--[[
    "name": "CursorUpgradeCarousel",
    "title": "Cursor Upgrade Carousel",
    "author": "raiguard",
    "description": "Shift+scroll to quickly access an item's upgrades or downgrades. If you do not have the item, the ghost cursor will be used instead (100% not cheaty!). Should be compatible with all mods out of the box, assuming they correctly defined their entities' upgrades. Users can also define their own custom upgrade paths in the mod settings."
--]]
local Event = require('__stdlib__/stdlib/event/event')

if script.active_mods['CursorUpgradeCarousel'] or script.active_mods['CursorEnhancements'] then
    return
end

-- build upgrade/downgrade registry
local function build_upgrade_registry()
    local prototypes = game.entity_prototypes
    local data = {}
    -- build default registry
    for name, prototype in pairs(prototypes) do
        if prototype.next_upgrade and prototype.items_to_place_this then
            local upgrade = prototype.next_upgrade.name
            for _, item in ipairs(prototype.items_to_place_this) do
                if not data[item.name] then
                    data[item.name] = {}
                end
                data[item.name].upgrade = upgrade
            end
            for _, item in ipairs(prototypes[upgrade].items_to_place_this) do
                if not data[item.name] then
                    data[item.name] = {}
                end
                data[item.name].downgrade = name
            end
        end
    end
    -- build custom registry
    for name, upgrade in pairs(load('return ' .. settings.global['picker-carousel-registry'].value)()) do
        -- get objects and validate them, or error if not
        local prototype = prototypes[name]
        if not prototype then
            game.print {'chat-message.invalid-name', name}
            goto continue
        end
        local upgrade_prototype = prototypes[upgrade]
        if not upgrade_prototype then
            game.print {'chat-message.invalid-upgrade-name', upgrade}
            goto continue
        end
        for _, item in ipairs(prototype.items_to_place_this or {}) do
            if not data[item.name] then
                data[item.name] = {}
            end
            data[item.name].upgrade = upgrade
        end
        for _, item in ipairs(upgrade_prototype.items_to_place_this or {}) do
            if not data[item.name] then
                data[item.name] = {}
            end
            data[item.name].downgrade = name
        end
        ::continue::
    end
    global.carousel_registry = data
end

Event.on_init(build_upgrade_registry)
Event.on_configuration_changed(build_upgrade_registry)

local matcher = function(event)
    return event and event.setting == 'picker-carousel-registry'
end
local runtime_set = defines.events.on_runtime_mod_setting_changed
Event.on_event(runtime_set, build_upgrade_registry, matcher)

local function cycle_carousel(event)
    local player = game.get_player(event.player_index)
    local settings = player.mod_settings
    if settings['picker-use-carousel'].value then
        local stack = player.cursor_stack
        local name
        -- check cursor stack and cursor ghost and set the name accordingly
        if stack and stack.valid_for_read and not stack.is_item_with_label then
            name = stack.name
        elseif player.cursor_ghost then
            name = player.cursor_ghost.name
        else
            return
        end

        local registry = global.carousel_registry
        -- get upgrade or downgrade depending on event
        local grade = event.input_name:find('forwards') and 'upgrade' or 'downgrade'
        -- if we're in the map editor and the setting is enabled, always give the actual item
        local always_give = settings['picker-carousel-always-give-in-map-editor'].value
        -- if the thing we're holding has an upgrade/downgrade
        if registry[name] and registry[name][grade] and player.clear_cursor() then
            local grade_name = registry[name][grade]
            local inventory = player.get_main_inventory()
            local contents = inventory.get_contents()
            local grade_items = game.entity_prototypes[grade_name].items_to_place_this
            for _, item in ipairs(grade_items) do
                if contents[item.name] then
                    -- we actually have this item, so replace the cursor stack from the inventory
                    stack.set_stack {name = item.name, count = inventory.remove {name = item.name, count = game.item_prototypes[item.name].stack_size}}
                    return
                elseif always_give and player.controller_type == defines.controllers.editor then
                    -- replace the cursor stack without taking from the inventory
                    stack.set_stack {name = item.name, count = game.item_prototypes[item.name].stack_size}
                    return
                end
            end
            -- if we're here, then they don't have any of the items, so put the first one in the ghost cursor
            player.cursor_ghost = grade_items[1].name
        end
    end
end
Event.on_event({'picker-carousel-forwards', 'picker-carousel-backwards'}, cycle_carousel)