-- SPDX-FileCopyrightText: © 2026 Vladimir Zorin <vladimir@deviant.guru>
-- SPDX-License-Identifier: LicenseRef-OWL-1.0-or-later
-- Licensed under OWL v1.0+. See LICENSE.

-- Exercises the DRM console backend's headless-testable parts: the pure
-- integer-upscale layout math, drm_core's error paths on non-DRM inputs,
-- and the gfx facade exports. The modeset/flip path needs a real
-- /dev/dri/card* at a VT and is covered by manual testing; set
-- LILUSH_TEST_DRM=1 to probe the real device (under a compositor this
-- exercises the master-busy error path — the probe must never leave a
-- modeset behind, so a successful open is closed immediately).

local testimony = require("testimony")
local drm_core = require("term.drm_core")
local drm_display = require("term.gfx.drm_display")
local gfx = require("term.gfx")

local A = testimony

local testify = testimony.new("== term.drm console backend ==")

testify:that("layout: 1920x1080 fits 480x300 at 3x, centered", function()
	local k, dx, dy = drm_display.layout(1920, 1080, 480, 300)
	A.assert_equal(3, k)
	A.assert_equal(240, dx)
	A.assert_equal(90, dy)
end)

testify:that("layout: 1280x1024 fits 480x300 at 2x, centered", function()
	local k, dx, dy = drm_display.layout(1280, 1024, 480, 300)
	A.assert_equal(2, k)
	A.assert_equal(160, dx)
	A.assert_equal(212, dy)
end)

testify:that("layout: 640x480 fits 480x300 at 1x, centered", function()
	local k, dx, dy = drm_display.layout(640, 480, 480, 300)
	A.assert_equal(1, k)
	A.assert_equal(80, dx)
	A.assert_equal(90, dy)
end)

testify:that("layout: exact fit leaves no borders", function()
	local k, dx, dy = drm_display.layout(960, 600, 480, 300)
	A.assert_equal(2, k)
	A.assert_equal(0, dx)
	A.assert_equal(0, dy)
end)

testify:that("layout: the tighter axis picks the factor", function()
	-- width would allow 4x, height only 2x
	local k = drm_display.layout(1920, 700, 480, 300)
	A.assert_equal(2, k)
end)

testify:that("layout: mode smaller than the canvas errors", function()
	local k, err = drm_display.layout(320, 240, 480, 300)
	A.assert_nil(k)
	A.assert_match("smaller than", err)
end)

testify:that("drm_core.open: nonexistent path returns nil, err", function()
	local d, err = drm_core.open("/nonexistent/card0")
	A.assert_nil(d)
	A.assert_not_nil(err)
end)

testify:that("drm_core.open: a regular file is not a DRM device", function()
	-- ioctl(DRM_IOCTL_SET_MASTER) fails on regular files; must not crash
	local path = os.tmpname()
	local f = io.open(path, "w")
	f:write("not a DRM device")
	f:close()
	local d, err = drm_core.open(path)
	os.remove(path)
	A.assert_nil(d)
	A.assert_match("not a DRM device", err)
end)

testify:that("gfx facade exports drm_display and drm_layout, fbdev is gone", function()
	A.assert_equal("function", type(gfx.drm_display))
	A.assert_equal("function", type(gfx.drm_layout))
	-- the fbdev backend is removed, not aliased
	A.assert_nil(gfx.fb_display)
	A.assert_nil(gfx.fb_layout)
	-- the Kitty exports are untouched
	A.assert_equal("function", type(gfx.display))
	A.assert_equal("function", type(gfx.loop))
	A.assert_equal("function", type(gfx.canvas))
end)

testify:that("drm display factory propagates device errors, console untouched", function()
	local c = gfx.canvas({ width = 8, height = 8 })
	local d, err = gfx.drm_display(c, { path = "/nonexistent/card0" })
	A.assert_nil(d)
	A.assert_not_nil(err)
end)

-- Opt-in probe against the real device: at a bare VT it takes master and
-- modesets (then restores immediately); under a compositor it must fail
-- with the clean master-busy error. Either verdict passes — what's tested
-- is that open() never crashes and never returns a half-open handle.
if os.getenv("LILUSH_TEST_DRM") then
	testify:that("drm_core.open: the real device opens cleanly or refuses cleanly", function()
		local d, err = drm_core.open()
		if d then
			local w, h = d:size()
			A.assert_true(w > 0 and h > 0)
			local info = d:info()
			A.assert_true(info.pitch >= w * 4)
			d:close()
		else
			A.assert_not_nil(err)
		end
	end)
end

testify:conclude()