movement.lua

function Entity:attemptPath(pathX, pathY)
    -- acquire path
    repeat
        self.path = self.map.finder:getPath(self.tileX, self.tileY, pathX, pathY)
        pathX = math.random(self.map.mapWidth)
        pathY = math.random(self.map.mapHeight)
    until self.path

    -- chain movements in path
    if self.path then
        self.target = {
            x = (pathX - 1) * self.map.tileWidth,
            y = (pathY - 1) * self.map.tileHeight
        }

        -- tween movement for X and Y over seconds
        local function TweenMovement(seconds, newX, newY)
            return function(go)
                -- change direction based on X movement
                if newX < self.tileX then
                    self.direction = 'left'
                elseif newX > self.tileX then
                    self.direction = 'right'
                end

                Timer.tween(seconds, {
                    [self] = {
                        -- tween pixel movement
                        x = (newX - 1) * self.map.tileWidth,
                        y = (newY - 1) * self.map.tileHeight
                    }
                })
                :finish(function()
                    -- keep our grid location updated
                    self.tileX = newX
                    self.tileY = newY
                    go()
                end)
            end
        end

        -- list of movement tweens we will chain
        local moveChain = Chain()
        for node, count in self.path:nodes() do

            -- go through each node and append a tween
            moveChain(TweenMovement(0.25, node:getX(), node:getY()))
        end

        -- add function at end to reset path, so we can try a new one
        moveChain(function(go)
            self.path = nil
            self.target = nil
            self:changeAnimation('idle')
            go()
        end)

        self:changeAnimation('walking')

        -- export movement chain so it can be chained with others later
        return function(go)
            moveChain()
            go()
        end
    end
end

function Map:update(dt)
    -- if the entities aren't in a movement turn, chain them to do as much
    if not self.entitiesMoving then
        self.entitiesMoving = true
        local moveChain = Chain()
        for k, v in pairs(self.entities) do
            moveChain(v:attemptPath(math.random(self.mapWidth),
                math.random(self.mapHeight)))
        end
        -- set entities not moving flag as last link in the chain
        moveChain(function(go) self.entitiesMoving = false end)
        moveChain()
    end

    for k, v in pairs(self.entities) do
        v:update(dt)
    end
end