using System;
using System.IO;
using System.Linq;
using System.Security.Cryptography;
using System.Threading;
using System.Threading.Tasks;
using Microsoft.Extensions.Hosting;
using Npgsql;
using PhoenixLib.Logging;

namespace Plugin.ResourceLoader.Services
{
    public class ResourceFilesPostgresSyncService : IHostedService
    {
        private readonly ResourceLoadingConfiguration _configuration;

        public ResourceFilesPostgresSyncService(ResourceLoadingConfiguration configuration)
        {
            _configuration = configuration;
        }

        public Task StartAsync(CancellationToken cancellationToken)
        {
            if (string.Equals(Environment.GetEnvironmentVariable("PARSER_DB_SYNC"), "false", StringComparison.OrdinalIgnoreCase))
            {
                return Task.CompletedTask;
            }

            try
            {
                string host = Environment.GetEnvironmentVariable("DATABASE_IP")
                              ?? Environment.GetEnvironmentVariable("POSTGRES_DATABASE_IP")
                              ?? "127.0.0.1";
                string port = Environment.GetEnvironmentVariable("DATABASE_PORT")
                              ?? Environment.GetEnvironmentVariable("POSTGRES_DATABASE_PORT")
                              ?? "5432";
                string db = Environment.GetEnvironmentVariable("DATABASE_NAME")
                            ?? Environment.GetEnvironmentVariable("POSTGRES_DATABASE_NAME")
                            ?? "game";
                string user = Environment.GetEnvironmentVariable("DATABASE_USER")
                              ?? Environment.GetEnvironmentVariable("POSTGRES_DATABASE_USER")
                              ?? "postgres";
                string pass = Environment.GetEnvironmentVariable("DATABASE_PASSWORD")
                              ?? Environment.GetEnvironmentVariable("POSTGRES_DATABASE_PASSWORD")
                              ?? "postgres";

                string root = _configuration.ResourcePaths;
                string datPath = _configuration.GameDataPath;
                string langPath = _configuration.GameLanguagePath;

                string[] datFiles = Directory.Exists(datPath)
                    ? Directory.GetFiles(datPath, "*", SearchOption.AllDirectories)
                    : Array.Empty<string>();
                string[] langFiles = Directory.Exists(langPath)
                    ? Directory.GetFiles(langPath, "*", SearchOption.AllDirectories)
                    : Array.Empty<string>();

                using var conn = new NpgsqlConnection($"Host={host};Port={port};Database={db};Username={user};Password={pass}");
                conn.Open();
                using var tx = conn.BeginTransaction();

                using (var cmd = new NpgsqlCommand(@"CREATE TABLE IF NOT EXISTS resource_files (
  id BIGSERIAL PRIMARY KEY,
  category TEXT NOT NULL,
  relative_path TEXT NOT NULL,
  sha256 TEXT NOT NULL,
  content BYTEA NOT NULL,
  size_bytes INT NOT NULL,
  synced_at TIMESTAMP NOT NULL DEFAULT NOW(),
  UNIQUE(category, relative_path)
);", conn, tx))
                {
                    cmd.ExecuteNonQuery();
                }

                UpsertFiles(conn, tx, root, "dat", datFiles);
                UpsertFiles(conn, tx, root, "lang", langFiles);

                tx.Commit();
                Log.Info($"[PARSER_DB_SYNC] Synced resource_files dat={datFiles.Length} lang={langFiles.Length}");
            }
            catch (Exception ex)
            {
                Log.Error("[PARSER_DB_SYNC] Failed to sync resource files", ex);
            }

            return Task.CompletedTask;
        }

        public Task StopAsync(CancellationToken cancellationToken) => Task.CompletedTask;

        private static void UpsertFiles(NpgsqlConnection conn, NpgsqlTransaction tx, string root, string category, string[] files)
        {
            foreach (string file in files.Where(File.Exists))
            {
                byte[] content = File.ReadAllBytes(file);
                string hash;
                using (SHA256 sha = SHA256.Create())
                {
                    hash = Convert.ToHexString(sha.ComputeHash(content));
                }

                string relative = Path.GetRelativePath(root, file).Replace('\\', '/');

                using var cmd = new NpgsqlCommand(@"INSERT INTO resource_files(category,relative_path,sha256,content,size_bytes,synced_at)
VALUES (@category,@path,@sha,@content,@size,NOW())
ON CONFLICT (category, relative_path)
DO UPDATE SET sha256=EXCLUDED.sha256, content=EXCLUDED.content, size_bytes=EXCLUDED.size_bytes, synced_at=NOW();", conn, tx);
                cmd.Parameters.AddWithValue("category", category);
                cmd.Parameters.AddWithValue("path", relative);
                cmd.Parameters.AddWithValue("sha", hash);
                cmd.Parameters.AddWithValue("content", content);
                cmd.Parameters.AddWithValue("size", content.Length);
                cmd.ExecuteNonQuery();
            }
        }
    }
}