package agent

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

// Real line shapes captured from sing-box v1.13.21 in the B3 spike,
// ANSI color sequences included (the core colorizes the level and
// the connection id even when its output is redirected to a file).
const (
	spikeAuthSS    = "+0000 2026-10-22 21:54:58 \x1b[36mINFO\x1b[0m [\x1b[38;5;51m1785752244\x1b[0m 0ms] inbound/shadowsocks[ss22]: [bob@example.com] inbound connection to 127.0.0.1:18080"
	spikeAuthMixed = "+0000 2026-10-22 21:54:58 \x1b[36mINFO\x1b[0m [\x1b[38;5;231m1630640343\x1b[0m 0ms] inbound/mixed[mixed-in]: [carol@example.com] inbound connection to 127.0.0.1:18080"
	spikeFromLine  = "+0000 2026-10-22 21:54:58 \x1b[36mINFO\x1b[0m [\x1b[38;5;51m1785752244\x1b[0m 0ms] inbound/shadowsocks[ss22]: inbound connection from 127.0.0.1:52076"
	spikeErrorLine = "+0000 2026-10-22 21:54:57 \x1b[31mERROR\x1b[0m [\x1b[38;5;158m398453065\x1b[0m 85ms] inbound/vless[vless-reality]: process connection from 127.0.0.1:42732: TLS handshake: REALITY: processed invalid connection"
	spikeStartLine = "+0000 2026-10-22 21:53:31 \x1b[36mINFO\x1b[0m inbound/mixed[mixed-in]: tcp server started at 127.0.0.1:24445"
)

func TestParseSingboxAuthLine(t *testing.T) {
	cases := []struct {
		line string
		want string
	}{
		{spikeAuthSS, "bob@example.com"},
		{spikeAuthMixed, "carol@example.com"},
		{spikeFromLine, ""},  // unauthenticated stage: never counts
		{spikeErrorLine, ""}, // failed handshake: never counts
		{spikeStartLine, ""},
		{"", ""},
	}
	for _, tc := range cases {
		if got := parseSingboxAuthLine(tc.line); got != tc.want {
			t.Errorf("parse(%q) = %q, want %q", tc.line, got, tc.want)
		}
	}
}

func TestSingboxOnlineTrackerPollAndGrace(t *testing.T) {
	path := filepath.Join(t.TempDir(), "singbox.log")
	now := time.Unix(1_700_000_000, 0)
	tr := newSingboxOnlineTracker(path)

	// No file yet: quiet no-op.
	tr.Poll(now)
	if got := tr.Online(now); len(got) != 0 {
		t.Fatalf("online = %v, want empty", got)
	}

	content := spikeFromLine + "\n" + spikeAuthSS + "\n" + spikeErrorLine + "\n"
	if err := os.WriteFile(path, []byte(content), 0o640); err != nil {
		t.Fatal(err)
	}
	tr.Poll(now)
	got := tr.Online(now)
	if len(got) != 1 || got[0] != "bob@example.com" {
		t.Fatalf("online = %v, want [bob@example.com]", got)
	}

	// Re-poll without new content: no double counting, same set.
	tr.Poll(now)
	if got := tr.Online(now); len(got) != 1 {
		t.Fatalf("online after idle poll = %v", got)
	}

	// Past the grace window the user ages out.
	if got := tr.Online(now.Add(singboxOnlineGrace + time.Second)); len(got) != 0 {
		t.Fatalf("online after grace = %v, want empty", got)
	}

	// A partial line (no trailing newline) is not consumed until it
	// completes. (bob is still within his grace window here; only
	// carol's appearance is being timed.)
	partial := spikeAuthMixed // no trailing \n yet
	if err := appendToFile(path, partial); err != nil {
		t.Fatal(err)
	}
	later := now.Add(time.Minute)
	tr.Poll(later)
	if got := tr.Online(later); strings.Contains(strings.Join(got, ","), "carol@example.com") {
		t.Fatalf("partial line must not count, online = %v", got)
	}
	if err := appendToFile(path, "\n"); err != nil {
		t.Fatal(err)
	}
	tr.Poll(later)
	got = tr.Online(later)
	if !strings.Contains(strings.Join(got, ","), "carol@example.com") {
		t.Fatalf("online after line completes = %v, want carol@example.com present", got)
	}
}

func TestSingboxOnlineTrackerTruncation(t *testing.T) {
	path := filepath.Join(t.TempDir(), "singbox.log")
	now := time.Unix(1_700_000_000, 0)
	tr := newSingboxOnlineTracker(path)
	if err := os.WriteFile(path, []byte(spikeAuthSS+"\n"+spikeAuthSS+"\n"), 0o640); err != nil {
		t.Fatal(err)
	}
	tr.Poll(now)

	// File shrinks below the cursor (rotation): rescan from the top.
	if err := os.WriteFile(path, []byte(spikeAuthMixed+"\n"), 0o640); err != nil {
		t.Fatal(err)
	}
	tr.Poll(now)
	got := tr.Online(now)
	joined := strings.Join(got, ",")
	if !strings.Contains(joined, "carol@example.com") || !strings.Contains(joined, "bob@example.com") {
		t.Fatalf("online after truncation = %v, want both users", got)
	}
}

func appendToFile(path, s string) error {
	f, err := os.OpenFile(path, os.O_WRONLY|os.O_APPEND, 0)
	if err != nil {
		return err
	}
	defer f.Close()
	_, err = f.WriteString(s)
	return err
}