package inbox

import (
	"errors"
	"os"
	"path/filepath"
	"strings"
	"testing"

	"bugabinga.net/luci/internal/trigger"
)

type badJSONEvent struct{}

func (badJSONEvent) Validate() error              { return nil }
func (badJSONEvent) EventKind() string            { return "bad" }
func (badJSONEvent) MarshalJSON() ([]byte, error) { return nil, errors.New("bad json") }

func TestWriteCreatesFinalJSONOnly(t *testing.T) {
	dir := t.TempDir()
	ref := "main"
	id, err := Write(dir, trigger.ManualEvent{Kind: "manual", Repo: "repo", Job: "check", Ref: &ref, RequestedBy: "oli"})
	if err != nil {
		t.Fatalf("Write() error = %v", err)
	}
	if _, err := os.Stat(filepath.Join(dir, id+".json")); err != nil {
		t.Fatalf("final event missing: %v", err)
	}
	if matches, _ := filepath.Glob(filepath.Join(dir, "*.tmp")); len(matches) != 0 {
		t.Fatalf("tmp files remain: %#v", matches)
	}
}

func TestWriteIDRejectsDuplicateWithoutChangingAcceptedEvent(t *testing.T) {
	dir := t.TempDir()
	ref := "main"
	first := trigger.ManualEvent{Kind: "manual", Repo: "repo", Job: "first", Ref: &ref}
	second := trigger.ManualEvent{Kind: "manual", Repo: "repo", Job: "second", Ref: &ref}
	if err := WriteID(dir, "42", first); err != nil {
		t.Fatal(err)
	}
	if err := WriteID(dir, "42", second); !errors.Is(err, os.ErrExist) {
		t.Fatalf("duplicate err=%v", err)
	}
	data, err := os.ReadFile(filepath.Join(dir, "42.json"))
	if err != nil || !strings.Contains(string(data), `"job":"first"`) {
		t.Fatalf("data=%s err=%v", data, err)
	}
}

func TestWriteRejectsInvalidEvent(t *testing.T) {
	if _, err := Write(t.TempDir(), trigger.PushEvent{Kind: "push"}); err == nil {
		t.Fatal("invalid event written")
	}
}

func TestWriteInjectedFilesystemFailures(t *testing.T) {
	ref := "main"
	valid := trigger.ManualEvent{Kind: "manual", Repo: "repo", Job: "check", Ref: &ref}
	boom := errors.New("boom")
	oldWrite := writeFile
	writeFile = func(string, []byte, os.FileMode) error { return boom }
	if _, err := Write(t.TempDir(), valid); !errors.Is(err, boom) {
		t.Fatalf("write err = %v", err)
	}
	writeFile = oldWrite
	oldRename := rename
	oldRemove := remove
	removed := false
	rename = func(string, string) error { return boom }
	remove = func(string) error { removed = true; return nil }
	if _, err := Write(t.TempDir(), valid); !errors.Is(err, boom) || !removed {
		t.Fatalf("rename err = %v removed=%v", err, removed)
	}
	rename = oldRename
	remove = oldRemove
}

func TestWriteRejectsFilesystemAndMarshalFailures(t *testing.T) {
	ref := "main"
	valid := trigger.ManualEvent{Kind: "manual", Repo: "repo", Job: "check", Ref: &ref}
	root := t.TempDir()
	file := filepath.Join(root, "file")
	if err := os.WriteFile(file, []byte("x"), 0o644); err != nil {
		t.Fatal(err)
	}
	if _, err := Write(filepath.Join(file, "inbox"), valid); err == nil {
		t.Fatal("Write accepted file parent")
	}
	if _, err := Write(t.TempDir(), badJSONEvent{}); err == nil {
		t.Fatal("Write accepted marshal failure")
	}
}

func TestClaimOnePrioritizesPushAndManualOverSchedule(t *testing.T) {
	dir := t.TempDir()
	scheduled := `{"kind":"schedule","repo":"repo","job":"nightly","rev":"abc","ref":"refs/heads/main","minute":"2026-03-04T03:00Z"}`
	push := `{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`
	if err := os.WriteFile(filepath.Join(dir, "1.json"), []byte(scheduled), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "2.json"), []byte(push), 0o644); err != nil {
		t.Fatal(err)
	}
	envelope, err := ClaimOne(dir)
	if err != nil || envelope.ID != "2" || envelope.Event.EventKind() != "push" {
		t.Fatalf("envelope=%#v err=%v", envelope, err)
	}
}

func TestClaimOneKeepsEventUntilAck(t *testing.T) {
	dir := t.TempDir()
	writePush := func(name string) {
		if err := os.WriteFile(filepath.Join(dir, name+".json"), []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
			t.Fatal(err)
		}
	}
	writePush("b")
	writePush("a")
	envelope, err := ClaimOne(dir)
	if err != nil {
		t.Fatalf("ClaimOne() error = %v", err)
	}
	if envelope == nil || envelope.ID != "a" {
		t.Fatalf("envelope = %#v", envelope)
	}
	if _, err := os.Stat(envelope.Path); err != nil {
		t.Fatalf("claimed event missing: %v", err)
	}
	if err := Ack(*envelope); err != nil {
		t.Fatalf("Ack() error = %v", err)
	}
	if _, err := os.Stat(envelope.Path); !os.IsNotExist(err) {
		t.Fatalf("acked event remains: %v", err)
	}
}

func TestFailDeadLettersClaimedEvent(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "a.json"), []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	envelope, err := ClaimOne(dir)
	if err != nil {
		t.Fatal(err)
	}
	failed, err := Fail(*envelope)
	if err != nil {
		t.Fatalf("Fail() error = %v", err)
	}
	if failed != filepath.Join(dir, "a.failed") {
		t.Fatalf("failed path = %q", failed)
	}
	if _, err := os.Stat(failed); err != nil {
		t.Fatalf("failed event missing: %v", err)
	}
}

func TestClaimOneIgnoresProcessingEvents(t *testing.T) {
	dir := t.TempDir()
	path := filepath.Join(dir, "a.json.processing")
	if err := os.WriteFile(path, []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	envelope, err := ClaimOne(dir)
	if err != nil || envelope != nil {
		t.Fatalf("envelope = %#v err=%v", envelope, err)
	}
}

func TestClaimOneRetainsEventAfterReadFailure(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "a.json"), []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	oldRead := readFile
	readFile = func(string) ([]byte, error) { return nil, errors.New("boom") }
	if _, err := ClaimOne(dir); err == nil {
		t.Fatal("read failure hidden")
	}
	readFile = oldRead
	if _, err := os.Stat(filepath.Join(dir, "a.json.processing")); err != nil {
		t.Fatalf("event lost after read failure: %v", err)
	}
}

func TestClaimOneDeadLettersInvalidEvent(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "bad.json"), []byte(`{"kind":`), 0o644); err != nil {
		t.Fatal(err)
	}
	if _, err := ClaimOne(dir); err == nil {
		t.Fatal("invalid JSON accepted")
	}
	if _, err := os.Stat(filepath.Join(dir, "bad.failed")); err != nil {
		t.Fatalf("invalid event not dead-lettered: %v", err)
	}
}

func TestClaimOneMissingDirIsEmpty(t *testing.T) {
	envelope, err := ClaimOne(filepath.Join(t.TempDir(), "missing"))
	if err != nil || envelope != nil {
		t.Fatalf("envelope=%#v err=%v", envelope, err)
	}
}

func TestClaimOneRejectsBadGlobReadAndJSON(t *testing.T) {
	if _, err := ClaimOne("["); err == nil {
		t.Fatal("bad glob accepted")
	}
	dir := t.TempDir()
	if err := os.Mkdir(filepath.Join(dir, "bad.json"), 0o755); err != nil {
		t.Fatal(err)
	}
	if _, err := ClaimOne(dir); err == nil {
		t.Fatal("directory event accepted")
	}
	dir = t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "bad.json"), []byte(`{"kind":`), 0o644); err != nil {
		t.Fatal(err)
	}
	if _, err := ClaimOne(dir); err == nil {
		t.Fatal("invalid JSON accepted")
	}
}

func TestClaimAckAndFailPropagateFilesystemErrors(t *testing.T) {
	boom := errors.New("boom")
	dir := t.TempDir()
	path := filepath.Join(dir, "a.json")
	if err := os.WriteFile(path, []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	oldRename := rename
	rename = func(string, string) error { return boom }
	if _, err := ClaimOne(dir); !errors.Is(err, boom) {
		t.Fatalf("claim err = %v", err)
	}
	rename = oldRename
	envelope, err := ClaimOne(dir)
	if err != nil {
		t.Fatal(err)
	}
	oldRemove := remove
	remove = func(string) error { return boom }
	if err := Ack(*envelope); !errors.Is(err, boom) {
		t.Fatalf("ack err = %v", err)
	}
	remove = oldRemove
	rename = func(string, string) error { return boom }
	if _, err := Fail(*envelope); !errors.Is(err, boom) {
		t.Fatalf("fail err = %v", err)
	}
	rename = oldRename
}

func TestListClassifiesPendingAndExcludesDone(t *testing.T) {
	dir := t.TempDir()
	data := []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`)
	for _, name := range []string{"1.json", "2.json.processing"} {
		if err := os.WriteFile(filepath.Join(dir, name), data, 0o644); err != nil {
			t.Fatal(err)
		}
	}
	if err := os.WriteFile(filepath.Join(dir, "2.done"), nil, 0o644); err != nil {
		t.Fatal(err)
	}
	pending, warnings, err := List(dir)
	if err != nil || len(warnings) != 0 || len(pending) != 1 || pending[0].ID != "1" || pending[0].Phase != "queued" {
		t.Fatalf("pending=%#v warnings=%v err=%v", pending, warnings, err)
	}
	ids, err := DoneIDs(dir)
	if err != nil || len(ids) != 1 || ids[0] != "2" {
		t.Fatalf("ids=%v err=%v", ids, err)
	}
}

func TestDoneAcknowledgesProcessingBeforeMarker(t *testing.T) {
	dir := t.TempDir()
	processing := filepath.Join(dir, "1.json.processing")
	if err := os.WriteFile(processing, []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := MarkDone(dir, "1"); err != nil {
		t.Fatal(err)
	}
	if err := AckDone(dir, "1"); err != nil {
		t.Fatal(err)
	}
	for _, path := range []string{processing, filepath.Join(dir, "1.done")} {
		if _, err := os.Stat(path); !os.IsNotExist(err) {
			t.Fatalf("remains %s: %v", path, err)
		}
	}
}

func TestProcessingListsClaimedEvents(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "1.json.processing"), []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := Processing(dir)
	if err != nil || len(got) != 1 || got[0].ID != "1" {
		t.Fatalf("got=%#v err=%v", got, err)
	}
}

func TestProcessingDeadLettersMalformedAndContinues(t *testing.T) {
	dir := t.TempDir()
	if err := os.WriteFile(filepath.Join(dir, "bad.json.processing"), []byte("{"), 0o644); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(filepath.Join(dir, "good.json.processing"), []byte(`{"kind":"push","repo":"repo","old":"0","new":"abc","ref":"refs/heads/main"}`), 0o644); err != nil {
		t.Fatal(err)
	}
	got, err := Processing(dir)
	if err != nil || len(got) != 1 || got[0].ID != "good" {
		t.Fatalf("got=%#v err=%v", got, err)
	}
	if _, err := os.Stat(filepath.Join(dir, "bad.failed")); err != nil {
		t.Fatalf("bad event not dead-lettered: %v", err)
	}
}