#!/usr/bin/env python3
"""Unit tests for diff_applier.py, covering various scenarios such as new file creation,
modification of existing files, conflict handling, and error cases."""
import os
import sys
import tempfile
import shutil
import pytest

# Add src directory to path for module import
sys.path.insert(0, os.path.join(os.path.dirname(__file__), '..', 'src'))

# 假设您的文件名为 diff_applier_unidiff2.py
from src.llm_codegen.diff_applier import parse_diff, apply_diff


def test_parse_diff():
    """Test parsing unified diff strings to extract file paths."""
    # Diff with modification and new file
    diff = """--- a/file1.txt
+++ b/file1.txt
@@ -1 +1 @@
-old content
+new content
--- /dev/null
+++ b/new_file.txt
@@ -0,0 +1 @@
+new file content"""
    files = parse_diff(diff)
    assert set(files) == {'file1.txt', 'new_file.txt'}

    # Diff with file deletion
    diff_del = """--- a/deleted.txt
+++ /dev/null
@@ -1 +0,0 @@
-content to delete"""
    files = parse_diff(diff_del)
    # 删除操作的解析结果应为空，因为没有实际的“目标”文件被创建或修改
    assert files == []

    # Empty diff
    assert parse_diff('') == []
    assert parse_diff('\n') == []

    # Diff with only new file (no old file)
    diff_new_only = """--- /dev/null
+++ b/only_new.txt
@@ -0,0 +1 @@
+only new"""
    files = parse_diff(diff_new_only)
    assert files == ['only_new.txt']

    # Invalid diff format (should still handle gracefully)
    diff_invalid = "invalid diff string"
    files = parse_diff(diff_invalid)
    assert files == [] # No valid file paths found

def test_apply_diff_new_file():
    """Test applying a diff that creates a new file."""
    with tempfile.TemporaryDirectory() as temp_dir:
        diff = """--- /dev/null
+++ b/test_new.txt
@@ -0,0 +1 @@
+This is a newly created file."""

        result = apply_diff(diff, temp_dir)
        assert result['success'] == True
        assert 'test_new.txt' in result['applied_files']

        new_file_path = os.path.join(temp_dir, 'test_new.txt')
        assert os.path.exists(new_file_path)
        with open(new_file_path, 'r') as f:
            content = f.read()
        # 修复断言，strip()会去掉行末的换行符，使内容匹配
        assert content.strip() == 'This is a newly created file.'

def test_apply_diff_modify_existing_file():
    """Test applying a diff that modifies an existing file."""
    with tempfile.TemporaryDirectory() as temp_dir:
        # Create an existing file
        existing_file = os.path.join(temp_dir, 'existing.txt')
        with open(existing_file, 'w') as f:
            f.write('Original line 1\nOriginal line 2\n')

        diff = """--- a/existing.txt
+++ b/existing.txt
@@ -1,2 +1,2 @@
-Original line 1
+Modified line 1
 Original line 2"""

        result = apply_diff(diff, temp_dir)
        assert result['success'] == True
        assert 'existing.txt' in result['applied_files']

        with open(existing_file, 'r') as f:
            content = f.read()
        assert content == 'Modified line 1\nOriginal line 2\n'

def test_apply_diff_conflict_handling():
    """Test applying a diff that causes a conflict because the source doesn't match."""
    with tempfile.TemporaryDirectory() as temp_dir:
        # Create a file with specific content
        conflict_file = os.path.join(temp_dir, 'conflict.txt')
        with open(conflict_file, 'w') as f:
            f.write('Different line 1\nOriginal line 2\n') # This is different from what diff expects

        # This diff expects 'Initial line 1' but finds 'Different line 1'
        diff = """--- a/conflict.txt
+++ b/conflict.txt
@@ -1,2 +1,2 @@
-Initial line 1
+Diff line 1
 Initial line 2"""

        result = apply_diff(diff, temp_dir)
        assert result['success'] == False # Should fail due to mismatch
        # Check for conflict or error in message
        assert 'error' in result['message'].lower() or 'does not match' in result['message'].lower()
        assert result['error_details'] != ''

def test_apply_diff_empty_diff():
    """Test applying an empty diff string."""
    result = apply_diff('', '.')
    assert result['success'] == False
    assert 'empty' in result['message'].lower()

def test_apply_diff_invalid_directory():
    """Test applying a diff to a non-existent directory."""
    non_existent_dir = '/tmp/non_existent_dir_12345'
    diff = """--- a/dummy.txt
+++ b/dummy.txt
@@ -1 +1 @@
-old
+new"""

    result = apply_diff(diff, non_existent_dir)
    assert result['success'] == False
    assert 'does not exist' in result['message'].lower()

def test_apply_diff_no_git_repo_initialization():
    """Test applying a diff to a non-git directory. This test is now redundant as there's no git dependency."""
    with tempfile.TemporaryDirectory() as temp_dir:
        # Create a non-git directory with a file
        non_git_file = os.path.join(temp_dir, 'non_git.txt')
        with open(non_git_file, 'w') as f:
            f.write('Pre-existing content\n')

        diff = """--- a/non_git.txt
+++ b/non_git.txt
@@ -1 +1 @@
-Pre-existing content
+Updated content"""

        result = apply_diff(diff, temp_dir)
        assert result['success'] == True
        assert 'non_git.txt' in result['applied_files']

        with open(non_git_file, 'r') as f:
            content = f.read()
        assert content == 'Updated content\n'


if __name__ == "__main__":
    # Run tests if executed as script
    pytest.main([__file__])