package anthropic

import (
	"bytes"
	"context"
	"encoding/json"
	"io"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"
)

func TestParseSSESingleEvent(t *testing.T) {
	body := "event: message_start\ndata: {\"type\":\"message_start\",\"message\":{\"id\":\"m1\",\"model\":\"X\"}}\n\n"
	ch := make(chan Event, 4)
	if err := parseSSE(context.Background(), strings.NewReader(body), ch); err != nil {
		t.Fatal(err)
	}
	close(ch)
	events := drain(ch)
	if len(events) != 1 || events[0].Type != "message_start" || events[0].Message.ID != "m1" {
		t.Errorf("events = %+v", events)
	}
}

func TestParseSSEMultiLineData(t *testing.T) {
	// "data:" can be split across multiple lines per spec; joined with '\n'.
	body := "data: {\"type\":\n" + "data: \"text_delta\",\"delta\":{\"type\":\"text_delta\",\"text\":\"hi\"}}\n\n"
	ch := make(chan Event, 4)
	if err := parseSSE(context.Background(), strings.NewReader(body), ch); err != nil {
		t.Fatal(err)
	}
	close(ch)
	events := drain(ch)
	if len(events) != 1 || events[0].Type != "text_delta" || events[0].Delta.Text != "hi" {
		t.Errorf("events = %+v", events)
	}
}

func TestParseSSEFlushTrailingWithoutBlank(t *testing.T) {
	body := "data: {\"type\":\"message_stop\"}"
	ch := make(chan Event, 4)
	if err := parseSSE(context.Background(), strings.NewReader(body), ch); err != nil {
		t.Fatal(err)
	}
	close(ch)
	events := drain(ch)
	if len(events) != 1 || events[0].Type != "message_stop" {
		t.Errorf("trailing flush missed: %+v", events)
	}
}

func TestStreamMessagesSendsRightHeaders(t *testing.T) {
	var gotAuth, gotVer string
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		gotAuth = r.Header.Get("authorization")
		gotVer = r.Header.Get("anthropic-version")
		w.Header().Set("content-type", "text/event-stream")
		w.Write([]byte("event: message_stop\ndata: {\"type\":\"message_stop\"}\n\n"))
	}))
	defer srv.Close()
	c := New(srv.URL, "fake-key")
	ch, err := c.StreamMessages(context.Background(), MessagesRequest{
		Model: "X", MaxTokens: 10,
		Messages: []Message{{Role: "user", Content: []ContentBlock{{"type": "text", "text": "hi"}}}},
	})
	if err != nil {
		t.Fatal(err)
	}
	for range ch {
	}
	if gotAuth != "Bearer fake-key" {
		t.Errorf("auth = %q", gotAuth)
	}
	if gotVer != DefaultAPIVersion {
		t.Errorf("anthropic-version = %q", gotVer)
	}
}

func TestStreamMessagesNon2xxErrors(t *testing.T) {
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.WriteHeader(http.StatusUnauthorized)
		w.Write([]byte(`{"error":{"type":"authentication_error","message":"bad key"}}`))
	}))
	defer srv.Close()
	c := New(srv.URL, "bad")
	_, err := c.StreamMessages(context.Background(), MessagesRequest{Model: "X", MaxTokens: 10})
	if err == nil || !strings.Contains(err.Error(), "401") {
		t.Errorf("err = %v", err)
	}
}

func TestStreamMessagesStreamErrorBecomesEvent(t *testing.T) {
	// Simulate an SSE stream that errors mid-stream.
	srv := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("content-type", "text/event-stream")
		flusher, _ := w.(http.Flusher)
		w.Write([]byte("event: message_start\ndata: {\"type\":\"message_start\"}\n\n"))
		flusher.Flush()
		// Hijack-style mid-stream close: not really an error in HTTP terms,
		// scanner just hits EOF cleanly. So no error event expected.
	}))
	defer srv.Close()
	c := New(srv.URL, "k")
	ch, err := c.StreamMessages(context.Background(), MessagesRequest{Model: "X", MaxTokens: 10})
	if err != nil {
		t.Fatal(err)
	}
	events := drain(ch)
	if len(events) != 1 || events[0].Type != "message_start" {
		t.Errorf("events = %+v", events)
	}
}

func TestMessagesRequestMarshalShape(t *testing.T) {
	req := MessagesRequest{
		Model: "MiniMax-M2.7", MaxTokens: 50, Stream: true,
		Messages: []Message{{Role: "user", Content: []ContentBlock{
			{"type": "text", "text": "hi"},
		}}},
	}
	raw, _ := json.Marshal(req)
	// stream:true present
	if !bytes.Contains(raw, []byte(`"stream":true`)) {
		t.Errorf("missing stream:true in %s", raw)
	}
	if !bytes.Contains(raw, []byte(`"model":"MiniMax-M2.7"`)) {
		t.Errorf("missing model: %s", raw)
	}
}

func drain(ch <-chan Event) []Event {
	var out []Event
	for ev := range ch {
		out = append(out, ev)
	}
	return out
}

// Compile-time check that io.EOF is exported so we don't accidentally
// remove the import.
var _ = io.EOF