package hostclaim

import (
	"errors"
	"reflect"
	"testing"
)

// plan10J2Recovery is a source's recovery op: restoring (with its rollback id)
// or reverting, the source executing at phase.
func plan10J2Recovery(kind, phase string) *Claim {
	c := &Claim{V: schemaVersion, Host: "a.go.example.com", Gen: 12,
		Holder: &Holder{Family: "instance", Incarnation: "inc", Location: "instances/a.go.example.com", Generation: "g1", Stamp: 10, Session: 11, WriterBox: "ie-box"},
		Op:     Op{Kind: kind, ID: "m1", Phase: phase, Exec: "ie-box", Participants: []string{"ie-box", "uk-box"}, Intent: map[string]string{"to": "uk", "source": "ie-box", "target": "uk-box"}}}
	if kind == KindRestoring {
		c.Op.Intent["rollback"] = "rb_abcdefghijklmnopqrstuvwxyz"
	}
	if kind == KindReverting {
		c.Op.Journal = map[string]string{JournalRevPhase: phase}
	}
	return c
}

func TestPlan10J2RecoverySessionRowsAreForwardOnly(t *testing.T) {
	for _, kind := range []string{KindRestoring, KindReverting} {
		for _, tc := range []struct {
			from, to string
			want     bool
		}{
			{"probing", "probing", true},
			{"probing", "probed", true},
			{"probed", "opened", true},
			{"opened", "opened", true},
			{"probing", "opened", false},
			{"probed", "probing", false},
			{"opened", "probed", false},
			{"opened", "probing", false},
			{"claimed", "probing", false},
			{"released", "claimed", false},
			{"verify", "probing", false},
			{"evidence", "verify", false},
			{"probing", "committed", false},
			{"probed", "committed", false},
		} {
			if got := SessionContinues(kind, tc.from, tc.to); got != tc.want {
				t.Errorf("SessionContinues(%s, %q, %q) = %v, want %v", kind, tc.from, tc.to, got, tc.want)
			}
		}
		for _, phase := range []string{"probing", "probed", "opened"} {
			if !SessionPhase(kind, phase) {
				t.Errorf("%s %s is not a session phase", kind, phase)
			}
		}
		for _, phase := range []string{"", "claimed", "released", "releasing", "evidence", "verify", "committed", "recovered"} {
			if SessionPhase(kind, phase) {
				t.Errorf("%s %q is a session phase", kind, phase)
			}
		}
		// Observation and teardown reach forward along the row only.
		for _, tc := range []struct {
			from, to string
			want     bool
		}{
			{"probing", "opened", true},
			{"probed", "opened", true},
			{"opened", "probing", false},
			{"probed", "probing", false},
			{"claimed", "probing", false},
		} {
			if got := SessionReaches(kind, tc.from, tc.to); got != tc.want {
				t.Errorf("SessionReaches(%s, %q, %q) = %v, want %v", kind, tc.from, tc.to, got, tc.want)
			}
			if got := SessionObserves(kind, tc.from, tc.to); got != tc.want {
				t.Errorf("SessionObserves(%s, %q, %q) = %v, want %v", kind, tc.from, tc.to, got, tc.want)
			}
		}
	}
	// A recovery row never lends its phases to another kind, and the landing
	// row stays as it was.
	for _, kind := range []string{KindMoving, KindServing, KindPurging} {
		if SessionContinues(kind, "probing", "probed") || SessionPhase(kind, "probing") {
			t.Errorf("%s gained a session row", kind)
		}
	}
	if SessionContinues(KindLanding, "probed", "opened") || SessionPhase(KindLanding, "opened") || !SessionContinues(KindLanding, "probed", "committed") {
		t.Error("the landing row changed")
	}
}

func TestPlan10J2KeepWriterSessionGuardsARecoveryStep(t *testing.T) {
	for _, tc := range []struct {
		kind  string
		steps []func(*Claim) error
	}{
		{KindRestoring, []func(*Claim) error{SetRestoringPhase("m1", PhaseProbing, PhaseProbed), SetRestoringPhase("m1", PhaseProbed, PhaseOpened)}},
		{KindReverting, []func(*Claim) error{SetRevPhase("m1", PhaseProbing, PhaseProbed, false), SetRevPhase("m1", PhaseProbed, PhaseOpened, false)}},
	} {
		t.Run(tc.kind, func(t *testing.T) {
			c := plan10J2Recovery(tc.kind, "probing")
			for i, step := range tc.steps {
				if err := KeepWriterSession("m1", step)(c); err != nil {
					t.Fatalf("step %d: %v", i, err)
				}
			}
			if c.Op.Phase != "opened" || c.Holder.Session != 11 || c.Holder.Stamp != 10 || c.Holder.Generation != "g1" || c.Holder.WriterBox != "ie-box" {
				t.Fatalf("the steps changed the session: %+v %+v", c.Op, *c.Holder)
			}
		})
	}
	to := func(phase string) func(*Claim) error {
		return func(c *Claim) error { c.Op.Phase = phase; return nil }
	}
	for _, kind := range []string{KindRestoring, KindReverting} {
		other := KindReverting
		if kind == KindReverting {
			other = KindRestoring
		}
		for name, tc := range map[string]struct {
			from string
			fn   func(*Claim) error
		}{
			"skipped step":   {"probing", to("opened")},
			"backward step":  {"probed", to("probing")},
			"generation":     {"probing", func(c *Claim) error { c.Holder.Generation = "fresh"; c.Op.Phase = "probed"; return nil }},
			"session":        {"probing", func(c *Claim) error { c.Holder.Session++; c.Op.Phase = "probed"; return nil }},
			"stamp":          {"probing", func(c *Claim) error { c.Holder.Stamp = c.Gen + 1; c.Op.Phase = "probed"; return nil }},
			"incarnation":    {"probing", func(c *Claim) error { c.Holder.Incarnation = "other"; c.Op.Phase = "probed"; return nil }},
			"writer box":     {"probing", func(c *Claim) error { c.Holder.WriterBox = "uk-box"; c.Op.Phase = "probed"; return nil }},
			"executor":       {"probing", func(c *Claim) error { c.Op.Exec = "uk-box"; c.Op.Phase = "probed"; return nil }},
			"other recovery": {"probing", func(c *Claim) error { c.Op.Kind = other; c.Op.Phase = "probed"; return nil }},
			"landing kind":   {"probing", func(c *Claim) error { c.Op.Kind = KindLanding; c.Op.Phase = "probed"; return nil }},
			"op id":          {"probing", func(c *Claim) error { c.Op.ID = "m2"; c.Op.Phase = "probed"; return nil }},
			"holder removed": {"probing", func(c *Claim) error { c.Holder = nil; return nil }},
		} {
			t.Run(kind+"/"+name, func(t *testing.T) {
				c := plan10J2Recovery(kind, tc.from)
				if err := KeepWriterSession("m1", tc.fn)(c); !errors.Is(err, ErrWrongState) {
					t.Fatalf("kept the session: %v", err)
				}
			})
		}
	}
	// claimed to probing starts the row. It is not a session-keeping step,
	// because no session was admitted before probing.
	c := plan10J2Recovery(KindRestoring, "claimed")
	before := *c.Holder
	if err := KeepWriterSession("m1", SetRestoringPhase("m1", PhaseClaimed, PhaseProbing))(c); !errors.Is(err, ErrWrongState) {
		t.Fatalf("claimed to probing kept a session: %v", err)
	}
	if !reflect.DeepEqual(*c.Holder, before) {
		t.Fatalf("holder changed: %+v", *c.Holder)
	}
}