package proxy

import (
	"encoding/json"
	"io"
	"strings"
	"testing"
)

func TestSSEScannerSplitsLines(t *testing.T) {
	input := "event: message\ndata: {\"a\":1}\n\n" +
		"data: {\"b\":2}\r\n\r\n" +
		"data: [DONE]\n\n"
	s := newSSEScanner(strings.NewReader(input))
	var lines []string
	for {
		line, err := s.Next()
		if line != nil {
			lines = append(lines, string(line))
		}
		if err == io.EOF {
			break
		}
		if err != nil {
			t.Fatalf("Next: %v", err)
		}
	}
	want := []string{
		"event: message\n",
		"data: {\"a\":1}\n",
		"\n",
		"data: {\"b\":2}\r\n",
		"\r\n",
		"data: [DONE]\n",
		"\n",
	}
	if len(lines) != len(want) {
		t.Fatalf("line count = %d, want %d (lines: %q)", len(lines), len(want), lines)
	}
	for i := range want {
		if lines[i] != want[i] {
			t.Fatalf("line[%d] = %q, want %q", i, lines[i], want[i])
		}
	}
}

func TestScanUsageChatStream(t *testing.T) {
	chunk := `data: {"id":"x","choices":[],"usage":{"prompt_tokens":12,"completion_tokens":9,"total_tokens":21}}`
	raw := scanUsage([]byte(chunk + "\n"))
	if raw == nil {
		t.Fatal("expected usage extracted")
	}
	var us usageShape
	if err := json.Unmarshal(raw, &us); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if us.PromptTokens != 12 || us.CompletionTokens != 9 {
		t.Fatalf("usage mismatch: %+v", us)
	}
}

func TestScanUsageResponsesCompleted(t *testing.T) {
	line := `data: {"type":"response.completed","response":{"id":"r1","status":"completed","usage":{"input_tokens":15,"output_tokens":11}}}`
	raw := scanUsage([]byte(line + "\n"))
	if raw == nil {
		t.Fatal("expected usage extracted from response.completed")
	}
	var us usageShape
	_ = json.Unmarshal(raw, &us)
	if us.InputTokens != 15 || us.OutputTokens != 11 {
		t.Fatalf("usage mismatch: %+v", us)
	}
}

func TestScanUsageIgnoresNonUsage(t *testing.T) {
	if raw := scanUsage([]byte(`data: {"type":"response.output_text.delta","delta":"hi"}`)); raw != nil {
		t.Fatalf("expected nil for non-usage line, got %s", raw)
	}
	if raw := scanUsage([]byte(`data: [DONE]`)); raw != nil {
		t.Fatal("expected nil for [DONE]")
	}
}

func TestExtractUsageChatBody(t *testing.T) {
	body := `{"id":"x","choices":[{"message":{"role":"assistant","content":"hi"}}],"usage":{"prompt_tokens":1,"completion_tokens":2,"total_tokens":3}}`
	raw := extractUsage([]byte(body))
	if raw == nil {
		t.Fatal("expected usage")
	}
	if !strings.Contains(string(raw), `"prompt_tokens":1`) {
		t.Fatalf("unexpected usage: %s", raw)
	}
}

func TestExtractUsageResponsesNested(t *testing.T) {
	// responses 顶层只有 response 对象，usage 嵌套其中
	body := `{"id":"r1","object":"response","status":"completed","response":{"usage":{"input_tokens":7,"output_tokens":8}}}`
	raw := extractUsage([]byte(body))
	if raw == nil {
		t.Fatal("expected nested usage")
	}
	var us usageShape
	_ = json.Unmarshal(raw, &us)
	if us.InputTokens != 7 || us.OutputTokens != 8 {
		t.Fatalf("usage mismatch: %+v", us)
	}
}

func TestUsageSinkMergesFields(t *testing.T) {
	// message_start 给 input，message_delta 给 output，合并后两者都在
	s := &usageSink{}
	s.push(json.RawMessage(`{"input_tokens":14,"output_tokens":0}`))
	s.push(json.RawMessage(`{"output_tokens":10}`))
	got := s.Shape()
	if got.InputTokens != 14 || got.OutputTokens != 10 {
		t.Fatalf("merge mismatch: %+v", got)
	}
	// chat 末块同时携带两字段
	s2 := &usageSink{}
	s2.push(json.RawMessage(`{"prompt_tokens":12,"completion_tokens":9}`))
	g := s2.Shape()
	if g.PromptTokens != 12 || g.CompletionTokens != 9 {
		t.Fatalf("chat usage mismatch: %+v", g)
	}
}