"""Unit tests for the pure, fast layers: parsing, validation, status mapping.

No model inference here, so this file runs in seconds.
"""

from __future__ import annotations

import io

import pytest

from docxextract import parsing
from docxextract.schema import (ExtractRequest, FieldStatus, UnsupportedMediaError,
                                ValidationError)


# ---------------------------------------------------------------- media sniff
def test_sniff_pdf():
    assert parsing.sniff(b"%PDF-1.7\n...") == "pdf"


@pytest.mark.parametrize("data,expected", [
    (b"\x89PNG\r\n\x1a\n", "png"),
    (b"\xff\xd8\xff\xe0", "jpeg"),
    (b"GIF89a...", "gif"),
    (b"BM....", "bmp"),
    (b"not a document", "unknown"),
])
def test_sniff_images(data, expected):
    assert parsing.sniff(data) == expected


def test_rejects_unknown_type(settings):
    with pytest.raises(UnsupportedMediaError):
        parsing.parse(b"just some text", settings)


def test_rejects_empty(settings):
    with pytest.raises(Exception):
        parsing.parse(b"", settings)


# ---------------------------------------------------------------- normalisation
def test_boxes_are_clamped_to_1000(settings):
    """LayoutLM indexes learned position embeddings; out-of-range raises."""
    words, boxes = parsing._normalize(
        ["a", "b"], [[-50, -50, 5000, 5000], [0, 0, 100, 100]], 100, 100)
    assert all(0 <= v <= 1000 for b in boxes for v in b)


def test_boxes_ordered_lowercase_first():
    _words, boxes = parsing._normalize(["a"], [[300, 400, 100, 200]], 1000, 1000)
    x0, y0, x1, y1 = boxes[0]
    assert x0 <= x1 and y0 <= y1


def test_zero_size_page_does_not_divide_by_zero():
    words, boxes = parsing._normalize(["a"], [[10, 10, 20, 20]], 0, 0)
    assert len(words) == 1 and len(boxes) == 1


# ---------------------------------------------------------------- parsing
def test_parses_pdf_text_layer(corpus_dir, settings, ground_truth):
    from pathlib import Path
    data = Path(ground_truth[0]["path"]).read_bytes()
    doc = parsing.parse(data, settings)
    assert doc.word_count > 50
    assert doc.source_type.value == "pdf_text_layer"
    assert doc.page_count >= 1


def test_parse_cache_hits_on_repeat(corpus_dir, settings, ground_truth):
    from pathlib import Path
    data = Path(ground_truth[0]["path"]).read_bytes()
    first = parsing.parse(data, settings)
    before = parsing.cache_stats()["hits"]
    second = parsing.parse(data, settings)
    assert second.document_id == first.document_id
    assert parsing.cache_stats()["hits"] > before


def test_blank_pdf_reports_no_words(tmp_path, settings):
    from reportlab.lib.pagesizes import A4
    from reportlab.pdfgen import canvas

    pytest.importorskip("pytesseract")
    if not parsing.tesseract_available():
        pytest.skip("Tesseract binary not on PATH")

    path = tmp_path / "blank.pdf"
    c = canvas.Canvas(str(path), pagesize=A4)
    c.showPage()
    c.save()
    doc = parsing.parse(path.read_bytes(), settings)
    # Either genuinely empty, or OCR of a blank page yields nothing usable.
    assert doc.word_count < 5


def test_tesseract_probe_does_not_raise():
    """The availability probe must never raise, whatever the environment."""
    assert isinstance(parsing.tesseract_available(), bool)


# ---------------------------------------------------------------- validation
def test_extract_request_rejects_empty_keys():
    with pytest.raises(Exception):
        ExtractRequest(keys=["", "   "])


def test_extract_request_deduplicates_preserving_order():
    req = ExtractRequest(keys=["b", "a", "b", "c"])
    assert req.keys == ["b", "a", "c"]


def test_extract_request_rejects_overlong_key():
    with pytest.raises(Exception):
        ExtractRequest(keys=["x" * 500])


# ---------------------------------------------------------------- status mapping
def test_status_below_threshold_is_low_confidence(settings):
    from docxextract.engine import Span
    from docxextract.service import ExtractionService

    service = ExtractionService(settings)
    span = Span(key="k", answer="$10.00", confidence=0.2, page=1, start=0, end=0)
    field = service._status_for(span, threshold=0.5, page_has_words=True)
    assert field.status is FieldStatus.LOW_CONFIDENCE
    # The value is still returned so a human reviewer can judge it.
    assert field.value == "$10.00"


def test_status_empty_answer_is_not_found(settings):
    from docxextract.engine import Span
    from docxextract.service import ExtractionService

    service = ExtractionService(settings)
    span = Span(key="k", answer="", confidence=0.99, page=1, start=-1, end=-1)
    field = service._status_for(span, threshold=0.5, page_has_words=True)
    assert field.status is FieldStatus.NOT_FOUND
    assert field.value is None


def test_status_high_confidence_is_extracted(settings):
    from docxextract.engine import Span
    from docxextract.service import ExtractionService

    service = ExtractionService(settings)
    span = Span(key="k", answer="INV-1", confidence=0.95, page=1, start=0, end=0)
    field = service._status_for(span, threshold=0.5, page_has_words=True)
    assert field.status is FieldStatus.EXTRACTED
    assert field.is_usable


def test_service_rejects_no_keys(settings, sample_pdf):
    from docxextract.service import ExtractionService
    service = ExtractionService(settings)
    with pytest.raises(ValidationError):
        service.extract(sample_pdf, [])


def test_service_rejects_blank_document(settings, tmp_path):
    from reportlab.lib.pagesizes import A4
    from reportlab.pdfgen import canvas

    from docxextract.service import ExtractionService

    pytest.importorskip("pytesseract")
    if not parsing.tesseract_available():
        pytest.skip("Tesseract binary not on PATH")

    path = tmp_path / "empty.pdf"
    c = canvas.Canvas(str(path), pagesize=A4)
    c.showPage()
    c.save()
    service = ExtractionService(settings)
    with pytest.raises(ValidationError):
        service.extract(path.read_bytes(), ["Total"])