"""Unit tests for markdown_parser module."""

import pytest
from pathlib import Path
from markdown_parser import (
  parse_markdown_file,
  find_section_at_line,
  MarkdownSection,
  ParsedDocument
)


@pytest.fixture
def tmp_markdown_file(tmp_path):
  """Fixture to create temporary markdown files for testing.
  
  Args:
      tmp_path: pytest temporary directory fixture
      
  Returns:
      Function that creates a markdown file with given content
  """
  
  def _create_file(content: str, filename: str = "test.md") -> Path:
    file_path = tmp_path / filename
    file_path.write_text(content, encoding="utf-8")
    return file_path
  
  return _create_file


# Tests for parse_markdown_file()

def test_i_can_parse_file_with_single_section(tmp_markdown_file):
  """Test parsing a file with a single header section."""
  content = """# Main Title
This is the content of the section.
It has multiple lines."""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert len(doc.sections) == 1
  assert doc.sections[0].level == 1
  assert doc.sections[0].title == "Main Title"
  assert "This is the content" in doc.sections[0].content
  assert doc.sections[0].start_line == 1
  assert doc.sections[0].end_line == 3


def test_i_can_parse_file_with_multiple_sections(tmp_markdown_file):
  """Test parsing a file with multiple sections at the same level."""
  content = """# Section One
Content of section one.

# Section Two
Content of section two.

# Section Three
Content of section three."""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert len(doc.sections) == 3
  assert doc.sections[0].title == "Section One"
  assert doc.sections[1].title == "Section Two"
  assert doc.sections[2].title == "Section Three"
  assert all(section.level == 1 for section in doc.sections)


def test_i_can_parse_file_with_nested_sections(tmp_markdown_file):
  """Test parsing a file with nested headers (different levels)."""
  content = """# Main Title
Introduction text.

## Subsection A
Content A.

## Subsection B
Content B.

### Sub-subsection
Nested content."""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert len(doc.sections) == 4
  assert doc.sections[0].level == 1
  assert doc.sections[0].title == "Main Title"
  assert doc.sections[1].level == 2
  assert doc.sections[1].title == "Subsection A"
  assert doc.sections[2].level == 2
  assert doc.sections[2].title == "Subsection B"
  assert doc.sections[3].level == 3
  assert doc.sections[3].title == "Sub-subsection"


def test_i_can_parse_file_without_headers(tmp_markdown_file):
  """Test parsing a file with no headers (plain text)."""
  content = """This is a plain text file.
It has no headers at all.
Just regular content."""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert len(doc.sections) == 1
  assert doc.sections[0].level == 0
  assert doc.sections[0].title == ""
  assert doc.sections[0].content == content
  assert doc.sections[0].start_line == 1
  assert doc.sections[0].end_line == 3


def test_i_can_parse_empty_file(tmp_markdown_file):
  """Test parsing an empty file."""
  content = ""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert len(doc.sections) == 1
  assert doc.sections[0].level == 0
  assert doc.sections[0].title == ""
  assert doc.sections[0].content == ""
  assert doc.sections[0].start_line == 1
  assert doc.sections[0].end_line == 1


def test_i_can_track_correct_line_numbers(tmp_markdown_file):
  """Test that line numbers are correctly tracked for each section."""
  content = """# First Section
Line 2
Line 3

# Second Section
Line 6
Line 7
Line 8"""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  assert doc.sections[0].start_line == 1
  assert doc.sections[0].end_line == 4
  assert doc.sections[1].start_line == 5
  assert doc.sections[1].end_line == 8


def test_i_cannot_parse_nonexistent_file():
  """Test that parsing a non-existent file raises FileNotFoundError."""
  fake_path = Path("/nonexistent/path/to/file.md")
  
  with pytest.raises(FileNotFoundError):
    parse_markdown_file(fake_path)


# Tests for find_section_at_line()

def test_i_can_find_section_at_specific_line(tmp_markdown_file):
  """Test finding a section at a line in the middle of content."""
  content = """# Section One
Line 2
Line 3

# Section Two
Line 6
Line 7"""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  section = find_section_at_line(doc, 3)
  
  assert section is not None
  assert section.title == "Section One"
  
  section = find_section_at_line(doc, 6)
  
  assert section is not None
  assert section.title == "Section Two"


def test_i_can_find_section_at_first_line(tmp_markdown_file):
  """Test finding a section at the header line itself."""
  content = """# Main Title
Content here."""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  section = find_section_at_line(doc, 1)
  
  assert section is not None
  assert section.title == "Main Title"


def test_i_can_find_section_at_last_line(tmp_markdown_file):
  """Test finding a section at its last line."""
  content = """# Section One
Line 2
Line 3

# Section Two
Line 6"""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  section = find_section_at_line(doc, 3)
  
  assert section is not None
  assert section.title == "Section One"
  
  section = find_section_at_line(doc, 6)
  
  assert section is not None
  assert section.title == "Section Two"


def test_i_cannot_find_section_for_invalid_line_number(tmp_markdown_file):
  """Test that invalid line numbers return None."""
  content = """# Title
Content"""
  
  file_path = tmp_markdown_file(content)
  doc = parse_markdown_file(file_path)
  
  # Negative line number
  assert find_section_at_line(doc, -1) is None
  
  # Zero line number
  assert find_section_at_line(doc, 0) is None
  
  # Line number beyond file length
  assert find_section_at_line(doc, 1000) is None