// Copyright (c) 2026 Juhapekka Piiroinen <jp@1337.fi>
// All Rights Reserved.
// AmoosedWeb project: https://amoosed.com
using System.Runtime.InteropServices;
using System.Security.Cryptography;
using System.Text;

const string sample = """
    {"schema":1,"gameId":"my-indie-game","revision":7,
     "minGameVersion":"1.0.0","maxGameVersion":"2.0.0",
     "items":[{"id":"release-1","kind":"release","path":"game/releases.json"}]}
    """;

if (Native.AbiRevision() != 16) throw new InvalidOperationException("Unsupported preview ABI revision");
const ulong requiredCapabilities = 0x03ff;
if (Native.Capabilities(out ulong capabilities) != 0 ||
    (capabilities & requiredCapabilities) != requiredCapabilities)
    throw new InvalidOperationException("The DLL lacks required Windows preview capabilities");
byte[] json = Encoding.UTF8.GetBytes(sample);
byte[] error = new byte[128];
int status = Native.CatalogueParse(json, (ulong)json.Length, out nint catalogue,
                                   error, (ulong)error.Length);
if (status != 0 || catalogue == 0)
    throw new InvalidOperationException($"Parse failed: {status}: {ErrorText(error)}");

try
{
    if (Native.CatalogueRevision(catalogue, out ulong revision) != 0 || revision != 7)
        throw new InvalidOperationException("Revision mismatch");
    if (Native.CatalogueItemCount(catalogue, out ulong count) != 0 || count != 1)
        throw new InvalidOperationException("Item count mismatch");
    if (Native.CatalogueItemString(catalogue, 0, 3, 0, 0, out ulong required) != 0)
        throw new InvalidOperationException("Length query failed");
    nint buffer = Marshal.AllocHGlobal(checked((int)required + 1));
    try
    {
        if (Native.CatalogueItemString(catalogue, 0, 3, buffer, required + 1,
                                       out _) != 0 ||
            Marshal.PtrToStringUTF8(buffer) != "game/releases.json")
            throw new InvalidOperationException("Path copy mismatch");
    }
    finally { Marshal.FreeHGlobal(buffer); }
}
finally { Native.CatalogueRelease(catalogue); }

byte[] invalid = Encoding.UTF8.GetBytes("{\"schema\":2}");
if (Native.CatalogueParse(invalid, (ulong)invalid.Length, out catalogue,
                          error, (ulong)error.Length) != 9 || catalogue != 0 ||
    string.IsNullOrEmpty(ErrorText(error)))
    throw new InvalidOperationException("Invalid catalogue was accepted");

string? origin = Environment.GetEnvironmentVariable("AMW_PREVIEW_SITE_ORIGIN");
if (origin is not null)
{
    RunSite(origin, Required("AMW_PREVIEW_SITE_OUTPUT"), null,
            Required("AMW_PREVIEW_MEMBER_KEY_PATH"), Required("AMW_PREVIEW_MEMBER_OUTPUT"));
    string external = Required("AMW_PREVIEW_EXTERNAL_ORIGIN");
    RunSite(external, Required("AMW_PREVIEW_EXTERNAL_OUTPUT"),
            File.ReadAllBytes(Required("AMW_PREVIEW_EXTERNAL_KEY_PATH")));
    RunSite(Required("AMW_PREVIEW_PIXEL_ORIGIN"), Required("AMW_PREVIEW_PIXEL_OUTPUT"), null);
    RunSite(Required("AMW_PREVIEW_FRAME_ORIGIN"), Required("AMW_PREVIEW_FRAME_OUTPUT"), null,
            resourcePath: "/amoosed.com/app/game/frame-note.txt");
    RunSite(Required("AMW_PREVIEW_AUDIO_ORIGIN"), Required("AMW_PREVIEW_AUDIO_OUTPUT"), null,
            resourcePath: "/amoosed.com/app/game/audio-note.txt");
    await RunCancellation(Required("AMW_PREVIEW_SLOW_ORIGIN"),
        Required("AMW_PREVIEW_SLOW_ARM"), Required("AMW_PREVIEW_SLOW_MARKER"),
        Path.GetDirectoryName(Required("AMW_PREVIEW_SITE_OUTPUT"))!);
    await RunPublishRace(Required("AMW_PREVIEW_SLOW_ORIGIN"),
        Required("AMW_PREVIEW_SLOW_ARM"), Required("AMW_PREVIEW_SLOW_MARKER"),
        Path.GetDirectoryName(Required("AMW_PREVIEW_SITE_OUTPUT"))!);
}
Console.WriteLine("OK: .NET 10 caller exercised the preview C ABI" +
                  (origin is null ? "" : " and verified hosted/external/pixel/frame/audio downloads"));

static string Required(string name) => Environment.GetEnvironmentVariable(name) ??
    throw new InvalidOperationException($"Missing {name}");

static async Task RunCancellation(string origin, string arm, string marker, string directory)
{
    byte[] originBytes = Encoding.UTF8.GetBytes(origin);
    byte[] error = new byte[256];
    if (Native.SiteOpenHosted(originBytes, (ulong)originBytes.Length, out nint site,
                              error, (ulong)error.Length) != 0 || site == 0)
        throw new InvalidOperationException($"Slow site open failed: {ErrorText(error)}");
    var target = Path.Combine(directory, $"cancelled-{Guid.NewGuid():N}.html");
    try
    {
        File.WriteAllText(arm, "armed");
        byte[] resource = Encoding.UTF8.GetBytes("/amoosed.com/app/index.html");
        byte[] output = Encoding.UTF8.GetBytes(target);
        var pending = Task.Run(() =>
        {
            int status = Native.SiteDownload(site, resource, (ulong)resource.Length,
                0, 0, output, (ulong)output.Length, out ulong bytes,
                error, (ulong)error.Length);
            return (status, bytes);
        });
        for (int i = 0; i < 500 && !File.Exists(marker) && !pending.IsCompleted; i++)
            await Task.Delay(20);
        bool inFlight = File.Exists(marker) && !pending.IsCompleted;
        Native.SiteCancel(site);
        var (status, bytes) = await pending;
        if (!inFlight || status != 7 || bytes != 0 || File.Exists(target) ||
            Directory.GetFiles(directory, Path.GetFileName(target) + ".amw-*").Length != 0)
            throw new InvalidOperationException($"In-flight cancel failed: status {status}, bytes {bytes}");
    }
    finally { File.Delete(arm); Native.SiteRelease(site); }
}

static async Task RunPublishRace(string origin, string arm, string marker, string directory)
{
    byte[] originBytes = Encoding.UTF8.GetBytes(origin);
    byte[] error = new byte[256];
    if (Native.SiteOpenHosted(originBytes, (ulong)originBytes.Length, out nint site,
                              error, (ulong)error.Length) != 0 || site == 0)
        throw new InvalidOperationException($"Race site open failed: {ErrorText(error)}");
    var target = Path.Combine(directory, $"raced-{Guid.NewGuid():N}.html");
    try
    {
        File.Delete(marker);
        File.WriteAllText(arm, "armed");
        byte[] resource = Encoding.UTF8.GetBytes("/amoosed.com/app/index.html");
        byte[] output = Encoding.UTF8.GetBytes(target);
        var pending = Task.Run(() =>
        {
            int status = Native.SiteDownload(site, resource, (ulong)resource.Length,
                0, 0, output, (ulong)output.Length, out ulong bytes,
                error, (ulong)error.Length);
            return (status, bytes);
        });
        for (int i = 0; i < 500 && !File.Exists(marker) && !pending.IsCompleted; i++)
            await Task.Delay(20);
        if (!File.Exists(marker) || pending.IsCompleted)
        {
            Native.SiteCancel(site);
            await pending;
            throw new InvalidOperationException("Download did not reach delayed carrier");
        }
        File.WriteAllText(target, "keep");
        var (status, bytes) = await pending;
        if (status != 8 || bytes != 0 || File.ReadAllText(target) != "keep" ||
            Directory.GetFiles(directory, Path.GetFileName(target) + ".amw-*").Length != 0)
            throw new InvalidOperationException($"Existing output race failed: status {status}, bytes {bytes}");
        Console.WriteLine("OK: C ABI reported ALREADY_EXISTS when output appeared during download");
    }
    finally { File.Delete(arm); Native.SiteRelease(site); }
}

static void RunSite(string origin, string outputPath, byte[]? credential,
                    string? memberKeyPath = null, string? memberOutput = null,
                    string? resourcePath = null)
{
    byte[] address = Encoding.UTF8.GetBytes(origin);
    byte[] error = new byte[256];
    int status = credential is null ?
        Native.SiteOpenHosted(address, (ulong)address.Length, out nint opened,
                              error, (ulong)error.Length) :
        Native.SiteOpenExternal(address, (ulong)address.Length, credential,
                                (ulong)credential.Length, out opened,
                                error, (ulong)error.Length);
    if (status != 0 || opened == 0)
        throw new InvalidOperationException($"Site open failed: {status}: {ErrorText(error)}");
    try
    {
        if (Native.SiteResourceCount(opened, out ulong count) != 0 || count == 0 ||
            Native.SiteEntryPath(opened, 0, 0, out ulong needed) != 0)
            throw new InvalidOperationException("Site catalogue is unavailable");
        if (Native.SiteMemberKeyId(opened, 0, 0, out ulong memberIdLength) != 0 ||
            memberIdLength != (ulong)"hello-members".Length)
            throw new InvalidOperationException("Verified member edition ID is unavailable");
        nint memberIdBuffer = Marshal.AllocHGlobal(checked((int)memberIdLength + 1));
        try
        {
            if (Native.SiteMemberKeyId(opened, memberIdBuffer, memberIdLength + 1, out _) != 0 ||
                Marshal.PtrToStringUTF8(memberIdBuffer) != "hello-members")
                throw new InvalidOperationException("Verified member edition ID differs");
        }
        finally { Marshal.FreeHGlobal(memberIdBuffer); }
        nint buffer = Marshal.AllocHGlobal(checked((int)needed + 1));
        string entry;
        try
        {
            if (Native.SiteEntryPath(opened, buffer, needed + 1, out _) != 0)
                throw new InvalidOperationException("Entry path copy failed");
            entry = Marshal.PtrToStringUTF8(buffer) ?? throw new InvalidOperationException("Missing entry");
        }
        finally { Marshal.FreeHGlobal(buffer); }
        string selected = resourcePath ?? entry;
        ulong entryIndex = ulong.MaxValue;
        for (ulong index = 0; index < count; index++)
        {
            if (ReadSiteField(opened, index, 1) == selected)
            {
                entryIndex = index;
                break;
            }
        }
        if (entryIndex == ulong.MaxValue ||
            Native.SiteResourceLength(opened, entryIndex, out ulong expectedLength) != 0 ||
            expectedLength == 0 ||
            ReadSiteField(opened, entryIndex, 3).Length == 0 ||
            ReadSiteField(opened, entryIndex, 4).Length == 0 ||
            ReadSiteField(opened, entryIndex, 5).Length == 0)
            throw new InvalidOperationException("Entry metadata is unavailable");
        string expectedHash = ReadSiteField(opened, entryIndex, 2);
        byte[] resource = Encoding.UTF8.GetBytes(selected);
        byte[] target = Encoding.UTF8.GetBytes(outputPath);
        status = Native.SiteDownload(opened, resource, (ulong)resource.Length, 0, 0,
                                     target, (ulong)target.Length, out ulong bytes,
                                     error, (ulong)error.Length);
        if (status != 0 || bytes != expectedLength ||
            (ulong)new FileInfo(outputPath).Length != bytes ||
            !Convert.ToHexString(SHA256.HashData(File.ReadAllBytes(outputPath)))
                .Equals(expectedHash, StringComparison.OrdinalIgnoreCase))
            throw new InvalidOperationException($"Verified download failed: {status}: {ErrorText(error)}");
        if (memberKeyPath is not null && memberOutput is not null)
        {
            byte[] memberResource = Encoding.UTF8.GetBytes("/amoosed.com/app/game/bonus/note.txt");
            byte[] memberTarget = Encoding.UTF8.GetBytes(memberOutput);
            status = Native.SiteDownload(opened, memberResource, (ulong)memberResource.Length,
                                         0, 0, memberTarget, (ulong)memberTarget.Length,
                                         out ulong deniedBytes, error, (ulong)error.Length);
            if (status != 10 || deniedBytes != 0 || File.Exists(memberOutput))
                throw new InvalidOperationException($"Missing member key returned {status} and {deniedBytes} bytes");
            byte[] key = Convert.FromHexString(File.ReadAllText(memberKeyPath).Trim());
            if (key.Length != 32) throw new InvalidOperationException("Invalid test member key");
            nint keyMemory = Marshal.AllocHGlobal(32);
            try
            {
                key[0] ^= 1;
                Marshal.Copy(key, 0, keyMemory, 32);
                key[0] ^= 1;
                status = Native.SiteDownload(opened, memberResource, (ulong)memberResource.Length,
                                             keyMemory, 32, memberTarget,
                                             (ulong)memberTarget.Length, out deniedBytes,
                                             error, (ulong)error.Length);
                if (status != 10 || deniedBytes != 0 || File.Exists(memberOutput))
                    throw new InvalidOperationException($"Wrong member key returned {status} and {deniedBytes} bytes");
                Marshal.Copy(key, 0, keyMemory, 32);
                status = Native.SiteDownload(opened, memberResource, (ulong)memberResource.Length,
                                             keyMemory, 32, memberTarget,
                                             (ulong)memberTarget.Length, out bytes,
                                             error, (ulong)error.Length);
                if (status != 0 || bytes == 0 || (ulong)new FileInfo(memberOutput).Length != bytes)
                    throw new InvalidOperationException($"Member download failed: {status}: {ErrorText(error)}");
            }
            finally
            {
                Marshal.Copy(new byte[32], 0, keyMemory, 32);
                Marshal.FreeHGlobal(keyMemory);
                Array.Clear(key);
            }
        }
    }
    finally { Native.SiteRelease(opened); }
}

static string ReadSiteField(nint site, ulong index, uint field)
{
    if (Native.SiteResourceString(site, index, field, 0, 0, out ulong needed) != 0)
        throw new InvalidOperationException("Resource metadata length query failed");
    nint memory = Marshal.AllocHGlobal(checked((int)needed + 1));
    try
    {
        if (Native.SiteResourceString(site, index, field, memory, needed + 1, out _) != 0)
            throw new InvalidOperationException("Resource metadata copy failed");
        return Marshal.PtrToStringUTF8(memory) ?? string.Empty;
    }
    finally { Marshal.FreeHGlobal(memory); }
}

static string ErrorText(byte[] bytes)
{
    int end = Array.IndexOf(bytes, (byte)0);
    return Encoding.UTF8.GetString(bytes, 0, end < 0 ? bytes.Length : end);
}

static class Native
{
    private const string Library = "AmoosedWebGameReaderC";
    [DllImport(Library, EntryPoint = "amw_preview_abi_revision", CallingConvention = CallingConvention.Cdecl)]
    internal static extern uint AbiRevision();
    [DllImport(Library, EntryPoint = "amw_preview_capabilities", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int Capabilities(out ulong available);
    [DllImport(Library, EntryPoint = "amw_preview_catalogue_parse", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int CatalogueParse(byte[] json, ulong length, out nint catalogue,
                                              byte[] error, ulong errorCapacity);
    [DllImport(Library, EntryPoint = "amw_preview_catalogue_release", CallingConvention = CallingConvention.Cdecl)]
    internal static extern void CatalogueRelease(nint catalogue);
    [DllImport(Library, EntryPoint = "amw_preview_catalogue_revision", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int CatalogueRevision(nint catalogue, out ulong revision);
    [DllImport(Library, EntryPoint = "amw_preview_catalogue_item_count", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int CatalogueItemCount(nint catalogue, out ulong count);
    [DllImport(Library, EntryPoint = "amw_preview_catalogue_item_string", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int CatalogueItemString(nint catalogue, ulong index, uint field,
                                                    nint output, ulong capacity, out ulong required);
    [DllImport(Library, EntryPoint = "amw_preview_site_open_hosted", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteOpenHosted(byte[] origin, ulong length, out nint site,
                                              byte[] error, ulong errorCapacity);
    [DllImport(Library, EntryPoint = "amw_preview_site_open_external", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteOpenExternal(byte[] origin, ulong length, byte[] credential,
                                                ulong credentialLength, out nint site,
                                                byte[] error, ulong errorCapacity);
    [DllImport(Library, EntryPoint = "amw_preview_site_release", CallingConvention = CallingConvention.Cdecl)]
    internal static extern void SiteRelease(nint site);
    [DllImport(Library, EntryPoint = "amw_preview_site_cancel", CallingConvention = CallingConvention.Cdecl)]
    internal static extern void SiteCancel(nint site);
    [DllImport(Library, EntryPoint = "amw_preview_site_resource_count", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteResourceCount(nint site, out ulong count);
    [DllImport(Library, EntryPoint = "amw_preview_site_entry_path", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteEntryPath(nint site, nint output, ulong capacity, out ulong required);
    [DllImport(Library, EntryPoint = "amw_preview_site_member_key_id", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteMemberKeyId(nint site, nint output, ulong capacity, out ulong required);
    [DllImport(Library, EntryPoint = "amw_preview_site_resource_length", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteResourceLength(nint site, ulong index, out ulong length);
    [DllImport(Library, EntryPoint = "amw_preview_site_resource_string", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteResourceString(nint site, ulong index, uint field,
                                                  nint output, ulong capacity, out ulong required);
    [DllImport(Library, EntryPoint = "amw_preview_site_download", CallingConvention = CallingConvention.Cdecl)]
    internal static extern int SiteDownload(nint site, byte[] resource, ulong resourceLength,
                                            nint memberKey, ulong memberKeyLength,
                                            byte[] outputPath, ulong outputPathLength,
                                            out ulong bytes, byte[] error, ulong errorCapacity);
}