// -----------------------------------------------------------------------------
// GhidraDecompilerAdapter.cs
// Sprint: SPRINT_20260119_006 ML Embeddings Corpus
// Task: MLEM-004 - Decompiled Code Extraction
// Description: Ghidra-based decompiler adapter implementation.
// -----------------------------------------------------------------------------


using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using System.Diagnostics;
using System.Text;
using System.Text.RegularExpressions;

namespace StellaOps.BinaryIndex.ML.Training;

/// <summary>
/// Ghidra-based decompiler adapter.
/// </summary>
public sealed partial class GhidraDecompilerAdapter : IDecompilerAdapter
{
    private readonly GhidraAdapterOptions _options;
    private readonly ILogger<GhidraDecompilerAdapter> _logger;

    /// <summary>
    /// Initializes a new instance of the <see cref="GhidraDecompilerAdapter"/> class.
    /// </summary>
    public GhidraDecompilerAdapter(
        IOptions<GhidraAdapterOptions> options,
        ILogger<GhidraDecompilerAdapter> logger)
    {
        _options = options.Value;
        _logger = logger;
    }

    /// <inheritdoc />
    public async Task<string?> DecompileAsync(
        string libraryName,
        string version,
        string functionName,
        CancellationToken cancellationToken = default)
    {
        _logger.LogDebug("Decompiling {Function} from {Library}:{Version}",
            functionName, libraryName, version);

        // This would call Ghidra headless analyzer
        // For now, return placeholder
        return await Task.FromResult<string?>($"int {functionName}(void *param_1) {{\n    int result;\n    // Decompiled code placeholder\n    result = 0;\n    return result;\n}}");
    }

    /// <inheritdoc />
    public async Task<string?> DecompileBytesAsync(
        ReadOnlyMemory<byte> bytes,
        string architecture,
        DecompilationOptions? options = null,
        CancellationToken cancellationToken = default)
    {
        options ??= DecompilationOptions.Default;

        if (string.IsNullOrEmpty(_options.GhidraPath))
        {
            _logger.LogWarning("Ghidra path not configured");
            return null;
        }

        try
        {
            // Create temp file with bytes
            var tempInput = Path.GetTempFileName();
            await File.WriteAllBytesAsync(tempInput, bytes.ToArray(), cancellationToken);

            var tempOutput = Path.GetTempFileName();

            try
            {
                // Run Ghidra headless
                var script = _options.DecompileScriptPath ?? "DecompileFunction.java";
                var args = $"-import {tempInput} -postScript {script} {tempOutput} -deleteProject -noanalysis";

                var result = await RunGhidraAsync(args, options.Timeout, cancellationToken);

                if (!result.Success)
                {
                    _logger.LogWarning("Ghidra decompilation failed: {Error}", result.Error);
                    return null;
                }

                if (File.Exists(tempOutput))
                {
                    var decompiled = await File.ReadAllTextAsync(tempOutput, cancellationToken);
                    return options.Simplify ? Normalize(decompiled) : decompiled;
                }

                return null;
            }
            finally
            {
                if (File.Exists(tempInput)) File.Delete(tempInput);
                if (File.Exists(tempOutput)) File.Delete(tempOutput);
            }
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Decompilation failed");
            return null;
        }
    }

    /// <inheritdoc />
    public string Normalize(string code, NormalizationOptions? options = null)
    {
        options ??= NormalizationOptions.Default;
        var result = code;

        // Strip comments
        if (options.StripComments)
        {
            result = StripCommentsRegex().Replace(result, "");
            result = LineCommentRegex().Replace(result, "");
        }

        // Normalize whitespace
        if (options.NormalizeWhitespace)
        {
            result = MultipleSpacesRegex().Replace(result, " ");
            result = EmptyLinesRegex().Replace(result, "\n");
            result = result.Trim();
        }

        // Normalize variable names
        if (options.NormalizeVariables)
        {
            var varCounter = 0;
            var varMap = new Dictionary<string, string>();

            result = VariableNameRegex().Replace(result, match =>
            {
                var name = match.Value;
                if (!varMap.TryGetValue(name, out var normalized))
                {
                    normalized = $"var_{varCounter++}";
                    varMap[name] = normalized;
                }
                return normalized;
            });
        }

        // Remove type casts
        if (options.RemoveTypeCasts)
        {
            result = TypeCastRegex().Replace(result, "");
        }

        // Truncate if too long
        if (result.Length > options.MaxLength)
        {
            result = result[..options.MaxLength] + "\n/* truncated */";
        }

        return result;
    }

    private async Task<(bool Success, string? Error)> RunGhidraAsync(
        string args,
        TimeSpan timeout,
        CancellationToken ct)
    {
        var analyzeHeadless = Path.Combine(_options.GhidraPath!, "support", "analyzeHeadless");

        var psi = new ProcessStartInfo
        {
            FileName = analyzeHeadless,
            Arguments = args,
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
            CreateNoWindow = true
        };

        using var process = new Process { StartInfo = psi };
        var output = new StringBuilder();
        var error = new StringBuilder();

        process.OutputDataReceived += (_, e) =>
        {
            if (e.Data is not null) output.AppendLine(e.Data);
        };
        process.ErrorDataReceived += (_, e) =>
        {
            if (e.Data is not null) error.AppendLine(e.Data);
        };

        process.Start();
        process.BeginOutputReadLine();
        process.BeginErrorReadLine();

        using var cts = CancellationTokenSource.CreateLinkedTokenSource(ct);
        cts.CancelAfter(timeout);

        try
        {
            await process.WaitForExitAsync(cts.Token);
            return (process.ExitCode == 0, error.Length > 0 ? error.ToString() : null);
        }
        catch (OperationCanceledException)
        {
            process.Kill(true);
            return (false, "Timeout");
        }
    }

    [GeneratedRegex(@"/\*.*?\*/", RegexOptions.Singleline)]
    private static partial Regex StripCommentsRegex();

    [GeneratedRegex(@"//.*$", RegexOptions.Multiline)]
    private static partial Regex LineCommentRegex();

    [GeneratedRegex(@"\s+")]
    private static partial Regex MultipleSpacesRegex();

    [GeneratedRegex(@"\n\s*\n")]
    private static partial Regex EmptyLinesRegex();

    [GeneratedRegex(@"\b(local_|param_|DAT_|FUN_)[a-zA-Z0-9_]+")]
    private static partial Regex VariableNameRegex();

    [GeneratedRegex(@"\(\s*[a-zA-Z_][a-zA-Z0-9_]*\s*\*?\s*\)")]
    private static partial Regex TypeCastRegex();
}

/// <summary>
/// Options for Ghidra adapter.
/// </summary>
public sealed record GhidraAdapterOptions
{
    /// <summary>
    /// Gets the path to Ghidra installation.
    /// </summary>
    public string? GhidraPath { get; init; }

    /// <summary>
    /// Gets the path to decompile script.
    /// </summary>
    public string? DecompileScriptPath { get; init; }

    /// <summary>
    /// Gets the project directory for temp projects.
    /// </summary>
    public string? ProjectDirectory { get; init; }
}