"""Tests for the shared render helpers in lib/wiki.py.

All pure string in, string out, except the pandoc contract test at the bottom,
which is the canary for a pandoc upgrade changing how relative links are written.
"""

import shutil
import subprocess
from pathlib import Path

import pytest

from lib.wiki import (
    assert_no_unresolved_md_links,
    expand_columns,
    extract_md_link_targets,
    markdown_to_wikitext,
    resolve_md_links,
    strip_first_h1,
)

# Paths need not exist on disk: resolution is non-strict, and only the missing
# vs. unpublished distinction consults the filesystem (covered with tmp_path).
SONGS = Path(__file__).resolve().parent / "_paths" / "songs"
HERE = SONGS / "pulse.md"
INDEX = {
    str((SONGS / "pulse.md").resolve()): "pulse under latent semantic envelopes",
    str((SONGS / "pulse_dev.md").resolve()): (
        "pulse under latent semantic envelopes - development notes"
    ),
    str((SONGS / "two words.md").resolve()): "Two words",
}


def resolve(wikitext, source=HERE):
    return resolve_md_links(wikitext, source, INDEX)


class TestStripFirstH1:
    def test_removes_heading_and_following_blank_line(self):
        assert strip_first_h1("# Title\n\nbody") == "body"

    def test_removes_only_the_first(self):
        assert strip_first_h1("# One\n\n# Two\n") == "# Two\n"

    def test_leaves_body_without_h1_alone(self):
        assert strip_first_h1("## Sub\n\nbody") == "## Sub\n\nbody"

    def test_finds_the_h1_even_when_a_deeper_heading_precedes_it(self):
        assert strip_first_h1("### Deep\n\n# Title\n") == "### Deep\n"


class TestExpandColumns:
    def test_splits_on_separator_and_wraps_each_in_poem(self):
        out = expand_columns('<pre class="columns">a\nb\n===\nc</pre>')
        assert out.count("<poem>") == 2
        assert "<poem>\na\nb\n</poem>" in out
        assert "<poem>\nc\n</poem>" in out
        assert out.startswith("<div style=")

    def test_three_columns_need_two_separators(self):
        out = expand_columns('<pre class="columns">a\n===\nb\n===\nc</pre>')
        assert out.count("<poem>") == 3

    def test_converts_markdown_emphasis(self):
        out = expand_columns('<pre class="columns">***a*** **b** *c*</pre>')
        assert "'''''a'''''" in out
        assert "'''b'''" in out
        assert "''c''" in out

    def test_unescapes_inline_html(self):
        out = expand_columns('<pre class="columns">&lt;b&gt;x&lt;/b&gt;</pre>')
        assert "<b>x</b>" in out

    def test_leaves_wikitext_without_a_columns_block_untouched(self):
        assert expand_columns("plain '''wikitext'''") == "plain '''wikitext'''"


class TestResolveMdLinks:
    def test_labelled_link_becomes_piped_wikilink(self):
        assert resolve("see [[pulse_dev.md|dev notes]] ok") == (
            "see [[pulse under latent semantic envelopes - development notes|dev notes]] ok"
        )

    def test_unlabelled_link_uses_the_page_title(self):
        assert resolve("[[pulse_dev.md]]") == (
            "[[pulse under latent semantic envelopes - development notes]]"
        )

    def test_label_identical_to_target_drops_the_pipe(self):
        assert resolve("[[pulse_dev.md|pulse_dev.md]]") == (
            "[[pulse under latent semantic envelopes - development notes]]"
        )

    def test_label_identical_to_the_page_title_drops_the_pipe(self):
        assert resolve("[[pulse_dev.md|pulse under latent semantic envelopes - development notes]]") == (
            "[[pulse under latent semantic envelopes - development notes]]"
        )

    def test_fragment_is_carried_onto_the_title(self):
        assert resolve("[[pulse_dev.md#Notes|x]]") == (
            "[[pulse under latent semantic envelopes - development notes#Notes|x]]"
        )

    def test_percent_encoding_in_target_is_decoded(self):
        assert resolve("[[two%20words.md|x]]") == "[[Two words|x]]"

    def test_parent_directory_target_resolves(self):
        assert resolve_md_links(
            "[[../pulse_dev.md|x]]", SONGS / "sub" / "a.md", INDEX
        ) == "[[pulse under latent semantic envelopes - development notes|x]]"

    def test_external_style_link_shape_also_resolves(self):
        # Insurance against a pandoc version writing relative targets this way.
        assert resolve("[pulse_dev.md dev notes]") == (
            "[[pulse under latent semantic envelopes - development notes|dev notes]]"
        )

    def test_absolute_url_is_left_alone(self):
        assert resolve("[https://example.com/x label]") == "[https://example.com/x label]"

    def test_non_md_wikilink_is_left_alone(self):
        assert resolve("[[Category:Songs]] [[Media:x.lrc|y]]") == (
            "[[Category:Songs]] [[Media:x.lrc|y]]"
        )

    def test_label_containing_a_pipe_is_preserved(self):
        assert resolve("[[pulse_dev.md|a|b]]").endswith("|a|b]]")

    def test_several_links_in_one_body(self):
        out = resolve("[[pulse_dev.md|a]] then [[two%20words.md|b]]")
        assert "|a]]" in out and "[[Two words|b]]" in out

    def test_missing_file_is_an_error(self):
        with pytest.raises(ValueError, match="does not exist"):
            resolve("[[nope.md|x]]")

    def test_existing_but_unpublished_file_is_an_error(self, tmp_path):
        (tmp_path / "draft.md").write_text("x", encoding="utf-8")
        with pytest.raises(ValueError, match="not published"):
            resolve_md_links("[[draft.md|x]]", tmp_path / "song.md", {})

    def test_error_names_the_source_file(self):
        with pytest.raises(ValueError, match=r"pulse\.md"):
            resolve("[[nope.md|x]]")


class TestUnresolvedLinkGuard:
    def test_accepts_output_with_no_md_reference(self):
        assert_no_unresolved_md_links("[[A page|x]] and [http://e.com y]", HERE)

    def test_rejects_leftover_wikilink(self):
        with pytest.raises(ValueError, match="unresolved wikilink"):
            assert_no_unresolved_md_links("[[notes.md|x]]", HERE)

    def test_rejects_leftover_external_style_link(self):
        with pytest.raises(ValueError, match="external-style"):
            assert_no_unresolved_md_links("[notes.md x]", HERE)

    def test_rejects_raw_markdown_link_left_in_a_columns_fence(self):
        with pytest.raises(ValueError, match="columns"):
            assert_no_unresolved_md_links("<poem>\nsee [x](notes.md)\n</poem>", HERE)

    def test_prose_mentioning_a_filename_is_not_a_link(self):
        assert_no_unresolved_md_links("edit <code>pulse.md</code> by hand", HERE)


class TestExtractMdLinkTargets:
    def test_finds_inline_targets(self):
        assert extract_md_link_targets("a [x](one.md) b [y](../two.md#f)") == [
            "one.md",
            "../two.md#f",
        ]

    def test_ignores_bodies_without_links(self):
        assert extract_md_link_targets("no links here") == []

    def test_finds_targets_inside_a_columns_fence(self):
        # The fence cannot render them, but the graph must still see the edge.
        assert extract_md_link_targets("```columns\n[x](one.md)\n```") == ["one.md"]


@pytest.mark.skipif(shutil.which("pandoc") is None, reason="pandoc not installed")
class TestPandocContract:
    """Pins the pandoc output shape that resolve_md_links depends on.

    If a pandoc upgrade starts writing relative link targets differently, this
    fails here instead of silently publishing a broken link.
    """

    def test_version(self):
        out = subprocess.run(
            ["pandoc", "--version"], capture_output=True, text=True, check=True
        ).stdout
        print(out.splitlines()[0])

    def test_relative_link_survives_the_full_render(self):
        wikitext = markdown_to_wikitext("see [dev notes](pulse_dev.md) here")
        assert resolve(wikitext).strip() == (
            "see [[pulse under latent semantic envelopes - development notes|dev notes]] here"
        )

    def test_unlabelled_relative_link_survives_the_full_render(self):
        wikitext = markdown_to_wikitext("[pulse_dev.md](pulse_dev.md)")
        assert resolve(wikitext).strip() == (
            "[[pulse under latent semantic envelopes - development notes]]"
        )

    def test_absolute_url_survives_untouched(self):
        wikitext = markdown_to_wikitext("[site](https://example.com/x)")
        assert resolve(wikitext).strip() == "[https://example.com/x site]"

    def test_columns_fence_renders_to_side_by_side_poems(self):
        wikitext = markdown_to_wikitext("```columns\n**A**\nl1\n===\n**B**\nl2\n```")
        assert wikitext.count("<poem>") == 2
        assert "'''A'''" in wikitext