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

namespace Island.StandardLib.Utils
{
    /// <summary>
    /// 本地配置文件的读写程序
    /// </summary>
    public class ConfigFileIO
    {
        private class Statement
        {
            internal bool isCommit;
            internal string name, value;

            internal Statement(string commit)
            {
                name = commit;
                isCommit = true;
            }

            internal Statement(string name, string value)
            {
                this.name = name;
                this.value = value;
            }

            internal string toLine()
            {
                StringBuilder sb = new StringBuilder();
                if (isCommit)
                {
                    sb.Append("#");
                    sb.Append(name);
                }
                else
                {
                    sb.Append(name);
                    sb.Append("=");
                    sb.Append(value);
                }
                return sb.ToString();
            }

            internal static Statement readLine(string line)
            {
                line = line.Trim().Replace("\n", "");
                if (line.Length == 0) return new Statement("");
                if (line[0] == '#') return new Statement(line.Substring(1));
                if (!line.Contains('=')) return new Statement(line);
                return new Statement(line.Substring(0, line.IndexOf('=')), line.Substring(line.IndexOf('=') + 1));
            }
        }

        List<Statement> statements;
        string file;

        /// <summary>
        /// 用文件路径初始化读写器
        /// </summary>
        /// <param name="file"></param>
        public ConfigFileIO(string file)
        {
            this.file = file;
            statements = new List<Statement>();
            StreamReader sr = new StreamReader(file, Encoding.UTF8);
            string buf;
            while ((buf = sr.ReadLine()) != null)
                statements.Add(Statement.readLine(buf));
            sr.Close();
        }

        public ConfigFileIO()
        {
            statements = new List<Statement>();
        }

        public string StorageFile { get => file; set => file = value; }

        /// <summary>
        /// 获取或设置一个属性，注意设置属性后如果要更改到硬盘需要手动调用 <see cref="Save"/> 保存更改
        /// </summary>
        /// <param name="name">属性名</param>
        /// <returns>属性值</returns>
        public string this[string name]
        {
            get
            {
                foreach (Statement statement in statements)
                {
                    if (!statement.isCommit && statement.name == name)
                        return statement.value;
                }
                return null;
            }
            set
            {
                foreach (Statement statement in statements)
                {
                    if (!statement.isCommit && statement.name == name)
                    {
                        statement.value = value;
                        return;
                    }
                }
                statements.Add(new Statement(name, value));
            }
        }

        /// <summary>
        /// 添加注释，注意手动 <see cref="Save"/>（若需要）
        /// </summary>
        /// <param name="commit">注释内容</param>
        public void AddCommit(string commit) => statements.Add(new Statement(commit));

        /// <summary>
        /// 获取值，如果没有那个属性则返回给定值
        /// </summary>
        /// <param name="name">属性名</param>
        /// <param name="default_ifnull">给定值</param>
        /// <returns>属性值</returns>
        public string SoftGet(string name, string default_ifnull = "")
        {
            string value = this[name];
            if (value == null) return default_ifnull;
            else return value;
        }

        /// <summary>
        /// 保存更改到硬盘
        /// </summary>
        public void Save()
        {
            StreamWriter sw = new StreamWriter(file, false, Encoding.UTF8);
            foreach (Statement statement in statements)
                sw.WriteLine(statement.toLine());
            sw.Flush();
            sw.Close();
        }
    }
}