from __future__ import annotations

from pathlib import Path

from pdf2md.ir import WarningCode, WarningSeverity
from pdf2md.quality import (
    MathCheckerUnavailable,
    MathCheckResult,
    check_asset_links,
    check_math_renderability,
    extract_math_expressions,
    merge_quality_results,
)


def test_missing_asset_link_is_counted(tmp_path: Path) -> None:
    asset_root = tmp_path / "assets"
    asset_root.mkdir()

    result = check_asset_links("![missing](assets/missing.png)", markdown_dir=tmp_path, asset_root=asset_root)

    assert result.missing_asset_link_count == 1
    assert result.invalid_asset_link_count == 0
    assert [warning.code for warning in result.warnings] == [WarningCode.ASSET_LINK_MISSING]


def test_existing_asset_link_passes_without_warning(tmp_path: Path) -> None:
    asset_root = tmp_path / "assets"
    asset_root.mkdir()
    (asset_root / "fig.png").write_bytes(b"image")

    result = check_asset_links("![fig](assets/fig.png)", markdown_dir=tmp_path, asset_root=asset_root)

    assert result.failure_count == 0
    assert result.warnings == ()


def test_invalid_asset_links_are_counted_without_fetching(tmp_path: Path) -> None:
    markdown = "\n".join(
        [
            "![remote](https://example.test/fig.png)",
            "![escape](../outside.png)",
            r"![absolute](C:\tmp\fig.png)",
        ]
    )

    result = check_asset_links(markdown, markdown_dir=tmp_path, asset_root=tmp_path / "assets")

    assert result.invalid_asset_link_count == 3
    assert result.missing_asset_link_count == 0
    assert [warning.code for warning in result.warnings] == [WarningCode.ASSET_LINK_INVALID] * 3


def test_asset_links_inside_code_are_ignored(tmp_path: Path) -> None:
    markdown = "```md\n![missing](assets/missing.png)\n```\n`![missing](assets/inline.png)`"

    result = check_asset_links(markdown, markdown_dir=tmp_path, asset_root=tmp_path / "assets")

    assert result.failure_count == 0
    assert result.warnings == ()


def test_math_render_failures_are_aggregated_with_fake_checker() -> None:
    def checker(body: str) -> MathCheckResult:
        return MathCheckResult(ok="bad" not in body, message=f"{body} failed")

    result = check_math_renderability("$x_i^2$\n\n$$\nbad_math\n$$", checker)

    assert result.math_render_error_count == 1
    assert [warning.code for warning in result.warnings] == [WarningCode.MATH_RENDER_FAILED]
    assert "bad_math failed" in result.warnings[0].message


def test_math_extraction_records_display_mode_and_markdown_spans() -> None:
    markdown = "Inline $x_i^2$ before\n\n$$\n\\frac{1}{2}\n$$\n"

    expressions = extract_math_expressions(markdown)

    assert [(expression.index, expression.body, expression.display) for expression in expressions] == [
        (0, "x_i^2", False),
        (1, "\\frac{1}{2}", True),
    ]
    assert [markdown[start:end] for start, end in (expression.markdown_span for expression in expressions)] == [
        "$x_i^2$",
        "$$\n\\frac{1}{2}\n$$",
    ]


def test_math_extraction_ignores_code_and_currency_like_text() -> None:
    markdown = "```tex\n$x$\n```\n`$y$`\nPrice $12.00$ and real $z$."

    expressions = extract_math_expressions(markdown)

    assert [(expression.body, expression.display) for expression in expressions] == [("z", False)]


def test_batch_math_checker_receives_expression_records() -> None:
    class BatchChecker:
        def __init__(self) -> None:
            self.expressions = ()

        def check_expressions(self, expressions):
            self.expressions = expressions
            return tuple(MathCheckResult(ok=expression.display) for expression in expressions)

    checker = BatchChecker()
    result = check_math_renderability("$inline$\n\n$$\ndisplay\n$$", checker)

    assert [expression.body for expression in checker.expressions] == ["inline", "display"]
    assert result.math_render_error_count == 1
    assert "inline" in result.warnings[0].message


def test_math_checker_unavailable_is_nonfatal() -> None:
    def checker(_: str) -> bool:
        raise MathCheckerUnavailable("local renderer missing")

    result = check_math_renderability("$x$", checker)

    assert result.math_render_error_count == 0
    assert result.warnings[0].code == WarningCode.MATH_RENDER_FAILED
    assert result.warnings[0].severity == WarningSeverity.INFO


def test_missing_math_checker_is_explicit_and_nonfatal() -> None:
    result = check_math_renderability("$x$")

    assert result.math_render_error_count == 0
    assert result.warnings[0].code == WarningCode.MATH_RENDER_FAILED
    assert result.warnings[0].severity == WarningSeverity.INFO


def test_merge_quality_results_combines_counts_and_warning_order(tmp_path: Path) -> None:
    asset_result = check_asset_links("![missing](assets/missing.png)", markdown_dir=tmp_path)
    math_result = check_math_renderability("$x$", lambda _: False)

    result = merge_quality_results(asset_result, math_result)

    assert result.missing_asset_link_count == 1
    assert result.math_render_error_count == 1
    assert [warning.code for warning in result.warnings] == [
        WarningCode.ASSET_LINK_MISSING,
        WarningCode.MATH_RENDER_FAILED,
    ]