-- SPDX-License-Identifier: MIT

local function usage(event_type, code)
    return event_type * 65536 + code
end

evdev = {
    BTN_MIDDLE = usage(1, 274),
    BTN_TOUCH = usage(1, 330),
    BTN_TOOL_FINGER = usage(1, 325),
    BTN_TOOL_QUINTTAP = usage(1, 328),
    BTN_TOOL_DOUBLETAP = usage(1, 333),
    BTN_TOOL_TRIPLETAP = usage(1, 334),
    BTN_TOOL_QUADTAP = usage(1, 335),
    REL_X = usage(2, 0),
    REL_Y = usage(2, 1),
    ABS_MT_SLOT = usage(3, 47),
    ABS_MT_TOUCH_MAJOR = usage(3, 48),
    ABS_MT_POSITION_X = usage(3, 53),
    ABS_MT_POSITION_Y = usage(3, 54),
    ABS_MT_TOOL_Y = usage(3, 61),
    ABS_MT_TRACKING_ID = usage(3, 57),
}

local plugin_callbacks = {}
libinput = {
    register = function(_, versions)
        assert(versions[1] == 1)
        return 1
    end,
    connect = function(_, name, callback)
        plugin_callbacks[name] = callback
    end,
    log_debug = function() end,
    log_error = function() end,
}

dofile(arg[1])

local function new_device(device_type)
    local callbacks = {}
    local device = {
        callbacks = callbacks,
        prepended = {},
        appended = {},
        enabled = {},
    }
    local usages = {
        [evdev.ABS_MT_SLOT] = true,
        [evdev.ABS_MT_TRACKING_ID] = true,
        [evdev.ABS_MT_POSITION_X] = true,
        [evdev.ABS_MT_POSITION_Y] = true,
        [evdev.BTN_TOUCH] = true,
        [evdev.BTN_TOOL_FINGER] = true,
        [evdev.BTN_TOOL_DOUBLETAP] = true,
        [evdev.BTN_TOOL_TRIPLETAP] = true,
        [evdev.BTN_TOOL_QUADTAP] = true,
        [evdev.BTN_TOOL_QUINTTAP] = true,
    }
    if device_type == "mouse" then
        usages[evdev.REL_X] = true
        usages[evdev.REL_Y] = true
    end
    function device:udev_properties()
        if device_type == "touchpad" then
            return { ID_INPUT_TOUCHPAD = true }
        elseif device_type == "mouse" then
            return { ID_INPUT_MOUSE = true }
        end
        return {}
    end
    function device:usages()
        return usages
    end
    function device:absinfos()
        return {
            [evdev.ABS_MT_POSITION_X] = {
                minimum = 0, maximum = 2833, resolution = 24,
            },
            [evdev.ABS_MT_POSITION_Y] = {
                minimum = 0, maximum = 1723, resolution = 24,
            },
        }
    end
    function device:enable_evdev_usage(code)
        self.enabled[code] = true
        usages[code] = true
    end
    function device:connect(name, callback)
        callbacks[name] = callback
    end
    function device:prepend_frame(frame)
        table.insert(self.prepended, frame)
    end
    function device:append_frame(frame)
        table.insert(self.appended, frame)
    end

    plugin_callbacks["new-evdev-device"](device)
    return device
end

local function event(code, value)
    return { usage = code, value = value }
end

local function contains(frame, code, value)
    if not frame then
        return false
    end
    for _, item in ipairs(frame) do
        if item.usage == code and (value == nil or item.value == value) then
            return true
        end
    end
    return false
end

local function feed(device, timestamp, frame)
    local output = device.callbacks["evdev-frame"](device, frame, timestamp)
    if output == nil then
        return frame
    end
    return output
end

local function down(device, timestamp, slot, tracking_id, x, y, count)
    local frame = {
        event(evdev.ABS_MT_SLOT, slot),
        event(evdev.ABS_MT_TRACKING_ID, tracking_id),
        event(evdev.ABS_MT_POSITION_X, x),
        event(evdev.ABS_MT_POSITION_Y, y),
    }
    if count == 1 then
        table.insert(frame, event(evdev.BTN_TOUCH, 1))
        table.insert(frame, event(evdev.BTN_TOOL_FINGER, 1))
    elseif count == 2 then
        table.insert(frame, event(evdev.BTN_TOOL_FINGER, 0))
        table.insert(frame, event(evdev.BTN_TOOL_DOUBLETAP, 1))
    elseif count == 3 then
        table.insert(frame, event(evdev.BTN_TOOL_DOUBLETAP, 0))
        table.insert(frame, event(evdev.BTN_TOOL_TRIPLETAP, 1))
    end
    return feed(device, timestamp, frame)
end

local function up(device, timestamp, slot, count_after)
    local frame = {
        event(evdev.ABS_MT_SLOT, slot),
        event(evdev.ABS_MT_TRACKING_ID, -1),
    }
    if count_after == 1 then
        table.insert(frame, event(evdev.BTN_TOOL_FINGER, 1))
        table.insert(frame, event(evdev.BTN_TOOL_DOUBLETAP, 0))
    elseif count_after == 0 then
        table.insert(frame, event(evdev.BTN_TOUCH, 0))
        table.insert(frame, event(evdev.BTN_TOOL_FINGER, 0))
    end
    return feed(device, timestamp, frame)
end

local button_device = new_device("mouse")

local function click_count()
    local count = 0
    for _, frame in ipairs(button_device.appended) do
        if contains(frame, evdev.BTN_MIDDLE, 1) then
            count = count + 1
        end
    end
    return count
end

local tests = {}

function tests.hold_tap_emits_middle_and_hides_tapper()
    local device = new_device("touchpad")
    down(device, 0, 0, 10, 1000, 1000, 1)
    local second_down = down(device, 200000, 1, 11, 1400, 1000, 2)
    assert(not contains(second_down, evdev.ABS_MT_TRACKING_ID, 11))
    assert(not contains(second_down, evdev.BTN_TOOL_DOUBLETAP, 1))
    local second_up = up(device, 260000, 1, 1)
    assert(not contains(second_up, evdev.ABS_MT_TRACKING_ID, -1))
    assert(click_count() == 1)
    assert(#device.appended == 0)
    up(device, 440000, 0, 0)
end

function tests.hold_doubletap_emits_two_middle_clicks()
    local device = new_device("touchpad")
    down(device, 0, 0, 20, 1000, 1000, 1)
    down(device, 200000, 1, 21, 1400, 1000, 2)
    up(device, 250000, 1, 1)
    down(device, 360000, 1, 22, 1400, 1000, 2)
    up(device, 420000, 1, 1)
    assert(click_count() == 2)
    up(device, 600000, 0, 0)
end

function tests.ordinary_two_finger_tap_passes_through()
    local device = new_device("touchpad")
    down(device, 0, 0, 30, 1000, 1000, 1)
    local second = down(device, 10000, 1, 31, 1400, 1000, 2)
    assert(contains(second, evdev.ABS_MT_TRACKING_ID, 31))
    assert(contains(second, evdev.BTN_TOOL_DOUBLETAP, 1))
    up(device, 70000, 1, 1)
    up(device, 80000, 0, 0)
    assert(click_count() == 0)
end

function tests.long_stationary_tap_is_consumed_without_click()
    local device = new_device("touchpad")
    down(device, 0, 0, 40, 1000, 1000, 1)
    down(device, 200000, 1, 41, 1400, 1000, 2)
    local second_up = up(device, 360001, 1, 1)
    assert(not contains(second_up, evdev.ABS_MT_TRACKING_ID, -1))
    assert(click_count() == 0)
    up(device, 500000, 0, 0)
end

function tests.tapper_movement_restores_normal_input()
    local device = new_device("touchpad")
    down(device, 0, 0, 50, 1000, 1000, 1)
    down(device, 200000, 1, 51, 1400, 1000, 2)
    local moved = feed(device, 230000, {
        event(evdev.ABS_MT_POSITION_X, 1430),
    })
    assert(#device.prepended == 1)
    assert(contains(device.prepended[1], evdev.ABS_MT_TRACKING_ID, 51))
    assert(contains(device.prepended[1], evdev.ABS_MT_POSITION_X, 1430))
    assert(not contains(moved, evdev.ABS_MT_POSITION_X, 1430))
    up(device, 260000, 1, 1)
    up(device, 400000, 0, 0)
    assert(click_count() == 0)
end

function tests.anchor_movement_prevents_recognition()
    local device = new_device("touchpad")
    down(device, 0, 0, 60, 1000, 1000, 1)
    feed(device, 150000, { event(evdev.ABS_MT_POSITION_X, 1040) })
    local second = down(device, 200000, 1, 61, 1400, 1000, 2)
    assert(contains(second, evdev.ABS_MT_TRACKING_ID, 61))
    up(device, 250000, 1, 1)
    up(device, 400000, 0, 0)
    assert(click_count() == 0)
end

function tests.anchor_movement_during_tap_restores_normal_input()
    local device = new_device("touchpad")
    down(device, 0, 0, 62, 1000, 1000, 1)
    down(device, 200000, 1, 63, 1400, 1000, 2)
    local moved = feed(device, 230000, {
        event(evdev.ABS_MT_SLOT, 0),
        event(evdev.ABS_MT_POSITION_X, 1040),
    })
    assert(#device.prepended == 1)
    assert(contains(device.prepended[1], evdev.ABS_MT_TRACKING_ID, 63))
    assert(contains(moved, evdev.ABS_MT_POSITION_X, 1040))
    up(device, 260000, 1, 1)
    up(device, 400000, 0, 0)
    assert(click_count() == 0)
end

function tests.anchor_can_move_pause_and_tap_repeatedly()
    local device = new_device("touchpad")
    down(device, 0, 0, 65, 1000, 1000, 1)

    feed(device, 500000, {
        event(evdev.ABS_MT_SLOT, 0),
        event(evdev.ABS_MT_POSITION_X, 1300),
        event(evdev.ABS_MT_POSITION_Y, 1100),
    })
    down(device, 650000, 1, 66, 1500, 1100, 2)
    up(device, 700000, 1, 1)
    assert(click_count() == 1)

    feed(device, 800000, {
        event(evdev.ABS_MT_SLOT, 0),
        event(evdev.ABS_MT_POSITION_X, 1800),
        event(evdev.ABS_MT_POSITION_Y, 1200),
    })
    down(device, 950000, 1, 67, 2000, 1200, 2)
    up(device, 1000000, 1, 1)
    assert(click_count() == 2)

    up(device, 1100000, 0, 0)
end

function tests.third_contact_restores_candidate()
    local device = new_device("touchpad")
    down(device, 0, 0, 70, 1000, 1000, 1)
    down(device, 200000, 1, 71, 1400, 1000, 2)
    local third = down(device, 230000, 2, 72, 1800, 1000, 3)
    assert(#device.prepended == 1)
    assert(contains(device.prepended[1], evdev.ABS_MT_TRACKING_ID, 71))
    assert(contains(third, evdev.ABS_MT_TRACKING_ID, 72))
    up(device, 260000, 2, 2)
    up(device, 280000, 1, 1)
    up(device, 400000, 0, 0)
    assert(click_count() == 0)
end

function tests.two_finger_hold_tap_remains_passthrough()
    local device = new_device("touchpad")
    down(device, 0, 0, 80, 1000, 1000, 1)
    down(device, 10000, 1, 81, 1400, 1000, 2)
    local third = down(device, 300000, 2, 82, 1800, 1000, 3)
    assert(contains(third, evdev.ABS_MT_TRACKING_ID, 82))
    up(device, 360000, 2, 2)
    up(device, 500000, 1, 1)
    up(device, 510000, 0, 0)
    assert(click_count() == 0)
    assert(#device.prepended == 0)
end

function tests.non_touchpad_is_ignored()
    local device = new_device("other")
    assert(device.callbacks["evdev-frame"] == nil)
    assert(not device.enabled[evdev.BTN_MIDDLE])
end

function tests.pointer_device_is_used_for_button_output()
    assert(button_device.enabled[evdev.BTN_MIDDLE])
    assert(button_device.callbacks["evdev-frame"] == nil)
end

local names = {}
for name in pairs(tests) do
    table.insert(names, name)
end
table.sort(names)
for _, name in ipairs(names) do
    button_device.appended = {}
    tests[name]()
    print("ok - " .. name)
end
print(string.format("%d tests passed", #names))