using System.Diagnostics;
using System.Text;
using CapySR.ProtoGen;

// dumped proto -> deduped proto -> protoc --csharp_out -> cmdid tables.
// dotnet run --project tools/CapySR.ProtoGen

var repoRoot = FindRepoRoot();
if (repoRoot is null)
{
    Console.Error.WriteLine("could not locate repo root (no Directory.Build.props found walking up)");
    return 1;
}

var sourceProto = Path.Combine(repoRoot, "stuff", "TurnBaseGameProto", "Raw", "StarRail.proto");
var packetIds = Path.Combine(repoRoot, "stuff", "TurnBaseGameProto", "Raw", "packetIds.txt");
var protocolProject = Path.Combine(repoRoot, "src", "CapySR.Protocol");
var cleanedProtoDir = Path.Combine(protocolProject, "Proto");
var cleanedProto = Path.Combine(cleanedProtoDir, "StarRail.proto");
var generatedDir = Path.Combine(protocolProject, "Generated");

if (!File.Exists(sourceProto))
{
    Console.Error.WriteLine($"source proto not found: {sourceProto}");
    return 1;
}

Directory.CreateDirectory(cleanedProtoDir);
Directory.CreateDirectory(generatedDir);

Console.WriteLine($"reading {Path.GetRelativePath(repoRoot, sourceProto)}");
var lines = File.ReadAllLines(sourceProto);
var declarations = ProtoParser.Parse(lines);

var messages = declarations.Count(d => d.Kind == DeclarationKind.Message);
var enums = declarations.Count(d => d.Kind == DeclarationKind.Enum);
Console.WriteLine($"parsed {declarations.Count} top-level declarations ({messages} messages, {enums} enums)");

// -- 2. resolve duplicate names -------------------------------------------

var taken = new HashSet<string>(StringComparer.Ordinal);
foreach (var declaration in declarations)
{
    taken.Add(declaration.Name);
}

var resolver = new DuplicateResolver(declarations, packetIds);
var renames = 0;
foreach (var group in declarations.GroupBy(d => d.Name, StringComparer.Ordinal).Where(g => g.Count() > 1).ToList())
{
    var candidates = group.ToList();
    var winner = resolver.PickWinner(candidates);

    Console.WriteLine($"  duplicate '{group.Key}':");
    foreach (var candidate in candidates)
    {
        var marker = ReferenceEquals(candidate, winner) ? "keep" : "    ";
        Console.WriteLine($"    [{marker}] line {candidate.SourceLine,5}  {resolver.Explain(candidate)}");
    }

    foreach (var loser in candidates.Where(c => !ReferenceEquals(c, winner)))
    {
        var replacement = ChooseReplacementName(loser, taken);
        Console.WriteLine($"      -> renamed to '{replacement}'");
        loser.Rename(replacement);
        taken.Add(replacement);
        renames++;
    }
}

Console.WriteLine($"resolved {renames} duplicate name(s)");

// names the dump's translation got wrong, keyed by cmdid
var knownRenames = new Dictionary<ushort, string>
{
    // the dump has 5 lineup requests but calls 719 a second JoinLineupScRsp and has no
    // ReplaceLineupScRsp at all. pearl-sr's dump names it ReplaceLineupScRsp.
    [719] = "ReplaceLineupScRsp",
};

foreach (var (cmdId, correct) in knownRenames)
{
    var target = declarations.FirstOrDefault(d => d.CmdId == cmdId);

    if (target is null)
    {
        Console.WriteLine($"  warning: no message with CmdID {cmdId} to rename to '{correct}'");
        continue;
    }

    if (declarations.Any(d => d.Name == correct))
    {
        Console.WriteLine($"  warning: '{correct}' already exists, leaving CmdID {cmdId} as '{target.Name}'");
        continue;
    }

    Console.WriteLine($"  rename: CmdID {cmdId} '{target.Name}' -> '{correct}'");
    target.Rename(correct);
    taken.Add(correct);
}

var stillDuplicated = declarations
    .GroupBy(d => d.Name, StringComparer.Ordinal)
    .Where(g => g.Count() > 1)
    .Select(g => g.Key)
    .ToList();

if (stillDuplicated.Count > 0)
{
    Console.Error.WriteLine($"unresolved duplicates remain: {string.Join(", ", stillDuplicated)}");
    return 1;
}

// -- 3. emit the cleaned proto --------------------------------------------

var sb = new StringBuilder(6 * 1024 * 1024);
sb.AppendLine("// <auto-generated>");
sb.AppendLine("//   generated by tools/CapySR.ProtoGen - do not edit");
sb.AppendLine("// </auto-generated>");
sb.AppendLine();
sb.AppendLine("syntax = \"proto3\";");
sb.AppendLine();
sb.AppendLine("option csharp_namespace = \"CapySR.Protocol\";");
sb.AppendLine();

foreach (var declaration in declarations)
{
    declaration.Write(sb);
}

File.WriteAllText(cleanedProto, sb.ToString());
Console.WriteLine($"wrote {Path.GetRelativePath(repoRoot, cleanedProto)} ({sb.Length / 1024} KiB)");

// -- 4. run protoc ---------------------------------------------------------

var protoc = ResolveProtoc(args);
if (protoc is null)
{
    Console.Error.WriteLine("protoc not found. Pass --protoc <path>, set PROTOC, or put it on PATH.");
    return 1;
}

Console.WriteLine($"running {protoc}");
var protocResult = Run(protoc,
[
    $"--csharp_out={generatedDir}",
    $"--proto_path={cleanedProtoDir}",
    "StarRail.proto",
]);

if (protocResult.ExitCode != 0)
{
    Console.Error.WriteLine("protoc failed:");
    Console.Error.WriteLine(protocResult.Output);
    return 1;
}

var generatedCs = Path.Combine(generatedDir, "StarRail.cs");
if (File.Exists(generatedCs))
{
    Console.WriteLine($"wrote {Path.GetRelativePath(repoRoot, generatedCs)} ({new FileInfo(generatedCs).Length / 1024} KiB)");
}

// -- 5. emit the CmdId tables ---------------------------------------------

var withCmdId = declarations
    .Where(d => d.Kind == DeclarationKind.Message && d.CmdId is > 0)
    .OrderBy(d => d.CmdId!.Value)
    .ToList();

var byId = new Dictionary<ushort, ProtoDeclaration>();
foreach (var declaration in withCmdId)
{
    if (!byId.TryAdd(declaration.CmdId!.Value, declaration))
    {
        Console.WriteLine(
            $"  warning: CmdID {declaration.CmdId} claimed by both '{byId[declaration.CmdId!.Value].Name}' " +
            $"and '{declaration.Name}' - keeping the first");
    }
}

var ordered = byId.OrderBy(kv => kv.Key).ToList();
Console.WriteLine($"found {ordered.Count} messages carrying a CmdID");

CrossCheckPacketIds(packetIds, byId);

WriteCmdIdEnum(Path.Combine(generatedDir, "CmdId.g.cs"), ordered);
WriteCmdIdTable(Path.Combine(generatedDir, "CmdIdTable.g.cs"), ordered);

Console.WriteLine("done");
return 0;

// ---------------------------------------------------------------------------

static string ChooseReplacementName(ProtoDeclaration declaration, HashSet<string> taken)
{
    if (declaration.ObfuscatedName is { Length: > 0 } obf && !taken.Contains(obf))
    {
        return obf;
    }

    for (var i = 2; ; i++)
    {
        var candidate = $"{declaration.Name}_Dup{i}";
        if (!taken.Contains(candidate))
        {
            return candidate;
        }
    }
}

static void CrossCheckPacketIds(string path, Dictionary<ushort, ProtoDeclaration> byId)
{
    if (!File.Exists(path))
    {
        Console.WriteLine("  (packetIds.txt not found, skipping cross-check)");
        return;
    }

    int agree = 0, disagree = 0, missing = 0;

    foreach (var line in File.ReadLines(path))
    {
        var trimmed = line.Trim();
        if (trimmed.Length == 0 || trimmed.StartsWith("//", StringComparison.Ordinal))
        {
            continue;
        }

        var eq = trimmed.IndexOf('=');
        if (eq < 0 || !ushort.TryParse(trimmed[..eq].Trim(), out var id))
        {
            continue;
        }

        var rest = trimmed[(eq + 1)..];
        var comment = rest.IndexOf("//", StringComparison.Ordinal);
        var name = (comment >= 0 ? rest[..comment] : rest).Trim();

        if (!byId.TryGetValue(id, out var declaration))
        {
            missing++;
        }
        else if (string.Equals(declaration.Name, name, StringComparison.Ordinal))
        {
            agree++;
        }
        else
        {
            disagree++;
        }
    }

    Console.WriteLine($"  packetIds.txt cross-check: {agree} agree, {disagree} disagree, {missing} not in proto");
}

static void WriteCmdIdEnum(string path, List<KeyValuePair<ushort, ProtoDeclaration>> ordered)
{
    var sb = new StringBuilder();
    sb.AppendLine("// <auto-generated>");
    sb.AppendLine("//   generated by tools/CapySR.ProtoGen - do not edit");
    sb.AppendLine("// </auto-generated>");
    sb.AppendLine();
    sb.AppendLine("namespace CapySR.Protocol;");
    sb.AppendLine();
    sb.AppendLine("public enum CmdId : ushort");
    sb.AppendLine("{");
    sb.AppendLine("    None = 0,");

    foreach (var (id, declaration) in ordered)
    {
        sb.AppendLine($"    {declaration.Name} = {id},");
    }

    sb.AppendLine("}");
    File.WriteAllText(path, sb.ToString());
    Console.WriteLine($"wrote {Path.GetFileName(path)} ({ordered.Count} entries)");
}

static void WriteCmdIdTable(string path, List<KeyValuePair<ushort, ProtoDeclaration>> ordered)
{
    // parallel arrays; parsers get resolved from the descriptor at runtime
    var sb = new StringBuilder();
    sb.AppendLine("// <auto-generated>");
    sb.AppendLine("//   generated by tools/CapySR.ProtoGen - do not edit");
    sb.AppendLine("// </auto-generated>");
    sb.AppendLine();
    sb.AppendLine("namespace CapySR.Protocol;");
    sb.AppendLine();
    sb.AppendLine("public static class CmdIdTable");
    sb.AppendLine("{");

    sb.AppendLine("    public static ReadOnlySpan<ushort> Ids =>");
    sb.AppendLine("    [");
    AppendWrapped(sb, ordered.Select(kv => kv.Key.ToString()));
    sb.AppendLine("    ];");
    sb.AppendLine();

    sb.AppendLine("    public static readonly string[] Names =");
    sb.AppendLine("    [");
    AppendWrapped(sb, ordered.Select(kv => $"\"{kv.Value.Name}\""));
    sb.AppendLine("    ];");

    sb.AppendLine("}");
    File.WriteAllText(path, sb.ToString());
    Console.WriteLine($"wrote {Path.GetFileName(path)}");
}

static void AppendWrapped(StringBuilder sb, IEnumerable<string> values)
{
    var line = new StringBuilder("        ");

    foreach (var value in values)
    {
        if (line.Length + value.Length + 2 > 116)
        {
            sb.AppendLine(line.ToString());
            line.Clear().Append("        ");
        }

        line.Append(value).Append(", ");
    }

    if (line.ToString().Trim().Length > 0)
    {
        sb.AppendLine(line.ToString());
    }
}

static string? FindRepoRoot()
{
    var dir = new DirectoryInfo(AppContext.BaseDirectory);
    while (dir is not null)
    {
        if (File.Exists(Path.Combine(dir.FullName, "Directory.Build.props")))
        {
            return dir.FullName;
        }

        dir = dir.Parent;
    }

    return null;
}

static string? ResolveProtoc(string[] args)
{
    var index = Array.IndexOf(args, "--protoc");
    if (index >= 0 && index + 1 < args.Length && File.Exists(args[index + 1]))
    {
        return args[index + 1];
    }

    if (Environment.GetEnvironmentVariable("PROTOC") is { Length: > 0 } fromEnv && File.Exists(fromEnv))
    {
        return fromEnv;
    }

    var exe = OperatingSystem.IsWindows() ? "protoc.exe" : "protoc";

    foreach (var pathDir in (Environment.GetEnvironmentVariable("PATH") ?? string.Empty)
                 .Split(Path.PathSeparator, StringSplitOptions.RemoveEmptyEntries))
    {
        try
        {
            var candidate = Path.Combine(pathDir.Trim('"'), exe);
            if (File.Exists(candidate))
            {
                return candidate;
            }
        }
        catch (ArgumentException)
        {
        }
    }

    // protoc-*/bin/protoc.exe at a drive root, how it usually gets unzipped
    foreach (var drive in DriveInfo.GetDrives().Where(d => d.IsReady))
    {
        try
        {
            foreach (var dir in Directory.EnumerateDirectories(drive.RootDirectory.FullName, "protoc-*"))
            {
                var candidate = Path.Combine(dir, "bin", exe);
                if (File.Exists(candidate))
                {
                    return candidate;
                }
            }
        }
        catch (Exception e) when (e is UnauthorizedAccessException or IOException)
        {
        }
    }

    return null;
}

static (int ExitCode, string Output) Run(string fileName, string[] arguments)
{
    var info = new ProcessStartInfo(fileName)
    {
        RedirectStandardOutput = true,
        RedirectStandardError = true,
        UseShellExecute = false,
    };

    foreach (var argument in arguments)
    {
        info.ArgumentList.Add(argument);
    }

    using var process = Process.Start(info)!;
    var stdout = process.StandardOutput.ReadToEnd();
    var stderr = process.StandardError.ReadToEnd();
    process.WaitForExit();

    return (process.ExitCode, stdout + stderr);
}