MPF/MPF.Core/Data/IniFile.cs

using System;
using System.Collections;
using System.Collections.Generic;
using System.IO;
using System.Linq;

namespace MPF.Core.Data
{
    public class IniFile : IDictionary<string, string>
    {
        private Dictionary<string, string> _keyValuePairs = [];

        public string this[string key]
        {
            get
            {
                _keyValuePairs ??= [];

                key = key.ToLowerInvariant();
                if (_keyValuePairs.TryGetValue(key, out string? val))
                    return val;

                return string.Empty;
            }
            set
            {
                _keyValuePairs ??= [];

                key = key.ToLowerInvariant();
                _keyValuePairs[key] = value;
            }
        }

        /// <summary>
        /// Create an empty INI file
        /// </summary>
        public IniFile()
        {
        }

        /// <summary>
        /// Populate an INI file from path
        /// </summary>
        public IniFile(string path)
        {
            this.Parse(path);
        }

        /// <summary>
        /// Populate an INI file from stream
        /// </summary>
        public IniFile(Stream stream)
        {
            this.Parse(stream);
        }

        /// <summary>
        /// Add or update a key and value to the INI file
        /// </summary>
        public void AddOrUpdate(string key, string value)
        {
            _keyValuePairs[key.ToLowerInvariant()] = value;
        }

        /// <summary>
        /// Remove a key from the INI file
        /// </summary>
        public void Remove(string key)
        {
            _keyValuePairs.Remove(key.ToLowerInvariant());
        }

        /// <summary>
        /// Read an INI file based on the path
        /// </summary>
        public bool Parse(string path)
        {
            // If we don't have a file, we can't read it
            if (!File.Exists(path))
                return false;

            using var fileStream = File.OpenRead(path);
            return Parse(fileStream);
        }

        /// <summary>
        /// Read an INI file from a stream
        /// </summary>
        public bool Parse(Stream stream)
        {
            // If the stream is invalid or unreadable, we can't process it
            if (stream == null || !stream.CanRead || stream.Position >= stream.Length - 1)
                return false;

            // Keys are case-insensitive by default
            try
            {
                using var sr = new StreamReader(stream);
                string section = string.Empty;
                while (!sr.EndOfStream)
                {
                    var line = sr.ReadLine()?.Trim();

                    // Empty lines are skipped
                    if (string.IsNullOrEmpty(line))
                    {
                        // No-op, we don't process empty lines
                    }

                    // Comments start with ';'
                    else if (line!.StartsWith(";"))
                    {
                        // No-op, we don't process comments
                    }

                    // Section titles are surrounded by square brackets
                    else if (line.StartsWith("["))
                    {
                        section = line.TrimStart('[').TrimEnd(']');
                    }

                    // Valid INI lines are in the format key=value
                    else if (line.Contains('='))
                    {
                        // Split the line by '=' for key-value pairs
                        string[] data = line.Split('=');

                        // If the value field contains an '=', we need to put them back in
                        string key = data[0].Trim();
                        string value = string.Join("=", data.Skip(1).ToArray()).Trim();

                        // Section names are prepended to the key with a '.' separating
                        if (!string.IsNullOrEmpty(section))
                            key = $"{section}.{key}";

                        // Set or overwrite keys in the returned dictionary
                        _keyValuePairs[key.ToLowerInvariant()] = value;
                    }

                    // All other lines are ignored
                }
            }
            catch
            {
                // We don't care what the error was, just catch and return
                return false;
            }

            return true;
        }

        /// <summary>
        /// Write an INI file to a path
        /// </summary>
        public bool Write(string path)
        {
            // If we don't have a valid dictionary with values, we can't write out
            if (_keyValuePairs == null || _keyValuePairs.Count == 0)
                return false;

            using var fileStream = File.OpenWrite(path);
            return Write(fileStream);
        }

        /// <summary>
        /// Write an INI file to a stream
        /// </summary>
        public bool Write(Stream stream)
        {
            // If we don't have a valid dictionary with values, we can't write out
            if (_keyValuePairs == null || _keyValuePairs.Count == 0)
                return false;

            // If the stream is invalid or unwritable, we can't output to it
            if (stream == null || !stream.CanWrite || stream.Position >= stream.Length - 1)
                return false;

            try
            {
                // Order the dictionary by keys to link sections together
                using var sw = new StreamWriter(stream);
                var orderedKeyValuePairs = _keyValuePairs.OrderBy(kvp => kvp.Key);

                string section = string.Empty;
                foreach (var keyValuePair in orderedKeyValuePairs)
                {
                    // Extract the key and value
                    string key = keyValuePair.Key;
                    string value = keyValuePair.Value;

                    // We assume '.' is a section name separator
                    if (key.Contains('.'))
                    {
                        // Split the key by '.'
                        string[] data = keyValuePair.Key.Split('.');

                        // If the key contains an '.', we need to put them back in
                        string newSection = data[0].Trim();
                        key = string.Join(".", data.Skip(1).ToArray()).Trim();

                        // If we have a new section, write it out
                        if (!string.Equals(newSection, section, StringComparison.OrdinalIgnoreCase))
                        {
                            sw.WriteLine($"[{newSection}]");
                            section = newSection;
                        }
                    }

                    // Now write out the key and value in a standardized way
                    sw.WriteLine($"{key}={value}");
                }
            }
            catch
            {
                // We don't care what the error was, just catch and return
                return false;
            }

            return true;
        }

        #region IDictionary Impelementations

        public ICollection<string> Keys => ((IDictionary<string, string>)_keyValuePairs).Keys;

        public ICollection<string> Values => ((IDictionary<string, string>)_keyValuePairs).Values;

        public int Count => ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).Count;

        public bool IsReadOnly => ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).IsReadOnly;

        public void Add(string key, string value)
        {
            ((IDictionary<string, string>)_keyValuePairs).Add(key.ToLowerInvariant(), value);
        }

        bool IDictionary<string, string>.Remove(string key)
        {
            return ((IDictionary<string, string>)_keyValuePairs).Remove(key.ToLowerInvariant());
        }

        public bool TryGetValue(string key, out string value)
        {
            bool result = ((IDictionary<string, string>)_keyValuePairs).TryGetValue(key.ToLowerInvariant(), out var temp);
            value = temp ?? string.Empty;
            return result;
        }

        public void Add(KeyValuePair<string, string> item)
        {
            var newItem = new KeyValuePair<string, string>(item.Key.ToLowerInvariant(), item.Value);
            ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).Add(newItem);
        }

        public void Clear()
        {
            ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).Clear();
        }

        public bool Contains(KeyValuePair<string, string> item)
        {
            var newItem = new KeyValuePair<string, string>(item.Key.ToLowerInvariant(), item.Value);
            return ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).Contains(newItem);
        }

        public bool ContainsKey(string key)
        {
            return _keyValuePairs.ContainsKey(key.ToLowerInvariant());
        }

        public void CopyTo(KeyValuePair<string, string>[] array, int arrayIndex)
        {
            ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).CopyTo(array, arrayIndex);
        }

        public bool Remove(KeyValuePair<string, string> item)
        {
            var newItem = new KeyValuePair<string, string>(item.Key.ToLowerInvariant(), item.Value);
            return ((ICollection<KeyValuePair<string, string>>)_keyValuePairs).Remove(newItem);
        }

        public IEnumerator<KeyValuePair<string, string>> GetEnumerator()
        {
            return ((IEnumerable<KeyValuePair<string, string>>)_keyValuePairs).GetEnumerator();
        }

        IEnumerator IEnumerable.GetEnumerator()
        {
            return ((IEnumerable)_keyValuePairs).GetEnumerator();
        }

        #endregion
    }
}