package restic_test

import (
	"encoding/json"
	"fmt"
	"os"
	"path/filepath"
	"testing"
	"time"

	"github.com/google/go-cmp/cmp"
	"github.com/google/go-cmp/cmp/cmpopts"
	"github.com/restic/restic/internal/restic"
)

func parseTimeUTC(s string) time.Time {
	t, err := time.Parse("2006-01-02 15:04:05", s)
	if err != nil {
		panic(err)
	}

	return t.UTC()
}

// Returns the maximum number of snapshots to be kept according to this policy.
// If any of the counts is -1 it will return 0.
func policySum(e *restic.ExpirePolicy) int {
	if e.Last == -1 || e.Hourly == -1 || e.Daily == -1 || e.Weekly == -1 || e.Monthly == -1 || e.Yearly == -1 {
		return 0
	}

	return e.Last + e.Hourly + e.Daily + e.Weekly + e.Monthly + e.Yearly
}

func TestExpireSnapshotOps(t *testing.T) {
	data := []struct {
		expectEmpty bool
		expectSum   int
		p           *restic.ExpirePolicy
	}{
		{true, 0, &restic.ExpirePolicy{}},
		{true, 0, &restic.ExpirePolicy{Tags: []restic.TagList{}}},
		{false, 22, &restic.ExpirePolicy{Daily: 7, Weekly: 2, Monthly: 3, Yearly: 10}},
	}
	for i, d := range data {
		isEmpty := d.p.Empty()
		if isEmpty != d.expectEmpty {
			t.Errorf("empty test %v: wrong result, want:\n  %#v\ngot:\n  %#v", i, d.expectEmpty, isEmpty)
		}
		hasSum := policySum(d.p)
		if hasSum != d.expectSum {
			t.Errorf("sum test %v: wrong result, want:\n  %#v\ngot:\n  %#v", i, d.expectSum, hasSum)
		}
	}
}

// ApplyPolicyResult is used to marshal/unmarshal the golden files for
// TestApplyPolicy.
type ApplyPolicyResult struct {
	Keep    restic.Snapshots    `json:"keep"`
	Reasons []restic.KeepReason `json:"reasons,omitempty"`
}

func loadGoldenFile(t testing.TB, filename string) (res ApplyPolicyResult) {
	buf, err := os.ReadFile(filename)
	if err != nil {
		t.Fatalf("error loading golden file %v: %v", filename, err)
	}

	err = json.Unmarshal(buf, &res)
	if err != nil {
		t.Fatalf("error unmarshalling golden file %v: %v", filename, err)
	}

	return res
}

func saveGoldenFile(t testing.TB, filename string, keep restic.Snapshots, reasons []restic.KeepReason) {
	res := ApplyPolicyResult{
		Keep:    keep,
		Reasons: reasons,
	}

	buf, err := json.MarshalIndent(res, "", "  ")
	if err != nil {
		t.Fatalf("error marshaling result: %v", err)
	}

	if err = os.WriteFile(filename, buf, 0644); err != nil {
		t.Fatalf("unable to update golden file: %v", err)
	}
}

func TestApplyPolicy(t *testing.T) {
	var testExpireSnapshots = restic.Snapshots{
		{Time: parseTimeUTC("2014-09-01 10:20:30")},
		{Time: parseTimeUTC("2014-09-02 10:20:30")},
		{Time: parseTimeUTC("2014-09-05 10:20:30")},
		{Time: parseTimeUTC("2014-09-06 10:20:30")},
		{Time: parseTimeUTC("2014-09-08 10:20:30")},
		{Time: parseTimeUTC("2014-09-09 10:20:30")},
		{Time: parseTimeUTC("2014-09-10 10:20:30")},
		{Time: parseTimeUTC("2014-09-11 10:20:30")},
		{Time: parseTimeUTC("2014-09-20 10:20:30")},
		{Time: parseTimeUTC("2014-09-22 10:20:30")},
		{Time: parseTimeUTC("2014-08-08 10:20:30")},
		{Time: parseTimeUTC("2014-08-10 10:20:30")},
		{Time: parseTimeUTC("2014-08-12 10:20:30")},
		{Time: parseTimeUTC("2014-08-13 10:20:30")},
		{Time: parseTimeUTC("2014-08-13 10:20:30.1")},
		{Time: parseTimeUTC("2014-08-15 10:20:30")},
		{Time: parseTimeUTC("2014-08-18 10:20:30")},
		{Time: parseTimeUTC("2014-08-20 10:20:30")},
		{Time: parseTimeUTC("2014-08-21 10:20:30")},
		{Time: parseTimeUTC("2014-08-22 10:20:30")},
		{Time: parseTimeUTC("2014-10-01 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-02 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-05 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-06 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-08 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-09 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-10 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-11 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-20 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-10-22 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-11-08 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-11-10 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-11-12 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-11-13 10:20:30"), Tags: []string{"foo"}},
		{Time: parseTimeUTC("2014-11-13 10:20:30.1"), Tags: []string{"bar"}},
		{Time: parseTimeUTC("2014-11-15 10:20:30"), Tags: []string{"foo", "bar"}},
		{Time: parseTimeUTC("2014-11-18 10:20:30")},
		{Time: parseTimeUTC("2014-11-20 10:20:30")},
		{Time: parseTimeUTC("2014-11-21 10:20:30")},
		{Time: parseTimeUTC("2014-11-22 10:20:30")},
		{Time: parseTimeUTC("2015-09-01 10:20:30")},
		{Time: parseTimeUTC("2015-09-02 10:20:30")},
		{Time: parseTimeUTC("2015-09-05 10:20:30")},
		{Time: parseTimeUTC("2015-09-06 10:20:30")},
		{Time: parseTimeUTC("2015-09-08 10:20:30")},
		{Time: parseTimeUTC("2015-09-09 10:20:30")},
		{Time: parseTimeUTC("2015-09-10 10:20:30")},
		{Time: parseTimeUTC("2015-09-11 10:20:30")},
		{Time: parseTimeUTC("2015-09-20 10:20:30")},
		{Time: parseTimeUTC("2015-09-22 10:20:30")},
		{Time: parseTimeUTC("2015-08-08 10:20:30")},
		{Time: parseTimeUTC("2015-08-10 10:20:30")},
		{Time: parseTimeUTC("2015-08-12 10:20:30")},
		{Time: parseTimeUTC("2015-08-13 10:20:30")},
		{Time: parseTimeUTC("2015-08-13 10:20:30.1")},
		{Time: parseTimeUTC("2015-08-15 10:20:30")},
		{Time: parseTimeUTC("2015-08-18 10:20:30")},
		{Time: parseTimeUTC("2015-08-20 10:20:30")},
		{Time: parseTimeUTC("2015-08-21 10:20:30")},
		{Time: parseTimeUTC("2015-08-22 10:20:30")},
		{Time: parseTimeUTC("2015-10-01 10:20:30")},
		{Time: parseTimeUTC("2015-10-02 10:20:30")},
		{Time: parseTimeUTC("2015-10-05 10:20:30")},
		{Time: parseTimeUTC("2015-10-06 10:20:30")},
		{Time: parseTimeUTC("2015-10-08 10:20:30")},
		{Time: parseTimeUTC("2015-10-09 10:20:30")},
		{Time: parseTimeUTC("2015-10-10 10:20:30")},
		{Time: parseTimeUTC("2015-10-11 10:20:30")},
		{Time: parseTimeUTC("2015-10-20 10:20:30")},
		{Time: parseTimeUTC("2015-10-22 10:20:30")},
		{Time: parseTimeUTC("2015-10-22 10:20:30")},
		{Time: parseTimeUTC("2015-10-22 10:20:30"), Tags: []string{"foo", "bar"}},
		{Time: parseTimeUTC("2015-10-22 10:20:30"), Tags: []string{"foo", "bar"}},
		{Time: parseTimeUTC("2015-10-22 10:20:30"), Tags: []string{"foo", "bar"}, Paths: []string{"path1", "path2"}},
		{Time: parseTimeUTC("2015-11-08 10:20:30")},
		{Time: parseTimeUTC("2015-11-10 10:20:30")},
		{Time: parseTimeUTC("2015-11-12 10:20:30")},
		{Time: parseTimeUTC("2015-11-13 10:20:30")},
		{Time: parseTimeUTC("2015-11-13 10:20:30.1")},
		{Time: parseTimeUTC("2015-11-15 10:20:30")},
		{Time: parseTimeUTC("2015-11-18 10:20:30")},
		{Time: parseTimeUTC("2015-11-20 10:20:30")},
		{Time: parseTimeUTC("2015-11-21 10:20:30")},
		{Time: parseTimeUTC("2015-11-22 10:20:30")},
		{Time: parseTimeUTC("2016-01-01 01:02:03")},
		{Time: parseTimeUTC("2016-01-01 01:03:03")},
		{Time: parseTimeUTC("2016-01-01 07:08:03")},
		{Time: parseTimeUTC("2016-01-03 07:02:03")},
		{Time: parseTimeUTC("2016-01-04 10:23:03")},
		{Time: parseTimeUTC("2016-01-04 11:23:03")},
		{Time: parseTimeUTC("2016-01-04 12:23:03")},
		{Time: parseTimeUTC("2016-01-04 12:24:03")},
		{Time: parseTimeUTC("2016-01-04 12:28:03")},
		{Time: parseTimeUTC("2016-01-04 12:30:03")},
		{Time: parseTimeUTC("2016-01-04 16:23:03")},
		{Time: parseTimeUTC("2016-01-05 09:02:03")},
		{Time: parseTimeUTC("2016-01-06 08:02:03")},
		{Time: parseTimeUTC("2016-01-07 10:02:03")},
		{Time: parseTimeUTC("2016-01-08 20:02:03")},
		{Time: parseTimeUTC("2016-01-09 21:02:03")},
		{Time: parseTimeUTC("2016-01-12 21:02:03")},
		{Time: parseTimeUTC("2016-01-12 21:08:03")},
		{Time: parseTimeUTC("2016-01-18 12:02:03")},
	}

	var tests = []restic.ExpirePolicy{
		{},
		{Last: 10},
		{Last: 15},
		{Last: 99},
		{Last: 200},
		{Hourly: 20},
		{Daily: 3},
		{Daily: 10},
		{Daily: 30},
		{Last: 5, Daily: 5},
		{Last: 2, Daily: 10},
		{Weekly: 2},
		{Weekly: 4},
		{Daily: 3, Weekly: 4},
		{Monthly: 6},
		{Daily: 2, Weekly: 2, Monthly: 6},
		{Yearly: 10},
		{Daily: 7, Weekly: 2, Monthly: 3, Yearly: 10},
		{Tags: []restic.TagList{{"foo"}}},
		{Tags: []restic.TagList{{"foo", "bar"}}},
		{Tags: []restic.TagList{{"foo"}, {"bar"}}},
		{Within: restic.ParseDurationOrPanic("1d")},
		{Within: restic.ParseDurationOrPanic("2d")},
		{Within: restic.ParseDurationOrPanic("7d")},
		{Within: restic.ParseDurationOrPanic("1m")},
		{Within: restic.ParseDurationOrPanic("1m14d")},
		{Within: restic.ParseDurationOrPanic("1y1d1m")},
		{Within: restic.ParseDurationOrPanic("13d23h")},
		{Within: restic.ParseDurationOrPanic("2m2h")},
		{Within: restic.ParseDurationOrPanic("1y2m3d3h")},
		{WithinHourly: restic.ParseDurationOrPanic("1y2m3d3h")},
		{WithinDaily: restic.ParseDurationOrPanic("1y2m3d3h")},
		{WithinWeekly: restic.ParseDurationOrPanic("1y2m3d3h")},
		{WithinMonthly: restic.ParseDurationOrPanic("1y2m3d3h")},
		{WithinYearly: restic.ParseDurationOrPanic("1y2m3d3h")},
		{Within: restic.ParseDurationOrPanic("1h"),
			WithinHourly:  restic.ParseDurationOrPanic("1d"),
			WithinDaily:   restic.ParseDurationOrPanic("7d"),
			WithinWeekly:  restic.ParseDurationOrPanic("1m"),
			WithinMonthly: restic.ParseDurationOrPanic("1y"),
			WithinYearly:  restic.ParseDurationOrPanic("9999y")},
		{Last: -1},             // keep all
		{Last: -1, Hourly: -1}, // keep all (Last overrides Hourly)
		{Hourly: -1},           // keep all hourlies
		{Daily: 3, Weekly: 2, Monthly: -1, Yearly: -1},
	}

	for i, p := range tests {
		t.Run("", func(t *testing.T) {

			keep, remove, reasons := restic.ApplyPolicy(testExpireSnapshots, p)

			if len(keep)+len(remove) != len(testExpireSnapshots) {
				t.Errorf("len(keep)+len(remove) = %d != len(testExpireSnapshots) = %d",
					len(keep)+len(remove), len(testExpireSnapshots))
			}

			if policySum(&p) > 0 && len(keep) > policySum(&p) {
				t.Errorf("not enough snapshots removed: policy allows %v snapshots to remain, but ended up with %v",
					policySum(&p), len(keep))
			}

			if len(keep) != len(reasons) {
				t.Errorf("got %d keep reasons for %d snapshots to keep, these must be equal", len(reasons), len(keep))
			}

			goldenFilename := filepath.Join("testdata", fmt.Sprintf("policy_keep_snapshots_%d", i))

			if *updateGoldenFiles {
				saveGoldenFile(t, goldenFilename, keep, reasons)
			}

			want := loadGoldenFile(t, goldenFilename)

			cmpOpts := cmpopts.IgnoreUnexported(restic.Snapshot{})

			if !cmp.Equal(want.Keep, keep, cmpOpts) {
				t.Error(cmp.Diff(want.Keep, keep, cmpOpts))
			}

			if !cmp.Equal(want.Reasons, reasons, cmpOpts) {
				t.Error(cmp.Diff(want.Reasons, reasons, cmpOpts))
			}
		})
	}
}