using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.IO;
using System.Reflection;
using System.Security.Cryptography;

namespace EMPlannerVerificationHost;

internal static class PluginPackagingChecks
{
    public static void Run()
    {
        string repositoryRoot = Directory.GetCurrentDirectory();
        string scriptPath = Path.Combine(repositoryRoot, "ClumsyPilot", "scripts", "Publish-ClumsyPilotPlugin.ps1");
        Verification.True(File.Exists(scriptPath), "plugin publish script exists");

        string managedDll = Path.Combine(AppContext.BaseDirectory, "ClumsyPilot.dll");
        Verification.True(File.Exists(managedDll), "verification host has managed ClumsyPilot.dll");
        VerifyBuildOutputMetadata();

        string packageRoot = Path.Combine(Path.GetTempPath(), "em-planner-plugin-package-" + Guid.NewGuid().ToString("N"));
        Directory.CreateDirectory(packageRoot);
        try
        {
            Publish(scriptPath, managedDll, packageRoot);
            VerifyPackage(repositoryRoot, packageRoot);

            Publish(scriptPath, managedDll, packageRoot);
            VerifyPackage(repositoryRoot, packageRoot);
            AssertNoStaleSiblingDirectories(packageRoot);
        }
        finally
        {
            if (Directory.Exists(packageRoot))
                Directory.Delete(packageRoot, true);
        }
    }

    private static void Publish(string scriptPath, string managedDll, string packageRoot)
    {
        var startInfo = new ProcessStartInfo
        {
            FileName = "powershell.exe",
            WorkingDirectory = Directory.GetCurrentDirectory(),
            UseShellExecute = false,
            CreateNoWindow = true,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
        };
        startInfo.ArgumentList.Add("-NoProfile");
        startInfo.ArgumentList.Add("-ExecutionPolicy");
        startInfo.ArgumentList.Add("Bypass");
        startInfo.ArgumentList.Add("-File");
        startInfo.ArgumentList.Add(scriptPath);
        startInfo.ArgumentList.Add("-ManagedDll");
        startInfo.ArgumentList.Add(managedDll);
        startInfo.ArgumentList.Add("-OutputDirectory");
        startInfo.ArgumentList.Add(packageRoot);

        using (var process = new Process { StartInfo = startInfo })
        {
            process.Start();
            string standardOutput = process.StandardOutput.ReadToEnd();
            string standardError = process.StandardError.ReadToEnd();
            process.WaitForExit();
            if (process.ExitCode != 0)
            {
                throw new InvalidOperationException("plugin publish exited " + process.ExitCode + ": " +
                    standardOutput + standardError);
            }
        }
    }

    private static void VerifyPackage(string repositoryRoot, string packageRoot)
    {
        string pluginsDirectory = Path.Combine(packageRoot, "plugins");
        Verification.True(Directory.Exists(pluginsDirectory), "plugins directory exists");

        var relativeFiles = new List<string>();
        string[] files = Directory.GetFiles(pluginsDirectory, "*", SearchOption.AllDirectories);
        for (int index = 0; index < files.Length; index++)
            relativeFiles.Add(Path.GetRelativePath(packageRoot, files[index]).Replace('\\', '/'));
        relativeFiles.Sort(StringComparer.Ordinal);

        Verification.Equal("plugins/ClumsyPilot.dll|plugins/TrajectoryPlanningVisualization.dll|" +
            "plugins/licenses/OSQP-LICENSE.txt|plugins/licenses/OSQP-NOTICE.txt|plugins/licenses/OSQP-VERSION.txt|" +
            "plugins/osqp.dll", string.Join("|", relativeFiles),
            "plugin tree contains exactly the managed DLLs, native DLL, and OSQP license files");

        string managedPlugin = Path.Combine(pluginsDirectory, "ClumsyPilot.dll");
        AssemblyName managedAssembly = AssemblyName.GetAssemblyName(managedPlugin);
        Verification.True(!string.IsNullOrWhiteSpace(managedAssembly.Name), "packaged ClumsyPilot.dll is managed");

        string visualizationPlugin = Path.Combine(pluginsDirectory, "TrajectoryPlanningVisualization.dll");
        AssemblyName visualizationAssembly = AssemblyName.GetAssemblyName(visualizationPlugin);
        Verification.Equal("TrajectoryPlanningVisualization", visualizationAssembly.Name,
            "packaged visualization DLL has the expected managed assembly name");

        string nativePlugin = Path.Combine(pluginsDirectory, "osqp.dll");
        Verification.Equal((ushort)0x8664, ReadPeMachine(nativePlugin), "packaged OSQP binary is x64");
        Verification.Equal(ReadExpectedOsqpHash(repositoryRoot), GetSha256(nativePlugin),
            "packaged OSQP hash matches SHA256SUMS");
    }

    private static void AssertNoStaleSiblingDirectories(string packageRoot)
    {
        string parentDirectory = Path.GetDirectoryName(packageRoot) ??
            throw new InvalidOperationException("temporary package root has no parent directory");
        string prefix = Path.GetFileName(packageRoot);
        string[] matchingDirectories = Directory.GetDirectories(parentDirectory, prefix + "*");
        Verification.Equal(1, matchingDirectories.Length, "publish leaves no stale sibling staging directory");
        Verification.Equal(packageRoot, matchingDirectories[0], "publish keeps only the requested temporary test root");
    }

    private static ushort ReadPeMachine(string path)
    {
        byte[] bytes = File.ReadAllBytes(path);
        Verification.True(bytes.Length > 0x40 && bytes[0] == 'M' && bytes[1] == 'Z', "OSQP has DOS header");
        int peOffset = BitConverter.ToInt32(bytes, 0x3c);
        Verification.True(peOffset >= 0 && peOffset + 6 <= bytes.Length && bytes[peOffset] == 'P' &&
            bytes[peOffset + 1] == 'E', "OSQP has PE header");
        return BitConverter.ToUInt16(bytes, peOffset + 4);
    }

    private static string ReadExpectedOsqpHash(string repositoryRoot)
    {
        string manifestPath = Path.Combine(repositoryRoot, "ClumsyPilot", "ThirdParty", "OSQP", "SHA256SUMS");
        string[] tokens = File.ReadAllText(manifestPath).Split((char[]?)null, StringSplitOptions.RemoveEmptyEntries);
        Verification.True(tokens.Length >= 2 && string.Equals(tokens[1], "win-x64/osqp.dll", StringComparison.Ordinal),
            "OSQP hash manifest describes the pinned x64 runtime");
        return tokens[0].ToLowerInvariant();
    }

    private static string GetSha256(string path)
    {
        return Convert.ToHexString(SHA256.HashData(File.ReadAllBytes(path))).ToLowerInvariant();
    }

    private static void VerifyBuildOutputMetadata()
    {
        string outputDirectory = AppContext.BaseDirectory;
        Verification.True(File.Exists(Path.Combine(outputDirectory, "osqp.dll")),
            "build output contains the pinned OSQP runtime");
        Verification.True(File.Exists(Path.Combine(outputDirectory, "licenses", "OSQP-LICENSE.txt")),
            "build output contains the OSQP license");
        Verification.True(File.Exists(Path.Combine(outputDirectory, "licenses", "OSQP-NOTICE.txt")),
            "build output contains the OSQP notice");
        Verification.True(File.Exists(Path.Combine(outputDirectory, "licenses", "OSQP-VERSION.txt")),
            "build output contains the OSQP version");
    }
}