local physics = require("physics")
physics.start()
 
display.setStatusBar( display.HiddenStatusBar )
 
-- Create some variables to say how much weight is being applied to the bridge and if it can be broken
local weight = 0
local breakable = true
 
-- The final "true" parameter overrides Corona's auto-scaling of large images
local background = display.newImage( "jungle_bkg.png", 0, 0, true )
background.x = display.contentWidth / 2
background.y = display.contentHeight / 2
 
local pole1 = display.newImage( "bamboo.png" )
pole1.x = 50; pole1.y = 250; pole1.rotation = -12
physics.addBody( pole1, "static", { friction=0.5 } )
 
local pole2 = display.newImage( "bamboo.png" )
pole2.x = 430; pole2.y = 250; pole2.rotation = 12
physics.addBody( pole2, "static", { friction=0.5 } )
 
local instructionLabel = display.newText( "touch boards to break bridge, touch rocks to remove", 22, 20, native.systemFont, 17 )
instructionLabel:setTextColor( 190, 255, 131, 150 )
 
local board = {}
local joint = {}
 
-- A touch listener to "break" bridge joints
local breakJoint = function( event )
        local t = event.target
        local phase = event.phase
 
        if "began" == phase then
                if breakable == true then
                        local myIndex = t.myIndex
                        print( "breaking joint at board#" .. myIndex )
                        joint[myIndex]:removeSelf() -- destroy joint
                        breakable = false
                end
        end
 
        -- Stop further propagation of touch event
        return true
end
 
-- A touch listener to remove rocks
local removeBody = function( event )
        local t = event.target
        local phase = event.phase
 
        if "began" == phase then
                t:removeSelf() -- destroy object
        end
        
        if t.myName == "coconut" then
                weight = weight - 5
        else
                weight = weight - 10
        end
 
        -- Stop further propagation of touch event
        return true
end
 
 
for j = 1,16 do
        board[j] = display.newImage( "board.png" )
        board[j].x = 20 + (j*26)
        board[j].y = 150
        board[j].myIndex = j -- for touch handler above
        board[j]:addEventListener( "touch", breakJoint ) -- assign touch listener to board
        board[j].myName = "board"
        
        physics.addBody( board[j], { density=0.8, friction=0.3, bounce=0.3 } )
        
        -- damping the board motion increases the "tension" in the bridge
        board[j].angularDamping = 5000
        board[j].linearDamping = 0.7
 
        -- create joints between boards
        if (j > 1) then
                prevLink = board[j-1] -- each board is joined with the one before it
        else
                prevLink = pole1 -- first board is joined to left pole
        end
        joint[j] = physics.newJoint( "pivot", prevLink, board[j], 6+(j*26), 150 )
 
end
 
-- join final board to right pole
joint[#joint + 1] = physics.newJoint( "pivot", board[16], pole2, 6+(17*26), 150 )
 
-- A function for a collision to apply weight to the bridge
local function onCollision()
 
        if event.object1.myName == "coconut" then
                weight = weight + 5
        elseif event.object1.myName == "rock" then
                weight = weight + 10
                end
end
 
Runtime:addEventListener( "collision", onCollision )
 
local balls = {}
 
-- function to drop random coconuts and rocks
local randomBall = function()
 
        choice = math.random( 100 )
        local ball
        
        if ( choice < 80 ) then
                ball = display.newImage( "coconut.png" )
                ball.x = 40 + math.random( 380 ); ball.y = -40
                physics.addBody( ball, { density=0.6, friction=0.6, bounce=0.6, radius=19 } )
                ball.angularVelocity = math.random(800) - 400
                ball.isSleepingAllowed = false
                ball.myName = "coconut" 
        else
                ball = display.newImage( "rock.png" )
                ball.x = 40 + math.random( 380 ); ball.y = -40
                physics.addBody( ball, { density=2.0, friction=0.6, bounce=0.2, radius=33 } )
                ball.angularVelocity = math.random(600) - 300
                ball.myName = "rock"
        
        end
        
        ball:addEventListener( "touch", removeBody ) -- assign touch listener to rock
        balls[#balls + 1] = ball        
end
 
-- run the above function 14 times
timer.performWithDelay( 1500, randomBall, 14 )
 
-- A weight listener to "break" bridge joints
local weightBreakJoint = function( event )
        if breakable == true then
                if weight >= 75 then
                        print( "Weight has broken the bridge" )
                        joint[(math.random(2,15))]:removeSelf() -- destroy joint
                        breakable = false
                end
        end
end
 
Runtime:addEventListener("enterFrame", weightBreakJoint)