app.R

# Real-Time Bus Tracking System - Surat, Gujarat

library(shiny)
library(googleway)
library(dplyr)
library(shinydashboard)

# Load API key and bus route data
source("api_key.R")
bus_routes <- read.csv("bus_routes.csv", stringsAsFactors = FALSE)

# Filter for Route 1, Bus 101
bus_route <- bus_routes %>% 
  filter(route_id == 1, bus_id == 101) %>%
  arrange(sequence)

# UI Definition
ui <- dashboardPage(
  dashboardHeader(title = "Real-Time Bus Tracking - Surat, Gujarat"),
  dashboardSidebar(
    sidebarMenu(
      menuItem("Map View", tabName = "map", icon = icon("map")),
      menuItem("Route Info", tabName = "info", icon = icon("info-circle")),
      actionButton("start_button", "Start Bus", icon = icon("play")),
      actionButton("stop_button", "Stop Bus", icon = icon("stop")),
      tags$div(
        style = "padding: 10px;",
        tags$p(strong("Source: "), bus_route$stop_name[1]),
        tags$p(strong("Destination: "), bus_route$stop_name[nrow(bus_route)])
      )
    )
  ),
  dashboardBody(
    tabItems(
      tabItem(tabName = "map",
        fluidRow(
          box(
            width = 12,
            google_mapOutput("map", height = "600px")
          )
        ),
        fluidRow(
          box(
            width = 6,
            title = "Bus Information",
            verbatimTextOutput("bus_info")
          ),
          box(
            width = 6,
            title = "Route Information",
            verbatimTextOutput("route_info")
          )
        )
      ),
      tabItem(tabName = "info",
        fluidRow(
          box(
            width = 6,
            title = "Instructions",
            tags$p("This app shows a bus moving along a route in Surat, Gujarat."),
            tags$p("The bus updates its position every 2 seconds."), 
            tags$p("Click 'Start Bus' to begin the simulation."),
            tags$p("The red marker represents the bus's current location."),
            tags$p("The blue line shows the complete route.")
          )
        )
      )
    )
  )
)

# Server Logic
server <- function(input, output, session) {
  
  # Initialize reactive values
  rv <- reactiveValues(
    position_index = 1,
    timer_active = FALSE,
    last_update = Sys.time(),
    initialized = FALSE
  )
  
  # Initialize map
  output$map <- renderGoogle_map({
    google_map(
      key = api_key,
      location = c(bus_route$latitude[1], bus_route$longitude[1]),
      zoom = 14,
      map_type_control = TRUE
    )
  })
  
  # Add route polyline
  observe({
    if (!rv$initialized) {
      google_map_update(map_id = "map") %>%
        add_polylines(
          data = bus_route,
          lat = "latitude", 
          lon = "longitude",
          stroke_colour = "#0000FF",
          stroke_weight = 5,
          stroke_opacity = 0.7
        )
      rv$initialized <- TRUE
    }
  })
  
  # Display bus information
  output$bus_info <- renderText({
    if(rv$timer_active) {
      invalidateLater(100)
    }
    
    current_pos <- bus_route[rv$position_index, ]
    
    paste(
      "Bus ID: 101",
      paste("Current Stop:", current_pos$stop_name),
      paste("Latitude:", current_pos$latitude),
      paste("Longitude:", current_pos$longitude),
      paste("Sequence:", current_pos$sequence),
      paste("Last Updated:", format(rv$last_update, "%H:%M:%S")),
      sep = "\n"
    )
  })
  
  # Update bus position marker
  observe({
    if(rv$timer_active) {
      invalidateLater(100)
      
      current_time <- Sys.time()
      time_diff <- as.numeric(difftime(current_time, rv$last_update, units = "secs"))
      
      if(time_diff >= 2) {
        rv$position_index <- (rv$position_index %% nrow(bus_route)) + 1
        rv$last_update <- current_time
      }
    }
    
    current_pos <- bus_route[rv$position_index, ]
    
    google_map_update(map_id = "map") %>%
      clear_markers() %>%
      add_markers(
        data = current_pos,
        lat = "latitude",
        lon = "longitude",
        marker_icon = "https://maps.google.com/mapfiles/ms/icons/red-dot.png",
        info_window = paste(
          "<b>Bus ID:</b> 101<br>",
          "<b>Stop:</b> ", current_pos$stop_name, "<br>",
          "<b>Sequence:</b> ", current_pos$sequence
        )
      )
  })
  
  # Start button handler
  observeEvent(input$start_button, {
    rv$timer_active <- TRUE
    rv$last_update <- Sys.time()
  })
  
  # Stop button handler
  observeEvent(input$stop_button, {
    rv$timer_active <- FALSE
  })
  
  # Display route information
  output$route_info <- renderText({
    paste(
      "Route ID:", bus_route$route_id[1], "\n",
      "Bus ID:", bus_route$bus_id[1], "\n",
      "Starting Point:", bus_route$stop_name[1], "\n",
      "Ending Point:", bus_route$stop_name[nrow(bus_route)], "\n",
      "Total Stops:", nrow(bus_route)
    )
  })
}

# Run application
shinyApp(ui, server)