import pytest
from src.diff_viewer import parse_diff, DiffFile, DiffHunk, parse_hunk_header, get_line_color, render_diff_text_immediate

def test_parse_diff_empty() -> None:
  result = parse_diff("")
  assert result == []

def test_parse_diff_none() -> None:
  result = parse_diff(None)  # type: ignore
  assert result == []

def test_parse_simple_diff() -> None:
  diff_text = """--- a/src/test.py
+++ b/src/test.py
@@ -1 +1 @@
-old
+new"""
  result = parse_diff(diff_text)
  assert len(result) == 1
  assert result[0].old_path == "src/test.py"
  assert result[0].new_path == "src/test.py"
  assert len(result[0].hunks) == 1
  assert result[0].hunks[0].header == "@@ -1 +1 @@"

def test_parse_diff_with_context() -> None:
  diff_text = """--- a/src/example.py
+++ b/src/example.py
@@ -10,5 +10,6 @@
 def existing_function():
     pass
-    old_line
+    old_line
+    new_line
     more_code"""
  result = parse_diff(diff_text)
  assert len(result) == 1
  assert result[0].old_path == "src/example.py"
  assert len(result[0].hunks) == 1
  hunk = result[0].hunks[0]
  assert hunk.old_start == 10
  assert hunk.old_count == 5
  assert hunk.new_start == 10
  assert hunk.new_count == 6
  assert "-    old_line" in hunk.lines
  assert "+    new_line" in hunk.lines

def test_parse_multiple_files() -> None:
  diff_text = """--- a/file1.py
+++ b/file1.py
@@ -1 +1 @@
-a
+b
--- a/file2.py
+++ b/file2.py
@@ -1 +1 @@
-c
+d"""
  result = parse_diff(diff_text)
  assert len(result) == 2
  assert result[0].old_path == "file1.py"
  assert result[1].old_path == "file2.py"

def test_parse_hunk_header() -> None:
  result = parse_hunk_header("@@ -10,5 +10,6 @@")
  assert result == (10, 5, 10, 6)
  
  result = parse_hunk_header("@@ -1 +1 @@")
  assert result == (1, 1, 1, 1)

def test_diff_line_classification() -> None:
  diff_text = """--- a/test.py
+++ b/test.py
@@ -1,3 +1,4 @@
 context line
-removed line
+removed line
+added line
 another context"""
  result = parse_diff(diff_text)
  hunk = result[0].hunks[0]
  assert any(line.startswith("-") for line in hunk.lines)
  assert any(line.startswith("+") for line in hunk.lines)
  assert any(line.startswith(" ") or not line.startswith(("-", "+")) for line in hunk.lines)

def test_get_line_color() -> None:
  assert get_line_color("+added") == "green"
  assert get_line_color("-removed") == "red"
  assert get_line_color("@@ -1,3 +1,4 @@") == "cyan"
  assert get_line_color(" context") == None

def test_render_diff_text_immediate() -> None:
  diff_text = """--- a/test.py
+++ b/test.py
@@ -1 +1 @@
-old
+new"""
  diff_files = parse_diff(diff_text)
  output = render_diff_text_immediate(diff_files)
  
  assert len(output) > 0
  assert ("File: test.py", "white") in output
  assert ("@@ -1 +1 @@", "cyan") in output
  assert ("-old", "red") in output
  assert ("+new", "green") in output