library(shiny)
library(docstring)
source("drive.R")

problemStatement <- 
    "This is a simulation of a car driving in a city and taking random \
turns left, right, make a U-turn, or not turn at all, with some probabilities \
which can be adjusted with the sliders. If we do not turn, we continue \
in the same direction we came from."

function(input, output) {

    output$problemStatement <- renderText(problemStatement)

    output$pathPlot <- renderPlot({
        input$goButton
        nturns  <- input$nturns

        nblocks <- input$nblocks
        pLeft   <- input$pLeft
        pRight  <- input$pRight
        pUTurn  <- input$pUTurn
        pStraight  <- 1 - pLeft - pRight - pUTurn

        prob <- c(pLeft, pRight, pStraight, pUTurn)
        #print(c('Prob: ',prob))
        tryCatch({
            drive(nturns, nblocks, prob)
        },
        error = function(cond) {
            plot(NULL, xlim=c(-nblocks,nblocks), ylim=c(-nblocks,nblocks))
            text(0, 0,'Probability of no-turn dropped below 0', col=2, cex=2)
        })
    })

    output$pStraight  <- renderText({
        pStraight  <- 1 - input$pLeft - input$pRight - input$pUTurn
        print(c('Prob. of going straight through the intersection: ', pStraight))
    })
}