rainfall.go

// Rainfall data extraction tool to pull daily total rainfall data for an entire year from NEORSD Rainfall dashboard
// See github.com/AlecIsaacson/Rainfall for details.
//
package main

import (
	"encoding/json"
	"flag"
	"fmt"
	"io/ioutil"
	"net/http"
	"net/url"
	"strconv"
	"time"
)

//NEORSD returns data in this struct.
type neorsdRainfallStruct struct {
	Draw            int `json:"draw"`
	RecordsTotal    int `json:"recordsTotal"`
	RecordsFiltered int `json:"recordsFiltered"`
	Data            []struct {
		TrendDataDay int     `json:"trend_data_day"`
		RainTotal    float64 `json:"rain_total"`
	} `json:"data"`
}

//Get the NEORSD rainfall info, returning the result as a byte string.
func getRainfall(urlToGet string, yearIndex int, month string, location string, logVerbose bool) []byte {
	if logVerbose {
		fmt.Println("In getRainfall")
	}

	//As you can see, most of the form attributes aren't required.  I've left them here in case they're needed some day.
	formData := url.Values{
		//"draw": {"4"},
		// "columns[0][data]": {"trend_data_day"},
		// "columns[0][name]": {""},
		// "columns[0][searchable]": {"true"},
		// "columns[0][orderable]": {"false"},
		// "columns[0][search][value]": {""},
		// "columns[0][search][regex]": {"false"},
		// "columns[1][data]": {"rain_total"},
		// "columns[1][name]": {""},
		// "columns[1][searchable]": {"true"},
		// "columns[1][orderable]": {"false"},
		// "columns[1][search][value]": {""},
		// "columns[1][search][regex]": {"false"},
		// "start": {"0"},
		// "length": {"10"},
		// "search[value]": {""},
		// "search[regex]": {"false"},
		"startingYear": {strconv.Itoa(yearIndex)},
		"rainfallSite": {location},
		//"day": {"1"},
		"month": {month},
		//"fullDate": {"March 1, 2012"},
	}

	//Post the request to NEORSD.
	resp, err := http.PostForm(urlToGet, formData)

	if logVerbose {
		fmt.Println("Form data:", formData)
		fmt.Println("NEORSD Response:", resp.Status)
	}

	if err != nil || resp.StatusCode != 200 {
		fmt.Println("Error")
		fmt.Println(resp)
	}

	defer resp.Body.Close()
	response, err := ioutil.ReadAll(resp.Body)

	if logVerbose {
		fmt.Println("Raw response:", string(response))
		fmt.Println("End of getRainfall")
	}
	return response
}

func main() {
	fmt.Println("GetRainfall v1.5")
	fmt.Println("Use -h for arguments.")
	fmt.Println("Output is Location, Year Month Day, and rainfall in inches (rounded to nearest hundreth).")
	fmt.Println("")
	location := flag.String("location", "Beachwood", "The name of the gauge location whose data you want to get")
	yearToGet := flag.Int("year", 2012, "Year of rainfall data to get")
	logVerbose := flag.Bool("verbose", false, "Writes verbose logs for debugging")
	flag.Parse()

	if *logVerbose {
		fmt.Println("Verbose logging enabled.")
		fmt.Println("Getting data for:", *location, *yearToGet)
	}

	//Define the APIs base URL
	neorsdBaseURL := "https://www.neorsd.org/Rainfall%20Dashboard/dataTableServerSide.php?rainfallDaily"

	//The NEORSD API defines this year as year 1.  Prior years are indexed backwards.
	//Yes, I could have used the Go time library, but it'd be more work.
	//yearOffset should be equal to last year.
	yearOffset := time.Now().Year() - 1
	yearIndex := *yearToGet - yearOffset
	months := []string{"January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"}

	//Iterate through the months, getting the daily rain totals for each.
	for _, month := range months {
		if *logVerbose {
			fmt.Println("Getting data for:", month, *yearToGet)
			fmt.Println("Year Offset:", yearOffset)
		}

		//Call the function to actually get the data.
		neorsdRainfallJSON := getRainfall(neorsdBaseURL, yearIndex, month, *location, *logVerbose)

		//Unmarshal the data into a struct
		if *logVerbose {
			fmt.Println("JSON response:", string(neorsdRainfallJSON))
			fmt.Println("Unmarshalling monitors into struct")
		}

		var neorsdRainfallList neorsdRainfallStruct
		if err := json.Unmarshal(neorsdRainfallJSON, &neorsdRainfallList); err != nil {
			panic(err)
		}

		if *logVerbose {
			fmt.Println(neorsdRainfallList)
		}

		//For each day of the month, write out the info we've got.
		for _, day := range neorsdRainfallList.Data {
			fmt.Printf("%v,%v %v %v,%.2f\n", *location, *yearToGet, month, day.TrendDataDay, day.RainTotal)
		}
	}
}