package middleware

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

	"github.com/gin-gonic/gin"
	"github.com/stretchr/testify/assert"
)

func TestTraceID(t *testing.T) {
	gin.SetMode(gin.TestMode)

	router := gin.New()
	router.Use(TraceID())
	router.GET("/test", func(c *gin.Context) {
		// 返回 trace ID 供验证
		traceID := GetTraceID(c)
		c.String(200, traceID)
	})

	tests := []struct {
		name               string
		incomingTraceID    string
		expectNewGenerated bool
	}{
		{
			name:               "generate new trace ID",
			incomingTraceID:    "",
			expectNewGenerated: true,
		},
		{
			name:               "reuse incoming trace ID",
			incomingTraceID:    "abc123xyz",
			expectNewGenerated: false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			w := httptest.NewRecorder()
			req, _ := http.NewRequest("GET", "/test", nil)
			if tt.incomingTraceID != "" {
				req.Header.Set(TraceIDHeader, tt.incomingTraceID)
			}
			router.ServeHTTP(w, req)

			// 检查响应头中的 trace ID
			responseTraceID := w.Header().Get(TraceIDHeader)
			assert.NotEmpty(t, responseTraceID)

			if tt.expectNewGenerated {
				// 新生成的 trace ID 应该包含日期格式
				assert.True(t, strings.Contains(responseTraceID, "-"))
				// 格式: YYYYMMDD-xxxxxxxx
				parts := strings.Split(responseTraceID, "-")
				assert.Equal(t, 2, len(parts))
				assert.Equal(t, 8, len(parts[0])) // YYYYMMDD
				assert.Equal(t, 16, len(parts[1])) // hex
			} else {
				assert.Equal(t, tt.incomingTraceID, responseTraceID)
			}

			// 响应体应该包含 trace ID
			body := w.Body.String()
			assert.Equal(t, responseTraceID, body)
		})
	}
}

func TestTraceID_SetInContext(t *testing.T) {
	gin.SetMode(gin.TestMode)

	var capturedTraceID string
	router := gin.New()
	router.Use(TraceID())
	router.GET("/test", func(c *gin.Context) {
		capturedTraceID = GetTraceID(c)
		c.String(200, "OK")
	})

	w := httptest.NewRecorder()
	req, _ := http.NewRequest("GET", "/test", nil)
	req.Header.Set(TraceIDHeader, "custom-trace-123")
	router.ServeHTTP(w, req)

	assert.Equal(t, "custom-trace-123", capturedTraceID)
}

func TestGetTraceID(t *testing.T) {
	gin.SetMode(gin.TestMode)

	tests := []struct {
		name         string
		setupContext func(*gin.Context)
		expected     string
	}{
		{
			name: "trace ID exists",
			setupContext: func(c *gin.Context) {
				c.Set(TraceIDKey, "existing-trace")
			},
			expected: "existing-trace",
		},
		{
			name:         "trace ID not exists",
			setupContext: func(c *gin.Context) {},
			expected:     "",
		},
		{
			name: "trace ID is not string",
			setupContext: func(c *gin.Context) {
				c.Set(TraceIDKey, 12345)
			},
			expected: "",
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			c, _ := gin.CreateTestContext(httptest.NewRecorder())
			tt.setupContext(c)

			result := GetTraceID(c)
			assert.Equal(t, tt.expected, result)
		})
	}
}

func TestGenerateTraceID(t *testing.T) {
	// 生成多个 trace ID，验证格式
	traceIDs := make(map[string]bool)
	for i := 0; i < 100; i++ {
		id := generateTraceID()
		traceIDs[id] = true

		// 验证格式
		parts := strings.Split(id, "-")
		assert.Equal(t, 2, len(parts), "trace ID should have 2 parts separated by -")
		assert.Equal(t, 8, len(parts[0]), "date part should be 8 characters (YYYYMMDD)")
		assert.Equal(t, 16, len(parts[1]), "random part should be 16 hex characters")
	}

	// 验证唯一性（100个应该都不同）
	assert.Equal(t, 100, len(traceIDs), "generated trace IDs should be unique")
}
