list daily weathers 구현

internal/app/flow/flow.go

@@ -4,6 +4,8 @@ import (
 	"context"
 	"errors"
 	"fmt"
+	"sort"
+	"time"
 
 	"github.com/neatflowcv/seven-skies/internal/pkg/domain"
 	"github.com/neatflowcv/seven-skies/internal/pkg/repository"
@@ -45,3 +47,86 @@ func (f *Flow) CreateWeather(ctx context.Context, weather *Weather) error {
 
 	return nil
 }
+
+func (f *Flow) ListDailyWeathers(
+	ctx context.Context,
+	timezone string,
+	now time.Time,
+) ([]*DailyWeather, error) {
+	location, err := time.LoadLocation(timezone)
+	if err != nil {
+		return nil, fmt.Errorf("error in load location: %w", err)
+	}
+
+	const aWeek = 7
+
+	localNow := now.In(location)
+
+	from := time.Date(localNow.Year(), localNow.Month(), localNow.Day(), 0, 0, 0, 0, location)
+	to := from.AddDate(0, 0, aWeek).Add(-time.Nanosecond)
+
+	weathers, err := f.repo.ListWeathers(ctx, from, to)
+	if err != nil {
+		return nil, fmt.Errorf("error in list daily weathers: %w", err)
+	}
+
+	weathersByDate := f.groupByDate(weathers, location)
+
+	var dailyWeathers []*DailyWeather
+
+	for dateKey, weathers := range weathersByDate {
+		newVar := f.mergeWeathers(dateKey, location, weathers)
+		dailyWeathers = append(dailyWeathers, newVar)
+	}
+
+	sort.Slice(dailyWeathers, func(i, j int) bool {
+		return dailyWeathers[i].Date.Before(dailyWeathers[j].Date)
+	})
+
+	return dailyWeathers, nil
+}
+
+func (*Flow) mergeWeathers(dateKey string, location *time.Location, weathers []*domain.Weather) *DailyWeather {
+	date, _ := time.Parse("2006-01-02", dateKey)
+	date = time.Date(date.Year(), date.Month(), date.Day(), 0, 0, 0, 0, location)
+
+	high := float64(weathers[0].Temperature().Value)
+	low := float64(weathers[0].Temperature().Value)
+	worstCondition := weathers[0].Condition()
+
+	for _, w := range weathers {
+		temp := float64(w.Temperature().Value)
+		if temp > high {
+			high = temp
+		}
+
+		if temp < low {
+			low = temp
+		}
+
+		if w.Condition().IsWorseThan(worstCondition) {
+			worstCondition = w.Condition()
+		}
+	}
+
+	newVar := &DailyWeather{
+		Date:      date,
+		High:      high,
+		Low:       low,
+		Condition: string(worstCondition),
+	}
+
+	return newVar
+}
+
+func (*Flow) groupByDate(weathers []*domain.Weather, location *time.Location) map[string][]*domain.Weather {
+	weathersByDate := make(map[string][]*domain.Weather)
+
+	for _, weather := range weathers {
+		localDate := weather.TargetDate().In(location)
+		dateKey := time.Date(localDate.Year(), localDate.Month(), localDate.Day(), 0, 0, 0, 0, location).Format("2006-01-02")
+		weathersByDate[dateKey] = append(weathersByDate[dateKey], weather)
+	}
+
+	return weathersByDate
+}

internal/app/flow/weather.go

@@ -9,3 +9,10 @@ type Weather struct {
 	Condition    string
 	Temperature  float64 // Celsius
 }
+
+type DailyWeather struct {
+	Date      time.Time
+	High      float64 // Celsius
+	Low       float64 // Celsius
+	Condition string
+}