package main

import (
	"bufio"
	"bytes"
	"encoding/base64"
	"encoding/json"
	"io"
	"math"
	"net"
	"strconv"
	"strings"
	"sync"
	"testing"
	"time"
)

type notifyingBuffer struct {
	mu     sync.Mutex
	buffer bytes.Buffer
	notify chan struct{}
}

func newNotifyingBuffer() *notifyingBuffer {
	return &notifyingBuffer{notify: make(chan struct{}, 1)}
}

func (b *notifyingBuffer) Write(p []byte) (int, error) {
	b.mu.Lock()
	defer b.mu.Unlock()
	n, err := b.buffer.Write(p)
	if n > 0 {
		select {
		case b.notify <- struct{}{}:
		default:
		}
	}
	return n, err
}

func (b *notifyingBuffer) String() string {
	b.mu.Lock()
	defer b.mu.Unlock()
	return b.buffer.String()
}

func TestRunVersion(t *testing.T) {
	var out bytes.Buffer
	code := run([]string{"version"}, strings.NewReader(""), &out, &bytes.Buffer{})
	if code != 0 {
		t.Fatalf("run version exit code = %d, want 0", code)
	}
	if strings.TrimSpace(out.String()) == "" {
		t.Fatalf("version output should not be empty")
	}
}

func TestRunStdioHelloAndPing(t *testing.T) {
	input := strings.NewReader(
		`{"id":1,"method":"hello","params":{}}` + "\n" +
			`{"id":2,"method":"ping","params":{}}` + "\n",
	)
	var out bytes.Buffer
	code := run([]string{"serve", "--stdio"}, input, &out, &bytes.Buffer{})
	if code != 0 {
		t.Fatalf("run serve exit code = %d, want 0", code)
	}

	lines := strings.Split(strings.TrimSpace(out.String()), "\n")
	if len(lines) != 2 {
		t.Fatalf("got %d response lines, want 2: %q", len(lines), out.String())
	}

	var first map[string]any
	if err := json.Unmarshal([]byte(lines[0]), &first); err != nil {
		t.Fatalf("failed to decode first response: %v", err)
	}
	if ok, _ := first["ok"].(bool); !ok {
		t.Fatalf("first response should be ok=true: %v", first)
	}
	firstResult, _ := first["result"].(map[string]any)
	if firstResult == nil {
		t.Fatalf("first response missing result object: %v", first)
	}
	capabilities, _ := firstResult["capabilities"].([]any)
	if len(capabilities) < 2 {
		t.Fatalf("hello should return capabilities: %v", firstResult)
	}
	var sawPushCapability bool
	for _, capability := range capabilities {
		if capability == "proxy.stream.push" {
			sawPushCapability = true
			break
		}
	}
	if !sawPushCapability {
		t.Fatalf("hello should advertise proxy.stream.push: %v", firstResult)
	}

	var second map[string]any
	if err := json.Unmarshal([]byte(lines[1]), &second); err != nil {
		t.Fatalf("failed to decode second response: %v", err)
	}
	if ok, _ := second["ok"].(bool); !ok {
		t.Fatalf("second response should be ok=true: %v", second)
	}
}

func TestRunStdioInvalidJSONAndUnknownMethod(t *testing.T) {
	input := strings.NewReader(
		`{"id":1,"method":"hello","params":{}` + "\n" +
			`{"id":2,"method":"unknown","params":{}}` + "\n",
	)
	var out bytes.Buffer
	code := run([]string{"serve", "--stdio"}, input, &out, &bytes.Buffer{})
	if code != 0 {
		t.Fatalf("run serve exit code = %d, want 0", code)
	}

	lines := strings.Split(strings.TrimSpace(out.String()), "\n")
	if len(lines) != 2 {
		t.Fatalf("got %d response lines, want 2: %q", len(lines), out.String())
	}

	var first map[string]any
	if err := json.Unmarshal([]byte(lines[0]), &first); err != nil {
		t.Fatalf("failed to decode first response: %v", err)
	}
	if ok, _ := first["ok"].(bool); ok {
		t.Fatalf("first response should be ok=false for invalid JSON: %v", first)
	}
	firstError, _ := first["error"].(map[string]any)
	if got := firstError["code"]; got != "invalid_request" {
		t.Fatalf("invalid JSON should return invalid_request; got=%v payload=%v", got, first)
	}

	var second map[string]any
	if err := json.Unmarshal([]byte(lines[1]), &second); err != nil {
		t.Fatalf("failed to decode second response: %v", err)
	}
	if ok, _ := second["ok"].(bool); ok {
		t.Fatalf("second response should be ok=false for unknown method: %v", second)
	}
	secondError, _ := second["error"].(map[string]any)
	if got := secondError["code"]; got != "method_not_found" {
		t.Fatalf("unknown method should return method_not_found; got=%v payload=%v", got, second)
	}
}

func TestRunStdioSessionResizeFlow(t *testing.T) {
	input := strings.NewReader(
		`{"id":1,"method":"session.open","params":{"session_id":"sess-stdio"}}` + "\n" +
			`{"id":2,"method":"session.attach","params":{"session_id":"sess-stdio","attachment_id":"a1","cols":120,"rows":40}}` + "\n" +
			`{"id":3,"method":"session.attach","params":{"session_id":"sess-stdio","attachment_id":"a2","cols":90,"rows":30}}` + "\n" +
			`{"id":4,"method":"session.status","params":{"session_id":"sess-stdio"}}` + "\n",
	)
	var out bytes.Buffer
	code := run([]string{"serve", "--stdio"}, input, &out, &bytes.Buffer{})
	if code != 0 {
		t.Fatalf("run serve exit code = %d, want 0", code)
	}

	lines := strings.Split(strings.TrimSpace(out.String()), "\n")
	if len(lines) != 4 {
		t.Fatalf("got %d response lines, want 4: %q", len(lines), out.String())
	}

	var status map[string]any
	if err := json.Unmarshal([]byte(lines[3]), &status); err != nil {
		t.Fatalf("failed to decode status response: %v", err)
	}
	if ok, _ := status["ok"].(bool); !ok {
		t.Fatalf("session.status should be ok=true: %v", status)
	}
	result, _ := status["result"].(map[string]any)
	if result == nil {
		t.Fatalf("session.status missing result object: %v", status)
	}
	effectiveCols, _ := result["effective_cols"].(float64)
	effectiveRows, _ := result["effective_rows"].(float64)
	if int(effectiveCols) != 90 || int(effectiveRows) != 30 {
		t.Fatalf("session smallest-wins effective size mismatch: got=%vx%v payload=%v", effectiveCols, effectiveRows, result)
	}
}

func TestProxyStreamRoundTrip(t *testing.T) {
	listener, err := net.Listen("tcp", "127.0.0.1:0")
	if err != nil {
		t.Fatalf("listen failed: %v", err)
	}
	defer listener.Close()

	done := make(chan struct{})
	go func() {
		defer close(done)
		conn, acceptErr := listener.Accept()
		if acceptErr != nil {
			return
		}
		defer conn.Close()

		buffer := make([]byte, 4)
		if _, readErr := io.ReadFull(conn, buffer); readErr != nil {
			return
		}
		if string(buffer) != "ping" {
			return
		}
		_, _ = conn.Write([]byte("pong"))
	}()

	eventOutput := newNotifyingBuffer()
	server := &rpcServer{
		nextStreamID:  1,
		nextSessionID: 1,
		streams:       map[string]*streamState{},
		sessions:      map[string]*sessionState{},
		frameWriter: &stdioFrameWriter{
			writer: bufio.NewWriter(eventOutput),
		},
	}
	defer server.closeAll()

	port := listener.Addr().(*net.TCPAddr).Port
	openResp := server.handleRequest(rpcRequest{
		ID:     1,
		Method: "proxy.open",
		Params: map[string]any{
			"host":       "127.0.0.1",
			"port":       port,
			"timeout_ms": 1000,
		},
	})
	if !openResp.OK {
		t.Fatalf("proxy.open failed: %+v", openResp)
	}
	openResult, _ := openResp.Result.(map[string]any)
	streamID, _ := openResult["stream_id"].(string)
	if streamID == "" {
		t.Fatalf("proxy.open missing stream_id: %+v", openResp)
	}

	writeResp := server.handleRequest(rpcRequest{
		ID:     2,
		Method: "proxy.write",
		Params: map[string]any{
			"stream_id":   streamID,
			"data_base64": base64.StdEncoding.EncodeToString([]byte("ping")),
		},
	})
	if !writeResp.OK {
		t.Fatalf("proxy.write failed: %+v", writeResp)
	}

	readResp := server.handleRequest(rpcRequest{
		ID:     3,
		Method: "proxy.stream.subscribe",
		Params: map[string]any{
			"stream_id": streamID,
		},
	})
	if !readResp.OK {
		t.Fatalf("proxy.stream.subscribe failed: %+v", readResp)
	}
	select {
	case <-eventOutput.notify:
	case <-time.After(2 * time.Second):
		t.Fatalf("timed out waiting for proxy.stream.data event")
	}

	lines := strings.Split(strings.TrimSpace(eventOutput.String()), "\n")
	if len(lines) == 0 || strings.TrimSpace(lines[0]) == "" {
		t.Fatalf("proxy.stream.data event output was empty")
	}

	var event map[string]any
	if err := json.Unmarshal([]byte(lines[0]), &event); err != nil {
		t.Fatalf("failed to decode stream event: %v", err)
	}
	if got := event["event"]; got != "proxy.stream.data" {
		t.Fatalf("unexpected stream event=%v payload=%v", got, event)
	}
	dataBase64, _ := event["data_base64"].(string)
	data, decodeErr := base64.StdEncoding.DecodeString(dataBase64)
	if decodeErr != nil {
		t.Fatalf("proxy.stream.data returned invalid base64: %v", decodeErr)
	}
	if string(data) != "pong" {
		t.Fatalf("proxy.stream.data payload=%q, want %q", string(data), "pong")
	}

	closeResp := server.handleRequest(rpcRequest{
		ID:     4,
		Method: "proxy.close",
		Params: map[string]any{
			"stream_id": streamID,
		},
	})
	if !closeResp.OK {
		t.Fatalf("proxy.close failed: %+v", closeResp)
	}

	select {
	case <-done:
	case <-time.After(2 * time.Second):
		t.Fatalf("proxy test server goroutine did not finish")
	}
}

func TestGetIntParamRejectsFractionalFloat64(t *testing.T) {
	params := map[string]any{
		"port":       80.9,
		"timeout_ms": 100.0,
	}

	if _, ok := getIntParam(params, "port"); ok {
		t.Fatalf("fractional float64 should be rejected")
	}

	timeout, ok := getIntParam(params, "timeout_ms")
	if !ok {
		t.Fatalf("integral float64 should be accepted")
	}
	if timeout != 100 {
		t.Fatalf("timeout_ms = %d, want 100", timeout)
	}
}

func TestRunStdioOversizedFrameContinuesServing(t *testing.T) {
	oversized := `{"id":1,"method":"ping","params":{"blob":"` + strings.Repeat("a", maxRPCFrameBytes) + `"}}`
	input := strings.NewReader(oversized + "\n" + `{"id":2,"method":"ping","params":{}}` + "\n")
	var out bytes.Buffer
	code := run([]string{"serve", "--stdio"}, input, &out, &bytes.Buffer{})
	if code != 0 {
		t.Fatalf("run serve exit code = %d, want 0", code)
	}

	lines := strings.Split(strings.TrimSpace(out.String()), "\n")
	if len(lines) != 2 {
		t.Fatalf("got %d response lines, want 2: %q", len(lines), out.String())
	}

	var first map[string]any
	if err := json.Unmarshal([]byte(lines[0]), &first); err != nil {
		t.Fatalf("failed to decode first response: %v", err)
	}
	if ok, _ := first["ok"].(bool); ok {
		t.Fatalf("first response should be oversized-frame error: %v", first)
	}
	firstError, _ := first["error"].(map[string]any)
	if got := firstError["code"]; got != "invalid_request" {
		t.Fatalf("oversized frame should return invalid_request; got=%v payload=%v", got, first)
	}

	var second map[string]any
	if err := json.Unmarshal([]byte(lines[1]), &second); err != nil {
		t.Fatalf("failed to decode second response: %v", err)
	}
	if ok, _ := second["ok"].(bool); !ok {
		t.Fatalf("second response should still be handled after oversized frame: %v", second)
	}
}

func TestProxyOpenInvalidParams(t *testing.T) {
	server := &rpcServer{
		nextStreamID:  1,
		nextSessionID: 1,
		streams:       map[string]*streamState{},
		sessions:      map[string]*sessionState{},
	}
	defer server.closeAll()

	resp := server.handleRequest(rpcRequest{
		ID:     1,
		Method: "proxy.open",
		Params: map[string]any{
			"host": "127.0.0.1",
			"port": strconv.Itoa(8080),
		},
	})
	if resp.OK {
		t.Fatalf("proxy.open with invalid port type should fail: %+v", resp)
	}
	errObj, _ := resp.Error, resp.Error
	if errObj == nil || errObj.Code != "invalid_params" {
		t.Fatalf("proxy.open invalid params should return invalid_params: %+v", resp)
	}
}

func TestSessionResizeCoordinator(t *testing.T) {
	server := &rpcServer{
		nextStreamID:  1,
		nextSessionID: 1,
		streams:       map[string]*streamState{},
		sessions:      map[string]*sessionState{},
	}
	defer server.closeAll()

	openResp := server.handleRequest(rpcRequest{
		ID:     1,
		Method: "session.open",
		Params: map[string]any{
			"session_id": "sess-rz",
		},
	})
	if !openResp.OK {
		t.Fatalf("session.open failed: %+v", openResp)
	}

	attachSmall := server.handleRequest(rpcRequest{
		ID:     2,
		Method: "session.attach",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-small",
			"cols":          90,
			"rows":          30,
		},
	})
	assertEffectiveSize(t, attachSmall, 90, 30)

	attachLarge := server.handleRequest(rpcRequest{
		ID:     3,
		Method: "session.attach",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-large",
			"cols":          120,
			"rows":          40,
		},
	})
	assertEffectiveSize(t, attachLarge, 90, 30) // RZ-001: smallest wins

	resizeLarge := server.handleRequest(rpcRequest{
		ID:     4,
		Method: "session.resize",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-large",
			"cols":          200,
			"rows":          60,
		},
	})
	assertEffectiveSize(t, resizeLarge, 90, 30) // RZ-002: still bounded by smallest

	detachSmall := server.handleRequest(rpcRequest{
		ID:     5,
		Method: "session.detach",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-small",
		},
	})
	assertEffectiveSize(t, detachSmall, 200, 60) // RZ-003: expands to next smallest

	detachLarge := server.handleRequest(rpcRequest{
		ID:     6,
		Method: "session.detach",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-large",
		},
	})
	assertEffectiveSize(t, detachLarge, 200, 60) // no attachments: keep last-known size
	assertAttachmentCount(t, detachLarge, 0)

	reattach := server.handleRequest(rpcRequest{
		ID:     7,
		Method: "session.attach",
		Params: map[string]any{
			"session_id":    "sess-rz",
			"attachment_id": "a-reconnect",
			"cols":          110,
			"rows":          50,
		},
	})
	assertEffectiveSize(t, reattach, 110, 50) // RZ-004: recompute from active attachments on reattach
}

func TestSessionInvalidParamsAndNotFound(t *testing.T) {
	server := &rpcServer{
		nextStreamID:  1,
		nextSessionID: 1,
		streams:       map[string]*streamState{},
		sessions:      map[string]*sessionState{},
	}
	defer server.closeAll()

	missingSession := server.handleRequest(rpcRequest{
		ID:     1,
		Method: "session.attach",
		Params: map[string]any{
			"session_id":    "missing",
			"attachment_id": "a1",
			"cols":          80,
			"rows":          24,
		},
	})
	if missingSession.OK || missingSession.Error == nil || missingSession.Error.Code != "not_found" {
		t.Fatalf("session.attach on missing session should return not_found: %+v", missingSession)
	}

	badSize := server.handleRequest(rpcRequest{
		ID:     2,
		Method: "session.attach",
		Params: map[string]any{
			"session_id":    "missing",
			"attachment_id": "a1",
			"cols":          0,
			"rows":          24,
		},
	})
	if badSize.OK || badSize.Error == nil || badSize.Error.Code != "invalid_params" {
		t.Fatalf("session.attach with cols=0 should return invalid_params: %+v", badSize)
	}
}

func assertEffectiveSize(t *testing.T, resp rpcResponse, wantCols, wantRows int) {
	t.Helper()
	if !resp.OK {
		t.Fatalf("expected ok response, got error: %+v", resp)
	}
	result, ok := resp.Result.(map[string]any)
	if !ok {
		t.Fatalf("response missing result map: %+v", resp)
	}
	gotCols := asInt(t, result["effective_cols"], "effective_cols")
	gotRows := asInt(t, result["effective_rows"], "effective_rows")
	if gotCols != wantCols || gotRows != wantRows {
		t.Fatalf("effective size = %dx%d, want %dx%d payload=%+v", gotCols, gotRows, wantCols, wantRows, result)
	}
}

func assertAttachmentCount(t *testing.T, resp rpcResponse, want int) {
	t.Helper()
	if !resp.OK {
		t.Fatalf("expected ok response, got error: %+v", resp)
	}
	result, ok := resp.Result.(map[string]any)
	if !ok {
		t.Fatalf("response missing result map: %+v", resp)
	}
	attachments, ok := result["attachments"].([]map[string]any)
	if ok {
		if len(attachments) != want {
			t.Fatalf("attachments len = %d, want %d payload=%+v", len(attachments), want, result)
		}
		return
	}
	attachmentsAny, ok := result["attachments"].([]any)
	if !ok {
		t.Fatalf("attachments field has unexpected type (%T) payload=%+v", result["attachments"], result)
	}
	if len(attachmentsAny) != want {
		t.Fatalf("attachments len = %d, want %d payload=%+v", len(attachmentsAny), want, result)
	}
}

func asInt(t *testing.T, value any, field string) int {
	t.Helper()
	switch typed := value.(type) {
	case int:
		return typed
	case int8:
		return int(typed)
	case int16:
		return int(typed)
	case int32:
		return int(typed)
	case int64:
		return int(typed)
	case uint:
		return int(typed)
	case uint8:
		return int(typed)
	case uint16:
		return int(typed)
	case uint32:
		return int(typed)
	case uint64:
		return int(typed)
	case float64:
		if typed != math.Trunc(typed) {
			t.Fatalf("%s should be integer-valued, got %v", field, typed)
		}
		return int(typed)
	default:
		t.Fatalf("%s has unexpected type %T (%v)", field, value, value)
		return 0
	}
}