using System;
using System.Collections.Generic;
using System.Data;
using System.IO;
using Junction.Domain;
using Junction.Persistence;
using Xunit;

namespace Junction.Tests.Unit
{
    /// <summary>
    /// Integration-style tests against a REAL SQLite file. Proves the native e_sqlite3
    /// library loads and runs on the Linux net8.0 test host (relevant to the net48 story).
    /// </summary>
    public sealed class SqliteSchemaTests : IDisposable
    {
        private readonly string _dbPath;
        private readonly string _connectionString;

        public SqliteSchemaTests()
        {
            _dbPath = Path.Combine(Path.GetTempPath(), "junction_test_" + Guid.NewGuid().ToString("N") + ".db");
            _connectionString = "Data Source=" + _dbPath;
        }

        public void Dispose()
        {
            try
            {
                if (File.Exists(_dbPath))
                {
                    File.Delete(_dbPath);
                }
            }
            catch
            {
                // best-effort cleanup
            }
        }

        [Fact]
        public void ConnectionFactory_OpensUsableConnection()
        {
            var factory = new SqliteConnectionFactory(_connectionString);

            using (IDbConnection connection = factory.CreateOpenConnection())
            {
                Assert.Equal(ConnectionState.Open, connection.State);

                using (var cmd = connection.CreateCommand())
                {
                    cmd.CommandText = "SELECT 1;";
                    var value = Convert.ToInt64(cmd.ExecuteScalar());
                    Assert.Equal(1L, value);
                }
            }
        }

        [Fact]
        public void EnsureCreated_CreatesAllThreeTables()
        {
            var factory = new SqliteConnectionFactory(_connectionString);

            Result result = SqliteSchema.EnsureCreated(factory);

            Assert.True(result.IsSuccess, DescribeErrors(result));

            var tables = QueryTableNames();
            Assert.Contains("machines", tables);
            Assert.Contains("latest_snapshots", tables);
            Assert.Contains("snapshot_items", tables);
        }

        [Fact]
        public void EnsureCreated_IsIdempotent()
        {
            var factory = new SqliteConnectionFactory(_connectionString);

            Result first = SqliteSchema.EnsureCreated(factory);
            Result second = SqliteSchema.EnsureCreated(factory);

            Assert.True(first.IsSuccess, DescribeErrors(first));
            Assert.True(second.IsSuccess, DescribeErrors(second));

            var tables = QueryTableNames();
            Assert.Contains("machines", tables);
            Assert.Contains("latest_snapshots", tables);
            Assert.Contains("snapshot_items", tables);
        }

        [Fact]
        public void EnsureCreated_OnOpenConnection_Works()
        {
            var factory = new SqliteConnectionFactory(_connectionString);

            using (IDbConnection connection = factory.CreateOpenConnection())
            {
                Result result = SqliteSchema.EnsureCreated(connection);
                Assert.True(result.IsSuccess, DescribeErrors(result));
            }
        }

        private List<string> QueryTableNames()
        {
            var names = new List<string>();
            var factory = new SqliteConnectionFactory(_connectionString);

            using (IDbConnection connection = factory.CreateOpenConnection())
            using (var cmd = connection.CreateCommand())
            {
                cmd.CommandText = "SELECT name FROM sqlite_master WHERE type = 'table';";
                using (var reader = cmd.ExecuteReader())
                {
                    while (reader.Read())
                    {
                        names.Add(reader.GetString(0));
                    }
                }
            }

            return names;
        }

        private static string DescribeErrors(Result result)
        {
            if (result.IsSuccess)
            {
                return "";
            }

            return string.Join("; ", System.Linq.Enumerable.Select(result.Errors, e => e.ToString()));
        }
    }
}