package executor

import (
	"context"
	"runtime"
	"strings"
	"testing"
	"time"
)

// TestRun_BinaryEmpty covers the ErrBinaryEmpty path. The agent-facing
// behavior is "list the cluster, fix the binary field" — we just guard the
// error here.
func TestRun_BinaryEmpty(t *testing.T) {
	_, err := Run(context.Background(), SparkSubmitOpts{Binary: "", Args: []string{"--help"}})
	if err == nil || !strings.Contains(err.Error(), "empty") {
		t.Fatalf("want empty-binary error, got %v", err)
	}
}

// TestRun_FakeBinary uses /bin/echo as a stand-in for spark-submit. We
// verify slice-form arg passing (no shell) by including an arg that would
// be catastrophic if interpreted by a shell.
func TestRun_FakeBinary(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("uses unix binary")
	}
	ctx, cancel := context.WithTimeout(context.Background(), 5*time.Second)
	defer cancel()

	res, err := Run(ctx, SparkSubmitOpts{
		Binary: "/bin/echo",
		Args:   []string{"--master", "yarn; rm -rf /tmp/this-should-not-exist"},
		Timeout: 3 * time.Second,
	})
	if err != nil {
		t.Fatalf("Run: %v", err)
	}
	if res.ExitCode != 0 {
		t.Fatalf("ExitCode: got %d, want 0", res.ExitCode)
	}
	// The arg must be passed through verbatim, not interpreted by a shell.
	if !strings.Contains(res.StdoutTail, "yarn; rm -rf /tmp/this-should-not-exist") {
		t.Errorf("stdout missing literal arg, got: %q", res.StdoutTail)
	}
	if res.AppID != "" {
		t.Errorf("AppID should be empty for echo, got %q", res.AppID)
	}
}

// TestRun_NonZeroExit captures the exit code when the binary returns !=0.
func TestRun_NonZeroExit(t *testing.T) {
	if runtime.GOOS == "windows" {
		t.Skip("uses unix binary")
	}
	res, err := Run(context.Background(), SparkSubmitOpts{
		Binary: "/bin/sh",
		Args:   []string{"-c", "exit 7"},
		Timeout: 3 * time.Second,
	})
	if err == nil {
		t.Fatal("want non-nil error from non-zero exit")
	}
	if res.ExitCode != 7 {
		t.Errorf("ExitCode: got %d, want 7", res.ExitCode)
	}
}

// TestMatchAppID locks down the regex so a YARN output tweak doesn't
// silently break app_id extraction.
func TestMatchAppID(t *testing.T) {
	cases := []struct {
		in, want string
	}{
		{"Submitted application application_12345_0001", "application_12345_0001"},
		{"... some prefix application_999_42 ... tail", "application_999_42"},
		{"no app id here", ""},
		{"", ""},
		{"application_1_2 application_3_4", "application_1_2"}, // first match
	}
	for _, tc := range cases {
		got := matchAppID(tc.in)
		if got != tc.want {
			t.Errorf("matchAppID(%q) = %q, want %q", tc.in, got, tc.want)
		}
	}
}

// TestCapBuf ensures the tail-capping behavior: writing more than `cap`
// bytes keeps the most recent `cap` bytes.
func TestCapBuf(t *testing.T) {
	b := &capBuf{cap: 10}
	// Write 20 bytes total in two chunks.
	if _, err := b.Write([]byte("0123456789")); err != nil {
		t.Fatal(err)
	}
	if _, err := b.Write([]byte("ABCDEFGHIJ")); err != nil {
		t.Fatal(err)
	}
	// Tail should be the last 10 bytes: "ABCDEFGHIJ".
	if got := b.String(); got != "ABCDEFGHIJ" {
		t.Errorf("capBuf tail: got %q, want %q", got, "ABCDEFGHIJ")
	}
}