package cli

import (
	"bytes"
	"encoding/json"
	"path/filepath"
	"testing"
	"time"

	"git.dcglab.co.uk/steve/emcli/internal/mail"
	"git.dcglab.co.uk/steve/emcli/internal/store"
)

type fakeMailer struct {
	uidValidity uint32
	maxUID      uint32
	headers     []mail.Header
	full        map[uint32]mail.Message

	// Multi-folder fields, used by folders/--all-folders tests. When
	// headersByFolder is non-nil Search consults it instead of headers.
	folders         []mail.FolderInfo
	headersByFolder map[string][]mail.Header
	searchErr       map[string]error
	searched        []string
}

func (f *fakeMailer) SelectFolder(string) (uint32, uint32, error) {
	return f.uidValidity, f.maxUID, nil
}
func (f *fakeMailer) FetchHeaders(_ string, uids []uint32) ([]mail.Header, error) {
	if len(uids) == 0 {
		return f.headers, nil
	}
	want := map[uint32]bool{}
	for _, u := range uids {
		want[u] = true
	}
	var out []mail.Header
	for _, h := range f.headers {
		if want[h.UID] {
			out = append(out, h)
		}
	}
	return out, nil
}
func (f *fakeMailer) FetchHeadersRange(string, uint32, uint32, int) ([]mail.Header, error) {
	return f.headers, nil
}
func (f *fakeMailer) FetchFull(_ string, uid uint32) (mail.Message, error) {
	return f.full[uid], nil
}
func (f *fakeMailer) Search(folder string, _ mail.SearchCriteria, _ int) ([]mail.Header, error) {
	f.searched = append(f.searched, folder)
	if err := f.searchErr[folder]; err != nil {
		return nil, err
	}
	if f.headersByFolder != nil {
		return f.headersByFolder[folder], nil
	}
	return f.headers, nil
}
func (f *fakeMailer) ListFolders() ([]mail.FolderInfo, error) {
	return f.folders, nil
}
func (f *fakeMailer) Logout() error { return nil }

func testKey() []byte {
	k := make([]byte, 32)
	for i := range k {
		k[i] = byte(i)
	}
	return k
}

func newDeps(t *testing.T, fm *fakeMailer) (Deps, *bytes.Buffer) {
	t.Helper()
	st, err := store.Open(filepath.Join(t.TempDir(), "e.db"))
	if err != nil {
		t.Fatalf("store: %v", err)
	}
	if err := st.InitKeys(testKey(), testKey()); err != nil {
		t.Fatalf("InitKeys: %v", err)
	}
	t.Cleanup(func() { st.Close() })
	_, err = st.AddAccount(store.Account{
		Name: "work", Mode: "RO", IMAPHost: "h", IMAPPort: 993, IMAPSecurity: "tls",
		AuthType: "password", Username: "me@example.com", Password: "pw",
		WhitelistInEnabled: true,
	})
	if err != nil {
		t.Fatalf("AddAccount: %v", err)
	}
	_ = st.AddWhitelist("work", store.DirIn, "@trusted.com")
	var buf bytes.Buffer
	d := Deps{
		Store: st,
		Dial:  func(store.Account) (Mailer, error) { return fm, nil },
		Now:   func() time.Time { return time.Date(2026, 6, 21, 0, 0, 0, 0, time.UTC) },
		Out:   &buf,
	}
	return d, &buf
}

func decode(t *testing.T, b []byte) map[string]any {
	t.Helper()
	var m map[string]any
	if err := json.Unmarshal(b, &m); err != nil {
		t.Fatalf("unmarshal %q: %v", b, err)
	}
	return m
}

func TestListNewFiltersBySenderAndState(t *testing.T) {
	fm := &fakeMailer{
		uidValidity: 1, maxUID: 100,
		headers: []mail.Header{
			{UID: 101, From: "bob@trusted.com", Subject: "hi"},
			{UID: 102, From: "eve@evil.com", Subject: "spam"}, // filtered out by whitelist
			{UID: 103, From: "ann@trusted.com", Subject: "yo"},
		},
	}
	d, buf := newDeps(t, fm)
	if err := ListCmd(d, "work", "INBOX", true, 0, 0, 50); err != nil {
		t.Fatalf("ListCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	if res["error"] != false {
		t.Fatalf("unexpected error: %v", res)
	}
	data := res["data"].(map[string]any)
	msgs := data["messages"].([]any)
	if len(msgs) != 2 { // 101 and 103; 102 filtered
		t.Fatalf("want 2 messages, got %d: %v", len(msgs), msgs)
	}
}

func TestGetFilteredReturnsNotFound(t *testing.T) {
	fm := &fakeMailer{
		uidValidity: 1, maxUID: 100,
		headers: []mail.Header{{UID: 102, From: "eve@evil.com", Subject: "spam"}},
		full: map[uint32]mail.Message{
			102: {Header: mail.Header{UID: 102, From: "eve@evil.com", Subject: "spam"}, BodyText: "secret"},
		},
	}
	d, buf := newDeps(t, fm)
	_ = GetCmd(d, "work", "INBOX", 102)
	res := decode(t, buf.Bytes())
	if res["error"] != true {
		t.Fatal("filtered get must return error envelope")
	}
	ed := res["error_detail"].(map[string]any)
	if ed["code"] != "not_found" {
		t.Fatalf("want not_found, got %v", ed["code"])
	}
}

func TestGetFilteredReturnsErrorForExit(t *testing.T) {
	fm := &fakeMailer{
		uidValidity: 1, maxUID: 100,
		headers: []mail.Header{{UID: 102, From: "eve@evil.com", Subject: "spam"}},
		full: map[uint32]mail.Message{
			102: {Header: mail.Header{UID: 102, From: "eve@evil.com", Subject: "spam"}, BodyText: "secret"},
		},
	}
	d, buf := newDeps(t, fm)
	err := GetCmd(d, "work", "INBOX", 102)
	if err == nil {
		t.Fatal("GetCmd on filtered uid must return non-nil error so caller can exit non-zero")
	}
	res := decode(t, buf.Bytes())
	if res["error"] != true {
		t.Fatalf("envelope must report error=true, got %v", res["error"])
	}
}

func TestSearchLimitCountsVisibleOnly(t *testing.T) {
	// fakeMailer.Search returns all headers regardless of the limit passed in.
	// Headers: UIDs 1,3,5 are visible (@trusted.com); UIDs 2,4 are filtered.
	// With limit=2, SearchCmd must return 2 visible messages — not fewer, which
	// would happen if the mail layer truncated to limit=2 before filtering.
	fm := &fakeMailer{
		uidValidity: 1, maxUID: 5,
		headers: []mail.Header{
			{UID: 1, From: "a@trusted.com", Subject: "one"},
			{UID: 2, From: "x@evil.com", Subject: "spam1"}, // filtered
			{UID: 3, From: "b@trusted.com", Subject: "two"},
			{UID: 4, From: "y@evil.com", Subject: "spam2"}, // filtered
			{UID: 5, From: "c@trusted.com", Subject: "three"},
		},
	}
	d, buf := newDeps(t, fm)
	if err := SearchCmd(d, "work", "INBOX", mail.SearchCriteria{}, 2); err != nil {
		t.Fatalf("SearchCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	if res["error"] != false {
		t.Fatalf("unexpected error envelope: %v", res)
	}
	data := res["data"].(map[string]any)
	msgs := data["messages"].([]any)
	// With pre-filter cap (old bug): limit=2 would have fetched UIDs 1,2 then
	// filtered, yielding only 1 visible. Correct behaviour: 2 visible (1,3).
	if len(msgs) != 2 {
		t.Fatalf("want 2 visible messages, got %d: %v", len(msgs), msgs)
	}
}

func TestAckAdvancesStateAndFiltered(t *testing.T) {
	fm := &fakeMailer{
		uidValidity: 1, maxUID: 100,
		headers: []mail.Header{
			{UID: 101, From: "bob@trusted.com", Subject: "hi"},
			{UID: 102, From: "eve@evil.com", Subject: "spam"},
		},
	}
	d, buf := newDeps(t, fm)
	// Acking a filtered uid (102) must be rejected as not-found.
	_ = AckCmd(d, "work", "INBOX", []uint32{102})
	if decode(t, buf.Bytes())["error"] != true {
		t.Fatal("acking filtered uid must fail")
	}
	// Acking a visible uid (101) succeeds and removes it from list --new.
	buf.Reset()
	if err := AckCmd(d, "work", "INBOX", []uint32{101}); err != nil {
		t.Fatalf("AckCmd 101: %v", err)
	}
	if decode(t, buf.Bytes())["error"] != false {
		t.Fatal("ack of visible uid should succeed")
	}
	buf.Reset()
	_ = ListCmd(d, "work", "INBOX", true, 0, 0, 50)
	data := decode(t, buf.Bytes())["data"].(map[string]any)
	msgs := data["messages"].([]any)
	if len(msgs) != 0 { // 101 acked, 102 filtered
		t.Fatalf("want 0 new messages, got %d", len(msgs))
	}
}

func TestFoldersListsMailboxes(t *testing.T) {
	fm := &fakeMailer{
		folders: []mail.FolderInfo{
			{Name: "INBOX", Delimiter: ".", Selectable: true},
			{Name: "INBOX.Archive", Delimiter: ".", Selectable: true},
			{Name: "Public", Delimiter: ".", Selectable: false},
		},
	}
	d, buf := newDeps(t, fm)
	if err := FoldersCmd(d, "work"); err != nil {
		t.Fatalf("FoldersCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	if res["error"] != false {
		t.Fatalf("unexpected error envelope: %v", res)
	}
	data := res["data"].(map[string]any)
	folders := data["folders"].([]any)
	if len(folders) != 3 {
		t.Fatalf("want 3 folders, got %d: %v", len(folders), folders)
	}
	first := folders[0].(map[string]any)
	if first["name"] != "INBOX" || first["delimiter"] != "." || first["selectable"] != true {
		t.Fatalf("unexpected first folder: %v", first)
	}
	last := folders[2].(map[string]any)
	if last["name"] != "Public" || last["selectable"] != false {
		t.Fatalf("unexpected last folder: %v", last)
	}
}

func TestSearchAllFoldersTagsFolderAndFilters(t *testing.T) {
	fm := &fakeMailer{
		folders: []mail.FolderInfo{
			{Name: "INBOX", Delimiter: ".", Selectable: true},
			{Name: "INBOX.Archive", Delimiter: ".", Selectable: true},
		},
		headersByFolder: map[string][]mail.Header{
			"INBOX": {
				{UID: 1, From: "a@trusted.com", Subject: "one"},
				{UID: 2, From: "x@evil.com", Subject: "spam"}, // filtered
			},
			"INBOX.Archive": {
				{UID: 7, From: "b@trusted.com", Subject: "two"},
			},
		},
	}
	d, buf := newDeps(t, fm)
	if err := SearchAllCmd(d, "work", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchAllCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	if res["error"] != false {
		t.Fatalf("unexpected error envelope: %v", res)
	}
	data := res["data"].(map[string]any)
	msgs := data["messages"].([]any)
	if len(msgs) != 2 {
		t.Fatalf("want 2 visible messages, got %d: %v", len(msgs), msgs)
	}
	m0 := msgs[0].(map[string]any)
	m1 := msgs[1].(map[string]any)
	if m0["folder"] != "INBOX" || m1["folder"] != "INBOX.Archive" {
		t.Fatalf("wrong folder tags: %v / %v", m0["folder"], m1["folder"])
	}
	skipped := data["skipped_folders"].([]any)
	if len(skipped) != 0 {
		t.Fatalf("want no skipped folders, got %v", skipped)
	}
}

func TestSearchAllFoldersSkipsNoselectAndErrors(t *testing.T) {
	fm := &fakeMailer{
		folders: []mail.FolderInfo{
			{Name: "INBOX", Delimiter: ".", Selectable: true},
			{Name: "Broken", Delimiter: ".", Selectable: true},
			{Name: "Public", Delimiter: ".", Selectable: false},
		},
		headersByFolder: map[string][]mail.Header{
			"INBOX": {{UID: 1, From: "a@trusted.com", Subject: "one"}},
		},
		searchErr: map[string]error{"Broken": errCommandFailed},
	}
	d, buf := newDeps(t, fm)
	if err := SearchAllCmd(d, "work", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchAllCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	if res["error"] != false {
		t.Fatalf("unexpected error envelope: %v", res)
	}
	for _, f := range fm.searched {
		if f == "Public" {
			t.Fatal("searched a \\Noselect folder")
		}
	}
	data := res["data"].(map[string]any)
	if got := len(data["messages"].([]any)); got != 1 {
		t.Fatalf("want 1 message, got %d", got)
	}
	skipped := data["skipped_folders"].([]any)
	if len(skipped) != 1 || skipped[0] != "Broken" {
		t.Fatalf("want skipped_folders [Broken], got %v", skipped)
	}
}

func TestSearchAllFoldersLimitCountsVisibleAcrossFolders(t *testing.T) {
	fm := &fakeMailer{
		folders: []mail.FolderInfo{
			{Name: "INBOX", Delimiter: ".", Selectable: true},
			{Name: "INBOX.Archive", Delimiter: ".", Selectable: true},
			{Name: "INBOX.Sent", Delimiter: ".", Selectable: true},
		},
		headersByFolder: map[string][]mail.Header{
			"INBOX": {
				{UID: 1, From: "a@trusted.com", Subject: "one"},
				{UID: 2, From: "x@evil.com", Subject: "spam"}, // filtered
			},
			"INBOX.Archive": {
				{UID: 3, From: "y@evil.com", Subject: "spam"}, // filtered
				{UID: 4, From: "b@trusted.com", Subject: "two"},
			},
			"INBOX.Sent": {
				{UID: 5, From: "c@trusted.com", Subject: "three"},
			},
		},
	}
	d, buf := newDeps(t, fm)
	if err := SearchAllCmd(d, "work", mail.SearchCriteria{}, 2); err != nil {
		t.Fatalf("SearchAllCmd: %v", err)
	}
	res := decode(t, buf.Bytes())
	data := res["data"].(map[string]any)
	msgs := data["messages"].([]any)
	if len(msgs) != 2 {
		t.Fatalf("want exactly 2 visible messages, got %d: %v", len(msgs), msgs)
	}
	for _, f := range fm.searched {
		if f == "INBOX.Sent" {
			t.Fatal("searched a folder after the visible limit was reached")
		}
	}
}

func TestSearchAllFoldersDoesNotBaseline(t *testing.T) {
	fm := &fakeMailer{
		folders: []mail.FolderInfo{
			{Name: "INBOX.Archive", Delimiter: ".", Selectable: true},
		},
		headersByFolder: map[string][]mail.Header{
			"INBOX.Archive": {{UID: 7, From: "b@trusted.com", Subject: "two"}},
		},
	}
	d, _ := newDeps(t, fm)
	if err := SearchAllCmd(d, "work", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchAllCmd: %v", err)
	}
	// IsNew errors (no folder_state row) iff the sweep did not baseline.
	if _, err := d.Store.IsNew("work", "INBOX.Archive", 7); err == nil {
		t.Fatal("sweep must not create a folder_state baseline for swept folders")
	}
}

func TestSearchEmptyEmitsHint(t *testing.T) {
	fm := &fakeMailer{uidValidity: 1, maxUID: 5}
	d, buf := newDeps(t, fm)
	if err := SearchCmd(d, "work", "INBOX", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchCmd: %v", err)
	}
	data := decode(t, buf.Bytes())["data"].(map[string]any)
	if hint, ok := data["hint"].(string); !ok || hint == "" {
		t.Fatalf("want non-empty hint on empty result, got %v", data["hint"])
	}

	// Non-empty results must omit the hint.
	fm2 := &fakeMailer{
		uidValidity: 1, maxUID: 5,
		headers: []mail.Header{{UID: 1, From: "a@trusted.com", Subject: "one"}},
	}
	d2, buf2 := newDeps(t, fm2)
	if err := SearchCmd(d2, "work", "INBOX", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchCmd: %v", err)
	}
	data2 := decode(t, buf2.Bytes())["data"].(map[string]any)
	if _, ok := data2["hint"]; ok {
		t.Fatalf("hint must be absent when messages exist, got %v", data2["hint"])
	}
}

func TestSearchAllFoldersEmptyEmitsHint(t *testing.T) {
	fm := &fakeMailer{
		folders:         []mail.FolderInfo{{Name: "INBOX", Delimiter: ".", Selectable: true}},
		headersByFolder: map[string][]mail.Header{},
	}
	d, buf := newDeps(t, fm)
	if err := SearchAllCmd(d, "work", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchAllCmd: %v", err)
	}
	data := decode(t, buf.Bytes())["data"].(map[string]any)
	if hint, ok := data["hint"].(string); !ok || hint == "" {
		t.Fatalf("want non-empty hint on empty sweep, got %v", data["hint"])
	}
}

// TestSearchEmptyHintIndistinguishableFromFiltered codifies the invisibility
// invariant for the empty-search hint: the envelope for "no mail at all" must
// be byte-identical to the envelope for "mail exists but is all filtered", so
// an empty result reveals nothing about inbound policy. Do not weaken this to
// a structural comparison.
func TestSearchEmptyHintIndistinguishableFromFiltered(t *testing.T) {
	absent := &fakeMailer{uidValidity: 1, maxUID: 5}
	dAbsent, bufAbsent := newDeps(t, absent)
	if err := SearchCmd(dAbsent, "work", "INBOX", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchCmd (absent): %v", err)
	}

	filtered := &fakeMailer{
		uidValidity: 1, maxUID: 5,
		headers: []mail.Header{
			{UID: 1, From: "x@evil.com", Subject: "spam1"},
			{UID: 2, From: "y@evil.com", Subject: "spam2"},
		},
	}
	dFiltered, bufFiltered := newDeps(t, filtered)
	if err := SearchCmd(dFiltered, "work", "INBOX", mail.SearchCriteria{}, 50); err != nil {
		t.Fatalf("SearchCmd (filtered): %v", err)
	}

	if !bytes.Equal(bufAbsent.Bytes(), bufFiltered.Bytes()) {
		t.Fatalf("empty-vs-filtered envelopes differ:\nabsent:   %s\nfiltered: %s",
			bufAbsent.Bytes(), bufFiltered.Bytes())
	}
}