package engine

import (
	"errors"
	"os"
	"path/filepath"
	"testing"
)

func TestCheckCommandAnswersLikeExecvp(t *testing.T) {
	rootfs := t.TempDir()
	for dir, mode := range map[string]os.FileMode{"usr/bin": 0o755, "usr/local/bin": 0o755, "opt/bin": 0o755} {
		if err := os.MkdirAll(filepath.Join(rootfs, dir), mode); err != nil {
			t.Fatal(err)
		}
	}
	for file, mode := range map[string]os.FileMode{
		"usr/bin/busybox":      0o755,
		"usr/bin/dash":         0o755,
		"usr/bin/notes":        0o644,
		"usr/local/bin/tool":   0o644, // shadowed by an executable later in PATH
		"usr/bin/tool":         0o755,
		"usr/local/bin/broken": 0o644,
	} {
		if err := os.WriteFile(filepath.Join(rootfs, file), []byte("#!/bin/sh\n"), mode); err != nil {
			t.Fatal(err)
		}
	}
	// merged /usr with a relative link, and a busybox applet with an absolute one
	for link, target := range map[string]string{"bin": "usr/bin", "usr/bin/sh": "dash", "usr/bin/ash": "/bin/busybox"} {
		if err := os.Symlink(target, filepath.Join(rootfs, link)); err != nil {
			t.Fatal(err)
		}
	}
	work := []Mount{{Mode: MountBind, Source: t.TempDir(), Dest: "/work"}}
	tests := []struct {
		name     string
		command  string
		workdir  string
		env      []EnvVar
		mounts   []Mount
		wantCode int // 0: runnable or not known before the start
	}{
		{"a name found in PATH", "sh", "", nil, nil, 0},
		{"an absolute path through the merged-usr link", "/bin/sh", "", nil, nil, 0},
		{"an absolute symlink resolved in the rootfs, not on the host", "ash", "", nil, nil, 0},
		{"a name nowhere in PATH", "missing", "", nil, nil, ExitNotFound},
		{"a path that does not exist", "/bin/missing", "", nil, nil, ExitNotFound},
		{"a file without an execute bit", "notes", "", nil, nil, ExitNotExecutable},
		{"a directory", "/usr/bin", "", nil, nil, ExitNotExecutable},
		{"an executable later in PATH wins over a non-executable earlier", "tool", "", nil, nil, 0},
		{"a non-executable and nothing after it", "broken", "", nil, nil, ExitNotExecutable},
		{"a path under a mount is not checked", "/work/build.sh", "", nil, work, 0},
		{"a relative path from a mounted workdir is not checked", "./build.sh", "/work", nil, work, 0},
		{"a path in an implicit tmpfs is not checked", "/tmp/x", "", nil, nil, 0},
		{"the image's PATH replaces the default", "sh", "", []EnvVar{{Key: "PATH", Value: "/opt/bin"}}, nil, ExitNotFound},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			spec := RunSpec{RootFS: rootfs, Command: []string{tt.command}, Workdir: tt.workdir, Env: tt.env, Mounts: tt.mounts}
			err := CheckCommand(spec)
			var commandErr *CommandError
			switch {
			case tt.wantCode == 0 && err != nil:
				t.Errorf("got %v, want the command to pass", err)
			case tt.wantCode != 0 && (!errors.As(err, &commandErr) || commandErr.Code != tt.wantCode):
				t.Errorf("got %v, want exit code %d", err, tt.wantCode)
			}
		})
	}
}