local widget = require( "widget" )
local storyboard = require( "storyboard" )
local scene = storyboard.newScene()
-- Our scene
function scene:createScene( event )
    local group = self.view

    local date = os.date( "*t" )
    local curDay = date.day
    local curMonth = date.month
    local curYear = date.year

    -- Creates a background
    local function create_bg()
        local background = display.newImage( "assets/background.png", true )
        group:insert( background )
    end

    --Returns name of month[i]
    local get_month_name =
    {
        "January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"
    }

    --Returns short name of month[i]
    local get_short_month_name =
    {
        "jan", "feb", "mar", "apr", "may", "jun", "jul", "aug", "sep", "oct", "nov", "dec"
    }

    --Returns days in a month, including for leap year
    local function get_days_in_month(month, year)
        local days_in_month = { 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31 }
        local d = days_in_month[month]

        -- check for leap year
        if (month == 2) then
            if year%4==0 and (year%100~=0 or year%400==0) then
                d = 29
            end
        end

        return d
    end

    --Returns day of week.
    local get_day_of_week =
    {
        "sun", "mon", "tue", "wed", "thu", "fri", "sat"
    }

    -- Creates the calendar
    local function create_calender( year, month, startDay, endDay )

        --Creates a "calender box" which shows selected month, year and the weekdays.
        local calBox = display.newRect( 0, 32, display.contentWidth, 37 )
        calBox:setFillColor( 0, 0, 0 )
        calBox.alpha = 0.4
        group:insert( calBox )

        --Selected month name
        local monthName = display.newText( get_month_name[month], 0, 0, 0, 0, native.systemFont, 20 )
        monthName:setTextColor( 255, 255, 255 )
        monthName:setReferencePoint(display.CenterLeftReferencePoint)
        monthName.x = 5
        monthName.y = calBox.y - 5
        group:insert( monthName )

        --Selected year name
        local yearName = display.newText( year, 0, 0, 0, 0, native.systemFont, 20 )
        yearName:setTextColor( 255, 255, 255 )
        yearName:setReferencePoint(display.CenterLeftReferencePoint)
        yearName.x = display.contentWidth - yearName.contentWidth
        yearName.y = calBox.y - 5
        group:insert( yearName )

        local x = 0
        local y = calBox.y + calBox.contentHeight*0.5
        local startNr = startDay + 1 --The starting day for the month. Adds 1 because a table index starts at 1.
        local endNr = endDay
        local goMonth = false
        local dayNr = 1

        --print(endDay)

        --Create a 5*7 grid.
        for j = 1, 5 do --5 rows
            for i = 1, 7 do --7 columns

                if i == startNr then
                    goMonth = true
                end

                --Creates a box for each day.
                local dayBox = display.newRect( x, y, display.contentWidth/7, 50 )
                dayBox:setFillColor( 255, 255, 255)
                dayBox.alpha = 0.4
                group:insert( dayBox )

                --Check where to start the selected month.
                if goMonth then
                    local curDayText
                    --If it's the first day of the month, show the name of the month.
                    if dayNr == 1 then
                        curDayText = dayNr .. " " .. get_short_month_name[month]
                    else
                        curDayText = dayNr
                    end

                    --A text representing each day nr.
                    local dayText = display.newText( curDayText, 0, 0, 0, 0, native.systemFont, 10 )
                    dayText:setTextColor( 0, 0, 0 )
                    dayText:setReferencePoint(display.CenterLeftReferencePoint)
                    dayText.x = x + 3
                    dayText.y = y + 7

                    --If it's the end of the month, stop showing day numbers.
                    if dayNr == endNr then
                        goMonth = false
                    else
                        dayNr = dayNr + 1
                    end
                    group:insert( dayText )
                end

                --Print out the day names on the calBox.
                if j == 1 then
                    local dayText = display.newText( get_day_of_week[i], 0, 0, 44, 0, native.systemFont, 14 )
                    dayText.x = dayBox.x + dayBox.contentWidth * 0.25
                    dayText.y = calBox.y + dayText.contentHeight - 3
                    group:insert( dayText )
                end

                --Create horizontal frames
                if j ~= 1 then
                    local frameBottom = display.newRect( x, y, dayBox.contentWidth+1, 1 )
                    frameBottom:setFillColor( 0, 0, 0 )
                    frameBottom.alpha = 1
                    group:insert( frameBottom )
                end

                --Create vertical frames
                if i ~= 1 then
                    local frameRight = display.newRect( x, y, 1, dayBox.contentHeight )
                    frameRight:setFillColor( 0, 0, 0 )
                    frameRight.alpha = 1
                    group:insert( frameRight )
                end

                x = x + display.contentWidth/7

            end

            y = y + 50
            x = 0
        end
    end

    local prevMonth
    local nextMonth

    --Creates buttons for going back and forth in months.
    local function create_buttons()

        local prevButton = widget.newButton
        {
            left = 15,
            top = 320,
            width = 80,
            height = 40,
            label = "<<",
            onRelease = jump_to_prev_month,
        }
        prevButton.xScale = 0.5
        prevButton.yScale = 0.5

        group:insert( prevButton )

        local nextButton = widget.newButton
        {
            left = display.contentWidth - 100,
            top = 320,
            width = 80,
            height = 40,
            label = ">>",
            onRelease = jump_to_next_month,
        }
        nextButton.xScale = 0.5
        nextButton.yScale = 0.5

        group:insert( nextButton )
    end

    --Remove objects
    local function remove_objects()
        for i=group.numChildren,1,-1 do
            local child = group[i]
            child.parent:remove( child )
            child = nil
        end
    end

    --Get the first day of the month
    local function get_start_day( cur_month, cur_year )
        local test = os.time{year = cur_year, month=cur_month, day=1}
        return tonumber(os.date("%w", test))
    end

    --Get the last day of the month
    local function get_end_day( cur_month, cur_year )
        return tonumber(get_days_in_month(cur_month, curYear))
    end

    --Go to the previous month.
    function jump_to_prev_month()
        --Remove all objects
        remove_objects()

        --Set the current month back to the previous month.
        curMonth = curMonth - 1

        --If the month is before January, go back to previous year.
        if curMonth < 1 then
            curMonth = 12
            curYear = curYear - 1
        end

        local startDayofMonth = get_start_day( curMonth, curYear )
        local endDayofMonth = get_end_day( curMonth, curYear )

        --Create background, buttons and calender.
        create_bg()
        create_buttons()
        create_calender( curYear, curMonth, startDayofMonth, endDayofMonth )

    end

    --Go to the next month.
    function jump_to_next_month()
        --Remove all objects
        remove_objects()

        --Set the current month back to the next month.
        curMonth = curMonth + 1
        --If the month is after December, go to the next year.
        if curMonth > 12 then
            curMonth = 1
            curYear = curYear + 1
        end

        local startDayofMonth = get_start_day( curMonth, curYear )
        local endDayofMonth = get_end_day( curMonth, curYear )

        --Create background, buttons and calender.
        create_bg()
        create_buttons()
        create_calender( curYear, curMonth, startDayofMonth, endDayofMonth )
    end

    --Create main
    local function main()
        local startDayofMonth = get_start_day( curMonth, curYear )
        local endDayofMonth = get_end_day( curMonth, curYear )

        --Create background, buttons and calender.
        create_bg()
        create_buttons()
        create_calender( curYear, curMonth, startDayofMonth, endDayofMonth )
    end
    main()

end

scene:addEventListener( "createScene" )

return scene