package llm

import (
	"context"
	"net/http"
	"net/http/httptest"
	"testing"
)

func sseProviderServer(t *testing.T, sse string) *httptest.Server {
	t.Helper()
	return httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
		w.Header().Set("Content-Type", "text/event-stream")
		_, _ = w.Write([]byte(sse))
	}))
}

func collectToolCallDeltas(t *testing.T, p Provider) []ToolCall {
	t.Helper()
	var got []ToolCall
	_, err := p.Stream(context.Background(), "s", []Message{{Role: RoleUser, Content: "hi"}}, nil, StreamOptions{},
		func(d StreamDelta) {
			if d.ToolCall != nil {
				got = append(got, *d.ToolCall)
			}
		})
	if err != nil {
		t.Fatal(err)
	}
	return got
}

// TestAnthropicEmitsCompletedToolCall：content_block_stop 一到就提前通知，
// 不等 message_stop。
func TestAnthropicEmitsCompletedToolCall(t *testing.T) {
	srv := sseProviderServer(t, ""+
		"data: {\"type\":\"message_start\",\"message\":{\"usage\":{\"input_tokens\":10}}}\n\n"+
		"data: {\"type\":\"content_block_start\",\"index\":0,\"content_block\":{\"type\":\"tool_use\",\"id\":\"t1\",\"name\":\"read\"}}\n\n"+
		"data: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"input_json_delta\",\"partial_json\":\"{\\\"path\\\":\\\"a\\\"}\"}}\n\n"+
		"data: {\"type\":\"content_block_stop\",\"index\":0}\n\n"+
		"data: {\"type\":\"message_stop\"}\n\n")
	defer srv.Close()
	p := &AnthropicProvider{BaseURL: srv.URL, APIKey: "k", Model: "m", MaxTokens: 128, HTTP: srv.Client()}
	got := collectToolCallDeltas(t, p)
	if len(got) != 1 {
		t.Fatalf("tool call deltas = %d, want 1", len(got))
	}
	if got[0].ID != "t1" || got[0].Name != "read" || got[0].Input != `{"path":"a"}` {
		t.Fatalf("tool call = %+v", got[0])
	}
}

// TestOpenAIEmitsCompletedToolCalls：下一个 index 出现时前一个调用完整；
// finish_reason 时最后一个完整。两者都通过 delta 通道提前通知。
func TestOpenAIEmitsCompletedToolCalls(t *testing.T) {
	srv := sseProviderServer(t, ""+
		"data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"id\":\"t1\",\"function\":{\"name\":\"read\",\"arguments\":\"{\\\"path\\\":\\\"\"}}]}}]}\n\n"+
		"data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":0,\"function\":{\"arguments\":\"a\\\"}\"}}]}}]}\n\n"+
		"data: {\"choices\":[{\"delta\":{\"tool_calls\":[{\"index\":1,\"id\":\"t2\",\"function\":{\"name\":\"read\",\"arguments\":\"{}\"}}]}}]}\n\n"+
		"data: {\"choices\":[{\"delta\":{},\"finish_reason\":\"tool_calls\"}]}\n\n"+
		"data: [DONE]\n\n")
	defer srv.Close()
	p := &OpenAIProvider{BaseURL: srv.URL, APIKey: "k", Model: "m", HTTP: srv.Client()}
	got := collectToolCallDeltas(t, p)
	if len(got) != 2 {
		t.Fatalf("tool call deltas = %d, want 2: %+v", len(got), got)
	}
	if got[0].ID != "t1" || got[0].Input != `{"path":"a"}` {
		t.Fatalf("first call = %+v", got[0])
	}
	if got[1].ID != "t2" || got[1].Input != "{}" {
		t.Fatalf("second call = %+v", got[1])
	}
}

// TestResponsesEmitsCompletedToolCall：output_item.done 的 parameters 已完整。
func TestResponsesEmitsCompletedToolCall(t *testing.T) {
	srv := sseProviderServer(t, ""+
		"data: {\"type\":\"response.output_item.done\",\"item\":{\"type\":\"function_call\",\"id\":\"item_1\",\"call_id\":\"c1\",\"name\":\"read\",\"arguments\":\"{\\\"path\\\":\\\"a\\\"}\"}}\n\n"+
		"data: {\"type\":\"response.completed\",\"response\":{\"output\":[{\"type\":\"function_call\",\"call_id\":\"c1\",\"name\":\"read\",\"arguments\":\"{\\\"path\\\":\\\"a\\\"}\"}],\"usage\":{\"input_tokens\":1,\"output_tokens\":1}}}\n\n")
	defer srv.Close()
	p := &ResponsesProvider{BaseURL: srv.URL, APIKey: "k", Model: "m", HTTP: srv.Client()}
	got := collectToolCallDeltas(t, p)
	if len(got) != 1 {
		t.Fatalf("tool call deltas = %d, want 1 (dedup by ID): %+v", len(got), got)
	}
	if got[0].ID != "c1" || got[0].Input != `{"path":"a"}` {
		t.Fatalf("tool call = %+v", got[0])
	}
}