local obs = obslua
local ffi = require("ffi")

-- Win32 API to retrieve global cursor position
ffi.cdef[[
    typedef struct {
        long x;
        long y;
    } POINT;
    bool GetCursorPos(POINT* lpPoint);
]]

local function get_mouse_position()
    local pt = ffi.new("POINT")
    if ffi.C.GetCursorPos(pt) then
        return pt.x, pt.y
    end
    return 0, 0
end

local source_info = {}
source_info.id = "cursor_png_follower"
source_info.type = obs.OBS_SOURCE_TYPE_INPUT
source_info.output_flags = obs.OBS_SOURCE_VIDEO

source_info.get_name = function()
    return "Cursor Image Follower"
end

-- Create Source Data Instance
source_info.create = function(settings, source)
    local data = {}
    data.context = source
    data.image_path = ""
    data.offset_x = 0
    data.offset_y = 0
    data.image_scale = 1.0
    
    -- Resolution mapping parameters
    data.screen_w = 1920
    data.screen_h = 1080
    data.canvas_w = 1280
    data.canvas_h = 720
    data.manual_scale_x = 1.0
    data.manual_scale_y = 1.0

    -- Smooth movement parameters
    data.enable_smooth = false
    data.smooth_speed = 0.15
    data.curr_x = nil
    data.curr_y = nil

    data.image_source = nil

    source_info.update(data, settings)
    return data
end

-- Destroy Source Resources
source_info.destroy = function(data)
    if data.image_source then
        obs.obs_source_release(data.image_source)
        data.image_source = nil
    end
    data = nil
end

-- Update Source Settings
source_info.update = function(data, settings)
    local new_path = obs.obs_data_get_string(settings, "image_path")
    data.offset_x = obs.obs_data_get_int(settings, "offset_x")
    data.offset_y = obs.obs_data_get_int(settings, "offset_y")
    data.image_scale = obs.obs_data_get_double(settings, "image_scale")

    -- Resolution and multiplier controls
    data.screen_w = obs.obs_data_get_int(settings, "screen_w")
    data.screen_h = obs.obs_data_get_int(settings, "screen_h")
    data.canvas_w = obs.obs_data_get_int(settings, "canvas_w")
    data.canvas_h = obs.obs_data_get_int(settings, "canvas_h")
    data.manual_scale_x = obs.obs_data_get_double(settings, "manual_scale_x")
    data.manual_scale_y = obs.obs_data_get_double(settings, "manual_scale_y")

    -- Easing toggle and speed
    data.enable_smooth = obs.obs_data_get_bool(settings, "enable_smooth")
    data.smooth_speed = obs.obs_data_get_double(settings, "smooth_speed")

    if new_path ~= data.image_path then
        data.image_path = new_path

        if data.image_source then
            obs.obs_source_release(data.image_source)
            data.image_source = nil
        end

        if data.image_path ~= "" then
            local img_settings = obs.obs_data_create()
            obs.obs_data_set_string(img_settings, "file", data.image_path)
            obs.obs_data_set_bool(img_settings, "unload", false)

            data.image_source = obs.obs_source_create("image_source", "cursor_png_tex", img_settings, nil)
            obs.obs_data_release(img_settings)
        end
    end
end

-- Render Method with Optional Ease In/Out Interpolation
source_info.video_render = function(data, effect)
    if not data.image_source then return end

    local mx, my = get_mouse_position()

    -- Screen-to-canvas coordinate mapping
    local scale_factor_x = (data.canvas_w / math.max(data.screen_w, 1)) * data.manual_scale_x
    local scale_factor_y = (data.canvas_h / math.max(data.screen_h, 1)) * data.manual_scale_y

    local target_x = (mx * scale_factor_x) + data.offset_x
    local target_y = (my * scale_factor_y) + data.offset_y

    local draw_x = target_x
    local draw_y = target_y

    if data.enable_smooth then
        -- Initialize tracking positions on first run
        if not data.curr_x or not data.curr_y then
            data.curr_x = target_x
            data.curr_y = target_y
        else
            -- Linear interpolation (Lerp) for ease in/out effect
            data.curr_x = data.curr_x + (target_x - data.curr_x) * data.smooth_speed
            data.curr_y = data.curr_y + (target_y - data.curr_y) * data.smooth_speed
        end
        draw_x = data.curr_x
        draw_y = data.curr_y
    else
        -- Reset positions when smooth is turned off
        data.curr_x = nil
        data.curr_y = nil
    end

    obs.gs_matrix_push()
    obs.gs_matrix_translate3f(draw_x, draw_y, 0.0)
    obs.gs_matrix_scale3f(data.image_scale, data.image_scale, 1.0)

    obs.obs_source_video_render(data.image_source)

    obs.gs_matrix_pop()
end

-- Properties UI
source_info.get_properties = function(data)
    local props = obs.obs_properties_create()

    obs.obs_properties_add_path(
        props, 
        "image_path", 
        "Image File (PNG):", 
        obs.OBS_PATH_FILE, 
        "Image Files (*.png *.jpg *.jpeg *.bmp *.gif)", 
        nil
    )

    -- Motion Easing Settings
    obs.obs_properties_add_bool(props, "enable_smooth", "Enable Ease In/Out Motion")
    obs.obs_properties_add_float_slider(props, "smooth_speed", "Smoothing Speed (Lower = Smoother):", 0.01, 0.50, 0.01)

    -- Resolution Mapping Settings
    obs.obs_properties_add_int(props, "screen_w", "Monitor Width (px):", 640, 7680, 1)
    obs.obs_properties_add_int(props, "screen_h", "Monitor Height (px):", 480, 4320, 1)
    obs.obs_properties_add_int(props, "canvas_w", "OBS Canvas Width (px):", 640, 7680, 1)
    obs.obs_properties_add_int(props, "canvas_h", "OBS Canvas Height (px):", 480, 4320, 1)

    -- Manual Scale Multipliers
    obs.obs_properties_add_float_slider(props, "manual_scale_x", "Manual Pos Scale X:", 0.1, 3.0, 0.01)
    obs.obs_properties_add_float_slider(props, "manual_scale_y", "Manual Pos Scale Y:", 0.1, 3.0, 0.01)

    -- Offsets & Size
    obs.obs_properties_add_int(props, "offset_x", "Offset X (px):", -2000, 2000, 1)
    obs.obs_properties_add_int(props, "offset_y", "Offset Y (px):", -2000, 2000, 1)
    obs.obs_properties_add_float_slider(props, "image_scale", "PNG Image Size:", 0.05, 5.0, 0.05)

    return props
end

source_info.get_defaults = function(settings)
    obs.obs_data_set_default_bool(settings, "enable_smooth", false)
    obs.obs_data_set_default_double(settings, "smooth_speed", 0.15)
    obs.obs_data_set_default_int(settings, "screen_w", 1920)
    obs.obs_data_set_default_int(settings, "screen_h", 1080)
    obs.obs_data_set_default_int(settings, "canvas_w", 1280)
    obs.obs_data_set_default_int(settings, "canvas_h", 720)
    obs.obs_data_set_default_double(settings, "manual_scale_x", 1.0)
    obs.obs_data_set_default_double(settings, "manual_scale_y", 1.0)
    obs.obs_data_set_default_int(settings, "offset_x", 0)
    obs.obs_data_set_default_int(settings, "offset_y", 0)
    obs.obs_data_set_default_double(settings, "image_scale", 1.0)
end

function script_description()
    return "Registers 'Cursor Image Follower' with resolution scaling and ease in/out motion options."
end

function script_load(settings)
    obs.obs_register_source(source_info)
end