package main

import (
	"bytes"
	"mime/multipart"
	"net/http"
	"net/http/httptest"
	"strconv"
	"testing"

	"github.com/gin-gonic/gin"
)

// 分片数学: 片数 ceil 与每片期望大小
func TestChunkMath(t *testing.T) {
	if got := expectedChunks(5<<30 + 1); got != 6 {
		t.Fatalf("expectedChunks(5GB+1) = %d, want 6", got)
	}
	if got := expectedChunks(5 << 30); got != 5 {
		t.Fatalf("expectedChunks(5GB) = %d, want 5", got)
	}
	if got := expectedChunkSize(5<<30+1, 0); got != chunkSize {
		t.Fatalf("chunk0 size = %d, want 1GB", got)
	}
	if got := expectedChunkSize(5<<30+1, 5); got != 1 {
		t.Fatalf("last chunk size = %d, want 1", got)
	}
}

func chunkRequest(t *testing.T, uploadID string, idx, totalChunks int, filename string, totalSize int64, content []byte) *gin.Context {
	t.Helper()
	var buf bytes.Buffer
	w := multipart.NewWriter(&buf)
	fw, err := w.CreateFormFile("chunk", "chunk")
	if err != nil {
		t.Fatal(err)
	}
	fw.Write(content)
	w.Close()
	req := httptest.NewRequest("POST", "/upload-chunk", &buf)
	req.Header.Set("Content-Type", w.FormDataContentType())
	req.Header.Set("X-Upload-Id", uploadID)
	req.Header.Set("X-Chunk-Index", strconv.Itoa(idx))
	req.Header.Set("X-Total-Chunks", strconv.Itoa(totalChunks))
	req.Header.Set("X-Filename", filename)
	req.Header.Set("X-Total-Size", strconv.FormatInt(totalSize, 10))
	rec := httptest.NewRecorder()
	c, _ := gin.CreateTestContext(rec)
	c.Request = req
	return c
}

// 校验拒绝路径: 非法 id / 小于阈值 / 越界 / 片数不匹配 / 超配额, 均不落盘
func TestChunkHandlerRejections(t *testing.T) {
	*auditDir = "" // 测试不写审计日志
	oldQuota := *quota
	*quota = 1 << 30
	defer func() { *quota = oldQuota }()

	cases := []struct {
		name   string
		id     string
		idx    int
		total  int
		fn     string
		size   int64
		status int
	}{
		{"invalid upload id", "bad id!", 0, 6, "x.bin", chunkThreshold + 1, http.StatusBadRequest},
		{"below threshold", "uploadid123456", 0, 1, "x.bin", chunkThreshold, http.StatusBadRequest},
		{"index out of range", "uploadid123456", 6, 6, "x.bin", chunkThreshold + 1, http.StatusBadRequest},
		{"chunk count mismatch", "uploadid123456", 0, 2, "x.bin", chunkThreshold + 1, http.StatusBadRequest},
		{"quota exceeded", "uploadid123456", 0, 6, "x.bin", chunkThreshold + 1, http.StatusInsufficientStorage},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			c := chunkRequest(t, tc.id, tc.idx, tc.total, tc.fn, tc.size, []byte("data"))
			uploadChunkHandler(c)
			if c.Writer.Status() != tc.status {
				t.Fatalf("status = %d, want %d", c.Writer.Status(), tc.status)
			}
		})
	}
}