"""Unit tests: markdown image-reference extraction (phase 125, task 02).

``extract_image_refs`` is a pure function (LOCKED A1 — the storage
content of ``Document.image_context``), so the tests pin the exact
contract the enrichment pipeline (tasks 03/04) will rely on:

* one :class:`ImageRef` per ``![alt](path)`` reference outside code
  fences (multiple per line extracted separately, same window);
* the context window — up to *N* paragraphs before and AFTER the
  reference paragraph, joined with blank lines, the reference
  paragraph itself excluded (the reference is already ``alt_text`` +
  ``path``);
* fence semantics identical to the chunker (PLAN §5) — fences are
  ATOMIC paragraphs (one context unit, blank lines inside don't split
  it) and references inside a fence are literal text — skipped;
* edge cases: empty alt, start/end of file, headings, paths with
  spaces, nested parens (accepted miss), empty content, no refs,
  1-based ``line_number``.
"""
from __future__ import annotations

import pytest

from app.rag.md_images import CONTEXT_PARAGRAPHS, ImageRef, extract_image_refs


def test_default_constant() -> None:
    assert CONTEXT_PARAGRAPHS == 2
    doc = "P1.\n\nP2.\n\nP3.\n\n![a](a.png)\n\nQ1.\n\nQ2.\n\nQ3.\n"
    assert extract_image_refs(doc) == extract_image_refs(doc, context_paragraphs=2)


def test_single_reference_with_surrounding_paragraphs() -> None:
    doc = (
        "# Title\n"
        "\n"
        "First paragraph.\n"
        "\n"
        "Second paragraph.\n"
        "\n"
        "![alt](image.png)\n"
        "\n"
        "Third paragraph.\n"
        "\n"
        "Fourth paragraph.\n"
    )
    refs = extract_image_refs(doc)
    assert refs == [
        ImageRef(
            path="image.png",
            alt_text="alt",
            context=(
                "First paragraph.\n\n"
                "Second paragraph.\n\n"
                "Third paragraph.\n\n"
                "Fourth paragraph."
            ),
            line_number=7,
        )
    ]


def test_multiple_references_on_different_lines() -> None:
    doc = (
        "Intro.\n"
        "\n"
        "Para A.\n"
        "\n"
        "![one](one.png)\n"
        "\n"
        "Para B.\n"
        "\n"
        "Para C.\n"
        "\n"
        "Para D.\n"
        "\n"
        "![two](two.png)\n"
        "\n"
        "Outro.\n"
    )
    refs = extract_image_refs(doc)
    assert [r.path for r in refs] == ["one.png", "two.png"]
    assert [r.alt_text for r in refs] == ["one", "two"]
    assert [r.line_number for r in refs] == [5, 13]
    # Each gets its OWN window (N=2 around its own paragraph — spaced
    # apart so the windows don't contain the other reference line).
    assert refs[0].context == "Intro.\n\nPara A.\n\nPara B.\n\nPara C."
    assert refs[1].context == "Para C.\n\nPara D.\n\nOutro."


def test_multiple_references_on_same_line_share_window() -> None:
    doc = "Before.\n\nSee ![a](a.png) and ![b](b.png) here.\n\nAfter.\n"
    refs = extract_image_refs(doc)
    assert [r.path for r in refs] == ["a.png", "b.png"]
    assert [r.alt_text for r in refs] == ["a", "b"]
    assert [r.line_number for r in refs] == [3, 3]
    # Same reference paragraph → same context, reference line excluded.
    assert refs[0].context == "Before.\n\nAfter."
    assert refs[1].context == "Before.\n\nAfter."


def test_reference_in_code_fence_is_skipped() -> None:
    doc = (
        "Intro.\n"
        "\n"
        "```\n"
        "![not real](fenced.png)\n"
        "```\n"
        "\n"
        "![real](real.png)\n"
    )
    refs = extract_image_refs(doc)
    assert [r.path for r in refs] == ["real.png"]
    # The fence is an ATOMIC paragraph and counts as one context unit
    # inside the N=2 window (chunker semantics, PLAN §5).
    assert refs[0].context == "Intro.\n\n```\n![not real](fenced.png)\n```"


def test_fence_with_blank_lines_inside_is_one_atomic_block() -> None:
    doc = (
        "P1.\n"
        "\n"
        "```\n"
        "line one\n"
        "\n"
        "line three\n"
        "```\n"
        "\n"
        "![a](a.png)\n"
    )
    refs = extract_image_refs(doc)
    assert len(refs) == 1
    # The fence (with its inner blank line) is ONE atomic context unit,
    # occupying a single slot of the N=2 window before the reference
    # (if it split on the inner blank line, the window would hold only
    # "P1" + the fence's first lines instead of P1 + the whole fence).
    assert refs[0].context == "P1.\n\n```\nline one\n\nline three\n```"


def test_tilde_fence_and_long_fence_markers() -> None:
    doc = "~~~\n![skip](skip.png)\n~~~\n\n![keep](keep.png)\n"
    assert [r.path for r in extract_image_refs(doc)] == ["keep.png"]
    # Four-backtick fence (marker = first three chars), inner blank line.
    doc = "````\n\n![skip](skip2.png)\n````\n\n![keep](keep2.png)\n"
    assert [r.path for r in extract_image_refs(doc)] == ["keep2.png"]


def test_unclosed_fence_skips_rest_of_file() -> None:
    doc = "```\n![skip](a.png)\nmore text after an unclosed fence\n"
    assert extract_image_refs(doc) == []


def test_reference_with_no_alt_text() -> None:
    refs = extract_image_refs("![](image.png)")
    assert refs == [
        ImageRef(path="image.png", alt_text="", context="", line_number=1)
    ]


def test_reference_at_start_of_file() -> None:
    doc = "![first](first.png)\n\nP1.\n\nP2.\n\nP3.\n"
    refs = extract_image_refs(doc)
    assert len(refs) == 1
    # Only paragraphs after exist; the N=2 cap still applies (P3 left out).
    assert refs[0].context == "P1.\n\nP2."
    assert refs[0].line_number == 1


def test_reference_at_end_of_file() -> None:
    doc = "P1.\n\nP2.\n\nP3.\n\nP4.\n\n![last](last.png)\n"
    refs = extract_image_refs(doc)
    assert len(refs) == 1
    # Only paragraphs before exist; the N=2 window is the two paragraphs
    # immediately before the reference (P1 and P2 left out).
    assert refs[0].context == "P3.\n\nP4."
    assert refs[0].line_number == 9


def test_reference_in_heading_line() -> None:
    doc = (
        "Intro paragraph.\n"
        "\n"
        "## ![alt](image.png)\n"
        "\n"
        "Outro paragraph.\n"
    )
    refs = extract_image_refs(doc)
    assert len(refs) == 1
    assert refs[0].alt_text == "alt"
    assert refs[0].path == "image.png"
    assert refs[0].line_number == 3
    # The heading line is the reference paragraph — excluded from the
    # context; only the surrounding text remains.
    assert refs[0].context == "Intro paragraph.\n\nOutro paragraph."
    assert "##" not in refs[0].context


def test_context_paragraphs_zero_and_custom() -> None:
    doc = "P1.\n\nP2.\n\nP3.\n\n![a](a.png)\n\nQ1.\n\nQ2.\n\nQ3.\n"
    assert extract_image_refs(doc, context_paragraphs=0)[0].context == ""
    assert extract_image_refs(doc, context_paragraphs=1)[0].context == "P3.\n\nQ1."
    assert (
        extract_image_refs(doc, context_paragraphs=3)[0].context
        == "P1.\n\nP2.\n\nP3.\n\nQ1.\n\nQ2.\n\nQ3."
    )
    # A window LARGER than the file gets whatever is available.
    assert (
        extract_image_refs(doc, context_paragraphs=10)[0].context
        == "P1.\n\nP2.\n\nP3.\n\nQ1.\n\nQ2.\n\nQ3."
    )


def test_negative_context_paragraphs_raises() -> None:
    with pytest.raises(ValueError, match="context_paragraphs must be >= 0"):
        extract_image_refs("![a](a.png)", context_paragraphs=-1)


def test_empty_and_reference_free_content() -> None:
    assert extract_image_refs("") == []
    assert extract_image_refs("\n\n   \n") == []
    assert extract_image_refs("# No images here\n\nJust plain text.\n") == []
    # A link is not an image reference; an empty target is not a ref.
    assert extract_image_refs("[a link](http://x.example/) ![empty]()\n") == []


def test_image_nested_in_link() -> None:
    refs = extract_image_refs("![alt](img.png) wrapped: [![alt](img2.png)](http://x/)\n")
    assert [r.path for r in refs] == ["img.png", "img2.png"]


def test_alt_text_with_nested_brackets() -> None:
    # The alt field is ``[^]]*`` — it may OPEN a bracket (``[``) but
    # the first CLOSING bracket (``]``) ends it: an alt with a nested
    # ``[`` (``a [1``) still captures the path, while an alt that
    # itself CARRIES a ``]`` (``a [1] v2``) breaks the whole match
    # (the ``]`` ends the alt field, and no ``(`` follows) — an
    # accepted miss, the locked regex's limitation (task 02), the
    # alt-side twin of the nested-parens path miss above.
    refs = extract_image_refs("![a [1](img.png)\n")
    assert refs == [ImageRef(path="img.png", alt_text="a [1", context="", line_number=1)]
    assert extract_image_refs("![a [1] v2](img.png)\n") == []


def test_paths_with_spaces_and_parens() -> None:
    # Spaces are fine; surrounding whitespace in the target is stripped.
    refs = extract_image_refs("![a](diagram v2.png) and ![b]( x.png )\n")
    assert [r.path for r in refs] == ["diagram v2.png", "x.png"]
    # Nested parens: the regex stops at the first ')' — an accepted
    # miss (rare in practice, phase 125 task 02).
    refs = extract_image_refs("![a](a(b).png)\n")
    assert refs[0].path == "a(b"


def test_line_numbers_are_one_based() -> None:
    doc = "\n\n\n# Head\n\n\n![a](a.png)\n"
    refs = extract_image_refs(doc)
    # Three leading blanks + "# Head" + two blanks = lines 1..6; the
    # reference is on line 7.
    assert refs[0].line_number == 7


def test_multi_line_reference_paragraph_contributes_nothing() -> None:
    # The reference sits in the MIDDLE of a paragraph (no blank lines):
    # the whole reference paragraph is excluded from the context.
    doc = (
        "Before.\n"
        "\n"
        "Line one.\n"
        "Line two with ![alt](img.png)\n"
        "Line three.\n"
        "\n"
        "After.\n"
    )
    refs = extract_image_refs(doc)
    assert refs[0].context == "Before.\n\nAfter."