"""Tests for codex.parsing.tex."""

from __future__ import annotations

import pytest

from codex.parsing.tex import (
    chunk_sections,
    chunk_text,
    extract_sections,
    flatten_inputs,
    latex_to_text,
)


class TestExtractSections:
    def test_two_sections_returned(self) -> None:
        latex = r"\section{Intro}" + "\nHello \\cite{foo} world\n"
        latex += r"\section{Method}" + "\nResult"
        sections = extract_sections(latex)
        assert len(sections) == 2

    def test_section_titles(self) -> None:
        latex = r"\section{Intro}" + "\nHello\n" + r"\section{Method}" + "\nResult"
        sections = extract_sections(latex)
        assert sections[0][0] == "Intro"
        assert sections[1][0] == "Method"

    def test_cite_removed_from_text(self) -> None:
        latex = r"\section{Intro}" + "\nHello \\cite{foo} world\n"
        latex += r"\section{Method}" + "\nResult"
        sections = extract_sections(latex)
        body = sections[0][1]
        assert r"\cite" not in body
        assert "foo" not in body

    def test_no_sections_returns_empty(self) -> None:
        assert extract_sections("No sections here at all.") == []

    def test_subsection_recognised(self) -> None:
        latex = r"\subsection{Background}" + "\nSome text."
        sections = extract_sections(latex)
        assert len(sections) == 1
        assert sections[0][0] == "Background"

    def test_comments_stripped(self) -> None:
        latex = r"\section{A}" + "\nHello % this is a comment\nWorld"
        sections = extract_sections(latex)
        assert "%" not in sections[0][1]
        assert "comment" not in sections[0][1]

    def test_math_stripped(self) -> None:
        latex = r"\section{A}" + "\nLet $x = 1$ and $$y = 2$$ be numbers."
        sections = extract_sections(latex)
        body = sections[0][1]
        assert "$" not in body


class TestChunkText:
    @pytest.fixture()
    def long_text(self) -> str:
        # Build a 600-word string with real sentences
        sentence = "The quick brown fox jumps over the lazy dog near the river. "
        words_per_sentence = len(sentence.split())
        repeats = (600 // words_per_sentence) + 1
        return (sentence * repeats).strip()

    def test_at_least_two_chunks(self, long_text: str) -> None:
        chunks = chunk_text(long_text, size=512, overlap=64)
        assert len(chunks) >= 2

    def test_each_chunk_within_size_bound(self, long_text: str) -> None:
        size, overlap = 512, 64
        chunks = chunk_text(long_text, size=size, overlap=overlap)
        for chunk in chunks:
            word_count = len(chunk.split())
            assert word_count <= size + overlap, (
                f"Chunk has {word_count} words, expected <= {size + overlap}"
            )

    def test_empty_text_returns_empty_list(self) -> None:
        assert chunk_text("") == []

    def test_short_text_returns_single_chunk(self) -> None:
        chunks = chunk_text("Hello world.", size=512, overlap=64)
        assert len(chunks) == 1

    def test_chunks_cover_all_content(self) -> None:
        # First chunk must start with first word, last chunk must end with last word
        text = " ".join(f"word{i}" for i in range(600))
        chunks = chunk_text(text, size=200, overlap=50)
        assert chunks[0].startswith("word0")
        assert chunks[-1].endswith("word599")


class TestLatexToText:
    def test_no_percent_in_output(self) -> None:
        latex = r"\section{A}" + "\nSome % comment\ntext."
        result = latex_to_text(latex)
        assert "%" not in result

    def test_no_cite_in_output(self) -> None:
        latex = r"\section{A}" + "\nHello \\cite{bar} world."
        result = latex_to_text(latex)
        assert r"\cite" not in result
        assert "bar" not in result

    def test_returns_string(self) -> None:
        latex = r"\section{A}" + "\nSimple text."
        result = latex_to_text(latex)
        assert isinstance(result, str)
        assert len(result) > 0

    def test_no_section_fallback(self) -> None:
        latex = r"Some \cite{foo} text with % comment"
        result = latex_to_text(latex)
        assert r"\cite" not in result
        assert "%" not in result


class TestFlattenInputs:
    def test_inlines_input_and_include(self) -> None:
        files = {
            "main.tex": r"Start \input{sec/intro} mid \include{proof} end",
            "sec/intro.tex": "INTRO BODY",
            "proof.tex": "PROOF BODY",
        }
        out = flatten_inputs(files["main.tex"], files)
        assert "INTRO BODY" in out
        assert "PROOF BODY" in out
        assert r"\input" not in out and r"\include" not in out

    def test_resolves_without_tex_suffix(self) -> None:
        # \input{intro} must resolve the archive member "intro.tex".
        files = {"main.tex": r"\input{intro}", "intro.tex": "BODY"}
        assert "BODY" in flatten_inputs(files["main.tex"], files)

    def test_recursive_includes(self) -> None:
        files = {"a.tex": r"X \input{b}", "b.tex": r"Y \input{c}", "c.tex": "Z"}
        out = flatten_inputs(files["a.tex"], files)
        assert "X" in out and "Y" in out and "Z" in out

    def test_unresolved_input_dropped(self) -> None:
        # A reference with no matching file is removed, not left as a directive.
        out = flatten_inputs(r"A \input{missing} B", {})
        assert r"\input" not in out
        assert "A" in out and "B" in out


class TestChunkSections:
    def test_pairs_carry_section_titles(self) -> None:
        latex = (
            r"\section{Introduction}" + "\nIntro body text here.\n"
            r"\section{Proof}" + "\nProof body text here.\n"
        )
        pairs = chunk_sections(latex)
        titles = [t for t, _ in pairs]
        assert "Introduction" in titles
        assert "Proof" in titles
        # No chunk spans a section boundary: each chunk belongs to one title.
        assert all(isinstance(c, str) and c for _, c in pairs)

    def test_fallback_titleless_when_no_sections(self) -> None:
        pairs = chunk_sections("Plain text with no section commands at all here.")
        assert pairs and all(title is None for title, _ in pairs)