Switch to using cobra for CLI

Makefile

@@ -1,10 +1,10 @@
 .DEFAULT_TARGET: all
 
-GO_FILES := $(wildcard *.go)
+GO_FILES := $(shell find . -type f -name '*.go')
 
-all: static/cities.csv sundial
+all: internal/core/cities.csv sundial
 
-static/cities.csv: scripts/makecsv.sh scripts/trim_csv.py
+internal/core/cities.csv: scripts/makecsv.sh scripts/trim_csv.py
 	scripts/makecsv.sh
 
 sundial: $(GO_FILES) static/cities.csv

cmd/root.go

@@ -0,0 +1,81 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+	"strings"
+	"time"
+
+	"github.com/riley-martine/sundial/internal/core"
+	"github.com/spf13/cobra"
+)
+
+// Set by goreleaser:
+// https://goreleaser.com/cookbooks/using-main.version/?h=version
+var version = "dev"
+
+var (
+	debug       bool
+	cityName    string
+	countryCode string
+	fipsCode    string
+	givenTime   string
+)
+
+var rootCmd = &cobra.Command{
+	Use:     "sundial --city CITY",
+	Short:   "Print the percent through the day or night.",
+	Version: version,
+	Long: `Sundial is a program to print the percent through the day or night.
+https://github.com/riley-martine/sundial`,
+	Run: func(cmd *cobra.Command, args []string) {
+		city, err := core.FindCity(cityName, countryCode, fipsCode)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			if strings.HasPrefix(err.Error(), "could not narrow") {
+				fmt.Fprintln(os.Stderr, "You may need to be more specific about which city you're in. Try specifying a country code (second field) and a fips code (third field).")
+				fmt.Fprintln(os.Stderr, "    e.g. sundial -city Washington -country US -fipscode IL")
+			}
+			os.Exit(1)
+		}
+
+		// This probably doesn't need ParseInLocation
+		// Adding that data back to the cities CSV balloons the size
+		t := time.Now()
+		if givenTime != "" {
+			t, err = time.Parse(time.UnixDate, givenTime)
+			if err != nil {
+				fmt.Fprintln(os.Stderr, err)
+				os.Exit(1)
+			}
+		}
+
+		out, err := core.GetPeriodPercent(city, t, debug)
+		if err != nil {
+			fmt.Fprintln(os.Stderr, err)
+			os.Exit(1)
+		}
+		fmt.Println(out)
+	},
+}
+
+func init() {
+	rootCmd.Flags().BoolVar(&debug, "debug", false, "Print debug logging. Default: false")
+
+	rootCmd.Flags().StringVar(&cityName, "city", "", "Name of city you're in. Required.")
+	rootCmd.MarkFlagRequired("city")
+	rootCmd.Flags().StringVar(&countryCode, "country", "", "Two-letter country code, e.g. 'US'. Not required if only one city with name.")
+	rootCmd.Flags().StringVar(&fipsCode, "fipscode", "", `Fipscode of region you're in. In the US, this is the two-letter state abbreviation.
+Otherwise, search http://download.geonames.org/export/dump/admin1CodesASCII.txt
+for '$countryCode.' and select the value after the period for the region you're in.
+Not required if only one city in country with name.`)
+
+	rootCmd.Flags().StringVar(&givenTime, "time", "", "Time to convert, in time.UnixDate format. Defaults to now.")
+}
+
+func Execute() {
+	if err := rootCmd.Execute(); err != nil {
+		// fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

go.mod

@@ -2,4 +2,12 @@ module github.com/riley-martine/sundial
 
 go 1.19
 
-require github.com/kelvins/sunrisesunset v0.0.0-20210220141756-39fa1bd816d5
+require (
+	github.com/kelvins/sunrisesunset v0.0.0-20210220141756-39fa1bd816d5
+	github.com/spf13/cobra v1.6.1
+)
+
+require (
+	github.com/inconshreveable/mousetrap v1.1.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
+)

go.sum

@@ -1,2 +1,13 @@
+github.com/cpuguy83/go-md2man/v2 v2.0.2/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
+github.com/inconshreveable/mousetrap v1.0.1/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
+github.com/inconshreveable/mousetrap v1.1.0 h1:wN+x4NVGpMsO7ErUn/mUI3vEoE6Jt13X2s0bqwp9tc8=
+github.com/inconshreveable/mousetrap v1.1.0/go.mod h1:vpF70FUmC8bwa3OWnCshd2FqLfsEA9PFc4w1p2J65bw=
 github.com/kelvins/sunrisesunset v0.0.0-20210220141756-39fa1bd816d5 h1:ouekCqYkMw4QXFCaLyYqjBe99/MUW4Qf3DJhCRh1G18=
 github.com/kelvins/sunrisesunset v0.0.0-20210220141756-39fa1bd816d5/go.mod h1:3oZ7G+fb8Z8KF+KPHxeDO3GWpEjgvk/f+d/yaxmDRT4=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/spf13/cobra v1.6.1 h1:o94oiPyS4KD1mPy2fmcYYHHfCxLqYjJOhGsCHFZtEzA=
+github.com/spf13/cobra v1.6.1/go.mod h1:IOw/AERYS7UzyrGinqmz6HLUo219MORXGxhbaJUqzrY=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
+gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
+gopkg.in/yaml.v3 v3.0.1/go.mod h1:K4uyk7z7BCEPqu6E+C64Yfv1cQ7kz7rIZviUmN+EgEM=

internal/core/core.go

@@ -0,0 +1,151 @@
+package core
+
+import (
+	"embed"
+	"encoding/csv"
+	"fmt"
+	"github.com/kelvins/sunrisesunset"
+	"io"
+	"strconv"
+	"time"
+)
+
+/*
+What I want to display: percent through the apparent solar day we are
+*/
+
+//go:embed cities.csv
+var fs embed.FS
+
+type CityInfo struct {
+	Name        string
+	CountryCode string
+	FipsCode    string
+	Latitude    float64
+	Longitude   float64
+}
+
+func (c *CityInfo) String() string {
+	return fmt.Sprintf("{%s, %s, %s, %0.2f, %0.2f}", c.Name, c.CountryCode, c.FipsCode, c.Latitude, c.Longitude)
+}
+
+func (c *CityInfo) GetSunriseSunset(at time.Time) (sunrise time.Time, sunset time.Time, err error) {
+	_, secondsOffset := at.Zone()
+	hoursOffset := float64(secondsOffset) / 60 / 60
+	p := sunrisesunset.Parameters{
+		Latitude:  c.Latitude,
+		Longitude: c.Longitude,
+		UtcOffset: hoursOffset,
+		Date:      at,
+	}
+
+	return p.GetSunriseSunset()
+}
+
+func GetPeriodPercent(c *CityInfo, at time.Time, debug bool) (string, error) {
+	if debug {
+		fmt.Printf("City: %#v\n", c)
+	}
+
+	sunrise, sunset, err := c.GetSunriseSunset(at)
+	if err != nil {
+		return "", err
+	}
+
+	if debug {
+		fmt.Println("Sunrise:", sunrise.Format("15:04:05")) // Sunrise: 06:11:44
+		fmt.Println("Sunset:", sunset.Format("15:04:05"))   // Sunset: 18:14:27
+		fmt.Println("Length of apparent solar time in mean solar time:", sunset.Sub(sunrise))
+		fmt.Println("Solar noon:", sunrise.Add(sunset.Sub(sunrise)/2).Format("15:04:05"))
+	}
+
+	dayDuration := sunset.Sub(sunrise)
+	if at.After(sunrise) && at.Before(sunset) {
+		hasPassed := at.Sub(sunrise)
+		if debug {
+			fmt.Println("Time passed since sunrise:", hasPassed)
+		}
+		fractionPassed := hasPassed.Seconds() / dayDuration.Seconds()
+		return fmt.Sprintf("%.0f%% ☉", fractionPassed*100), nil
+	}
+
+	// https://glossary.ametsoc.org/wiki/Mean_solar_day
+	meanDayDuration, err := time.ParseDuration("86400s")
+	if err != nil {
+		return "", err
+	}
+	nightDuration := meanDayDuration - dayDuration
+
+	if at.Before(sunrise) {
+		nightEnd := sunrise
+		nightStart := nightEnd.Add(-nightDuration)
+		hasPassedNight := at.Sub(nightStart)
+		fractionPassedNight := hasPassedNight.Seconds() / nightDuration.Seconds()
+		if debug {
+			fmt.Println("Time passed since sunset:", hasPassedNight)
+		}
+		return fmt.Sprintf("%.0f%% ☾", fractionPassedNight*100), nil
+	}
+
+	if at.After(sunset) {
+		nightStart := sunset
+		hasPassedNight := at.Sub(nightStart)
+		fractionPassedNight := hasPassedNight.Seconds() / nightDuration.Seconds()
+		if debug {
+			fmt.Println("Time passed since sunset:", hasPassedNight)
+		}
+		return fmt.Sprintf("%.0f%% ☾", fractionPassedNight*100), nil
+	}
+
+	panic("This should never happen")
+}
+
+func FindCity(name, countryCode, fipsCode string) (*CityInfo, error) {
+	// TODO cache successful runs and don't bother with opening this
+	file, err := fs.Open("cities.csv")
+	if err != nil {
+		return nil, err
+	}
+
+	r := csv.NewReader(file)
+	r.Comma = '\t'
+	r.ReuseRecord = true
+
+	cities := []*CityInfo{}
+	for {
+		record, err := r.Read()
+		if err == io.EOF {
+			break
+		} else if err != nil {
+			return nil, err
+		}
+
+		if record[0] != name {
+			continue
+		}
+
+		if countryCode != "" && record[1] != countryCode {
+			continue
+		}
+
+		if fipsCode != "" && record[2] != fipsCode {
+			continue
+		}
+		lat, err := strconv.ParseFloat(record[3], 64)
+		if err != nil {
+			return nil, err
+		}
+		long, err := strconv.ParseFloat(record[4], 64)
+		if err != nil {
+			return nil, err
+		}
+		cities = append(cities, &CityInfo{Name: record[0], CountryCode: record[1], FipsCode: record[2], Latitude: lat, Longitude: long})
+	}
+	if len(cities) == 0 {
+		return nil, fmt.Errorf("unable to find city '%s' in country '%s' with fips code '%s'", name, countryCode, fipsCode)
+	}
+	if len(cities) > 1 {
+		return nil, fmt.Errorf("could not narrow down between cities: %+v", cities)
+	}
+	return cities[0], nil
+}