package telegram

import (
	"strings"
	"testing"
)

func TestParser_SingleTelegram(t *testing.T) {
	p := New(nil)
	telegrams := p.Append("ZCZC TEST MESSAGE NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram, got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC TEST MESSAGE NNNN") {
		t.Errorf("unexpected telegram content: %s", telegrams[0])
	}
}

func TestParser_MultipleTelegrams(t *testing.T) {
	p := New(nil)
	// Simulate two telegrams arriving in one burst
	telegrams := p.Append("ZCZC MSG1 NNNN ZCZC MSG2 NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram (non-greedy stops at first NNNN), got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC MSG1 NNNN") {
		t.Errorf("unexpected telegram content: %s", telegrams[0])
	}

	// Second telegram should be in buffer
	telegrams = p.Append("")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram from remaining buffer, got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC MSG2 NNNN") {
		t.Errorf("unexpected telegram content: %s", telegrams[0])
	}
}

func TestParser_NNNNInBufferStart(t *testing.T) {
	p := New(nil)
	// Simulate leftover NNNN from previous truncation
	telegrams := p.Append("NNNN ZCZC TEST NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram, got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC TEST NNNN") {
		t.Errorf("unexpected telegram content: %s", telegrams[0])
	}
}

func TestParser_NoTelegram(t *testing.T) {
	p := New(nil)
	telegrams := p.Append("some random noise without markers")
	if len(telegrams) != 0 {
		t.Fatalf("expected 0 telegrams, got %d", len(telegrams))
	}
}

func TestParser_PartialTelegram(t *testing.T) {
	p := New(nil)
	// First line: start of telegram
	telegrams := p.Append("ZCZC PARTIAL")
	if len(telegrams) != 0 {
		t.Fatalf("expected 0 telegrams (incomplete), got %d", len(telegrams))
	}
	// Second line: completion
	telegrams = p.Append("CONTINUES HERE NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram after completion, got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC PARTIAL") || !strings.Contains(telegrams[0], "CONTINUES HERE NNNN") {
		t.Errorf("unexpected telegram content: %s", telegrams[0])
	}
}

func TestParser_BufferOverflow(t *testing.T) {
	p := New(nil)
	// Fill buffer beyond maxBufferSize
	largeData := strings.Repeat("A", maxBufferSize+100)
	telegrams := p.Append(largeData)
	if len(telegrams) != 0 {
		t.Fatalf("expected 0 telegrams from noise, got %d", len(telegrams))
	}

	// Buffer should have been truncated; add a valid telegram
	telegrams = p.Append("ZCZC AFTER OVERFLOW NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram after overflow, got %d", len(telegrams))
	}
}

func TestParser_NonGreedyMatch(t *testing.T) {
	p := New(nil)
	// Two telegrams in same line - non-greedy should capture first only
	telegrams := p.Append("ZCZC FIRST NNNN ZCZC SECOND NNNN")
	if len(telegrams) != 1 {
		t.Fatalf("expected 1 telegram, got %d", len(telegrams))
	}
	if !strings.Contains(telegrams[0], "ZCZC FIRST NNNN") {
		t.Errorf("expected first telegram, got: %s", telegrams[0])
	}
	if strings.Contains(telegrams[0], "SECOND") {
		t.Errorf("non-greedy match should not include second telegram: %s", telegrams[0])
	}
}

func TestRemoveEmpty(t *testing.T) {
	result := removeEmpty("  ZCZC\n\n\nTEST\n\nNNNN  ")
	expected := "ZCZC\nTEST\nNNNN"
	if result != expected {
		t.Errorf("removeEmpty(%q) = %q, want %q", "  ZCZC\n\n\nTEST\n\nNNNN  ", result, expected)
	}
}