package state

import (
	"strings"
	"testing"
	"time"
)

func TestPlanPruneOlderThan(t *testing.T) {
	now := time.Date(2026, 6, 8, 12, 0, 0, 0, time.UTC)
	olderThan := 48 * time.Hour
	plan := PlanPrune([]PruneCandidate{
		{Path: "old.txt", UpdatedAt: now.Add(-72 * time.Hour)},
		{Path: "fresh.txt", UpdatedAt: now.Add(-24 * time.Hour)},
	}, PrunePlanOptions{Now: now, OlderThan: &olderThan})

	if got, want := pruneCandidatePaths(plan.Pruned), "old.txt"; got != want {
		t.Fatalf("pruned = %q, want %q", got, want)
	}
	if got, want := pruneCandidatePaths(plan.Preserved), "fresh.txt"; got != want {
		t.Fatalf("preserved = %q, want %q", got, want)
	}
}

func TestPlanPruneKeepLatest(t *testing.T) {
	now := time.Date(2026, 6, 8, 12, 0, 0, 0, time.UTC)
	keepLatest := 2
	plan := PlanPrune([]PruneCandidate{
		{Path: "old.txt", UpdatedAt: now.Add(-72 * time.Hour)},
		{Path: "new.txt", UpdatedAt: now.Add(-1 * time.Hour)},
		{Path: "middle.txt", UpdatedAt: now.Add(-24 * time.Hour)},
	}, PrunePlanOptions{KeepLatest: &keepLatest})

	if got, want := pruneCandidatePaths(plan.Pruned), "old.txt"; got != want {
		t.Fatalf("pruned = %q, want %q", got, want)
	}
	if got, want := pruneCandidatePaths(plan.Preserved), "new.txt,middle.txt"; got != want {
		t.Fatalf("preserved = %q, want %q", got, want)
	}
}

func TestPlanPruneCombinedPolicyPreservesLatestBeforeAgeCheck(t *testing.T) {
	now := time.Date(2026, 6, 8, 12, 0, 0, 0, time.UTC)
	olderThan := 48 * time.Hour
	keepLatest := 1
	plan := PlanPrune([]PruneCandidate{
		{Path: "oldest.txt", UpdatedAt: now.Add(-96 * time.Hour)},
		{Path: "old.txt", UpdatedAt: now.Add(-72 * time.Hour)},
		{Path: "fresh.txt", UpdatedAt: now.Add(-24 * time.Hour)},
	}, PrunePlanOptions{Now: now, OlderThan: &olderThan, KeepLatest: &keepLatest})

	if got, want := pruneCandidatePaths(plan.Pruned), "oldest.txt,old.txt"; got != want {
		t.Fatalf("pruned = %q, want %q", got, want)
	}
	if got, want := pruneCandidatePaths(plan.Preserved), "fresh.txt"; got != want {
		t.Fatalf("preserved = %q, want %q", got, want)
	}
}

func TestPlanPruneDeterministicTieBreaking(t *testing.T) {
	now := time.Date(2026, 6, 8, 12, 0, 0, 0, time.UTC)
	keepLatest := 1
	plan := PlanPrune([]PruneCandidate{
		{Path: "b.txt", UpdatedAt: now},
		{Path: "a.txt", UpdatedAt: now},
		{Path: "c.txt", UpdatedAt: now.Add(-time.Hour)},
	}, PrunePlanOptions{KeepLatest: &keepLatest})

	if got, want := pruneCandidatePaths(plan.Preserved), "a.txt"; got != want {
		t.Fatalf("preserved = %q, want %q", got, want)
	}
	if got, want := pruneCandidatePaths(plan.Pruned), "c.txt,b.txt"; got != want {
		t.Fatalf("pruned = %q, want %q", got, want)
	}
}

func pruneCandidatePaths(candidates []PruneCandidate) string {
	paths := make([]string, 0, len(candidates))
	for _, candidate := range candidates {
		paths = append(paths, candidate.Path)
	}
	return strings.Join(paths, ",")
}