-- SimpleSlides.lua
--
-- Version 0.1
--
-- By John Hartman
--
-- Thanks to tid-kijyun, whose tally-counter.lua I used as a framework.
-- https://gist.github.com/tid-kijyun/477c723ea42d22903ebe6b6cee3f77a1

obs = obslua

-- The name of our controlling Sources must begin with this string
source_key = 'SimpleSlides:'

-- We accept files with the following extensions (acceptable to the Image Source)
allowed_filetypes = {
    ["png"] = true,
    ["jpg"] = true,
    ["jpeg"] = true,
    ["bmp"] = true,
    ["gif"] = true,
}
    
-- A table of slide show data, indexed by Source name.
-- Each entry contains a sorted list of filenames, and the index of the current slide.
slide_shows = {}

-- The currently active slideshow: hotkeys and buttons apply to this one
active_source_name  = ""

-- Slide actions
SHOW_SLIDE = 0
NEXT_SLIDE = 1
PREV_SLIDE = 2
FIRST_SLIDE = 3

hotkey_reset_id    = obs.OBS_INVALID_HOTKEY_ID
hotkey_next_id     = obs.OBS_INVALID_HOTKEY_ID
hotkey_previous_id = obs.OBS_INVALID_HOTKEY_ID

-- script_description returns the description shown to the user
function script_description()
    print("in script_description")
    return [[<h2>SimpleSlides</h2>
            <p>Use an Image Source whose names begin with "SimpleSlides:" to
            display sequential image files from a directory, creating a simple
            slide show without the memory limitations of the OBS Image Slide
            Show. However, some frames may be dropped during image changes.</p>
            
            <p>The filespec in the Image Source is used to specify the directory.
            Files of type png, jpg, jpeg, bmp, and gif will be shown.
            Files are shown in sort order: XXX1 will be followed
            by XXX10, not by XXX2, so you may need to normalize
            your filenames (XXX01, XXX02...)</p>

            <p>Slides may be changed via assignable hotkey, or via the buttons
            below. Hotkeys and buttons act only if a SimpleSlide Image Source
            is visible in the Preview or Program window.</p>
            
            <p>You can have multiple independent slide shows using Sources with
            unique names: for example "SimpleSlides: lyrics" and
            "SimpleSlides: sermon graphics". Hotkeys and buttons will act on
            whichever slideshow is visible in the Preview or Program window,
            with Program taking precedence.</p>
           ]]
end

----------------------------------------------------------
-- script_properties defines the properties that the user
-- can change for the entire script module itself
function script_properties()
    print("in script_properties")
    
    local props = obs.obs_properties_create()
    obs.obs_properties_add_button(props, "next_button",     " NEXT ", next_button_clicked)
    obs.obs_properties_add_button(props, "previous_button", " PREV ", previous_button_clicked)
    obs.obs_properties_add_button(props, "reset_button",    "RESET",  reset_button_clicked)

    return props
end

-- script_update is called when script settings are changed
function script_update(settings)
    print('in script_update')
end

-- script_defaults is called to set the default settings
function script_defaults(settings)
    print("in script_defaults")
end

-- script_save is called when the script is saved
-- We save our hotkey assignments
function script_save(settings)
    print("in script_save")
    local save_array = obs.obs_hotkey_save(hotkey_reset_id)
    obs.obs_data_set_array(settings, "reset_hotkey", save_array)
    obs.obs_data_array_release(save_array)

    save_array = obs.obs_hotkey_save(hotkey_next_id)
    obs.obs_data_set_array(settings, "next_slide_hotkey", save_array)
    obs.obs_data_array_release(save_array)
    
    save_array = obs.obs_hotkey_save(hotkey_previous_id)
    obs.obs_data_set_array(settings, "previous_slide_hotkey", save_array)
    obs.obs_data_array_release(save_array)
end

-- script_load is called on startup
function script_load(settings)
    print("in script_load")
    obs.obs_frontend_add_save_callback(on_save)
    obs.obs_frontend_add_event_callback(handle_frontend_event)

    -- Connect our hotkeys
    hotkey_reset_id = obs.obs_hotkey_register_frontend("reset_button_thingy", "[SimpleSlides]Reset", reset)
    hotkey_next_id  = obs.obs_hotkey_register_frontend("next_button_thingy", "[SimpleSlides]Next", next_slide)
    hotkey_previous_id = obs.obs_hotkey_register_frontend("previous_button_thingy", "[SimpleSlides]Previous", previous_slide)

    local save_array = obs.obs_data_get_array(settings, "reset_hotkey")
    obs.obs_hotkey_load(hotkey_reset_id, save_array)
    obs.obs_data_array_release(save_array)

    save_array = obs.obs_data_get_array(settings, "next_slide_hotkey")
    obs.obs_hotkey_load(hotkey_next_id, save_array)
    obs.obs_data_array_release(save_array)
    
    local save_array = obs.obs_data_get_array(settings, "previous_slide_hotkey")
    obs.obs_hotkey_load(hotkey_previous_id, save_array)
    obs.obs_data_array_release(save_array)
end

-- on_save(loading) is called at startup and when a scene collection is loaded.
-- on_save(saving) is called when anything in a scene_collection is changed, 
-- just before a new scene collection is loaded, and during showdown.
function on_save(save_data, saving, private_data)
	print( "on_save(" .. (saving and "saving)" or "loading)"))
	if not saving then
        -- TODO: should loading a new scene-set wipe all slideshow data?
        select_slideshow("on_save(load)")
    else
        -- TODO: a change to one of our sources should reset it's slideshow data
        select_slideshow("on_save(save)")
	end
end

function handle_frontend_event(event)
	if event == obs.OBS_FRONTEND_EVENT_SCENE_CHANGED then
        -- get a preview event before this anyway, so avoid duplicate action
        print("OBS_FRONTEND_EVENT_SCENE_CHANGED")
    elseif event == obs.OBS_FRONTEND_EVENT_PREVIEW_SCENE_CHANGED then
        select_slideshow("OBS_FRONTEND_EVENT_PREVIEW_SCENE_CHANGED")
    elseif event == obs.OBS_FRONTEND_EVENT_SCENE_LIST_CHANGED then
       print("OBS_FRONTEND_EVENT_SCENE_LIST_CHANGED")
	elseif event == obs.OBS_FRONTEND_EVENT_EXIT then
	   print("OBS_FRONTEND_EVENT_EXIT")
	elseif event == obs.OBS_FRONTEND_EVENT_FINISHED_LOADING then
	   print("OBS_FRONTEND_FINISHED_LOADING")
    else
       print("Front end event " .. event)
    end
end

-- Given a path, return the directory part (including final slash or backslash)
-- file part, extension part (not including dot)
-- if there's no directory part, or extension, some strings may be empty
-- Yes, I know you could do it in one line using regex.
function splitpath(filespec)
    local path, name, extension

    local i = #filespec
    while i > 0 do
        local ch = string.sub(filespec,i,i)
        if ch == '\\' or ch == '/' then break end
        i = i - 1
    end

    if i == 0 then
        path = ''
    else
        path = string.sub(filespec,1,i)
    end

    local j = #filespec
    while j > i+1 do
        local ch = string.sub(filespec,j,j)
        if ch == '.' then break end
        j = j - 1
    end

    if j == i+1 then
        name = string.sub(filespec,i+1)
        extension = ''
    else
        name = string.sub(filespec,i+1,j-1)
        extension = string.sub(filespec,j+1)
    end
    
    return path, name, extension
end

-- If we don't have slideshow data for special_image_name, create it now
function create_slideshow_if_needed(special_image_name)
    if slide_shows[special_image_name] then
        print('    slideshow exists for "' .. special_image_name .. '"')
    else
        print('    creating slideshow for "' .. special_image_name .. '"')

        local show = {}
        
        local source = obs.obs_get_source_by_name(special_image_name)
        if source == nil then 
            print('ERROR: no source for "' .. special_image_name .. '"')
        else
            -- Filespec is as entered when the source was created, possibly
            -- changed if the scene was saved after we advanced to another slide.
            -- We extract the parts we need (currently just the path)
            local settings = obs.obs_source_get_settings(source)
            if not settings then
                print('ERROR: no settings for "' .. special_image_name .. '"')
            else
                local filespec = obs.obs_data_get_string(settings, 'file')
                obs.obs_data_release(settings)
                
                local path, name, extension
                path, name, extension = splitpath(filespec)
                print('Filespec="' .. filespec .. '" path="' .. path .. '" name="' .. name .. '" ext="' .. extension .. '"')

                local filenames = {}
                local dir = obslua.os_opendir(path)
                local entry
                repeat
                    entry = obslua.os_readdir(dir)
                    if entry and not entry.directory then
                        local xpath
                        xpath, name, extension = splitpath(entry.d_name)

                        if allowed_filetypes[string.lower(extension)] then
                            -- print('  Image file="' .. entry.d_name .. '"')
                            table.insert(filenames, path .. entry.d_name)
                        end
                    end
                until not entry
                obslua.os_closedir(dir)
                
                -- Alphabetize (case insensitive) the filenames
                table.sort(filenames, function(a,b) return string.lower(a) < string.lower(b) end )

                -- Save the slideshow for later use
                show['filenames'] = filenames
                show['current_slide'] = 1
                slide_shows[special_image_name] = show

                do_slide('from create_slideshow_if_needed', FIRST_SLIDE)
            end
            obs.obs_source_release(source)
        end
    end
end

-- If the scene has a source_key source, return its name; else ""
function get_key_source(label, scenesource)
    retval = ''

    if scenesource ~= nil then
        local scene_name = obs.obs_source_get_name(scenesource)
        print(label .. ' get_key_source for "' .. scene_name .. '"')

        local scene = obs.obs_scene_from_source(scenesource)
        local items = obs.obs_scene_enum_items(scene)
        for i, item in pairs(items) do
            local item_source = obs.obs_sceneitem_get_source(item)
            local item_name = obs.obs_source_get_name(item_source)
            -- print( '  ' .. label .. ' "' .. scene_name .. '" source "' .. item_name .. '"')
            if obs.obs_source_get_id(item_source) == "image_source" then
                ix,len = string.find(item_name, source_key)
                if ix == 1 then
                    print( '  ' .. label .. ' "' .. scene_name .. '" has "' .. item_name .. '"')
                    retval = item_name
                    break
                end
            end
        end
        obs.sceneitem_list_release(items)
    end

    return retval
end

-- Select a slide show.
-- Called after save or load, and for OBS_FRONTEND_EVENT_PREVIEW_SCENE_CHANGED,
-- which is also called on scene activation
function select_slideshow(label)
    print('select_slideshow ' .. label)

    -- no show active unless we find one
    local desired_source_name = ''

    local scenesource = obs.obs_frontend_get_current_scene()
    desired_source_name = get_key_source("Program", scenesource)
    obs.obs_source_release(scenesource)

    if desired_source_name == '' then
        -- Program has no slideshow, see if Preview does
        scenesource = obs.obs_frontend_get_current_preview_scene()
        desired_source_name = get_key_source("Preview", scenesource)
        obs.obs_source_release(scenesource)
    end

    if desired_source_name ~= '' then
        create_slideshow_if_needed(desired_source_name)
    end

    if active_source_name ~= desired_source_name then
        active_source_name = desired_source_name
        do_slide(label, SHOW_SLIDE)
    end
end

function do_slide(label, action)
    print('do_slide ' .. label .. ' with action ' .. action)

    if active_source_name ~= '' then
        show = slide_shows[active_source_name]
        if not show then
            print('ERROR: no slideshow exists for "' .. active_source_name .. '"')
        else
            local source = obs.obs_get_source_by_name(active_source_name)
            if source then
                local current_slide = show['current_slide']
                local filenames     = show['filenames']

                if action == SHOW_SLIDE then
                    -- no change to slide index
                elseif action == NEXT_SLIDE then
                    if current_slide < #filenames then
                        current_slide = current_slide + 1
                    end
                elseif action == PREV_SLIDE then
                    if current_slide > 1 then
                        current_slide = current_slide - 1
                    end
                elseif action == FIRST_SLIDE then
                    current_slide = 1
                else
                    print('ERROR: invalid action ' .. action .. ' requested for "' .. active_source_name .. '"')
                end

                show['current_slide'] = current_slide
                local new_filename = filenames[current_slide]
                local current_filename = ''

                local nowSettings = obs.obs_source_get_settings(source)
                if not nowSettings then
                    print( "ERROR: Failed to get current settings for " .. active_source_name )
                else
                    current_filename = obs.obs_data_get_string(nowSettings, "file") 
                    obs.obs_data_release(nowSettings)
                    -- print( "Old file for " .. active_source_name .. ' is ' .. current_filename)
                end
                
                if new_filename ~= current_filename then
                    local settings = obs.obs_data_create()
                    obs.obs_data_set_string(settings, "file", new_filename)
                    obs.obs_source_update(source, settings)
                    obs.obs_data_release(settings)

                    print( "File[" .. current_slide .. "] for " .. active_source_name .. ' is ' .. new_filename)
                end

                obs.obs_source_release(source)
            end
        end
    end
end

function reset_button_clicked(props, p)
    reset(true)
    return false
end

function next_button_clicked(props, p)
    next_slide(true)
    return false
end

function previous_button_clicked(props, p)
    previous_slide(true)
    return false
end

function reset(pressed)
    if pressed then
        do_slide('reset', FIRST_SLIDE)
    end
end

function next_slide(pressed)
    if pressed then
        do_slide('next_slide', NEXT_SLIDE)
    end
end

function previous_slide(pressed)
    if pressed then
        do_slide('next_slide', PREV_SLIDE)
    end
end