import pytest
import tempfile
import os
from pathlib import Path
from src.diff_viewer import (
  parse_diff, DiffFile, DiffHunk, parse_hunk_header, 
  get_line_color, render_diff_text_immediate,
  create_backup, apply_patch_to_file, restore_from_backup, cleanup_backup
)

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

def test_create_backup() -> None:
  with tempfile.TemporaryDirectory() as tmpdir:
    test_file = Path(tmpdir) / "test.py"
    test_file.write_text("original content\n")
    
    backup_path = create_backup(str(test_file))
    assert backup_path is not None
    assert Path(backup_path).exists()
    assert Path(backup_path).read_text() == "original content\n"

def test_create_backup_nonexistent() -> None:
  result = create_backup("/nonexistent/file.py")
  assert result is None

def test_apply_patch_simple() -> None:
  with tempfile.TemporaryDirectory() as tmpdir:
    test_file = Path(tmpdir) / "test.py"
    test_file.write_text("old\n")
    
    patch = f"""--- a/{test_file.name}
+++ b/{test_file.name}
@@ -1 +1 @@
-old
+new"""
    
    success, msg = apply_patch_to_file(patch, tmpdir)
    assert success
    assert test_file.read_text() == "new\n"

def test_apply_patch_with_context() -> None:
  with tempfile.TemporaryDirectory() as tmpdir:
    test_file = Path(tmpdir) / "example.py"
    test_file.write_text("line 1\nline 2\nline 3\n")
    
    patch = f"""--- a/{test_file.name}
+++ b/{test_file.name}
@@ -1,3 +1,3 @@
-line 1
-line 2
+line one
+line two
 line 3"""
    
    success, msg = apply_patch_to_file(patch, tmpdir)
    assert success
    content = test_file.read_text()
    assert "line one" in content
    assert "line two" in content

def test_restore_from_backup() -> None:
  with tempfile.TemporaryDirectory() as tmpdir:
    test_file = Path(tmpdir) / "test.py"
    test_file.write_text("modified\n")
    backup_file = test_file.with_suffix(".py.backup")
    backup_file.write_text("original\n")
    
    success = restore_from_backup(str(test_file))
    assert success
    assert test_file.read_text() == "original\n"

def test_cleanup_backup() -> None:
  with tempfile.TemporaryDirectory() as tmpdir:
    test_file = Path(tmpdir) / "test.py"
    test_file.write_text("content\n")
    backup_file = test_file.with_suffix(".py.backup")
    backup_file.write_text("backup\n")
    
    cleanup_backup(str(test_file))
    assert not backup_file.exists()