DependencyControl = require('l0.DependencyControl') {
	name: 'ScrollHandler'
	description: 'Library to save and load subtitle grid scrollbar positions'
	author: 'CoffeeFlux'
	version: '1.1.0'
	moduleName: 'Flux.ScrollHandler'
    url: 'https://github.com/TypesettingTools/CoffeeFlux-Aegisub-Scripts/blob/master/modules/Flux.ScrollHandler.moon'
    feed: 'https://raw.githubusercontent.com/TypesettingTools/CoffeeFlux-Aegisub-Scripts/master/DependencyControl.json'
    {
    	'ffi'
    }
}

ffi = DependencyControl\requireModules!

-- WARNING: Hilarious hacks below

ffi.cdef [[
uintptr_t GetForegroundWindow();
uintptr_t SendMessageA(uintptr_t hWnd, uintptr_t Msg, uintptr_t wParam, uintptr_t lParam);
uintptr_t FindWindowExA(uintptr_t hWndParent, uintptr_t hWndChildAfter, uintptr_t lpszClass, uintptr_t lpszWindow);
]]

msgs = {
    WM_VSCROLL: 0x0115
    SBM_SETPOS: 0xE0
    SBM_GETPOS: 0xE1
    SB_THUMBPOSITION: 4
    SB_ENDSCROLL: 8
    SB_SETTEXT: 0x401
}

class ScrollHandler
	new: =>
		@scrollPositions = {}

	checkHandle: =>
		if not @handle
			@handle = {}
			@handle.App = ffi.C.GetForegroundWindow!
			@handle.Container = ffi.C.FindWindowExA @handle.App, 0, ffi.cast('uintptr_t','wxWindowNR'), 0
			@handle.SubsGrid = ffi.C.FindWindowExA @handle.Container, 0, 0, 0
			@handle.ScrollBar = ffi.C.FindWindowExA @handle.SubsGrid, 0, 0, 0
		@handle.App != 0

	savePos: (key) =>
		return unless checkHandle @
		@scrollPositions[key] = tonumber ffi.C.SendMessageA @handle.ScrollBar, msgs.SBM_GETPOS, 0, 0
		-- aegisub.dialog.status_msg string.format 'Jumpscroll %s: saved position %d'\format key, @scrollpos[key]

	loadPos: (key) =>
		return unless @scrollPositions[key] and checkHandle @
		ffi.C.SendMessageA @handle.SubsGrid, msgs.WM_VSCROLL, msgs.SB_THUMBPOSITION, @handle.ScrollBar
		ffi.C.SendMessageA @handle.ScrollBar, msgs.SBM_SETPOS, @scrollPositions[key], 0
		ffi.C.SendMessageA @handle.SubsGrid, msgs.WM_VSCROLL, msgs.SB_ENDSCROLL, @handle.ScrollBar
		-- aegisub.dialog.status_msg string.format 'Jumpscroll %s: scrolled to position %d'\format key, @scrollpos[key]

	version: DependencyControl

return DependencyControl\register ScrollHandler