package convert

import (
	"encoding/json"
	"testing"
)

// ---- ExtractUsageJSON: 非流式各协议 ----

func TestExtractUsageJSONChat(t *testing.T) {
	body := []byte(`{
		"id": "chatcmpl-1",
		"object": "chat.completion",
		"choices": [{"index": 0, "message": {"role": "assistant", "content": "hi"}}],
		"usage": {
			"prompt_tokens": 11,
			"completion_tokens": 7,
			"total_tokens": 18,
			"prompt_tokens_details": {"cached_tokens": 4}
		}
	}`)
	u, ok := ExtractUsageJSON(body, ProtoChat)
	if !ok {
		t.Fatalf("expected ok=true")
	}
	if u.InputTokens != 11 || u.OutputTokens != 7 {
		t.Fatalf("chat usage = %+v, want input=11 output=7", u)
	}
	if u.CacheReadTokens != 4 {
		t.Fatalf("chat cacheRead = %d, want 4", u.CacheReadTokens)
	}
}

func TestExtractUsageJSONMessages(t *testing.T) {
	body := []byte(`{
		"id": "msg_1",
		"type": "message",
		"role": "assistant",
		"content": [{"type": "text", "text": "hi"}],
		"usage": {
			"input_tokens": 15,
			"output_tokens": 8,
			"cache_read_input_tokens": 3,
			"cache_creation_input_tokens": 2
		}
	}`)
	u, ok := ExtractUsageJSON(body, ProtoMessages)
	if !ok {
		t.Fatalf("expected ok=true")
	}
	if u.InputTokens != 15 || u.OutputTokens != 8 || u.CacheReadTokens != 3 || u.CacheCreationTokens != 2 {
		t.Fatalf("messages usage = %+v", u)
	}
}

func TestExtractUsageJSONResponses(t *testing.T) {
	body := []byte(`{
		"id": "resp_1",
		"object": "response",
		"output": [],
		"usage": {
			"input_tokens": 13,
			"output_tokens": 9,
			"input_tokens_details": {"cached_tokens": 5}
		}
	}`)
	u, ok := ExtractUsageJSON(body, ProtoResponses)
	if !ok {
		t.Fatalf("expected ok=true")
	}
	if u.InputTokens != 13 || u.OutputTokens != 9 || u.CacheReadTokens != 5 {
		t.Fatalf("responses usage = %+v", u)
	}
}

func TestExtractUsageJSONInvalidAndMissing(t *testing.T) {
	if _, ok := ExtractUsageJSON([]byte("not json"), ProtoChat); ok {
		t.Fatalf("invalid json should not report ok")
	}
	if _, ok := ExtractUsageJSON([]byte(`{"id": "x"}`), ProtoChat); ok {
		t.Fatalf("missing usage should not report ok")
	}
	// 空对象 usage：全 0 视为无效
	if _, ok := ExtractUsageJSON([]byte(`{"usage": {}}`), ProtoChat); ok {
		t.Fatalf("empty usage should not report ok")
	}
}

// ---- StreamUsageAccum: 流式各协议 ----

func feedLines(t *testing.T, proto string, lines ...string) TokenUsage {
	t.Helper()
	acc := NewStreamUsageAccum()
	for _, ln := range lines {
		acc.Feed([]byte(ln), proto)
	}
	return acc.Usage()
}

func TestStreamUsageChatFinalChunk(t *testing.T) {
	// 前面的 chunk 不带 usage；最后一个 chunk 带完整 usage
	u := feedLines(t, ProtoChat,
		`{"id":"c1","object":"chat.completion.chunk","choices":[{"delta":{"content":"he"}}]}`,
		`{"id":"c1","object":"chat.completion.chunk","choices":[{"delta":{"content":"llo"}}]}`,
		`{"id":"c1","object":"chat.completion.chunk","choices":[],"usage":{"prompt_tokens":11,"completion_tokens":7,"prompt_tokens_details":{"cached_tokens":4}}}`,
	)
	if u.InputTokens != 11 || u.OutputTokens != 7 || u.CacheReadTokens != 4 {
		t.Fatalf("chat stream usage = %+v", u)
	}
}

func TestStreamUsageMessagesStartAndDelta(t *testing.T) {
	// message_start 带 input/cache，message_delta 带 output；逐字段取 max 合并
	u := feedLines(t, ProtoMessages,
		`{"type":"message_start","message":{"id":"msg_1","usage":{"input_tokens":15,"cache_read_input_tokens":3,"cache_creation_input_tokens":2}}}`,
		`{"type":"content_block_delta","delta":{"type":"text_delta","text":"hi"}}`,
		`{"type":"message_delta","delta":{"stop_reason":"end_turn"},"usage":{"output_tokens":8}}`,
	)
	if u.InputTokens != 15 || u.OutputTokens != 8 || u.CacheReadTokens != 3 || u.CacheCreationTokens != 2 {
		t.Fatalf("messages stream usage = %+v", u)
	}
}

func TestStreamUsageResponsesCompleted(t *testing.T) {
	// response.completed 事件的用量嵌在 response.usage 下
	u := feedLines(t, ProtoResponses,
		`{"type":"response.output_text.delta","delta":"hi"}`,
		`{"type":"response.completed","response":{"id":"resp_1","usage":{"input_tokens":13,"output_tokens":9,"input_tokens_details":{"cached_tokens":5}}}}`,
	)
	if u.InputTokens != 13 || u.OutputTokens != 9 || u.CacheReadTokens != 5 {
		t.Fatalf("responses stream usage = %+v", u)
	}
}

func TestStreamUsageIgnoresNonDataPayloads(t *testing.T) {
	// [DONE]、垃圾行、空对象都不应产生用量
	u := feedLines(t, ProtoChat, `[DONE]`, `{`, ``, `{"choices":[]}`)
	if u.has() {
		t.Fatalf("expected zero usage, got %+v", u)
	}
}

func TestStreamUsageFeedKeepsMaxAcrossEvents(t *testing.T) {
	// 同一字段在多个事件出现时取较大值（防乱序/重复）
	u := feedLines(t, ProtoMessages,
		`{"type":"message_start","message":{"usage":{"input_tokens":15}}}`,
		`{"type":"message_delta","usage":{"output_tokens":5}}`,
		`{"type":"message_delta","usage":{"output_tokens":8}}`,
	)
	if u.InputTokens != 15 || u.OutputTokens != 8 {
		t.Fatalf("max-merge usage = %+v", u)
	}
}

// ---- usage JSON 结构合法性（防止手写 struct 漂移）----

func TestUsageJSONRoundTrip(t *testing.T) {
	u := TokenUsage{InputTokens: 10, OutputTokens: 5, CacheReadTokens: 2, CacheCreationTokens: 1}
	b, err := json.Marshal(u)
	if err != nil {
		t.Fatalf("marshal: %v", err)
	}
	var back TokenUsage
	if err := json.Unmarshal(b, &back); err != nil {
		t.Fatalf("unmarshal: %v", err)
	}
	if back != u {
		t.Fatalf("round trip = %+v, want %+v", back, u)
	}
}