package exec

import (
	"context"
	"errors"
	"io"
	"log/slog"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"testing"
	"time"

	"git.yeij.top/AskaEth/Cyrene_v2/internal/config"
)

// discardLogger returns a logger that writes nowhere, keeping test output clean.
func discardLogger() *slog.Logger {
	return slog.New(slog.NewTextHandler(io.Discard, nil))
}

// requireBin skips the test when name is not on PATH.
func requireBin(t *testing.T, name string) {
	t.Helper()
	if _, err := exec.LookPath(name); err != nil {
		t.Skipf("%s not available: %v", name, err)
	}
}

// enabledCfg builds an enabled sandbox config with a single allowlisted command
// and optional allowed roots.
func enabledCfg(command string, roots ...string) config.ExecSandbox {
	return config.ExecSandbox{
		Enabled:      true,
		CommandList:  []string{command},
		AllowedRoots: roots,
	}
}

func newEnabledExecutor(t *testing.T, cfg config.ExecSandbox) *TerminalExecutor {
	t.Helper()
	ex, err := New(cfg, discardLogger())
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	return ex
}

func TestTerminal_DefaultDisabled_Refuses(t *testing.T) {
	t.Parallel()
	ex, err := New(config.ExecSandbox{Enabled: false}, discardLogger())
	if err != nil {
		t.Fatalf("New: %v", err)
	}
	_, err = ex.Execute(context.Background(), ExecRequest{Command: []string{"echo", "hi"}})
	if !errors.Is(err, ErrExecutionDisabled) {
		t.Fatalf("err = %v, want ErrExecutionDisabled", err)
	}
}

func TestTerminal_NewNilLogger(t *testing.T) {
	t.Parallel()
	if _, err := New(config.ExecSandbox{}, nil); !errors.Is(err, ErrNilLogger) {
		t.Fatalf("err = %v, want ErrNilLogger", err)
	}
}

func TestTerminal_NewEnabledNeedsRoot(t *testing.T) {
	t.Parallel()
	_, err := New(enabledCfg("echo"), discardLogger())
	if !errors.Is(err, ErrNoAllowedRoot) {
		t.Fatalf("err = %v, want ErrNoAllowedRoot", err)
	}
}

func TestTerminal_Allowlist_Allowed(t *testing.T) {
	t.Parallel()
	requireBin(t, "echo")
	ex := newEnabledExecutor(t, enabledCfg("echo", t.TempDir()))

	res, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"echo", "hello"}})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	if res.ExitCode != 0 {
		t.Errorf("ExitCode = %d, want 0", res.ExitCode)
	}
	if !strings.Contains(res.Stdout, "hello") {
		t.Errorf("Stdout = %q, want contain hello", res.Stdout)
	}
	if res.Truncated {
		t.Errorf("Truncated = true, want false")
	}
	if res.PID <= 0 {
		t.Errorf("PID = %d, want > 0", res.PID)
	}
	if res.StartedAt.IsZero() || res.EndedAt.IsZero() {
		t.Errorf("timestamps must be set")
	}
}

func TestTerminal_Allowlist_Denied(t *testing.T) {
	t.Parallel()
	requireBin(t, "echo")
	// pwd is allowlisted; echo is not.
	ex := newEnabledExecutor(t, enabledCfg("pwd", t.TempDir()))
	_, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"echo", "hi"}})
	if !errors.Is(err, ErrCommandNotAllowed) {
		t.Fatalf("err = %v, want ErrCommandNotAllowed", err)
	}
}

func TestTerminal_Injection_Rejected(t *testing.T) {
	t.Parallel()
	requireBin(t, "echo")
	ex := newEnabledExecutor(t, enabledCfg("echo", t.TempDir()))

	cases := []struct {
		name string
		arg  string
	}{
		{"semicolon", "a;b"},
		{"pipe", "a|b"},
		{"ampersand", "a&b"},
		{"subshell", "$(rm -rf /)"},
		{"backtick", "`id`"},
		{"redirect-out", ">out"},
		{"redirect-in", "<in"},
		{"newline", "a\nb"},
		{"traversal", "../etc"},
	}
	for _, c := range cases {
		c := c
		t.Run(c.name, func(t *testing.T) {
			t.Parallel()
			_, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"echo", c.arg}})
			if !errors.Is(err, ErrCommandInjection) {
				t.Errorf("arg %q: err = %v, want ErrCommandInjection", c.arg, err)
			}
		})
	}
}

func TestTerminal_WorkDir_DefaultToRoot(t *testing.T) {
	t.Parallel()
	requireBin(t, "pwd")
	root := t.TempDir()
	ex := newEnabledExecutor(t, enabledCfg("pwd", root))

	res, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"pwd"}})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	realRoot := root
	if r, err := filepath.EvalSymlinks(root); err == nil {
		realRoot = r
	}
	if !strings.Contains(res.Stdout, realRoot) {
		t.Errorf("Stdout = %q, want contain %q", res.Stdout, realRoot)
	}
}

func TestTerminal_WorkDir_OutsideRejected(t *testing.T) {
	t.Parallel()
	requireBin(t, "echo")
	ex := newEnabledExecutor(t, enabledCfg("echo", t.TempDir()))
	_, err := ex.Execute(context.Background(), ExecRequest{
		Command: []string{"echo", "hi"},
		WorkDir: os.TempDir(),
	})
	if !errors.Is(err, ErrWorkDirOutsideRoot) {
		t.Fatalf("err = %v, want ErrWorkDirOutsideRoot", err)
	}
}

func TestTerminal_Timeout_Killed(t *testing.T) {
	t.Parallel()
	requireBin(t, "sleep")
	ex := newEnabledExecutor(t, enabledCfg("sleep", t.TempDir()))

	start := time.Now()
	_, err := ex.Execute(context.Background(), ExecRequest{
		Command: []string{"sleep", "5"},
		Timeout: 200 * time.Millisecond,
	})
	if !errors.Is(err, ErrTimeout) {
		t.Fatalf("err = %v, want ErrTimeout", err)
	}
	if elapsed := time.Since(start); elapsed > 3*time.Second {
		t.Errorf("timeout took %v, want ~200ms (process not killed)", elapsed)
	}
}

func TestTerminal_Output_Truncated(t *testing.T) {
	t.Parallel()
	requireBin(t, "head")
	ex := newEnabledExecutor(t, enabledCfg("head", t.TempDir()))

	res, err := ex.Execute(context.Background(), ExecRequest{
		Command:        []string{"head", "-c", "2000000", "/dev/zero"},
		MaxOutputBytes: 100,
	})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	if !res.Truncated {
		t.Errorf("Truncated = false, want true")
	}
	if len(res.Stdout) != 100 {
		t.Errorf("len(Stdout) = %d, want 100", len(res.Stdout))
	}
}

func TestTerminal_NonZeroExit_ReportedNotError(t *testing.T) {
	t.Parallel()
	requireBin(t, "false")
	ex := newEnabledExecutor(t, enabledCfg("false", t.TempDir()))

	res, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"false"}})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	if res.ExitCode != 1 {
		t.Errorf("ExitCode = %d, want 1", res.ExitCode)
	}
}

func TestTerminal_Stdin_Passthrough(t *testing.T) {
	t.Parallel()
	requireBin(t, "cat")
	ex := newEnabledExecutor(t, enabledCfg("cat", t.TempDir()))

	res, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"cat"}, Stdin: []byte("ping")})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	if res.Stdout != "ping" {
		t.Errorf("Stdout = %q, want ping", res.Stdout)
	}
}

func TestTerminal_Env_Whitelist(t *testing.T) {
	t.Parallel()
	requireBin(t, "env")
	root := t.TempDir()

	// No allowlist: any injected variable is refused before launching.
	noEnv := newEnabledExecutor(t, enabledCfg("env", root))
	_, err := noEnv.Execute(context.Background(), ExecRequest{Command: []string{"env"}, Env: map[string]string{"FOO": "bar"}})
	if !errors.Is(err, ErrEnvNotAllowed) {
		t.Fatalf("no-allowlist err = %v, want ErrEnvNotAllowed", err)
	}

	// Allowlisted variable is applied.
	cfg := enabledCfg("env", root)
	cfg.AllowedEnv = []string{"FOO"}
	ex := newEnabledExecutor(t, cfg)
	res, err := ex.Execute(context.Background(), ExecRequest{Command: []string{"env"}, Env: map[string]string{"FOO": "bar"}})
	if err != nil {
		t.Fatalf("Execute: %v", err)
	}
	if !strings.Contains(res.Stdout, "FOO=bar") {
		t.Errorf("Stdout = %q, want contain FOO=bar", res.Stdout)
	}
}

func TestTerminal_EmptyCommand(t *testing.T) {
	t.Parallel()
	ex := newEnabledExecutor(t, enabledCfg("echo", t.TempDir()))
	_, err := ex.Execute(context.Background(), ExecRequest{})
	if !errors.Is(err, ErrEmptyCommand) {
		t.Fatalf("err = %v, want ErrEmptyCommand", err)
	}
}