = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Divine Tower of Limgrave
    [6]  = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Nomadic Merchant
    [7]  = { weight = 10, requiredEventFlag = "0" },           -- Raya Lucaria: Debate Parlor
    [8]  = { weight = 10, requiredEventFlag = "0" },           -- Mountaintop of the Giants: Giant's Corpse
    [9]  = { weight = 10, requiredEventFlag = "0" },           -- Roundtable Hold: The Round Table
    [10] = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Waypoint Ruins with a Stake of Marika
    [11] = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Blaidd
    [12] = { weight = 10, requiredEventFlag = "0" },           -- Mt. Gelmir: Abductor Virgins
    [13] = { weight = 10, requiredEventFlag = "0" },           -- Leyndell, Royal Capital: The Queens Bedchamber
    [14] = { weight = 10, requiredEventFlag = "0" },           -- Weeping Peninsula: Walking Mausoleum
    [15] = { weight = 10, requiredEventFlag = "0" },           -- Redmane Caste: Castalian Jerren
    [16] = { weight = 10, requiredEventFlag = "0" },           -- Liurnia: Wraithcaller Rider
    [17] = { weight = 10, requiredEventFlag = "0" },           -- Stormveil: Main Gate
    [18] = { weight = 10, requiredEventFlag = "0" },           -- Jarburg: Living Jars
    [19] = { weight = 10, requiredEventFlag = "0" },           -- Nokstella: Giant Skeleton
    [20] = { weight = 10, requiredEventFlag = "0" },           -- Volcano Manor: Lady Tanith
    [21] = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Caravan
    [22] = { weight = 10, requiredEventFlag = "0" },           -- Limgrave: Guardian Golem
    [23] = { weight = 10, requiredEventFlag = "0" },           -- Catacombs: Erdtree Roots
    --[24] = { weight = 10, requiredEventFlag = "82002" },     -- Abyssal Woods: Midra's Manse
    [25] = { weight = 10, requiredEventFlag = "82002" },       -- Belurat: Main Gate
    [26] = { weight = 10, requiredEventFlag = "82002" },       -- Cathedral of Manus Metyr: Emyr's Throne
    --[27] = { weight = 10, requiredEventFlag = "82002" },     -- Jagged Peak: Jagged Peak Drake
    [28] = { weight = 10, requiredEventFlag = "82002" },       -- Ruins of Rauh: Pond
    [29] = { weight = 10, requiredEventFlag = "82002" },       -- Black Keep: Burning Boats
    [30] = { weight = 10, requiredEventFlag = "82002" },       -- Gravesite Plains: View of the Scadutree
    [31] = { weight = 10, requiredEventFlag = "82002" },       -- Midra's Manse: Family Portrait
    [32] = { weight = 10, requiredEventFlag = "82002" },       -- Scadu Altus: Furnace Golem
    [33] = { weight = 10, requiredEventFlag = "82002" },       -- Cerulean Coast: Spirit Eel
    [34] = { weight = 10, requiredEventFlag = "82002" },       -- Gravesite Plains: Miquella's Cross
    -- Modded
    [35] = { weight = 11, requiredEventFlag = "76490" },       -- Bestial Sanctum: Bestial Undercroft - Unlocks when opening the Bestial Santum Grace
    [36] = { weight = 11, requiredEventFlag = "71233" },       -- Deeproot Depths: Bridge - Unlocks when opening the Deeproot Depths Grace
    [37] = { weight = 11, requiredEventFlag = "71235" },       -- Deeproot Depths: Knight - Unlocks when opening the Acrosst the Roots Grace
    [38] = { weight = 11, requiredEventFlag = "12030393" },    -- Deeproot Depths: Nox Shrine - Unlocks when defeating Aled, knight of Godwyn
    [39] = { weight = 11, requiredEventFlag = "17000801" },    -- Noxumbra: Great Hall - Unlocks when encountering Daegraf
    [40] = { weight = 11, requiredEventFlag = "73019" },       -- Santum of Eiglay: Walkway - Unlocks when opening the Santum of Eiglay Grace
    [41] = { weight = 11, requiredEventFlag = "30190161" },    -- Santum of Eiglay: Petting Golem - Unlocked after unlocking the nearby gate
    [42] = { weight = 11, requiredEventFlag = "30190181" },    -- Santum of Eiglar: Abductor Virgin - Unlocked after opening the bridge
    [43] = { weight = 11, requiredEventFlag = "0" },           -- Minor Erdtree: Erdtree Network Portal - Unlocked by default
    [44] = { weight = 11, requiredEventFlag = "9131" },        -- Forge of the Giants: Portal - Unlocked defeating the Fire Giant
    [45] = { weight = 11, requiredEventFlag = "10019800" },    -- Lake of Rot: Grand Cloister Statue - Unlocked after encoutering Scion of the Sealed God
    [46] = { weight = 11, requiredEventFlag = "16009800" },    -- Volcano Manor: Bossroom - Unlocked after encountering Rykard
    [47] = { weight = 11, requiredEventFlag = "0" },           -- Volcano Manor: Hanging Cages - Unlocked by default
    [48] = { weight = 11, requiredEventFlag = "12059850" },    -- Mohgwyn Palace: Bird Wall Mount - Unlocked after encountering Konrad
    [49] = { weight = 11, requiredEventFlag = "71251" },       -- Moghwyn Palace: Ruins Gate - Unlocked after activating the Palace Approach Ledge-Road site of grace
    [50] = { weight = 11, requiredEventFlag = "0" },           -- Mohgwyn Palace: Pots - Unlocked by default
    [51] = { weight = 11, requiredEventFlag = "12057790" },    -- Mohgwyn Palace: Abberant Campfire - Unlocked after obtaining the Crucifix of Eochaid
    [52] = { weight = 11, requiredEventFlag = "12059800" },    -- Mohgwyn Palace: Statue of Mogh - Unlocked after encountering Mogh
    [53] = { weight = 11, requiredEventFlag = "0" },           -- Sanctuary of Lost Knowledge: Halls - Unlocked by default
    [54] = { weight = 11, requiredEventFlag = "0" },           -- Sanctuary of Lost Knowledge: Statue - Unlocked by default
    [55] = { weight = 11, requiredEventFlag = "71227" },       -- Spiritshaper Grounds: Woods - Unlocked after unlocking the Aqueduct-Facing Cliffs Grace
    [56] = { weight = 11, requiredEventFlag = "12020439" },    -- Spiritshaper Grounds: Howling Wolf - Unlocked after triggering the first wolf event
    [57] = { weight = 11, requiredEventFlag = "76938" },       -- Finger Ruins of Dheo: Approach - Unlocked after unlocking the Finger Ruins of Dheo Grace
    [58] = { weight = 11, requiredEventFlag = "30209010" },    -- Vulgar Militia Stronghold: Spike Traps - Unlocked after lowering the final drawbridge
    [59] = { weight = 11, requiredEventFlag = "30209011" },    -- Vulgar Militia Stronghold: Camp - Unlocked after lowering the first drawbridge
    [60] = { weight = 11, requiredEventFlag = "71608" },       -- Volcano Manor: Lava Pool Bridge - Unlocked after unlocking the Manor Passage site of grace
    [61] = { weight = 11, requiredEventFlag = "76419" },       -- Redmane Castle: Bridge Gate - Unlocked after unlocking the Redmane Castle Plaza Grace
    [62] = { weight = 11, requiredEventFlag = "18009800" },    -- Fringe Folk: Staircase - Unlocked after meeting the boss of the area for the first time
    [63] = { weight = 11, requiredEventFlag = "73208" },       -- Sellia: Overlook - Unlocked after unlocking the Sellia Crystal Tunnel Grace
    [64] = { weight = 11, requiredEventFlag = "76214" },       -- Caria Manor: Approach - Unlocked after unlocking the Caria Manor Grace
    [65] = { weight = 11, requiredEventFlag = "318300" },      -- Raya Crystalia: Start - Unlocked after unlocking the Raya Crystalia Grace
    [66] = { weight = 11, requiredEventFlag = "40008808" },    -- Fog Rift Catacombs: Godskin Noble Bridge - Unlocked after defeating the Godskin Noble
    [67] = { weight = 11, requiredEventFlag = "40001414" },    -- Fog Rift Catacombs: Grand Hall - Unlocked after opening the door to the Grand Hall
    [68] = { weight = 11, requiredEventFlag = "18009850" },    -- Stranded Graveyard: Praying Guilty - Unlocked after meeting the boss of the area for the first time
    [69] = { weight = 11, requiredEventFlag = "71313" },       -- Farum Azula: Farum Ruins Overview - Unlocked after unlocking the Dragonlord's Annex Grace
    [70] = { weight = 11, requiredEventFlag = "71504" },       -- Miquella's Haligtree: Drainage Channel - Unlocked after unlocking the Haligtree Roots Grace
    [71] = { weight = 11, requiredEventFlag = "2049439850" },  -- Fort of Reprimand: Overview - Unlocked after meeting the boss of the area for the first time
    [72] = { weight = 11, requiredEventFlag = "76968" },       -- Sarrulat, Basin Town - Unlocked after unlocking the Sarrulat, Basin Town Grace
    [73] = { weight = 11, requiredEventFlag = "76158" },       -- Castle Morne Town - Unlocked after unlocking the Castle Morne Lift Grace
    [74] = { weight = 11, requiredEventFlag = "1043310003" },  -- Castle Morne Habibi Approach - Unlocked after Castle Morne Town Grace
    [75] = { weight = 11, requiredEventFlag = "31820800" },    -- Habibi Hall - Unlocked after defeating Habibi
    [76] = { weight = 11, requiredEventFlag = "1041320691" },  -- Turtle Sea - Unlocked after doing the turtle puzzle
    [77] = { weight = 11, requiredEventFlag = "15000754" },    -- HaligTree Sealed Gate - Unlocked after Defeating Rotten Sentry
    [78] = { weight = 11, requiredEventFlag = "1036450001" },  -- Carian Nexus - Unlocked after grace
    [79] = { weight = 11, requiredEventFlag = "1051569206" },  -- StarGazer Ruins - Unlocked after Jellyfish Puzzle
    [80] = { weight = 11, requiredEventFlag = "0" },           -- Roundtable MapMaker - Unlocked by default
}

-------------------------------------------------------------------
-- Code
-------------------------------------------------------------------
local LoadingScreensPopulated = false
local MENU_LOAD_ENTRY_COUNT = 34
local MENU_LOAD_INDEX_MAX = 33

local function IsValidLoadingScreenId(id)
    return type(id) == "number" and LoadingScreensInfo[id] ~= nil
end

local function SetMenuLoadEntryIfValid(menuIndex, loadingScreenId)
    if not IsValidLoadingScreenId(loadingScreenId) then
        Log("Skipping invalid loading screen id", loadingScreenId, "for menu index", menuIndex)
        return false
    end

    SetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.MENU_LOAD_ENTRIES(menuIndex), loadingScreenId)
    return true
end

function LoadingScreenHandler()
    -- SetNextLoadingScreenToPrevPlusOne()
    if LoadingScreensPopulated then
        MonitorLoadingScreenEventFlags()
        return
    end
    LoadingScreensPopulated = true

    if GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.CURRENT_MENU_LOAD_INDEX) ~= 1 then
        LimitLoadingScreenAmountHandler()
        return
    end

    PopulateLoadingScreens()
end

function PopulateLoadingScreens()
    local currentLoadingScreenTable = GetCurrentLoadingScreenTable()
    -- Get the last 5 played loading screens
    -- First loading screen on startup is on index 1
    -- In Lua, indices start at 1 instead of 0, meaning in this table we include index 2
    local lastFiveOld = {
        [currentLoadingScreenTable[31]] = true,
        [currentLoadingScreenTable[32]] = true,
        [currentLoadingScreenTable[33]] = true,
        [currentLoadingScreenTable[1]] = true,
        [currentLoadingScreenTable[2]] = true
    }

    local availableIndices = {}
    for index, info in pairs(LoadingScreensInfo) do
        if info.weight > 0 and (info.requiredEventFlag == "0" or env(GetEventFlag, info.requiredEventFlag) == TRUE) then
            table.insert(availableIndices, index)
        end
    end

    if #availableIndices == 0 then
        act(10001, "[WARNING!] Not enough available loading screens to populate table. At least 1 need to be possible. Loading screens were not updated.")
        return
    end

    local used = {}
    for i = 0, 33 do
        -- Neccessary evil for making it so high weight loading screens dont get placed in index 0 or index 1
        -- If not the weight based priority system has no use because the high weight items will be at an index that
        -- require a full rotation before they show up.
        local index = i + 2
        if index > 33 then
            index = index - 34
        end

        local candidates = {}
        for _, idx in ipairs(availableIndices) do
            if not used[idx] then -- Exclude already added loading screens
                if i > 4 or lastFiveOld[idx] == nil then -- For first 5, exclude lastFiveOld
                    table.insert(candidates, idx)
                end
            end
        end

        -- If constraints are too strict, relax them in stages to avoid assigning invalid id 0.
        if #candidates == 0 then
            for _, idx in ipairs(availableIndices) do
                if not used[idx] then
                    table.insert(candidates, idx)
                end
            end
        end
        if #candidates == 0 then
            for _, idx in ipairs(availableIndices) do
                table.insert(candidates, idx)
            end
        end

        local selectedIdx = nil
        if #candidates ~= 0 then
            -- Calculating total weight
            local totalWeight = 0
            for _, idx in ipairs(candidates) do
                totalWeight = totalWeight + LoadingScreensInfo[idx].weight
            end
            -- Weighted random selection
            local rand = math.random() * totalWeight
            local cumulative = 0
            for _, idx in ipairs(candidates) do
                cumulative = cumulative + LoadingScreensInfo[idx].weight
                if rand <= cumulative then
                    selectedIdx = idx
                    break
                end
            end

            -- Floating-point rounding can rarely skip every branch; force a valid fallback.
            if selectedIdx == nil then
                selectedIdx = candidates[#candidates]
            end
            
            used[selectedIdx] = true
        end

        if selectedIdx ~= nil then
            SetMenuLoadEntryIfValid(index, selectedIdx)
        end
    end

    -- local _table = GetCurrentLoadingScreenTable()
    -- table.sort(_table)
    -- Log(unpack(_table))   
end

function SetNextLoadingScreenToPrevPlusOne()
    local currentIndex = GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.CURRENT_MENU_LOAD_INDEX) -- Range 0 - 33

    local prevMenuLoadIndex = currentIndex
    local prevID = GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.MENU_LOAD_ENTRIES(prevMenuLoadIndex)) or 0
    if prevID == 0 or prevID == nil or not IsValidLoadingScreenId(prevID) then
        return
    end

    local maxIdx = 0
    for idx, _ in pairs(LoadingScreensInfo) do
        if idx > maxIdx then
            maxIdx = idx
        end
    end
    local nextID = prevID
    local attempts = 0
    repeat
        nextID = nextID + 1
        if maxIdx > 0 and nextID > maxIdx then
            nextID = 1
        end
        attempts = attempts + 1
    until attempts > maxIdx or IsValidLoadingScreenId(nextID)

    if not IsValidLoadingScreenId(nextID) then
        return
    end

    local nextMenuLoadIndex = currentIndex + 1
    if nextMenuLoadIndex > MENU_LOAD_INDEX_MAX then
        nextMenuLoadIndex = 0
    end
    SetMenuLoadEntryIfValid(nextMenuLoadIndex, nextID)
    Log("[" .. nextMenuLoadIndex .. "]", prevID, "->", nextID)
end

function GetCurrentLoadingScreenTable()
    local _table = {}
    for i = 0, 33, 1 do
        table.insert(_table, GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.MENU_LOAD_ENTRIES(i)))
    end
    return _table
end

local monitoredFlags = nil
function MonitorLoadingScreenEventFlags()
    -- Collect all loading screens that require a flag and are currently locked.
    if monitoredFlags == nil then
        monitoredFlags = {}
        for index, info in pairs(LoadingScreensInfo) do
            if info.requiredEventFlag ~= "0" and env(GetEventFlag, info.requiredEventFlag) ~= TRUE then
                monitoredFlags[info.requiredEventFlag] = index
            end
        end
    elseif next(monitoredFlags) == nil then
        return
    end

    -- Monitoring loop (call this function periodically, e.g., every frame or on event update)
    for flag, index in pairs(monitoredFlags) do
        if env(GetEventFlag, flag) == TRUE then
            local nextMenuLoadIndex = GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.CURRENT_MENU_LOAD_INDEX) + 1
            if nextMenuLoadIndex > MENU_LOAD_INDEX_MAX then
                nextMenuLoadIndex = 0
            end

            SetMenuLoadEntryIfValid(nextMenuLoadIndex, index)
            monitoredFlags[flag] = nil
        end
    end
end

local nextLoadingScreen = 0
function LimitLoadingScreenAmountHandler()
    if nextLoadingScreen ~= 0 then
        return
    end

    local currentTable = GetCurrentLoadingScreenTable()
    local currentIndex =  GetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.CURRENT_MENU_LOAD_INDEX) -- Range 0 - 33
    local nextTableIndex = currentIndex + 2 -- Not +1 because lua starts its table index at 1
    if nextTableIndex > MENU_LOAD_ENTRY_COUNT then
        nextTableIndex = nextTableIndex - MENU_LOAD_ENTRY_COUNT
    end

    local _nextLoadingScreen = currentTable[nextTableIndex]
    local nextLoadingScreenInfo = LoadingScreensInfo[_nextLoadingScreen]
    local nextLoadingScreenFlag = nextLoadingScreenInfo and nextLoadingScreenInfo.requiredEventFlag or nil -- Doublecheck eventflag in case of character swap

    if nextLoadingScreenInfo ~= nil and (nextLoadingScreenFlag == "0" or env(GetEventFlag, nextLoadingScreenFlag) == TRUE) then
        nextLoadingScreen = _nextLoadingScreen
        return
    end

    SetPointerValue(GAME_BASE.CS_NOW_LOADING_HELPER.CURRENT_MENU_LOAD_INDEX, 1)
    PopulateLoadingScreens() -- Since index will be reset to 1

    local refreshedTable = GetCurrentLoadingScreenTable()
    local refreshedFirst = refreshedTable[1]
    if IsValidLoadingScreenId(refreshedFirst) then
        nextLoadingScreen = refreshedFirst
    else
        nextLoadingScreen = 0
    end
end