package changes

import (
	"strings"
	"testing"
	"time"

	"gitea.maximumdirect.net/eric/weatherreporter/internal/module"
	"gitea.maximumdirect.net/eric/weatherreporter/internal/timeutil"
)

func TestCompareDailyNoMeaningfulChanges(t *testing.T) {
	previous := dailySnapshot(t, 60, 70, 30, "8 AM", nil, false)
	current := dailySnapshot(t, 61, 71, 35, "8:30 AM", nil, false)

	changes, err := CompareDaily(previous, current, testThresholds())
	if err != nil {
		t.Fatalf("CompareDaily() error = %v", err)
	}
	if len(changes) != 0 {
		t.Fatalf("changes = %#v, want none", changes)
	}
}

func TestCompareDailyTemperatureThreshold(t *testing.T) {
	previous := dailySnapshot(t, 50, 70, 10, "8 AM", nil, false)
	current := dailySnapshot(t, 58, 79, 10, "8 AM", nil, false)

	changes, err := CompareDaily(previous, current, testThresholds())
	if err != nil {
		t.Fatalf("CompareDaily() error = %v", err)
	}
	if countType(changes, "temperature_shift") != 2 {
		t.Fatalf("changes = %#v, want low and high temperature changes", changes)
	}
}

func TestCompareDailyPrecipTimingShift(t *testing.T) {
	previous := dailySnapshot(t, 60, 70, 60, "8 AM", nil, false)
	current := dailySnapshot(t, 60, 70, 60, "11 AM", nil, false)

	changes, err := CompareDaily(previous, current, testThresholds())
	if err != nil {
		t.Fatalf("CompareDaily() error = %v", err)
	}
	if countType(changes, "precip_timing_shift") != 1 {
		t.Fatalf("changes = %#v, want timing shift", changes)
	}
}

func TestCompareDailyAlertAddedAndRemoved(t *testing.T) {
	previous := dailySnapshot(t, 60, 70, 10, "8 AM", []string{"Wind Advisory"}, false)
	current := dailySnapshot(t, 60, 70, 10, "8 AM", []string{"Flood Watch"}, false)

	changes, err := CompareDaily(previous, current, testThresholds())
	if err != nil {
		t.Fatalf("CompareDaily() error = %v", err)
	}
	if countType(changes, "alert_added") != 1 || countType(changes, "alert_removed") != 1 {
		t.Fatalf("changes = %#v, want one alert added and one removed", changes)
	}
}

func TestCompareDailyIndicatorChange(t *testing.T) {
	previous := dailySnapshot(t, 60, 70, 10, "8 AM", nil, false)
	current := dailySnapshot(t, 60, 70, 10, "8 AM", nil, true)

	changes, err := CompareDaily(previous, current, testThresholds())
	if err != nil {
		t.Fatalf("CompareDaily() error = %v", err)
	}
	if countType(changes, "snow_risk_change") != 1 {
		t.Fatalf("changes = %#v, want snow risk change", changes)
	}
}

func TestCompareDailyRequiresComparisonStanzas(t *testing.T) {
	_, err := CompareDaily(snapshot(t), dailySnapshot(t, 60, 70, 10, "8 AM", nil, false), testThresholds())
	if err == nil {
		t.Fatal("CompareDaily() error = nil, want missing stanza error")
	}
	if !strings.Contains(err.Error(), "derived_daily_summary") {
		t.Fatalf("error = %q, want derived_daily_summary context", err.Error())
	}
}

func dailySnapshot(t *testing.T, low int, high int, precip int, precipTime string, alerts []string, snow bool) module.Snapshot {
	t.Helper()
	relevant := make([]alertSummaryStanza, 0, len(alerts))
	for _, alert := range alerts {
		relevant = append(relevant, alertSummaryStanza{Event: alert})
	}
	return snapshot(t,
		module.Output{ID: module.DerivedDailySummary, StanzaName: "derived_daily_summary", Value: dailySummaryStanza{
			Date:          "2026-05-29",
			HighTempF:     &high,
			LowTempF:      &low,
			MaxPopPercent: &precip,
		}},
		module.Output{ID: module.DerivedDaypartSummaries, StanzaName: "derived_daypart_summaries", Value: map[string]daypartSummaryStanza{
			"morning": {Period: period("2026-05-29T06:00:00Z", "2026-05-29T10:00:00Z"), TempRangeF: "60-70", Snow: snow},
		}},
		module.Output{ID: module.PrecipTiming, StanzaName: "precip_timing", Value: precipTimingStanza{MaxPopPercent: &precip, MaxPopTime: precipTime}},
		module.Output{ID: module.AlertDigest, StanzaName: "alert_digest", Value: alertDigestStanza{Relevant: relevant}},
	)
}

func snapshot(t *testing.T, outputs ...module.Output) module.Snapshot {
	t.Helper()
	snapshot, err := module.NewSnapshot(outputs)
	if err != nil {
		t.Fatalf("NewSnapshot() error = %v", err)
	}
	return snapshot
}

func period(start string, end string) timeutil.Period {
	return timeutil.Period{Start: at(start), End: at(end)}
}

func testThresholds() Thresholds {
	return Thresholds{
		TemperatureDegrees:       5,
		PrecipProbabilityPoints:  20,
		WindGustMilesPerHour:     10,
		PrecipTimingShiftMinutes: 120,
	}
}

func countType(changes []Change, changeType string) int {
	var count int
	for _, change := range changes {
		if change.Type == changeType {
			count++
		}
	}
	return count
}

func at(value string) time.Time {
	parsed, err := time.Parse(time.RFC3339, value)
	if err != nil {
		panic(err)
	}
	return parsed
}