package domain

import (
	"encoding/json"
	"testing"
)

// eventTypesUnderTest is the full lifecycle vocabulary the spec (§9 item 5)
// requires validators for; a validator that panics or accepts garbage for any
// of these on adversarial input is a defect regardless of whether real
// producers happen to send well-formed payloads.
var eventTypesUnderTest = []string{
	"TaskCreated", "TaskLeased", "TaskReleased", "TaskLaunchAcknowledged", "TaskCompleted", "TaskFailed",
	"TaskBlocked", "TaskNeedsAttention", "ApprovalRequested", "ApprovalGranted", "ApprovalDenied",
	"TaskAmended", "QuotaReported", "StandupAdvisory",
}

// FuzzValidatePayload feeds arbitrary JSON object shapes at every known event
// type's validator and requires it to either return a typed ErrInvalid or
// accept — never panic. The seed corpus below exercises adjacent-to-valid and
// wildly-malformed shapes (wrong types, huge strings, nested structures,
// nulls, NaN-adjacent floats via JSON) for each type.
func FuzzValidatePayload(f *testing.F) {
	seeds := []string{
		`{}`,
		`null`,
		`{"source":"jsonl","external_id":"1","project":"p"}`,
		`{"source":123,"external_id":null,"project":[]}`,
		`{"harness_id":"h1","ttl":60,"expected_version":1}`,
		`{"harness_id":"h1","until_ns":1e300,"expected_version":1.5}`,
		`{"handoff_ref":"` + fakeHash() + `","anchor_sha":"` + fakeSHA() + `"}`,
		`{"handoff_ref":123,"anchor_sha":true}`,
		`{"report_ref":"` + fakeHash() + `","receipt":{"harness_id":"h1","consumed":1}}`,
		`{"report_ref":"","receipt":{}}`,
		`{"reason":"x"}`,
		`{"reason":123}`,
		`{"blocker":"x","handoff_ref":"` + fakeHash() + `"}`,
		`{"blocker":""}`,
		`{"amendment":"x"}`,
		`{"subject_ref":"x","options":["a","b"]}`,
		`{"subject_ref":123,"options":null}`,
		`{"harness_id":"h1","consumed":90.5}`,
		`{"harness_id":"h1","consumed":-1}`,
		`{"harness_id":"h1","consumed":"a lot"}`,
		`{"items":["standup line"]}`,
		`{"items":null}`,
		`{"a":{"b":{"c":{"d":[1,2,3,{"e":"f"}]}}}}`,
		`{"x":` + hugeString() + `}`,
	}
	for _, s := range seeds {
		f.Add(s)
	}

	f.Fuzz(func(t *testing.T, raw string) {
		var p map[string]any
		if err := json.Unmarshal([]byte(raw), &p); err != nil {
			return // not a JSON object; ValidateEvent itself rejects non-objects before reaching ValidatePayload
		}
		for _, typ := range eventTypesUnderTest {
			func() {
				defer func() {
					if r := recover(); r != nil {
						t.Fatalf("ValidatePayload(%q, %s) panicked: %v", typ, raw, r)
					}
				}()
				err := ValidatePayload(typ, p)
				if err != nil && err != ErrInvalid {
					// must still be a typed validation error, wrapping ErrInvalid
					if !isInvalid(err) {
						t.Fatalf("ValidatePayload(%q, %s) returned non-typed error: %v", typ, raw, err)
					}
				}
			}()
		}
	})
}

// FuzzValidateEvent exercises the full envelope path (schema version, surface
// requirement, type allow-list, payload size/parseability) with arbitrary
// type names, surfaces, and payload bytes, proving no combination panics.
func FuzzValidateEvent(f *testing.F) {
	f.Add("TaskCreated", "system", 2, []byte(`{"source":"jsonl","external_id":"1","project":"p"}`))
	f.Add("", "", 0, []byte(``))
	f.Add("Bogus", "system", 2, []byte(`{}`))
	f.Add("TaskCreated", "", 2, []byte(`{"source":"jsonl","external_id":"1","project":"p"}`))
	f.Add("TaskCreated", "system", 1, []byte(`not json`))
	f.Add("QuotaReported", "system", 2, []byte(`null`))
	f.Add("TaskCompleted", "system", 99, []byte(`{"report_ref":"x","receipt":{}}`))

	f.Fuzz(func(t *testing.T, typ, surface string, schema int, payload []byte) {
		defer func() {
			if r := recover(); r != nil {
				t.Fatalf("ValidateEvent panicked: type=%q surface=%q schema=%d payload=%q: %v", typ, surface, schema, payload, r)
			}
		}()
		e := Event{
			SchemaVersion: schema,
			Type:          typ,
			TaskID:        "t1",
			Payload:       payload,
			Surface:       surface,
		}
		_ = ValidateEvent(e)
	})
}

func isInvalid(err error) bool {
	for e := err; e != nil; {
		if e == ErrInvalid {
			return true
		}
		u, ok := e.(interface{ Unwrap() error })
		if !ok {
			return false
		}
		e = u.Unwrap()
	}
	return false
}

func fakeHash() string {
	b := make([]byte, 32)
	for i := range b {
		b[i] = byte(i)
	}
	s := ""
	for _, c := range b {
		s += string("0123456789abcdef"[c>>4]) + string("0123456789abcdef"[c&0xf])
	}
	return s
}

func fakeSHA() string {
	s := ""
	for i := 0; i < 40; i++ {
		s += "a"
	}
	return s
}

func hugeString() string {
	b, _ := json.Marshal(make([]byte, 0))
	_ = b
	s := `"`
	for i := 0; i < 5000; i++ {
		s += "x"
	}
	return s + `"`
}