"""scan → (candidates) → verify → apply → revert on a synthetic epub2md output, without any model."""

from __future__ import annotations

from pathlib import Path

from conftest import needs_latex, needs_pandoc
from formula_img2latex import pipeline
from formula_img2latex.cli import main
from formula_img2latex.engines.vlm import parse_answer, prepare_image
from formula_img2latex.sources.base import scan_markdown
from formula_img2latex.store import Workspace


def _inject(ws: Workspace, by_asset: dict[str, str]) -> None:
    """Pretend an engine answered (tests must not need a model server).

    The mechanics are tested here, not the calibrated thresholds (test_core.test_decision_rules),
    so the contrast threshold is set low enough for the synthetic images.
    """
    ws.settings["thresholds"] = {"min_contrast": 0.1}
    ws.save_meta()
    for f in ws.all():
        for name, tex in by_asset.items():
            if f.asset.endswith(name):
                f.candidates.append({"engine": "test", "model": "fixture", "tex": tex, "is_formula": True})
                ws.save(f)


def test_scan_markdown_skips_code_and_detects_display(epub2md_dir: Path) -> None:
    refs = scan_markdown(epub2md_dir / "chapters" / "001-kapitel.md")
    assert [(r.target.rsplit("/", 1)[1], r.display) for r in refs] == [
        ("0001-inline.jpg", False), ("0002-display.jpg", True), ("0003-figure.png", True)]


def test_scan_classifies(epub2md_dir: Path) -> None:
    source, ws = pipeline.open_all(epub2md_dir, None, create=True)
    pipeline.scan(source, ws, quiet=True)
    labels = {f.asset.rsplit("/", 1)[1]: (f.classify["label"], f.known_formula) for f in ws.all()}
    assert labels["0001-inline.jpg"] == ("formula", False)
    assert labels["0002-display.jpg"] == ("formula", True)       # epub2md warning
    assert labels["0003-figure.png"][0] == "figure"
    assert ws.root == epub2md_dir.parent / "buch.formulas"


@needs_latex
@needs_pandoc
def test_verify_apply_revert_roundtrip(epub2md_dir: Path) -> None:
    source, ws = pipeline.open_all(epub2md_dir, None, create=True)
    pipeline.scan(source, ws, quiet=True)
    _inject(ws, {"0001-inline.jpg": r"L = \{ - \sqrt{2} , \sqrt{2} \}",          # comma: wrong, repaired to ;
                 "0002-display.jpg": r"x_{2,k}=\arcsin\left(-\frac{3}{5}\right)+2k\pi"})
    counts = pipeline.verify_all(source, ws, preset="cm", workers=2, quiet=True)
    st = {f.asset.rsplit("/", 1)[1]: f for f in ws.all()}
    inline = st["0001-inline.jpg"]
    assert inline.verification["best"]["tex"].replace(" ", "") == r"L=\{-\sqrt{2};\sqrt{2}\}"
    assert inline.status == "auto_accepted", inline.reason
    assert sum(counts.values()) == 2
    md = epub2md_dir / "chapters" / "001-kapitel.md"
    before = md.read_text(encoding="utf-8")

    pipeline.apply(source, ws, quiet=True)
    after = md.read_text(encoding="utf-8")
    assert "lautet $L = \\{ - \\sqrt{2} ; \\sqrt{2} \\}$." in after or "lautet $L=\\{-\\sqrt{2};\\sqrt{2}\\}$." in after
    assert "```\n![kein](../media/images/0001-inline.jpg)\n```" in after      # code block untouched
    assert "0003-figure.png" in after
    pipeline.apply(source, ws, quiet=True)                                        # idempotent
    assert md.read_text(encoding="utf-8") == after

    pipeline.revert(source, ws, quiet=True)
    assert md.read_text(encoding="utf-8") == before


@needs_latex
def test_revert_refuses_hand_edited_files(epub2md_dir: Path) -> None:
    source, ws = pipeline.open_all(epub2md_dir, None, create=True)
    pipeline.scan(source, ws, quiet=True)
    _inject(ws, {"0001-inline.jpg": r"L=\{-\sqrt{2};\sqrt{2}\}"})
    pipeline.verify_all(source, ws, preset="cm", workers=1, quiet=True)
    pipeline.apply(source, ws, quiet=True)
    md = epub2md_dir / "chapters" / "001-kapitel.md"
    md.write_text(md.read_text(encoding="utf-8") + "\nHandnotiz\n", encoding="utf-8")
    assert pipeline.revert(source, ws, quiet=True)["skipped"] == 1
    assert "Handnotiz" in md.read_text(encoding="utf-8")


def test_cli_errors(tmp_path: Path, capsys) -> None:
    assert main(["status", str(tmp_path / "fehlt")]) == 1
    (tmp_path / "leer").mkdir()
    assert main(["scan", str(tmp_path / "leer")]) == 2
    assert "weder eine epub2md-Ausgabe" in capsys.readouterr().err


def test_engine_answer_parsing() -> None:
    assert parse_answer('{"is_formula": true, "latex": "x^2"}') == ("x^2", True)
    assert parse_answer('```json\n{"is_formula": true, "latex": "\\frac{a}{b}"}\n```') == ("\\frac{a}{b}", True)
    assert parse_answer('{"is_formula": true, "latex": "\\sqrt{2}"}') == ("\\sqrt{2}", True)   # unescaped backslash
    assert parse_answer('{"is_formula": false, "latex": ""}') == (None, False)
    assert parse_answer("x_1 + x_2") == ("x_1 + x_2", None)


def test_prepare_image_enlarges_small_formulas(epub2md_dir: Path) -> None:
    import io

    from PIL import Image
    data = (epub2md_dir / "media" / "images" / "0001-inline.jpg").read_bytes()
    with Image.open(io.BytesIO(prepare_image(data, "x.jpg"))) as im:
        assert im.height >= 96 and im.mode == "L"