package cli

import (
	"bytes"
	"strings"
	"testing"
	"time"

	terminal "golang.org/x/term"
)

type mockTerminalWriter struct {
	buf bytes.Buffer
}

func (m *mockTerminalWriter) Write(p []byte) (n int, err error) {
	return m.buf.Write(p)
}

func TestCompleterRoot(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// 1. Single tab on empty line: ambiguous, no advance
	newLine, newPos, ok := completer.Callback("", 0, '\t')
	if !ok || newLine != "" || newPos != 0 {
		t.Fatalf("Expected empty line and ok=true, got newLine=%q, newPos=%d, ok=%v", newLine, newPos, ok)
	}
	if mock.buf.Len() != 0 {
		t.Fatalf("Expected no terminal output on 1st tab, got %q", mock.buf.String())
	}

	// 2. Second tab immediately after: displays all root options
	newLine, newPos, ok = completer.Callback("", 0, '\t')
	if !ok || newLine != "" || newPos != 0 {
		t.Fatalf("Expected empty line and ok=true, got newLine=%q, newPos=%d, ok=%v", newLine, newPos, ok)
	}
	out := mock.buf.String()
	if !strings.Contains(out, "interface") || !strings.Contains(out, "ip") || !strings.Contains(out, "routing") {
		t.Fatalf("Expected root commands in double tab output, got: %s", out)
	}
}

func TestCompleterSlashRoot(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// 1. Single tab on "/": ambiguous, no advance
	newLine, newPos, ok := completer.Callback("/", 1, '\t')
	if !ok || newLine != "/" || newPos != 1 {
		t.Fatalf("Expected '/' and ok=true, got %q", newLine)
	}

	// 2. Second tab on "/": displays root choices
	newLine, newPos, ok = completer.Callback("/", 1, '\t')
	if !ok || newLine != "/" {
		t.Fatalf("Expected '/' and ok=true, got %q", newLine)
	}
	out := mock.buf.String()
	if !strings.Contains(out, "interface") || !strings.Contains(out, "ip") {
		t.Fatalf("Expected options on double tab, got: %s", out)
	}
}

func TestCompleterUniqueMatch(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// "/in" should complete to "/interface " on first tab
	newLine, newPos, ok := completer.Callback("/in", 3, '\t')
	if !ok {
		t.Fatalf("Expected ok=true")
	}
	if newLine != "/interface " {
		t.Fatalf("Expected '/interface ', got %q", newLine)
	}
	if newPos != len("/interface ") {
		t.Fatalf("Expected newPos=%d, got %d", len("/interface "), newPos)
	}

	// "rout" should complete to "routing " on first tab
	newLine, newPos, ok = completer.Callback("rout", 4, '\t')
	if !ok || newLine != "routing " {
		t.Fatalf("Expected 'routing ', got %q", newLine)
	}
}

func TestCompleterCommonPrefix(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// "/ip dh" matches "dhcp-client" and "dhcp-server" -> LCP is "dhcp-"
	newLine, newPos, ok := completer.Callback("/ip dh", 6, '\t')
	if !ok || newLine != "/ip dhcp-" {
		t.Fatalf("Expected '/ip dhcp-', got %q", newLine)
	}
	if newPos != len("/ip dhcp-") {
		t.Fatalf("Expected newPos=%d, got %d", len("/ip dhcp-"), newPos)
	}

	// Immediate second tab should show the two options
	mock.buf.Reset()
	newLine, newPos, ok = completer.Callback(newLine, newPos, '\t')
	if !ok || newLine != "/ip dhcp-" {
		t.Fatalf("Expected '/ip dhcp-', got %q", newLine)
	}
	out := mock.buf.String()
	if !strings.Contains(out, "dhcp-client") || !strings.Contains(out, "dhcp-server") {
		t.Fatalf("Expected dhcp choices, got: %s", out)
	}
}

func TestCompleterSubsectionsDoubleTab(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	subsections := []struct {
		input       string
		expectedIn  []string
		description string
	}{
		{
			input:       "/ip ",
			expectedIn:  []string{"address", "dhcp-client", "dhcp-server", "dns", "firewall", "route", "service"},
			description: "/ip subsections",
		},
		{
			input:       "/interface ",
			expectedIn:  []string{"bridge", "eoip", "pppoe-client", "vlan", "vrrp", "wireguard", "print", "enable", "disable"},
			description: "/interface subsections",
		},
		{
			input:       "/interface bridge ",
			expectedIn:  []string{"add", "disable", "enable", "port", "print", "remove"},
			description: "/interface bridge actions and port",
		},
		{
			input:       "/interface bridge port ",
			expectedIn:  []string{"add", "disable", "enable", "print", "remove"},
			description: "/interface bridge port actions",
		},
		{
			input:       "/ip firewall ",
			expectedIn:  []string{"address-list", "filter", "mangle", "nat"},
			description: "/ip firewall subsections",
		},
		{
			input:       "/ip firewall filter ",
			expectedIn:  []string{"add", "disable", "enable", "print", "remove"},
			description: "/ip firewall filter actions",
		},
		{
			input:       "/ip service ",
			expectedIn:  []string{"disable", "enable", "print", "set"},
			description: "/ip service actions",
		},
		{
			input:       "/ip service enable ",
			expectedIn:  []string{"ssh", "telnet", "www", "www-ssl"},
			description: "/ip service enable service choices",
		},
		{
			input:       "/certificate ",
			expectedIn:  []string{"add", "add-ca", "export", "issue-letsencrypt", "print", "remove"},
			description: "/certificate subsections",
		},
		{
			input:       "/routing ",
			expectedIn:  []string{"bgp", "filter", "ospf"},
			description: "/routing subsections",
		},
		{
			input:       "/routing bgp ",
			expectedIn:  []string{"instance", "network", "peer", "routes"},
			description: "/routing bgp subsections",
		},
		{
			input:       "/routing ospf ",
			expectedIn:  []string{"area", "instance", "interface", "neighbor"},
			description: "/routing ospf subsections",
		},
		{
			input:       "/tool ",
			expectedIn:  []string{"bandwidth-test", "ping", "traceroute"},
			description: "/tool subsections",
		},
		{
			input:       "/user ",
			expectedIn:  []string{"add", "print", "remove", "set"},
			description: "/user actions",
		},
		{
			input:       "/system ",
			expectedIn:  []string{"identity", "reboot", "resource"},
			description: "/system subsections",
		},
		{
			input:       "/system identity ",
			expectedIn:  []string{"print", "set"},
			description: "/system identity actions",
		},
	}

	for _, tc := range subsections {
		t.Run(tc.description, func(t *testing.T) {
			mock.buf.Reset()
			// Tab 1
			completer.Callback(tc.input, len(tc.input), '\t')
			// Tab 2
			completer.Callback(tc.input, len(tc.input), '\t')
			out := mock.buf.String()
			for _, expected := range tc.expectedIn {
				if !strings.Contains(out, expected) {
					t.Errorf("In %s, expected %q in output, got: %s", tc.description, expected, out)
				}
			}
		})
	}
}

func TestCompleterParameters(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// Under /ip firewall filter add, double tab should show parameter options
	mock.buf.Reset()
	completer.Callback("/ip firewall filter add ", len("/ip firewall filter add "), '\t')
	completer.Callback("/ip firewall filter add ", len("/ip firewall filter add "), '\t')
	out := mock.buf.String()
	expectedParams := []string{"action=", "chain=", "comment=", "dst-address=", "protocol=", "src-address="}
	for _, p := range expectedParams {
		if !strings.Contains(out, p) {
			t.Errorf("Expected param %q in output, got: %s", p, out)
		}
	}

	// Complete "ch" -> "chain=" (no space after =)
	newLine, _, ok := completer.Callback("/ip firewall filter add ch", len("/ip firewall filter add ch"), '\t')
	if !ok || newLine != "/ip firewall filter add chain=" {
		t.Fatalf("Expected parameter completion 'chain=', got %q", newLine)
	}

	// At "chain=", 2 tabs should show values ("forward", "input", "output")
	mock.buf.Reset()
	completer.Callback(newLine, len(newLine), '\t')
	completer.Callback(newLine, len(newLine), '\t')
	out = mock.buf.String()
	if !strings.Contains(out, "forward") || !strings.Contains(out, "input") || !strings.Contains(out, "output") {
		t.Fatalf("Expected chain values, got: %s", out)
	}

	// Complete value "chain=f" -> "chain=forward " (with trailing space!)
	newLine, _, ok = completer.Callback("/ip firewall filter add chain=f", len("/ip firewall filter add chain=f"), '\t')
	if !ok || newLine != "/ip firewall filter add chain=forward " {
		t.Fatalf("Expected 'chain=forward ', got %q", newLine)
	}

	// Once "chain=forward " is used, double tab should NOT suggest "chain=" again
	mock.buf.Reset()
	completer.Callback(newLine, len(newLine), '\t')
	completer.Callback(newLine, len(newLine), '\t')
	out = mock.buf.String()
	if strings.Contains(out, "chain=") {
		t.Fatalf("Expected already used 'chain=' to be omitted, got: %s", out)
	}
	if !strings.Contains(out, "action=") {
		t.Fatalf("Expected 'action=' still present, got: %s", out)
	}
}

func TestCompleterDoubleTabTimeout(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	// Press 1
	completer.Callback("/ip ", 4, '\t')

	// Artificially advance time past timeout
	completer.lastTabTime = time.Now().Add(-1500 * time.Millisecond)

	// Press 2 (after timeout): should be treated as new 1st tab, so NO print!
	mock.buf.Reset()
	completer.Callback("/ip ", 4, '\t')
	if mock.buf.Len() != 0 {
		t.Fatalf("Expected no output after timeout, got: %s", mock.buf.String())
	}

	// Press 3 (within 1s of Press 2): should be 2nd tab and print!
	completer.Callback("/ip ", 4, '\t')
	if mock.buf.Len() == 0 {
		t.Fatalf("Expected output on 2nd tab within timeout")
	}
}

func TestCompleterIgnoredNonTab(t *testing.T) {
	mock := &mockTerminalWriter{}
	completer := NewCompleter(mock, nil)

	_, _, ok := completer.Callback("/ip ", 4, 'a')
	if ok {
		t.Fatalf("Expected ok=false for non-tab key 'a'")
	}
}

type testTerminalRW struct {
	in  bytes.Buffer
	out bytes.Buffer
}

func (rw *testTerminalRW) Read(p []byte) (n int, err error) {
	return rw.in.Read(p)
}

func (rw *testTerminalRW) Write(p []byte) (n int, err error) {
	return rw.out.Write(p)
}

func TestCompleterWithRealTerminal(t *testing.T) {
	rw := &testTerminalRW{}
	term := terminal.NewTerminal(rw, "[admin@DebTik] > ")
	completer := NewCompleter(term, nil)
	term.AutoCompleteCallback = completer.Callback

	// Feed input: "/ip " followed by 2 tabs, then "firewall print\r\n"
	rw.in.WriteString("/ip \t\tfirewall print\r\n")

	line, err := term.ReadLine()
	if err != nil {
		t.Fatalf("ReadLine error: %v", err)
	}
	if line != "/ip firewall print" {
		t.Fatalf("Expected '/ip firewall print', got %q", line)
	}

	out := rw.out.String()
	// Output should contain the subsections formatted on double tab
	if !strings.Contains(out, "address") || !strings.Contains(out, "firewall") || !strings.Contains(out, "route") {
		t.Fatalf("Terminal output missing double-tab options: %s", out)
	}
}

func TestCompleterFullInteractiveSession(t *testing.T) {
	rw := &testTerminalRW{}
	term := terminal.NewTerminal(rw, "[admin@DebTik] > ")
	completer := NewCompleter(term, nil)
	term.AutoCompleteCallback = completer.Callback

	// Type /int<Tab>br<Tab>po<Tab><Tab><Tab>pr<Tab>\r\n
	rw.in.WriteString("/int\tbr\tpo\t\t\tpr\t\r\n")

	line, err := term.ReadLine()
	if err != nil {
		t.Fatalf("ReadLine error: %v", err)
	}
	if line != "/interface bridge port print " {
		t.Fatalf("Expected '/interface bridge port print ', got %q", line)
	}

	out := rw.out.String()
	if !strings.Contains(out, "add") || !strings.Contains(out, "disable") || !strings.Contains(out, "print") {
		t.Fatalf("Expected bridge port options in output, got: %s", out)
	}
}