package tools

import (
	"context"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"
)

// ---- S0：冻结基底与 CAS 回收 ----

func write(t *testing.T, path, content string) {
	t.Helper()
	if err := os.MkdirAll(filepath.Dir(path), 0o755); err != nil {
		t.Fatal(err)
	}
	if err := os.WriteFile(path, []byte(content), 0o644); err != nil {
		t.Fatal(err)
	}
}

func read(t *testing.T, path string) string {
	t.Helper()
	b, err := os.ReadFile(path)
	if err != nil {
		t.Fatal(err)
	}
	return string(b)
}

// 冻结：硬链接基底 + 基线清单；.agentx 不进基底。
func TestFreezeBaseManifest(t *testing.T) {
	dir := t.TempDir()
	write(t, filepath.Join(dir, "a.md"), "alpha")
	write(t, filepath.Join(dir, "sub", "b.txt"), "beta")
	write(t, filepath.Join(dir, ".agentx", "transcript.jsonl"), "{}")
	frozen := filepath.Join(dir+"-ws", "t1")
	manifest, err := freezeBase(dir, frozen)
	if err != nil {
		t.Fatal(err)
	}
	if len(manifest) != 2 {
		t.Fatalf("manifest = %v（.agentx 必须排除）", manifest)
	}
	if strings.TrimSpace(read(t, filepath.Join(frozen, "a.md"))) != "alpha" {
		t.Fatal("frozen copy content mismatch")
	}
	if _, err := os.Lstat(filepath.Join(frozen, ".agentx")); !os.IsNotExist(err) {
		t.Fatal(".agentx must not be frozen")
	}
	// 基底不可变验证：改 upper 前先确认冻结文件是硬链接（与源同 inode——
	// 原地写会穿透，这是文档化的边界；CAS 依赖哈希清单而非 inode）。
}

// 回收：新增/修改 CAS 写回；删除（whiteout 形态在集成测试覆盖，这里用
// 直接删 upper 对应目标的语义等价路径——applyUpper 只看 upper 内容）。
func TestApplyUpperAddModDel(t *testing.T) {
	dir := t.TempDir()
	write(t, filepath.Join(dir, "keep.txt"), "keep")
	write(t, filepath.Join(dir, "mod.txt"), "old")
	write(t, filepath.Join(dir, "gone.txt"), "gone")
	frozen := filepath.Join(dir+"-ws", "t1")
	manifest, err := freezeBase(dir, frozen)
	if err != nil {
		t.Fatal(err)
	}
	upper := filepath.Join(dir+"-ws", "t1", "upper")
	write(t, filepath.Join(upper, "new.txt"), "new content")
	write(t, filepath.Join(upper, "mod.txt"), "new value")
	// 删除：upper 里放 whiteout 等价物不可构造（需真实 overlayfs）；
	// applyUpper 的删除分支由集成测试覆盖。此处验证 add/mod。

	changes, err := applyUpper(upper, dir, manifest)
	if err != nil {
		t.Fatal(err)
	}
	if strings.TrimSpace(read(t, filepath.Join(dir, "new.txt"))) != "new content" {
		t.Fatal("add must land")
	}
	if strings.TrimSpace(read(t, filepath.Join(dir, "mod.txt"))) != "new value" {
		t.Fatal("mod must land (CAS ok)")
	}
	ops := map[string]Change{}
	for _, c := range changes {
		ops[c.Rel] = c
	}
	if ops["new.txt"].Op != "add" || !ops["new.txt"].Applied {
		t.Fatalf("new.txt change = %+v", ops["new.txt"])
	}
	if ops["mod.txt"].Op != "mod" || !ops["mod.txt"].Applied {
		t.Fatalf("mod.txt change = %+v", ops["mod.txt"])
	}
}

// 冲突：目标被外部改动（哈希 ≠ 基线）→ 双存 *.conflict-*，原文件不动。
func TestApplyUpperConflictDoubleStore(t *testing.T) {
	dir := t.TempDir()
	write(t, filepath.Join(dir, "doc.md"), "base")
	frozen := filepath.Join(dir+"-ws", "t1")
	manifest, err := freezeBase(dir, frozen)
	if err != nil {
		t.Fatal(err)
	}
	write(t, filepath.Join(dir, "doc.md"), "externally changed") // 会话侧被外部改
	upper := filepath.Join(dir+"-ws", "t1", "upper")
	write(t, filepath.Join(upper, "doc.md"), "sandbox wrote this")

	changes, err := applyUpper(upper, dir, manifest)
	if err != nil {
		t.Fatal(err)
	}
	if strings.TrimSpace(read(t, filepath.Join(dir, "doc.md"))) != "externally changed" {
		t.Fatal("conflict must not overwrite the externally changed file")
	}
	found := false
	for _, c := range changes {
		if c.Rel == "doc.md" && c.Conflict && !c.Applied {
			found = true
		}
	}
	if !found {
		t.Fatalf("changes = %+v", changes)
	}
	// 双存文件存在且内容是沙箱侧新内容。
	matches, _ := filepath.Glob(filepath.Join(dir, "doc.md.conflict-*"))
	if len(matches) == 0 || strings.TrimSpace(read(t, matches[0])) != "sandbox wrote this" {
		t.Fatalf("conflict copy missing: %v", matches)
	}
}

// 变更摘要：数量与冲突提示。
func TestWorkspaceChangeSummary(t *testing.T) {
	s := workspaceChangeSummary([]Change{
		{Rel: "a", Op: "add", Applied: true},
		{Rel: "b", Op: "mod", Applied: true},
		{Rel: "c", Op: "del", Applied: true},
		{Rel: "d", Op: "mod", Conflict: true},
	})
	for _, want := range []string{"新增 1", "修改 1", "删除 1", "冲突 1"} {
		if !strings.Contains(s, want) {
			t.Fatalf("summary %q missing %q", s, want)
		}
	}
	if workspaceChangeSummary(nil) != "" {
		t.Fatal("empty changes must yield empty summary")
	}
}

// ---- 集成（本机有 bwrap 时执行）：真实 overlay 三件套 + whiteout ----

func TestSandboxWorkspaceOverlayRoundtrip(t *testing.T) {
	if _, err := exec.LookPath("bwrap"); err != nil {
		t.Skip("bwrap not available")
	}
	oldOverlay := workspaceOverlay
	workspaceOverlay = true
	defer func() { workspaceOverlay = oldOverlay }()

	dir := t.TempDir()
	write(t, filepath.Join(dir, "原文件.txt"), "orig")
	write(t, filepath.Join(dir, "将删除.txt"), "delete me")
	spec := ExecSpec{
		Bin: "/bin/bash", Args: []string{"-c", `
set -e
echo 'sandbox new' > 新文件.txt
echo 'modified' > 原文件.txt
rm 将删除.txt
echo done
`},
		Dir: dir, Env: []string{"PATH=/usr/bin:/bin"},
	}
	out := &strings.Builder{}
	proc, err := sandboxBackend{}.Start(context.Background(), spec, out)
	if err != nil {
		t.Fatal(err)
	}
	if err := proc.Wait(); err != nil {
		t.Fatalf("wait: %v (output: %s)", err, out.String())
	}
	if strings.TrimSpace(read(t, filepath.Join(dir, "新文件.txt"))) != "sandbox new" {
		t.Fatal("new file must be applied")
	}
	if strings.TrimSpace(read(t, filepath.Join(dir, "原文件.txt"))) != "modified" {
		t.Fatal("modified file must be applied")
	}
	if _, err := os.Stat(filepath.Join(dir, "将删除.txt")); !os.IsNotExist(err) {
		t.Fatal("deleted file must be removed after apply")
	}
	// -ws 兄弟目录已清理。
	matches, _ := filepath.Glob(dir + "-ws/*")
	if len(matches) != 0 {
		t.Fatalf("workspace roots must be cleaned: %v", matches)
	}
	s := proc.(interface{ Summary() string }).Summary()
	if !strings.Contains(s, "新增 1") || !strings.Contains(s, "删除 1") {
		t.Fatalf("summary = %q", s)
	}
}

// 超时丢弃：超时杀灭后 upper 不落地（半写状态不进会话目录）。
func TestSandboxWorkspaceOverlayTimeoutDiscards(t *testing.T) {
	if _, err := exec.LookPath("bwrap"); err != nil {
		t.Skip("bwrap not available")
	}
	oldOverlay := workspaceOverlay
	workspaceOverlay = true
	defer func() { workspaceOverlay = oldOverlay }()

	dir := t.TempDir()
	spec := ExecSpec{
		Bin: "/bin/bash", Args: []string{"-c", "echo partial > 半写.txt; sleep 30"},
		Dir: dir, Env: []string{"PATH=/usr/bin:/bin"}, Timeout: 1e9,
	}
	ctx, cancel := context.WithTimeout(context.Background(), shortTimeout())
	defer cancel()
	out := &strings.Builder{}
	proc, err := sandboxBackend{}.Start(ctx, spec, out)
	if err != nil {
		t.Fatal(err)
	}
	_ = proc.Wait()
	if _, err := os.Stat(filepath.Join(dir, "半写.txt")); !os.IsNotExist(err) {
		t.Fatal("partial write must NOT land after timeout")
	}
	if !strings.Contains(proc.(interface{ Summary() string }).Summary(), "丢弃") {
		t.Fatal("summary must state discard")
	}
}

func shortTimeout() time.Duration { return 1500 * time.Millisecond }

// -ws 壳目录在空时移除（不随会话累积）。
func TestOverlayCleansShellDir(t *testing.T) {
	if _, err := exec.LookPath("bwrap"); err != nil {
		t.Skip("bwrap not available")
	}
	old := workspaceOverlay
	workspaceOverlay = true
	defer func() { workspaceOverlay = old }()
	dir := t.TempDir()
	spec := ExecSpec{Bin: "/bin/bash", Args: []string{"-c", "echo hi"}, Dir: dir, Env: []string{"PATH=/usr/bin:/bin"}}
	proc, err := sandboxBackend{}.Start(context.Background(), spec, &strings.Builder{})
	if err != nil {
		t.Fatal(err)
	}
	if err := proc.Wait(); err != nil {
		t.Fatal(err)
	}
	if _, serr := os.Stat(dir + "-ws"); !os.IsNotExist(serr) {
		t.Fatalf("-ws shell dir must be removed when empty: %v", serr)
	}
}