package handler

import (
	"encoding/json"
	"net/http"
	"net/http/httptest"
	"strings"
	"testing"

	"github.com/gin-gonic/gin"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
	"github.com/tidwall/gjson"
	"github.com/tidwall/sjson"
)

func TestOpenAIHandleStreamingAwareError_JSONEscaping(t *testing.T) {
	tests := []struct {
		name    string
		errType string
		message string
	}{
		{
			name:    "包含双引号的消息",
			errType: "server_error",
			message: `upstream returned "invalid" response`,
		},
		{
			name:    "包含反斜杠的消息",
			errType: "server_error",
			message: `path C:\Users\test\file.txt not found`,
		},
		{
			name:    "包含双引号和反斜杠的消息",
			errType: "upstream_error",
			message: `error parsing "key\value": unexpected token`,
		},
		{
			name:    "包含换行符的消息",
			errType: "server_error",
			message: "line1\nline2\ttab",
		},
		{
			name:    "普通消息",
			errType: "upstream_error",
			message: "Upstream service temporarily unavailable",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			gin.SetMode(gin.TestMode)
			w := httptest.NewRecorder()
			c, _ := gin.CreateTestContext(w)
			c.Request = httptest.NewRequest(http.MethodGet, "/", nil)

			h := &OpenAIGatewayHandler{}
			h.handleStreamingAwareError(c, http.StatusBadGateway, tt.errType, tt.message, true)

			body := w.Body.String()

			// 验证 SSE 格式：event: error\ndata: {JSON}\n\n
			assert.True(t, strings.HasPrefix(body, "event: error\n"), "应以 'event: error\\n' 开头")
			assert.True(t, strings.HasSuffix(body, "\n\n"), "应以 '\\n\\n' 结尾")

			// 提取 data 部分
			lines := strings.Split(strings.TrimSuffix(body, "\n\n"), "\n")
			require.Len(t, lines, 2, "应有 event 行和 data 行")
			dataLine := lines[1]
			require.True(t, strings.HasPrefix(dataLine, "data: "), "第二行应以 'data: ' 开头")
			jsonStr := strings.TrimPrefix(dataLine, "data: ")

			// 验证 JSON 合法性
			var parsed map[string]any
			err := json.Unmarshal([]byte(jsonStr), &parsed)
			require.NoError(t, err, "JSON 应能被成功解析，原始 JSON: %s", jsonStr)

			// 验证结构
			errorObj, ok := parsed["error"].(map[string]any)
			require.True(t, ok, "应包含 error 对象")
			assert.Equal(t, tt.errType, errorObj["type"])
			assert.Equal(t, tt.message, errorObj["message"])
		})
	}
}

func TestOpenAIHandleStreamingAwareError_NonStreaming(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)

	h := &OpenAIGatewayHandler{}
	h.handleStreamingAwareError(c, http.StatusBadGateway, "upstream_error", "test error", false)

	// 非流式应返回 JSON 响应
	assert.Equal(t, http.StatusBadGateway, w.Code)

	var parsed map[string]any
	err := json.Unmarshal(w.Body.Bytes(), &parsed)
	require.NoError(t, err)
	errorObj, ok := parsed["error"].(map[string]any)
	require.True(t, ok)
	assert.Equal(t, "upstream_error", errorObj["type"])
	assert.Equal(t, "test error", errorObj["message"])
}

func TestOpenAIEnsureForwardErrorResponse_WritesFallbackWhenNotWritten(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)

	h := &OpenAIGatewayHandler{}
	wrote := h.ensureForwardErrorResponse(c, false)

	require.True(t, wrote)
	require.Equal(t, http.StatusBadGateway, w.Code)

	var parsed map[string]any
	err := json.Unmarshal(w.Body.Bytes(), &parsed)
	require.NoError(t, err)
	errorObj, ok := parsed["error"].(map[string]any)
	require.True(t, ok)
	assert.Equal(t, "upstream_error", errorObj["type"])
	assert.Equal(t, "Upstream request failed", errorObj["message"])
}

func TestOpenAIEnsureForwardErrorResponse_DoesNotOverrideWrittenResponse(t *testing.T) {
	gin.SetMode(gin.TestMode)
	w := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(w)
	c.Request = httptest.NewRequest(http.MethodGet, "/", nil)
	c.String(http.StatusTeapot, "already written")

	h := &OpenAIGatewayHandler{}
	wrote := h.ensureForwardErrorResponse(c, false)

	require.False(t, wrote)
	require.Equal(t, http.StatusTeapot, w.Code)
	assert.Equal(t, "already written", w.Body.String())
}

// TestOpenAIHandler_GjsonExtraction 验证 gjson 从请求体中提取 model/stream 的正确性
func TestOpenAIHandler_GjsonExtraction(t *testing.T) {
	tests := []struct {
		name       string
		body       string
		wantModel  string
		wantStream bool
	}{
		{"正常提取", `{"model":"gpt-4","stream":true,"input":"hello"}`, "gpt-4", true},
		{"stream false", `{"model":"gpt-4","stream":false}`, "gpt-4", false},
		{"无 stream 字段", `{"model":"gpt-4"}`, "gpt-4", false},
		{"model 缺失", `{"stream":true}`, "", true},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			body := []byte(tt.body)
			modelResult := gjson.GetBytes(body, "model")
			model := ""
			if modelResult.Type == gjson.String {
				model = modelResult.String()
			}
			stream := gjson.GetBytes(body, "stream").Bool()
			require.Equal(t, tt.wantModel, model)
			require.Equal(t, tt.wantStream, stream)
		})
	}
}

// TestOpenAIHandler_GjsonValidation 验证修复后的 JSON 合法性和类型校验
func TestOpenAIHandler_GjsonValidation(t *testing.T) {
	// 非法 JSON 被 gjson.ValidBytes 拦截
	require.False(t, gjson.ValidBytes([]byte(`{invalid json`)))

	// model 为数字 → 类型不是 gjson.String，应被拒绝
	body := []byte(`{"model":123}`)
	modelResult := gjson.GetBytes(body, "model")
	require.True(t, modelResult.Exists())
	require.NotEqual(t, gjson.String, modelResult.Type)

	// model 为 null → 类型不是 gjson.String，应被拒绝
	body2 := []byte(`{"model":null}`)
	modelResult2 := gjson.GetBytes(body2, "model")
	require.True(t, modelResult2.Exists())
	require.NotEqual(t, gjson.String, modelResult2.Type)

	// stream 为 string → 类型既不是 True 也不是 False，应被拒绝
	body3 := []byte(`{"model":"gpt-4","stream":"true"}`)
	streamResult := gjson.GetBytes(body3, "stream")
	require.True(t, streamResult.Exists())
	require.NotEqual(t, gjson.True, streamResult.Type)
	require.NotEqual(t, gjson.False, streamResult.Type)

	// stream 为 int → 同上
	body4 := []byte(`{"model":"gpt-4","stream":1}`)
	streamResult2 := gjson.GetBytes(body4, "stream")
	require.True(t, streamResult2.Exists())
	require.NotEqual(t, gjson.True, streamResult2.Type)
	require.NotEqual(t, gjson.False, streamResult2.Type)
}

// TestOpenAIHandler_InstructionsInjection 验证 instructions 的 gjson/sjson 注入逻辑
func TestOpenAIHandler_InstructionsInjection(t *testing.T) {
	// 测试 1：无 instructions → 注入
	body := []byte(`{"model":"gpt-4"}`)
	existing := gjson.GetBytes(body, "instructions").String()
	require.Empty(t, existing)
	newBody, err := sjson.SetBytes(body, "instructions", "test instruction")
	require.NoError(t, err)
	require.Equal(t, "test instruction", gjson.GetBytes(newBody, "instructions").String())

	// 测试 2：已有 instructions → 不覆盖
	body2 := []byte(`{"model":"gpt-4","instructions":"existing"}`)
	existing2 := gjson.GetBytes(body2, "instructions").String()
	require.Equal(t, "existing", existing2)

	// 测试 3：空白 instructions → 注入
	body3 := []byte(`{"model":"gpt-4","instructions":"   "}`)
	existing3 := strings.TrimSpace(gjson.GetBytes(body3, "instructions").String())
	require.Empty(t, existing3)

	// 测试 4：sjson.SetBytes 返回错误时不应 panic
	// 正常 JSON 不会产生 sjson 错误，验证返回值被正确处理
	validBody := []byte(`{"model":"gpt-4"}`)
	result, setErr := sjson.SetBytes(validBody, "instructions", "hello")
	require.NoError(t, setErr)
	require.True(t, gjson.ValidBytes(result))
}
