package server

import (
	"context"
	"testing"
	"time"

	"github.com/noahlann/nnet/internal/codec"
	codecpkg "github.com/noahlann/nnet/pkg/codec"
	ctxpkg "github.com/noahlann/nnet/pkg/context"
	protocolpkg "github.com/noahlann/nnet/pkg/protocol"
	requestpkg "github.com/noahlann/nnet/pkg/request"
	responsepkg "github.com/noahlann/nnet/pkg/response"
)

// --- minimal fakes for Context/Request/Header

type fakeHeader struct{ m map[string]interface{} }

func (h *fakeHeader) Get(key string) interface{} { return h.m[key] }
func (h *fakeHeader) Set(key string, value interface{}) {
	if h.m == nil {
		h.m = map[string]interface{}{}
	}
	h.m[key] = value
}
func (h *fakeHeader) Encode() ([]byte, error) { return nil, nil }
func (h *fakeHeader) Decode([]byte) error     { return nil }
func (h *fakeHeader) Clone() requestpkg.FrameHeader {
	c := &fakeHeader{m: make(map[string]interface{}, len(h.m))}
	for k, v := range h.m {
		c.m[k] = v
	}
	return c
}

type fakeRequest struct{ header requestpkg.FrameHeader }

func (r *fakeRequest) Raw() []byte                    { return nil }
func (r *fakeRequest) Data() interface{}              { return nil }
func (r *fakeRequest) Bind(v interface{}) error       { return nil }
func (r *fakeRequest) Header() requestpkg.FrameHeader { return r.header }
func (r *fakeRequest) DataBytes() []byte              { return nil }
func (r *fakeRequest) Protocol() protocolpkg.Protocol { return nil }
func (r *fakeRequest) ProtocolVersion() string        { return "" }

type fakeConn struct{}

func (f *fakeConn) ID() string         { return "" }
func (f *fakeConn) RemoteAddr() string { return "" }
func (f *fakeConn) LocalAddr() string  { return "" }
func (f *fakeConn) Write([]byte) error { return nil }
func (f *fakeConn) Close() error       { return nil }

type fakeCtx struct {
	ctx  context.Context
	req  requestpkg.Request
	vals map[string]interface{}
	conn ctxpkg.Connection
}

func (f *fakeCtx) Deadline() (time.Time, bool)       { return time.Time{}, false }
func (f *fakeCtx) Done() <-chan struct{}             { return nil }
func (f *fakeCtx) Err() error                        { return nil }
func (f *fakeCtx) Value(key interface{}) interface{} { return nil }
func (f *fakeCtx) Request() requestpkg.Request       { return f.req }
func (f *fakeCtx) Response() responsepkg.Response    { return nil }
func (f *fakeCtx) Connection() ctxpkg.Connection     { return f.conn }
func (f *fakeCtx) Set(k string, v interface{}) {
	if f.vals == nil {
		f.vals = map[string]interface{}{}
	}
	f.vals[k] = v
}
func (f *fakeCtx) Get(k string) interface{}     { return f.vals[k] }
func (f *fakeCtx) MustGet(k string) interface{} { return f.vals[k] }
func (f *fakeCtx) GetString(k string) string {
	if v, ok := f.vals[k].(string); ok {
		return v
	}
	return ""
}
func (f *fakeCtx) GetInt(k string) int {
	if v, ok := f.vals[k].(int); ok {
		return v
	}
	return 0
}
func (f *fakeCtx) GetBool(k string) bool {
	if v, ok := f.vals[k].(bool); ok {
		return v
	}
	return false
}

func newCtxWithHeaderCodec(name string) ctxpkg.Context {
	req := &fakeRequest{header: &fakeHeader{m: map[string]interface{}{"codec": name}}}
	return &fakeCtx{ctx: context.Background(), req: req, conn: &fakeConn{}}
}

// 测试用的resolver实现
type testHeaderResolver struct{}

func (r *testHeaderResolver) ResolveForDecode(registry codecpkg.Registry, ctx ctxpkg.Context, raw []byte, header protocolpkg.FrameHeader) (codecpkg.Codec, error) {
	if ctx != nil && ctx.Request() != nil && ctx.Request().Header() != nil {
		if v := ctx.Request().Header().Get("codec"); v != nil {
			if name, ok := v.(string); ok && name != "" {
				return registry.Get(name)
			}
		}
	}
	return nil, nil
}

func (r *testHeaderResolver) ResolveForEncode(registry codecpkg.Registry, ctx ctxpkg.Context, data interface{}, header protocolpkg.FrameHeader) (codecpkg.Codec, error) {
	// 编码时也尝试从header获取
	if header != nil {
		if v := header.Get("codec"); v != nil {
			if name, ok := v.(string); ok && name != "" {
				return registry.Get(name)
			}
		}
	}
	return nil, nil
}

type testRawDataResolver struct{}

func (r *testRawDataResolver) ResolveForDecode(registry codecpkg.Registry, ctx ctxpkg.Context, raw []byte, header protocolpkg.FrameHeader) (codecpkg.Codec, error) {
	if len(raw) > 0 {
		b0 := raw[0]
		if len(raw) > 1 {
			bl := raw[len(raw)-1]
			if (b0 == '{' && bl == '}') || (b0 == '[' && bl == ']') {
				return registry.Get("json")
			}
		}
	}
	return nil, nil
}

func (r *testRawDataResolver) ResolveForEncode(registry codecpkg.Registry, ctx ctxpkg.Context, data interface{}, header protocolpkg.FrameHeader) (codecpkg.Codec, error) {
	// 编码时无法从原始数据判断，返回nil
	return nil, nil
}

func TestResolveCodec_HeaderPreferred(t *testing.T) {
	reg := codec.NewRegistry()
	_ = reg.Register("json", codec.NewJSONCodec())
	chain := codecpkg.NewResolverChain(reg, "")
	// 添加一个测试resolver
	chain.Add(&testHeaderResolver{})
	ctx := newCtxWithHeaderCodec("json")
	c, err := chain.ResolveForDecode(ctx, []byte(nil), ctx.Request().Header())
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if c.Name() != "json" {
		t.Fatalf("want json, got %s", c.Name())
	}
}

func TestResolveCodec_DefaultFallback(t *testing.T) {
	reg := codec.NewRegistry()
	chain := codecpkg.NewResolverChain(reg, "binary")
	c, err := chain.ResolveForDecode(nil, []byte(nil), nil)
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if c.Name() != "binary" {
		t.Fatalf("want binary, got %s", c.Name())
	}
}

func TestResolveCodec_JSONHeuristic(t *testing.T) {
	reg := codec.NewRegistry()
	_ = reg.Register("json", codec.NewJSONCodec())
	chain := codecpkg.NewResolverChain(reg, "")
	// 添加一个测试resolver
	chain.Add(&testRawDataResolver{})
	raw := []byte(`{"a":1}`)
	c, err := chain.ResolveForDecode(nil, raw, nil)
	if err != nil {
		t.Fatalf("unexpected err: %v", err)
	}
	if c.Name() != "json" {
		t.Fatalf("want json by heuristic, got %s", c.Name())
	}
}