HoldDown.lua

--[[-----------------------------------------------------------------------

The MIT License (MIT)

Copyright (c) 2010-2020 Mark Rogaski

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GwHoldDown = {}
GwHoldDown.__index = GwHoldDown

--- GwHoldDown constructor function.
-- @param interval The length, in seconds, of the hold-down interval.
-- @param limit The maximum hold time when the continue method is invoked.
-- If no value is supplied, the interval value is used.
-- @return An initialized GwHoldDown instance.
function GwHoldDown:new(interval, limit)
    assert(type(interval) == 'number')
    assert(type(limit) == 'number' or limit == nil)
    local self = {}
    setmetatable(self, GwHoldDown)
    self.interval = interval
    if limit then
        self.limit = limit
    else
        self.limit = interval
    end
    self.timestamp = 0
    self.scale = 0
    return self
end

--- Update the timer interval.
-- @param interval The length, in seconds, of the hold-down interval.
-- @param limit The maximum hold time when the continue method is invoked.
-- @return The GwHoldDown instance.
function GwHoldDown:set(interval, limit)
    assert(type(interval) == 'number')
    gw.Debug(GW_LOG_DEBUG, 'hold-down set; timer=%s, interval=%d, limit=%s', tostring(self), interval, tostring(limit))
    self.interval = interval
    if limit then
        self.limit = limit
    else
        self.limit = interval
    end
    return self
end

--- Start the hold-down interval.
-- @param f (optional) A callback function that will be called when the timer expires.
-- @return The time at which the interval will end.
function GwHoldDown:start(f)
    local function handler(frame, elapsed)
        if not self:hold() then
            gw.Debug(GW_LOG_NOTICE, 'hold-down expired; timer=%s', tostring(self))
            if type(f) == 'function' then
                gw.Debug(GW_LOG_NOTICE, 'triggered hold-down callback; function=%s', tostring(f))
                f()
            end
            frame:SetScript('OnUpdate', nil)
        end
    end

    local t = time()
    local expiry = t + self.interval
    self.timestamp = t
    self.scale = 0

    local frame = CreateFrame('frame')
    frame:SetScript('OnUpdate', handler)

    gw.Debug(GW_LOG_NOTICE, 'hold-down start; timer=%s, timestamp=%d, expiry=%d, function=%s',
            tostring(self), self.timestamp, expiry, tostring(f))
    return expiry
end

--- Continue the hold down, scaling the interval.
function GwHoldDown:continue()
    -- Pass-through for first invocation
    if self.timestamp == 0 then
        return self:start()
    end

    -- Increase scaling factor
    if self.interval * 2 ^ (self.scale + 1) <= self.limit then
        self.scale = self.scale + 1
    end

    -- Set the timer
    local t = time()
    local expiry = t + self.interval * 2 ^ self.scale
    self.timestamp = t

    gw.Debug(GW_LOG_NOTICE, 'hold-down continue; timer=%s, timestamp=%d, scale=%d, expiry=%d',
            tostring(self), self.timestamp, self.scale, expiry)

    return expiry
end

--- Clear the hold-down timer.
function GwHoldDown:clear()
    self.timestamp = 0
    self.scale = 0
    gw.Debug(GW_LOG_NOTICE, 'hold-down cleared; timer=%s', tostring(self))
end

--- Test the hold-down status.
-- @return True if a hold-down is in effect, false otherwise.
function GwHoldDown:hold()
    if self.timestamp > 0 then
        local t = time()
        return self.timestamp + self.interval * 2 ^ self.scale > t
    else
        return false
    end
end


GwHoldDownCache = {}
GwHoldDownCache.__index = GwHoldDownCache

--- GwHoldDownCache constructor function.
-- @param interval The length, in seconds, of the hold-down interval.
-- @param soft_max Table size threshold for compaction.
-- @param hard_max Limit on table size.
-- @return An initialized GwHoldDownCache instance.
function GwHoldDownCache:new(interval, soft_max, hard_max)
    assert(type(interval) == 'number')
    assert(type(soft_max) == 'number')
    assert(type(hard_max) == 'number')
    local self = {}
    setmetatable(self, GwHoldDownCache)
    self.interval = interval
    self.soft_max = soft_max
    self.hard_max = hard_max
    self.cache = {}
    return self
end

--- Test the hold-down status of an element.
-- @return True if a hold-down is in effect, false otherwise.
function GwHoldDownCache:hold(s)
    local t = time()
    local rv = false

    -- Check for hold-down
    if self.cache[s] == nil then
        self.cache[s] = t
        gw.Debug(GW_LOG_DEBUG, 'cache miss; target=%s, cache=%s', s, tostring(self))
    else
        gw.Debug(GW_LOG_DEBUG, 'cache hit; target=%s, cache=%s', s, tostring(self))
        if self.cache[s] > t + self.interval then
            rv = true
        else
            self.cache[s] = nil
            gw.Debug(GW_LOG_DEBUG, 'cache expire; target=%s, cache=%s', s, tostring(self))
        end
    end

    -- Prune if necessary
    if #self.cache > self.soft_max then
        for k, v in pairs(self.cache) do
            if v > t + self.interval then
                table.remove(self.cache, k)
                gw.Debug(GW_LOG_DEBUG, 'cache soft prune; target=%s, cache=%s', k, tostring(self))
            end
        end
    end

    -- Hard prune if necessary
    if #self.cache > self.hard_max then
        local index = {}
        for k, ts in pairs(self.cache) do
            table.insert(index, {ts, k})
        end
        table.sort(index, function(a, b) return a[1] < b [1] end)
        for i = self.hard_max, #index do
            table.remove(self.cache, index[i][2])
            gw.Debug(GW_LOG_DEBUG, 'cache hard prune; target=%s, cache=%s', index[i][2], tostring(self))
        end
    end

    return rv
end