# python_list_insert.py
my_list = [10, 20, 30]
print(f"Original list: {my_list}")

# Append an element
my_list.append(40)
print(f"After append(40): {my_list}")

# Insert an element at a specific index
my_list.insert(1, 15) # Insert 15 at index 1
print(f"After insert(1, 15): {my_list}")

# Insert at the beginning
my_list.insert(0, 5)
print(f"After insert(0, 5): {my_list}")

# python_list_delete.py
my_list = [5, 10, 15, 20, 30, 40, 15]
print(f"Original list: {my_list}")

# Delete by index using del
del my_list[2] # Deletes 15 at index 2
print(f"After del my_list[2]: {my_list}")

# Pop an element by index (and get its value)
popped_value = my_list.pop(0) # Pops 5
print(f"After pop(0): {my_list}, Popped value: {popped_value}")

# Pop the last element
last_value = my_list.pop() # Pops 40
print(f"After pop(): {my_list}, Popped value: {last_value}")

# Remove by value (removes first occurrence)
my_list.remove(15) # Removes the first 15 (which is now at index 3)
print(f"After remove(15): {my_list}")

# Attempt to remove a non-existent value (will raise ValueError)
try:
    my_list.remove(99)
except ValueError as e:
    print(f"Error trying to remove 99: {e}")

# python_dict_insert.py
my_dict = {'name': 'Alice', 'age': 30}
print(f"Original dict: {my_dict}")

# Insert a new key-value pair
my_dict['city'] = 'New York'
print(f"After adding 'city': {my_dict}")

# Update an existing key's value (this is not insertion, but a common operation)
my_dict['age'] = 31
print(f"After updating 'age': {my_dict}")

# Insert multiple items using update()
my_dict.update({'occupation': 'Engineer', 'country': 'USA'})
print(f"After update(): {my_dict}")

# python_dict_delete.py
my_dict = {'name': 'Bob', 'age': 25, 'city': 'London', 'occupation': 'Developer'}
print(f"Original dict: {my_dict}")

# Delete by key using del
del my_dict['city']
print(f"After del my_dict['city']: {my_dict}")

# Pop an element by key (and get its value)
popped_age = my_dict.pop('age')
print(f"After pop('age'): {my_dict}, Popped age: {popped_age}")

# Pop a non-existent key with a default value
non_existent_value = my_dict.pop('country', 'Not Found')
print(f"After pop('country', 'Not Found'): {my_dict}, Value: {non_existent_value}")

# Attempt to pop a non-existent key without default (will raise KeyError)
try:
    my_dict.pop('gender')
except KeyError as e:
    print(f"Error trying to pop 'gender': {e}")

# Pop an arbitrary item
popped_item = my_dict.popitem()
print(f"After popitem(): {my_dict}, Popped item: {popped_item}")

# Create a test directory for these examples
mkdir -p filesystem_test
cd filesystem_test

echo "--- Creating files and directories ---"

# Create an empty file
touch my_file.txt
echo "File 'my_file.txt' created."

# Create a file with some content
echo "Hello, world!" > another_file.log
echo "File 'another_file.log' created with content."

# Create a new directory
mkdir my_directory
echo "Directory 'my_directory' created."

# Create nested directories in one go
mkdir -p nested/sub/dir
echo "Nested directory 'nested/sub/dir' created."

echo "--- Current file system state ---"
ls -RF

cd filesystem_test # Ensure we are in the test directory from previous example

echo "--- Deleting files and directories ---"

# Delete a single file
rm my_file.txt
echo "File 'my_file.txt' deleted."

# Delete another file
rm another_file.log
echo "File 'another_file.log' deleted."

# Delete an empty directory
rmdir my_directory
echo "Directory 'my_directory' deleted."

# Note: rmdir will fail if the directory is not empty
# Let's try creating a file in nested/sub/dir and then try to rmdir the parent
touch nested/sub/dir/temp.txt
echo "Created temp.txt in nested/sub/dir."

echo "Attempting to rmdir nested/sub/dir (will fail as it's not empty):"
rmdir nested/sub/dir || echo "rmdir failed as expected." # The || echo part is to show the failure gracefully

# To remove non-empty directories and their contents, use 'rm -r'
# Be very careful with 'rm -rf' (force, recursive) as it bypasses most warnings.
rm -r nested
echo "Directory 'nested' and its contents deleted recursively."

echo "--- Current file system state after deletions ---"
ls -RF

# Clean up the test directory
cd ..
rmdir filesystem_test
echo "Cleaned up filesystem_test directory."

# Create a sample file for text manipulation
echo -e "Line 1: Apples\nLine 2: Bananas\nLine 3: Cherries\nLine 4: Dates" > fruits.txt
echo "Original fruits.txt:"
cat fruits.txt
echo ""

echo "--- Inserting Text ---"

# Insert a line before line 3
# '3i' means "insert before line 3"
# Note: The 'sed -i' flag modifies the file in-place. Use 'sed' without '-i' to preview.
sed -i '3iLine 2.5: Grapes' fruits.txt
echo "After inserting 'Line 2.5: Grapes' before line 3:"
cat fruits.txt
echo ""

# Insert a line after a specific pattern
# '/Bananas/a' means "append after line matching 'Bananas'"
sed -i '/Bananas/aLine 2.7: Oranges' fruits.txt
echo "After inserting 'Line 2.7: Oranges' after 'Bananas':"
cat fruits.txt
echo ""

# Insert at the beginning of the file (before line 1)
sed -i '1iSTART: Fruit List' fruits.txt
echo "After inserting 'START: Fruit List' at the beginning:"
cat fruits.txt
echo ""

# Insert at the end of the file ($a means "append to last line")
sed -i '$aEND: List Complete' fruits.txt
echo "After inserting 'END: List Complete' at the end:"
cat fruits.txt
echo ""

# Insert text at a specific column within a line (more complex with sed/awk)
# Let's insert "fresh " before "Apples" on line 2
# Note: This is a substitution, not a pure "insertion" in the line context,
# but it achieves the effect of adding text.
sed -i 's/Line 1: Apples/Line 1: fresh Apples/' fruits.txt
echo "After inserting 'fresh ' on Line 1:"
cat fruits.txt

# Reset fruits.txt for deletion examples
echo -e "Header\nItem A\nItem B\nItem C\nFooter\nItem B (duplicate)" > fruits.txt
echo "Original fruits.txt:"
cat fruits.txt
echo ""

echo "--- Deleting Text ---"

# Delete a specific line number (e.g., line 3)
sed -i '3d' fruits.txt
echo "After deleting line 3 (Item B):"
cat fruits.txt
echo ""

# Delete lines matching a pattern (e.g., lines containing "Item C")
sed -i '/Item C/d' fruits.txt
echo "After deleting lines containing 'Item C':"
cat fruits.txt
echo ""

# Delete the first occurrence of a specific string on a line (substitution)
# 's/old_text//' replaces old_text with nothing, effectively deleting it.
sed -i 's/Header//' fruits.txt
echo "After deleting 'Header' from its line:"
cat fruits.txt
echo ""

# Delete the last line ($d)
sed -i '$d' fruits.txt
echo "After deleting the last line ('Item B (duplicate)'):"
cat fruits.txt
echo ""

# Delete an entire file (using rm)
rm fruits.txt
echo "File 'fruits.txt' deleted."

# Create a SQLite database (if it doesn't exist)
sqlite3 my_database.db <<EOF
-- Create a simple table
CREATE TABLE IF NOT EXISTS users (
    id INTEGER PRIMARY KEY AUTOINCREMENT,
    name TEXT NOT NULL,
    email TEXT UNIQUE
);

-- Insert a single row, specifying all columns
INSERT INTO users (name, email) VALUES ('Alice', 'alice@example.com');

-- Insert another row, without specifying columns (values must be in column order)
INSERT INTO users VALUES (2, 'Bob', 'bob@example.com');

-- Insert multiple rows
INSERT INTO users (name, email) VALUES
    ('Charlie', 'charlie@example.com'),
    ('David', 'david@example.com');

-- Insert a row with a NULL email
INSERT INTO users (name) VALUES ('Eve');

-- Select all data to show insertions
SELECT * FROM users;
EOF

# Continue with the same SQLite database
sqlite3 my_database.db <<EOF
-- View current data before deletion
.headers on
.mode column
SELECT * FROM users;
.headers off
.mode list

-- Delete a specific user by ID
DELETE FROM users WHERE id = 2; -- Deletes Bob

-- Delete users whose name starts with 'D'
DELETE FROM users WHERE name LIKE 'D%'; -- Deletes David

-- Delete users with a NULL email
DELETE FROM users WHERE email IS NULL; -- Deletes Eve

-- Select all data after deletions
.headers on
.mode column
SELECT * FROM users;
EOF

# Clean up the database file
rm my_database.db
echo "Cleaned up my_database.db."

echo "--- Initializing Git repository ---"
# Initialize a new Git repository
mkdir git_example
cd git_example
git init
echo ""

echo "--- Adding new files ---"
# Create a new file
echo "This is the first line." > file1.txt
echo "This is the second line." >> file1.txt

# Add the new file to the staging area
git add file1.txt
echo "Added file1.txt to staging area."
git status
echo ""

# Commit the staged changes
git commit -m "Initial commit: Add file1.txt"
echo "Committed file1.txt."
git log --oneline --max-count=1
echo ""

echo "--- Adding changes to an existing file ---"
# Modify an existing file
echo "This is a new line for file1." >> file1.txt

# Add the modified file to the staging area
git add file1.txt
echo "Added modified file1.txt to staging area."
git status
echo ""

# Create another file and add it
echo "Content for file2." > file2.txt
git add file2.txt
echo "Added file2.txt to staging area."
git status
echo ""

# Commit all staged changes
git commit -m "Update file1 and add file2"
echo "Committed updates."
git log --oneline --max-count=2

cd git_example # Ensure we are in the example directory

echo "--- Deleting files from Git ---"

# Delete a file from the working directory and stage its removal
git rm file2.txt
echo "Removed file2.txt from working directory and staged for commit."
git status
echo ""

# Commit the deletion
git commit -m "Remove file2.txt"
echo "Committed file2.txt removal."
git log --oneline --max-count=1
ls -F
echo ""

echo "--- Deleting changes / Restoring files ---"
# Modify file1.txt to simulate unwanted changes
echo "This line will be deleted." >> file1.txt
echo "Modified file1.txt with an unwanted line."
cat file1.txt
echo ""

# Discard changes in the working directory (restores to last commit)
git restore file1.txt
echo "Discarded changes to file1.txt."
cat file1.txt
echo ""

# Unstage a file (moves it from staging area back to modified state)
echo "Another unwanted line." >> file1.txt
git add file1.txt # Stage it first
echo "Added unwanted changes to staging."
git status
echo ""

git restore --staged file1.txt # Unstage it
echo "Unstaged file1.txt."
git status
echo ""

# Note: The file itself is still modified, just not staged.
cat file1.txt

# Clean up the Git example directory
cd ..
rm -rf git_example
echo "Cleaned up git_example directory."