package main

import (
	"testing"

	"golang.org/x/sys/unix"
)

const sampleMountinfo = `22 1 252:0 / / rw,relatime shared:1 - ext4 /dev/mapper/vg-root rw
30 22 0:5 / /dev rw,nosuid shared:2 - devtmpfs udev rw
95 22 8:1 / /media/u/Data rw,relatime shared:50 - ext4 /dev/sda1 rw
96 22 8:1 /photos /mnt/photos\040bind rw,relatime shared:50 - ext4 /dev/sda1 rw
`

func TestParseMountinfo(t *testing.T) {
	es := parseMountinfo(sampleMountinfo)
	if len(es) != 4 {
		t.Fatalf("应解析出 4 条：%d", len(es))
	}
	if e := es[3]; e.Point != "/mnt/photos bind" || e.Root != "/photos" || e.Major != 8 || e.Minor != 1 || e.FSType != "ext4" || e.Source != "/dev/sda1" {
		t.Errorf("解析不正确：%+v", e)
	}
}

// fakeSystem 模拟挂载表、UUID 与设备号
type fakeSystem struct {
	info  string
	uuid  map[uint64]string
	devs  map[string]uint64 // 路径前缀 → 设备号（最长匹配）
	stats []string
}

func (f *fakeSystem) mountinfo() []mountEntry  { return parseMountinfo(f.info) }
func (f *fakeSystem) uuids() map[uint64]string { return f.uuid }
func (f *fakeSystem) devOf(p string) (uint64, error) {
	f.stats = append(f.stats, p)
	best, dev := "", uint64(0)
	for prefix, d := range f.devs {
		if within(p, prefix) && len(prefix) >= len(best) {
			best, dev = prefix, d
		}
	}
	if best == "" {
		return 0, unix.ENOENT
	}
	return dev, nil
}

func TestIdentifyAndLocate(t *testing.T) {
	sda := unix.Mkdev(8, 1)
	root := unix.Mkdev(252, 0)
	sys := &fakeSystem{
		info: sampleMountinfo,
		uuid: map[uint64]string{sda: "aaaa-1111", root: "rootuuid"},
		devs: map[string]uint64{"/": root, "/media/u/Data": sda, "/mnt/photos bind": sda},
	}
	// 系统盘：只记路径
	if id := identify(sys, "/home/u/docs"); !id.SystemDisk || id.UUID != "" {
		t.Errorf("系统盘上的目录：%+v", id)
	}
	// 外接盘：UUID + 设备内路径
	id := identify(sys, "/media/u/Data/资料/合同")
	if id.UUID != "aaaa-1111" || id.RelPath != "/资料/合同" || id.SystemDisk || id.MountPoint != "/media/u/Data" {
		t.Fatalf("外接盘上的目录：%+v", id)
	}
	src := localSource{Path: id.Path, UUID: id.UUID, RelPath: id.RelPath}
	if p, err := locate(sys, src); err != nil || p != "/media/u/Data/资料/合同" {
		t.Errorf("设备在原位置：%q %v", p, err)
	}
	// bind mount 的子目录
	if p, err := locate(sys, localSource{Path: "/mnt/photos bind/2024", UUID: "aaaa-1111", RelPath: "/photos/2024"}); err != nil || p != "/mnt/photos bind/2024" {
		t.Errorf("bind mount：%q %v", p, err)
	}

	// 设备拔出：UUID 不在了
	sys.uuid = map[uint64]string{root: "rootuuid"}
	if _, err := locate(sys, src); err == nil || err.State != "device_missing" {
		t.Errorf("设备拔出应为 device_missing：%v", err)
	}

	// 设备插回，但挂到了别的位置（sdb）
	sdb := unix.Mkdev(8, 17)
	sys.uuid = map[uint64]string{sdb: "aaaa-1111", root: "rootuuid"}
	sys.info = "22 1 252:0 / / rw - ext4 /dev/mapper/vg-root rw\n97 22 8:17 / /media/u/Data1 rw - ext4 /dev/sdb1 rw\n"
	if p, err := locate(sys, src); err != nil || p != "/media/u/Data1/资料/合同" {
		t.Errorf("挂载位置变化后应能找到：%q %v", p, err)
	}

	// 另一块盘挂在原路径上：UUID 不同，不会被误认
	sys.uuid = map[uint64]string{sdb: "bbbb-2222", root: "rootuuid"}
	sys.info = "22 1 252:0 / / rw - ext4 /dev/mapper/vg-root rw\n97 22 8:17 / /media/u/Data rw - ext4 /dev/sdb1 rw\n"
	if _, err := locate(sys, src); err == nil || err.State != "device_missing" {
		t.Errorf("换了一块盘应为 device_missing：%v", err)
	}

	// 设备已连接但没有挂载（例如自动挂载）：会访问原路径触发挂载
	sys.uuid = map[uint64]string{sda: "aaaa-1111", root: "rootuuid"}
	sys.info = "22 1 252:0 / / rw - ext4 /dev/mapper/vg-root rw\n"
	sys.stats = nil
	if _, err := locate(sys, src); err == nil || err.State != "device_missing" || !contains(err.Message, "没有挂载") {
		t.Errorf("已连接未挂载：%v", err)
	}
	if len(sys.stats) == 0 || sys.stats[0] != src.Path {
		t.Errorf("应访问原路径以触发自动挂载：%v", sys.stats)
	}

	// 只记路径的目录
	if p, err := locate(sys, localSource{Path: "/home/u/docs"}); err != nil || p != "/home/u/docs" {
		t.Errorf("系统盘：%q %v", p, err)
	}
}