using System;
using System.Collections.Generic;
using System.IO;
using NLog;

namespace DataModel.Process
{
    public class QueryRepository
    {
        /// <summary>
        /// Repository name
        /// </summary>
        public string Name { get; }

        /// <summary>
        /// Repository base directory
        /// </summary>
        public string BaseDirectory { get; }

        /// <summary>
        /// In memory cache
        /// </summary>
        private static readonly Dictionary<string, string> cache = new Dictionary<string, string>();

        /// <summary>
        /// Shared logger instance
        /// </summary>
        private static readonly Logger logger = LogManager.GetCurrentClassLogger();

        /// <summary>
        /// Constructor
        /// </summary>
        /// <param name="name">Repository name</param>
        /// <param name="baseDirectory">Repository base directory</param>
        public QueryRepository(string name, string baseDirectory)
        {
            Name = name;
            BaseDirectory = baseDirectory;

            if (!Directory.Exists(baseDirectory))
            {
                Directory.CreateDirectory(baseDirectory);
            }

            logger.Info($"Query repository '{name}' initialized at base directory '{baseDirectory}'.");
        }

        /// <summary>
        /// Gets query SQL
        /// </summary>
        /// <param name="queryName">Name of query to get SQL for</param>
        /// <returns>Query SQL</returns>
        public string GetQuery(string queryName)
        {
            string querySource = string.Empty;

            if (!cache.TryGetValue(queryName, out querySource))
            {
                //Check if file exists
                string fullPath = Path.Combine(BaseDirectory, $"{queryName}.sql");
                if (!File.Exists(fullPath))
                {
                    throw new Exception($"Cannot retreive query '{queryName}': '{fullPath}' does not exist");
                }

                //Read file
                querySource = File.ReadAllText(fullPath);

                querySource = querySource.Replace("PRODDTA", "PRODDTA");
                querySource = querySource.Replace("ARCDTAPD", "ARCDTAPD");
                File.WriteAllText(fullPath, querySource);

                //Cache source
                cache.Add(queryName, querySource);
            }

            return querySource;
        }

        /// <summary>
        /// Sets querie's SQL
        /// </summary>
        /// <param name="queryName">Name of query to set SQL for</param>
        /// <param name="querySource">SQL to set for query</param>
        public void SetQuery(string queryName, string querySource)
        {
            logger.Info($"[{Name}] setting SQL for query '{queryName}'.");

            //Update cache
            cache[queryName] = querySource;

            //Write source to file
            string fullPath = Path.Combine(BaseDirectory, $"{queryName}.sql");
            File.WriteAllText(fullPath, querySource);
        }

        /// <summary>
        /// Indexer override
        /// </summary>
        /// <param name="queryName">Name of query</param>
        /// <returns>SQL for query</returns>
        public string this[string queryName]
        {
            get => GetQuery(queryName);
            set => SetQuery(queryName, value);
        }
    }
}