using System;
using System.IO;
using Microsoft.Data.Sqlite;
using SabreTools.Hashing;
using SabreTools.IO.Extensions;
using SabreTools.Skippers;

namespace Headerer
{
    internal static class Extract
    {
        /// <summary>
        /// Detect header skipper compliance and create an output file
        /// </summary>
        /// <param name="file">Name of the file to be parsed</param>
        /// <param name="outDir">Output directory to write the file to, empty means the same directory as the input file</param>
        /// <param name="nostore">True if headers should not be stored in the database, false otherwise</param>
        /// <returns>True if the output file was created, false otherwise</returns>
        public static bool DetectTransformStore(string file, string? outDir, bool nostore)
        {
            // Create the output directory if it doesn't exist
            if (!string.IsNullOrWhiteSpace(outDir) && !Directory.Exists(outDir))
                Directory.CreateDirectory(outDir);

            Console.WriteLine($"\nGetting skipper information for '{file}'");

            // Get the skipper rule that matches the file, if any
            SkipperMatch.Init();
            Rule rule = SkipperMatch.GetMatchingRule(file, string.Empty);

            // If we have an empty rule, return false
            if (rule.Tests == null || rule.Tests.Length == 0 || rule.Operation != HeaderSkipOperation.None)
                return false;

            Console.WriteLine("File has a valid copier header");

            // Get the header bytes from the file first
            string hstr;
            try
            {
                // Extract the header as a string for the database
                using var fs = File.OpenRead(file);
                int startOffset = int.Parse(rule.StartOffset ?? "0");
                byte[] hbin = new byte[startOffset];
                fs.Read(hbin, 0, startOffset);
                hstr = ByteArrayExtensions.ByteArrayToString(hbin)!;
            }
            catch
            {
                return false;
            }

            // Apply the rule to the file
            string newfile = string.IsNullOrWhiteSpace(outDir) ? Path.GetFullPath(file) + ".new" : Path.Combine(outDir, Path.GetFileName(file));
            rule.TransformFile(file, newfile);

            // If the output file doesn't exist, return false
            if (!File.Exists(newfile))
                return false;

            // Now add the information to the database if it's not already there
            if (!nostore)
            {
                string sha1 = HashTool.GetFileHash(newfile, HashType.SHA1) ?? string.Empty;
                AddHeaderToDatabase(hstr, sha1, rule.SourceFile!);
            }

            return true;
        }

        /// <summary>
        /// Add a header to the database
        /// </summary>
        /// <param name="header">String representing the header bytes</param>
        /// <param name="SHA1">SHA-1 of the deheadered file</param>
        /// <param name="type">Name of the source skipper file</param>
        private static void AddHeaderToDatabase(string header, string SHA1, string source)
        {
            // Ensure the database exists
            Database.EnsureDatabase();

            // Open the database connection
            SqliteConnection dbc = new(Database.HeadererConnectionString);
            dbc.Open();

            string query = $"SELECT * FROM data WHERE sha1='{SHA1}' AND header='{header}'";
            var slc = new SqliteCommand(query, dbc);
            SqliteDataReader sldr = slc.ExecuteReader();
            bool exists = sldr.HasRows;

            if (!exists)
            {
                query = $"INSERT INTO data (sha1, header, type) VALUES ('{SHA1}', '{header}', '{source}')";
                slc = new SqliteCommand(query, dbc);
                Console.WriteLine($"Result of inserting header: {slc.ExecuteNonQuery()}"); // TODO: Gate behind debug flag
            }

            // Dispose of database objects
            slc.Dispose();
            sldr.Dispose();
            dbc.Dispose();
        }
    }
}