usgsrivergauge.go

package main

import (
	"fmt"
	jww "github.com/spf13/jwalterweatherman"
	"io/ioutil"
	"net/http"
	"strings"
	"time"
)

type USGSGaugeDataRow struct {
	CubicFeetPerSecond float64 // Maps to USGS parameter 00060 (Discharge, cubic feet per second)
	GaugeHeight        float64 // Maps to USGS parameter 00065 (Gage height, feet)
}

// The data source URL. Take this, append the gaugeID, and that's the URL to get gauge data.
const gaugeUrl = "http://waterdata.usgs.gov/wa/nwis/uv?cb_all_00060_00065=on&cb_00060=on&cb_00065=on&format=rdb&period=1&site_no="

// getTextForGauge MUST return a text string, which is what will be read aloud as the text for this gauge.
// It may be an error message or the actual result string, but it must be able to be read by the speech synthesizer.
func getTextForGauge(gauge *USGSGaugeConf, configuration *Configuration) string {
	// Make the HTTP request
	resp, err := http.Get(fmt.Sprintf("%s%d", gaugeUrl, gauge.Id))
	if err != nil {
		jww.CRITICAL.Println("Error fetching data for gauge", gauge.Id, ". Error was: ", err)
		return fmt.Sprintf("Unable to fetch data for the gauging station on the %s.", gauge.FriendlyName)
	}
	defer resp.Body.Close()
	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		jww.CRITICAL.Println("Error reading response body for gauge", gauge.Id, ". Error was: ", err)
		return fmt.Sprintf("Unable to read data for the gauging station on the %s.", gauge.FriendlyName)
	}

	// Get the text file returned by the server in a line-by-line format we can look through.
	bodyTxt := string(body)
	bodyLines := strings.Split(bodyTxt, "\n")

	// Run through the whole file by lines. For now we're just going to keep going until we get the very last row. (The only data we care about is the most recent)
	headerRow := ""
	lastRow := ""
	for _, rowData := range bodyLines {
		// Look for the header row. It'll be the first non-commented row we find. Once we find it we can stop looking.
		if headerRow == "" && len(rowData) > 9 && rowData[:9] == "agency_cd" {
			headerRow = rowData
		}

		if len(rowData) > 5 && rowData[:4] == "USGS" {
			lastRow = rowData
		}
	}

	// Now we find out which columns in the tab-delimited file are the ones we want by parsing the header row
	datetimeCol, cfpsCol, gaugeHeightCol := -1, -1, -1
	headers := strings.Split(headerRow, "\t")
	for index, header := range headers {
		if header == "datetime" {
			datetimeCol = index
		}

		// this column header wasn't datetime, and we know that any column we're interested in will have a _ in it,
		// so we'll split that first, ignoring any columns that might not be what we want.
		headerSplit := strings.Split(header, "_")
		if len(headerSplit) > 1 {
			switch headerSplit[len(headerSplit)-1] {
			case "00060":
				cfpsCol = index
			case "00065":
				gaugeHeightCol = index
			}
		}
	}

	// Sanity check to make sure valid columns found
	if datetimeCol == -1 || cfpsCol == -1 || gaugeHeightCol == -1 {
		jww.CRITICAL.Println("Gauge", gauge.Id, "could not find valid data on any row... Aborting for this gauge.")
		return fmt.Sprintf("Could not recieve valid data from the gauging station on the %s.", gauge.FriendlyName)
	}

	// Now that we know which columns we're looking for yank the data out of there.
	splitLastRow := strings.Split(lastRow, "\t")
	t, err := time.Parse("2006-01-02 15:04", splitLastRow[datetimeCol])
	if err != nil {
		jww.CRITICAL.Println("Gauge", gauge.Id, "could not parse time, aborting for gauge. Error was: ", err)
		return fmt.Sprintf("Could not recieve valid data from the gauging station on the %s.", gauge.FriendlyName)
	}

	// Format our final output TXT!
	timeStr := t.Format("January 02 at 03:04 PM") // Define what we want our output time string to look like
	outStr := fmt.Sprintf("At %s the gauging station on the %s reported %s cubic feet per second, at a height of %s feet.", timeStr, gauge.FriendlyName, splitLastRow[cfpsCol], splitLastRow[gaugeHeightCol])
	jww.DEBUG.Println("Gauge", gauge.Id, "generated text: ", outStr)

	return outStr
}

/*
// Convert "2" to "2nd", etc...
func ordinalForDayNumber(x int) string {
	suffix := "th"
	switch x {
	case 1, 21, 31:
		suffix = "st"
	case 2, 22:
		suffix = "nd"
	case 3, 23:
		suffix = "rd"
	}
	return strconv.Itoa(x) + suffix
}
*/