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

namespace DrillTools
{
    /// <summary>
    /// 二钻涨缩系数的 ini 持久化存储。
    /// 存放于 %LocalAppData%\DrillTools\scaling.ini，UTF-8 无 BOM，
    /// 只保留最近一次涨缩记录（模式 + 输入值 + 源文件名）。
    /// </summary>
    internal static class ScalingProfileStore
    {
        private const string SectionName = "LastScaling";
        private const string KeyMode = "Mode";
        private const string KeyInputX = "InputX";
        private const string KeyInputY = "InputY";
        private const string KeyFileName = "FileName";

        /// <summary>
        /// ini 配置文件完整路径：%LocalAppData%\DrillTools\scaling.ini
        /// </summary>
        private static string GetIniPath()
        {
            string dir = Path.Combine(
                Environment.GetFolderPath(Environment.SpecialFolder.LocalApplicationData),
                "DrillTools");
            return Path.Combine(dir, "scaling.ini");
        }

        /// <summary>
        /// 读取上次涨缩记录。
        /// 文件不存在或缺少必需键（含模式无法解析）时返回 null；其它 IO 异常向上抛出，由调用边界处理。
        /// </summary>
        public static ScalingRecord? Load()
        {
            string path = GetIniPath();
            if (!File.Exists(path))
                return null;

            // 简易 ini 解析：按 [section] 切节，仅在目标节内收集 key=value
            var values = new Dictionary<string, string>(StringComparer.OrdinalIgnoreCase);
            bool inSection = false;
            foreach (var raw in File.ReadAllLines(path))
            {
                string line = raw.Trim();
                if (line.Length == 0 || line.StartsWith(";"))
                    continue;

                // 节标题
                if (line.StartsWith("[") && line.EndsWith("]"))
                {
                    inSection = line.Equals($"[{SectionName}]", StringComparison.OrdinalIgnoreCase);
                    continue;
                }

                if (!inSection)
                    continue;

                int eq = line.IndexOf('=');
                if (eq <= 0)
                    continue;

                string key = line.Substring(0, eq).Trim();
                string val = line.Substring(eq + 1).Trim();
                values[key] = val;
            }

            // 必需键校验：缺任一或模式无法解析视为无有效记录（容错损坏）
            if (!values.TryGetValue(KeyMode, out string? modeStr) ||
                !values.TryGetValue(KeyInputX, out string? inputX) ||
                !values.TryGetValue(KeyInputY, out string? inputY))
                return null;

            if (!Enum.TryParse(modeStr, out ScalingMode mode))
                return null;

            // 文件名为可选追溯字段
            values.TryGetValue(KeyFileName, out string? fileName);

            return new ScalingRecord(mode, inputX, inputY, fileName);
        }

        /// <summary>
        /// 写入涨缩记录，整体覆盖。自动创建目录。失败时抛出异常，由调用边界处理。
        /// </summary>
        public static void Save(ScalingMode mode, string inputX, string inputY, string fileName)
        {
            string path = GetIniPath();
            string? dir = Path.GetDirectoryName(path);
            if (!string.IsNullOrEmpty(dir))
                Directory.CreateDirectory(dir);

            var content =
                $"[{SectionName}]\r\n" +
                $"{KeyMode}={mode}\r\n" +
                $"{KeyInputX}={inputX}\r\n" +
                $"{KeyInputY}={inputY}\r\n" +
                $"{KeyFileName}={fileName}\r\n";

            // UTF-8 无 BOM（项目文件编码规范）
            File.WriteAllText(path, content, new UTF8Encoding(false));
        }
    }

    /// <summary>
    /// 涨缩系数持久化记录（只读）。
    /// </summary>
    internal sealed class ScalingRecord
    {
        public ScalingMode Mode { get; }
        public string InputX { get; }
        public string InputY { get; }
        public string? FileName { get; }

        public ScalingRecord(ScalingMode mode, string inputX, string inputY, string? fileName)
        {
            Mode = mode;
            InputX = inputX;
            InputY = inputY;
            FileName = fileName;
        }
    }
}