using System.Collections.Generic;
using System.IO;
using System.Runtime.CompilerServices;
using System.Text.RegularExpressions;
using NUnit.Framework;

namespace ProjectM.Tests
{
    /// <summary>
    /// Anti-regression guard for the "an edit swallowed the [Test] attribute" hazard — a real dead test shipped at
    /// EnemyAIMathTests.cs:107 (a regression guard for the enemy-stuck-on-cover fix that silently never ran). Scans
    /// every *Tests.cs source file in this directory and FAILS if a parameterless public-void method (the suite's
    /// test-method shape — every helper is static, so `public void` uniquely selects tests) is not immediately
    /// preceded by a runner attribute. File I/O is available at EditMode-test time.
    /// </summary>
    public class TestAttributeGuardTests
    {
        static string ThisDir([CallerFilePath] string p = "") => Path.GetDirectoryName(p);

        static readonly Regex TestMethod = new Regex(@"^\s*public\s+void\s+[A-Za-z_]\w*\s*\(\s*\)", RegexOptions.Compiled);
        static readonly Regex RunnerAttr = new Regex(@"\[\s*(Test|TestCase|TestCaseSource|Theory|SetUp|TearDown|OneTimeSetUp|OneTimeTearDown)\b", RegexOptions.Compiled);

        [Test]
        public void Every_Public_Void_Test_Method_Has_A_Runner_Attribute()
        {
            var dir = ThisDir();
            Assert.IsTrue(Directory.Exists(dir), $"Test source dir not found: {dir}");

            var offenders = new List<string>();
            foreach (var file in Directory.GetFiles(dir, "*Tests.cs"))
            {
                var lines = File.ReadAllLines(file);
                for (int i = 0; i < lines.Length; i++)
                {
                    if (!TestMethod.IsMatch(lines[i]))
                        continue;
                    // Walk upward past blank / comment lines to the nearest attribute or non-trivial line.
                    bool attributed = false;
                    for (int j = i - 1; j >= 0; j--)
                    {
                        string t = lines[j].Trim();
                        if (t.Length == 0 || t.StartsWith("//") || t.StartsWith("/*") || t.StartsWith("*"))
                            continue;
                        if (t.StartsWith("["))
                        {
                            if (RunnerAttr.IsMatch(t)) { attributed = true; break; }
                            continue; // a non-runner attribute line — keep scanning the attribute block
                        }
                        break; // hit a brace / statement: no attribute block above this method
                    }
                    if (!attributed)
                        offenders.Add($"{Path.GetFileName(file)}:{i + 1}  {lines[i].Trim()}");
                }
            }

            Assert.IsEmpty(offenders,
                "Test methods missing a runner attribute (swallowed [Test]?):\n" + string.Join("\n", offenders));
        }
    }
}