"""
Testes unitários do core do pdf-toolkit.
"""

import io
from pathlib import Path

import pytest
from PIL import Image

from core.validators import validate_pdf, is_pdf_stream, is_pdf_file
from core.engine import PDFEngine


# ── Helpers ─────────────────────────────────────────────────────────

def make_dummy_pdf() -> bytes:
    """Gera um PDF mínimo válido para testes."""
    return (
        b"%PDF-1.4\n"
        b"1 0 obj\n<< /Type /Catalog /Pages 2 0 R >>\nendobj\n"
        b"2 0 obj\n<< /Type /Pages /Kids [3 0 R] /Count 1 >>\nendobj\n"
        b"3 0 obj\n<< /Type /Page /Parent 2 0 R /MediaBox [0 0 612 792]\n"
        b"   /Resources << /Font << /F1 4 0 R >> >>\n"
        b"   /Contents 5 0 R\n>>\nendobj\n"
        b"4 0 obj\n<< /Type /Font /Subtype /Type1 /BaseFont /Helvetica >>\nendobj\n"
        b"5 0 obj\n<< /Length 44 >>\nstream\nBT /F1 12 Tf 100 700 Td (Hello) Tj ET\nendstream\nendobj\n"
        b"xref\n0 6\n0000000000 65535 f \n0000000009 00000 n \n0000000058 00000 n \n0000000115 00000 n \n0000000266 00000 n \n0000000340 00000 n \n"
        b"trailer\n<< /Size 6 /Root 1 0 R >>\nstartxref\n462\n%%EOF\n"
    )


engine = PDFEngine()


# ── Tests ───────────────────────────────────────────────────────────

class TestCompress:
    def test_compress_ebook(self):
        pdf = make_dummy_pdf()
        result = engine.compress(pdf, preset="ebook")
        assert isinstance(result, bytes)
        assert result[:4] == b"%PDF"
        # PDF mínimo não tem imagens, então tamanho fica similar
        # mas a estrutura deve ser válida
        info = engine.inspect(result)
        assert info["valid"] is True

    def test_compress_screen(self):
        pdf = make_dummy_pdf()
        result = engine.compress(pdf, preset="screen")
        assert isinstance(result, bytes)
        assert result[:4] == b"%PDF"

    def test_compress_invalid_preset(self):
        pdf = make_dummy_pdf()
        # Preset inválido usa o padrão (ebook) sem levantar erro
        # O comportamento é fallback seguro
        result = engine.compress(pdf, preset="invalid")
        assert isinstance(result, bytes)
        assert result[:4] == b"%PDF"


class TestInspect:
    def test_inspect_valid_pdf(self):
        pdf = make_dummy_pdf()
        info = engine.inspect(pdf, "test.pdf")
        assert info["valid"] is True
        assert info["pages"] == 1
        assert info["file_size_mb"] >= 0
        assert info["filename"] == "test.pdf"

    def test_inspect_invalid_data(self):
        info = engine.inspect(b"not a pdf", "fake.pdf")
        assert info["valid"] is False
        assert info["error"] != ""


class TestPdfa:
    def test_detect_pdfa_returns_dict(self):
        pdf = make_dummy_pdf()
        result = engine.detect_pdfa(pdf)
        assert isinstance(result, dict)
        assert "is_pdfa" in result
        assert "level" in result
        assert "method" in result

    def test_pdfa_to_regular_noop_on_common(self):
        pdf = make_dummy_pdf()
        result = engine.pdfa_to_regular(pdf)
        assert isinstance(result, bytes)
        assert result[:4] == b"%PDF"

    def test_compress_pdfa_preserves_structure(self):
        pdf = make_dummy_pdf()
        result = engine.compress_pdfa(pdf, quality=50)
        assert isinstance(result, bytes)
        assert result[:4] == b"%PDF"


class TestOperations:
    def test_merge_single(self):
        pdf = make_dummy_pdf()
        result = engine.merge([(pdf, "a.pdf")])
        assert result[:4] == b"%PDF"
        info = engine.inspect(result)
        assert info["pages"] == 1

    def test_merge_multiple(self):
        pdf = make_dummy_pdf()
        result = engine.merge([(pdf, "a.pdf"), (pdf, "b.pdf")])
        info = engine.inspect(result)
        assert info["pages"] == 2

    def test_split(self):
        pdf = make_dummy_pdf()
        results = engine.split(pdf, [(0, 0)], "teste")
        assert len(results) == 1
        nome, dados = results[0]
        assert "teste" in nome
        assert dados[:4] == b"%PDF"

    def test_extract_pages(self):
        pdf = make_dummy_pdf()
        result = engine.extract(pdf, [0])
        assert result[:4] == b"%PDF"
        info = engine.inspect(result)
        assert info["pages"] == 1

    def test_rotate(self):
        pdf = make_dummy_pdf()
        result = engine.rotate(pdf, [(0, 90)])
        assert result[:4] == b"%PDF"

    def test_extract_text(self):
        pdf = make_dummy_pdf()
        text = engine.text(pdf)
        assert "Hello" in text

    def test_extract_images_empty(self):
        pdf = make_dummy_pdf()
        imgs = engine.images(pdf)
        assert imgs == []