package main

import (
	"os"
	"path/filepath"
	"strconv"
	"strings"
	"testing"
)

// aMachine gives findSession a /proc and an X socket directory of the test's own.
func aMachine(t *testing.T, env map[string]string) (proc, sockets string) {
	t.Helper()
	root := t.TempDir()
	proc, sockets = filepath.Join(root, "proc"), filepath.Join(root, "x11")
	for _, d := range []string{proc, sockets} {
		if err := os.MkdirAll(d, 0o755); err != nil {
			t.Fatal(err)
		}
	}
	wasProc, wasX, wasEnv := procRoot, x11Sockets, getenv
	procRoot, x11Sockets = proc, sockets
	getenv = func(k string) string { return env[k] }
	t.Cleanup(func() { procRoot, x11Sockets, getenv = wasProc, wasX, wasEnv })
	return proc, sockets
}

func aProcess(t *testing.T, proc string, pid int, comm string, env ...string) {
	t.Helper()
	dir := filepath.Join(proc, strconv.Itoa(pid))
	if err := os.MkdirAll(dir, 0o755); err != nil {
		t.Fatal(err)
	}
	_ = os.WriteFile(filepath.Join(dir, "comm"), []byte(comm+"\n"), 0o644)
	_ = os.WriteFile(filepath.Join(dir, "environ"), []byte(strings.Join(env, "\x00")+"\x00"), 0o644)
}

func aSocket(t *testing.T, dir, name string) {
	t.Helper()
	if err := os.WriteFile(filepath.Join(dir, name), nil, 0o644); err != nil {
		t.Fatal(err)
	}
}

func TestSessionTheWindowManagersDisplayAndCookieAreTheSessions(t *testing.T) {
	proc, sockets := aMachine(t, map[string]string{"MESH_OPERATOR_HOME": "/home/op"})
	aSocket(t, sockets, "X1")
	aProcess(t, proc, 3, "bash", "DISPLAY=:9", "XAUTHORITY=/stale")
	aProcess(t, proc, 4, "kitty", "DISPLAY=:1", "XAUTHORITY=/home/op/.Xauthority")
	aProcess(t, proc, 5, "i3", "DISPLAY=:1.0", "XAUTHORITY=/home/op/.Xauthority")
	aProcess(t, proc, 6, "sshd", "PATH=/bin")
	s, err := findSession()
	if err != nil {
		t.Fatal(err)
	}
	if s.Display != ":1.0" || s.XAuthority != "/home/op/.Xauthority" || !strings.Contains(s.FoundBy, "i3") {
		t.Fatalf("%+v: a display without a socket (:9) is skipped, and the window manager's is preferred", s)
	}
	if got := strings.Join(s.Env(), " "); got != "DISPLAY=:1.0 XAUTHORITY=/home/op/.Xauthority" {
		t.Fatalf("env %s", got)
	}
}

func TestSessionTheOnlySocketWithTheHomesCookieIsTheFallback(t *testing.T) {
	home := t.TempDir()
	_ = os.WriteFile(filepath.Join(home, ".Xauthority"), []byte("c"), 0o600)
	_, sockets := aMachine(t, map[string]string{"MESH_OPERATOR_HOME": home})
	aSocket(t, sockets, "X0")
	s, err := findSession()
	if err != nil || s.Display != ":0" || s.XAuthority != filepath.Join(home, ".Xauthority") || s.FoundBy != "socket" {
		t.Fatalf("%+v %v", s, err)
	}
}

func TestSessionNoSessionIsSaidNotGuessed(t *testing.T) {
	_, sockets := aMachine(t, map[string]string{})
	if _, err := findSession(); err == nil || !strings.Contains(err.Error(), "no graphical session") {
		t.Fatalf("none: %v", err)
	}
	aSocket(t, sockets, "X0")
	aSocket(t, sockets, "X1")
	if _, err := findSession(); err == nil || !strings.Contains(err.Error(), "2 X sockets") {
		t.Fatalf("two: %v", err)
	}
}

func TestSessionTheProcessesOwnDisplayComesFirst(t *testing.T) {
	_, sockets := aMachine(t, map[string]string{"DISPLAY": ":2", "XAUTHORITY": "/a"})
	aSocket(t, sockets, "X2")
	s, err := findSession()
	if err != nil || s.Display != ":2" || s.FoundBy != "environment" {
		t.Fatalf("%+v %v", s, err)
	}
}