package agent

import (
	"io"
	"os"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"github.com/x-grk/longpolling-remote-access/internal/proto"
)

// A terminal opened with a folder starts its shell there; a folder that is
// not there leaves it at home.
func TestStartPTYDir(t *testing.T) {
	dir, err := filepath.EvalSymlinks(t.TempDir())
	if err != nil {
		t.Fatal(err)
	}
	sub := filepath.Join(dir, "sub dir")
	if err := os.Mkdir(sub, 0o755); err != nil {
		t.Fatal(err)
	}
	if got := ptyPwd(t, sub); got != sub {
		t.Fatalf("pwd = %q, want %q", got, sub)
	}
	home, _ := filepath.EvalSymlinks(homeDir(""))
	if got := ptyPwd(t, filepath.Join(dir, "missing")); got != home {
		t.Fatalf("pwd for a missing folder = %q, want home %q", got, home)
	}
}

// ptyPwd opens a terminal at dir and returns where its shell is.
func ptyPwd(t *testing.T, dir string) string {
	t.Helper()
	t.Setenv("SHELL", "/bin/sh")
	p, err := StartPTY("", dir)
	if err != nil {
		t.Fatal(err)
	}
	defer p.Close()
	if _, err := p.Write([]byte("echo \"@@$(pwd -P)@@\"\n")); err != nil {
		t.Fatal(err)
	}
	var out strings.Builder
	buf := make([]byte, 4096)
	deadline := time.Now().Add(5 * time.Second)
	for time.Now().Before(deadline) {
		n, err := p.Read(buf)
		out.Write(buf[:n])
		s := out.String()
		// The echoed command line has "@@$(pwd" in it; the answer does not.
		for _, part := range strings.Split(s, "@@") {
			if strings.HasPrefix(part, "/") && strings.Contains(s, part+"@@") {
				return part
			}
		}
		if err != nil {
			break
		}
	}
	t.Fatalf("no pwd in %q", out.String())
	return ""
}

// A terminal tells the folder its shell is in now, after a cd.
func TestPTYCwd(t *testing.T) {
	dir, err := filepath.EvalSymlinks(t.TempDir())
	if err != nil {
		t.Fatal(err)
	}
	sub := filepath.Join(dir, "next one")
	if err := os.Mkdir(sub, 0o755); err != nil {
		t.Fatal(err)
	}
	t.Setenv("SHELL", "/bin/sh")
	p, err := StartPTY("", dir)
	if err != nil {
		t.Fatal(err)
	}
	defer p.Close()
	go func() { _, _ = io.Copy(io.Discard, p) }()
	if _, err := p.Write([]byte("cd 'next one'\n")); err != nil {
		t.Fatal(err)
	}
	var got string
	for i := 0; i < 50; i++ {
		if got, err = p.Cwd(); err == nil && got == sub {
			return
		}
		time.Sleep(100 * time.Millisecond)
	}
	t.Fatalf("Cwd = %q, %v; want %q", got, err, sub)
}

// The panel asks for a terminal's folder by its session.
func TestTermCwdTask(t *testing.T) {
	dir, _ := filepath.EvalSymlinks(t.TempDir())
	t.Setenv("SHELL", "/bin/sh")
	p, err := StartPTY("", dir)
	if err != nil {
		t.Fatal(err)
	}
	defer p.Close()
	termsBySID.Store("s1", p)
	defer termsBySID.Delete("s1")
	res, err := dispatchTask(proto.TaskEnvelope{Type: proto.TaskTermCwd, Args: []byte(`{"session":"s1"}`)})
	if err != nil || res.(map[string]string)["path"] != dir {
		t.Fatalf("term.cwd = %v, %v; want %q", res, err, dir)
	}
	if _, err := dispatchTask(proto.TaskEnvelope{Type: proto.TaskTermCwd, Args: []byte(`{"session":"nope"}`)}); err == nil {
		t.Fatal("an unknown session has a folder")
	}
}