// Copyright (c) StellaOps. All rights reserved.
// Licensed under AGPL-3.0-or-later. See LICENSE in the project root.

using System.Collections.Immutable;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using StellaOps.BinaryIndex.Disassembly;

namespace StellaOps.BinaryIndex.Ghidra;

/// <summary>
/// Ghidra-based disassembly plugin providing broad architecture support as a fallback backend.
/// Ghidra is used for complex cases where B2R2 has limited coverage, supports 20+ architectures,
/// and provides mature decompilation, Version Tracking, and BSim capabilities.
/// </summary>
/// <remarks>
/// This plugin has lower priority than B2R2 since Ghidra requires external process invocation
/// (Java-based headless analysis) which is slower than native .NET disassembly. It serves as
/// the fallback when B2R2 returns low-confidence results or for architectures B2R2 handles poorly.
/// </remarks>
public sealed class GhidraDisassemblyPlugin : IDisassemblyPlugin, IDisposable
{
    /// <summary>
    /// Plugin identifier.
    /// </summary>
    public const string PluginId = "stellaops.disasm.ghidra";

    private readonly IGhidraService _ghidraService;
    private readonly GhidraOptions _options;
    private readonly ILogger<GhidraDisassemblyPlugin> _logger;
    private readonly TimeProvider _timeProvider;
    private bool _disposed;

    private static readonly DisassemblyCapabilities s_capabilities = new()
    {
        PluginId = PluginId,
        Name = "Ghidra Disassembler",
        Version = "11.x", // Ghidra 11.x
        SupportedArchitectures =
        [
            // All architectures supported by both B2R2 and Ghidra
            CpuArchitecture.X86,
            CpuArchitecture.X86_64,
            CpuArchitecture.ARM32,
            CpuArchitecture.ARM64,
            CpuArchitecture.MIPS32,
            CpuArchitecture.MIPS64,
            CpuArchitecture.RISCV64,
            CpuArchitecture.PPC32,
            CpuArchitecture.PPC64, // Ghidra supports PPC64 better than B2R2
            CpuArchitecture.SPARC,
            CpuArchitecture.SH4,
            CpuArchitecture.AVR,
            // Additional architectures Ghidra supports
            CpuArchitecture.WASM
        ],
        SupportedFormats =
        [
            BinaryFormat.ELF,
            BinaryFormat.PE,
            BinaryFormat.MachO,
            BinaryFormat.WASM,
            BinaryFormat.Raw
        ],
        SupportsLifting = true, // P-Code lifting
        SupportsCfgRecovery = true, // Full CFG recovery and decompilation
        Priority = 25 // Lower than B2R2 (50) - used as fallback
    };

    /// <summary>
    /// Creates a new Ghidra disassembly plugin.
    /// </summary>
    /// <param name="ghidraService">The Ghidra analysis service.</param>
    /// <param name="options">Ghidra options.</param>
    /// <param name="logger">Logger instance.</param>
    /// <param name="timeProvider">Time provider for timestamps.</param>
    public GhidraDisassemblyPlugin(
        IGhidraService ghidraService,
        IOptions<GhidraOptions> options,
        ILogger<GhidraDisassemblyPlugin> logger,
        TimeProvider timeProvider)
    {
        _ghidraService = ghidraService ?? throw new ArgumentNullException(nameof(ghidraService));
        _options = options?.Value ?? throw new ArgumentNullException(nameof(options));
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
    }

    /// <inheritdoc />
    public DisassemblyCapabilities Capabilities => s_capabilities;

    /// <inheritdoc />
    public BinaryInfo LoadBinary(Stream stream, CpuArchitecture? archHint = null, BinaryFormat? formatHint = null)
    {
        ArgumentNullException.ThrowIfNull(stream);
        ObjectDisposedException.ThrowIf(_disposed, this);

        // Copy stream to memory for analysis
        using var memStream = new MemoryStream();
        stream.CopyTo(memStream);
        return LoadBinary(memStream.ToArray(), archHint, formatHint);
    }

    /// <inheritdoc />
    public BinaryInfo LoadBinary(ReadOnlySpan<byte> bytes, CpuArchitecture? archHint = null, BinaryFormat? formatHint = null)
    {
        ObjectDisposedException.ThrowIf(_disposed, this);

        var byteArray = bytes.ToArray();
        _logger.LogDebug("Loading binary with Ghidra plugin (size: {Size} bytes)", byteArray.Length);

        // Run Ghidra analysis synchronously for IDisassemblyPlugin contract
        var analysisTask = RunGhidraAnalysisAsync(byteArray, archHint, formatHint, CancellationToken.None);
        var result = analysisTask.GetAwaiter().GetResult();

        // Map Ghidra metadata to BinaryInfo
        var format = MapFormat(result.Metadata.Format);
        var architecture = MapArchitecture(result.Metadata.Architecture, result.Metadata.AddressSize);
        var endianness = result.Metadata.Endianness.Equals("little", StringComparison.OrdinalIgnoreCase)
            ? Endianness.Little
            : Endianness.Big;
        var abi = DetectAbi(format);

        _logger.LogInformation(
            "Loaded binary with Ghidra: Format={Format}, Architecture={Architecture}, Processor={Processor}",
            format, architecture, result.Metadata.Processor);

        var metadata = new Dictionary<string, object>
        {
            ["size"] = byteArray.Length,
            ["ghidra_processor"] = result.Metadata.Processor,
            ["ghidra_version"] = result.Metadata.GhidraVersion,
            ["analysis_duration_ms"] = result.Metadata.AnalysisDuration.TotalMilliseconds,
            ["function_count"] = result.Functions.Length,
            ["import_count"] = result.Imports.Length,
            ["export_count"] = result.Exports.Length
        };

        if (result.Metadata.Compiler is not null)
        {
            metadata["compiler"] = result.Metadata.Compiler;
        }

        return new BinaryInfo(
            Format: format,
            Architecture: architecture,
            Bitness: result.Metadata.AddressSize,
            Endianness: endianness,
            Abi: abi,
            EntryPoint: result.Metadata.EntryPoint,
            BuildId: result.BinaryHash,
            Metadata: metadata,
            Handle: new GhidraBinaryHandle(result, byteArray));
    }

    /// <inheritdoc />
    public IEnumerable<CodeRegion> GetCodeRegions(BinaryInfo binary)
    {
        ArgumentNullException.ThrowIfNull(binary);
        ObjectDisposedException.ThrowIf(_disposed, this);

        var handle = GetHandle(binary);

        // Extract code regions from Ghidra memory blocks
        foreach (var block in handle.Result.MemoryBlocks)
        {
            if (block.IsExecutable)
            {
                yield return new CodeRegion(
                    Name: block.Name,
                    VirtualAddress: block.Start,
                    FileOffset: block.Start - handle.Result.Metadata.ImageBase,
                    Size: (ulong)block.Size,
                    IsExecutable: block.IsExecutable,
                    IsReadable: true, // Executable sections are readable
                    IsWritable: block.IsWritable);
            }
        }
    }

    /// <inheritdoc />
    public IEnumerable<SymbolInfo> GetSymbols(BinaryInfo binary)
    {
        ArgumentNullException.ThrowIfNull(binary);
        ObjectDisposedException.ThrowIf(_disposed, this);

        var handle = GetHandle(binary);

        // Map functions to symbols
        foreach (var func in handle.Result.Functions)
        {
            var binding = func.IsExternal ? SymbolBinding.Global : SymbolBinding.Local;

            yield return new SymbolInfo(
                Name: func.Name,
                Address: func.Address,
                Size: (ulong)func.Size,
                Type: SymbolType.Function,
                Binding: binding,
                Section: DetermineSection(handle.Result.MemoryBlocks, func.Address));
        }

        // Also include exports as symbols
        foreach (var export in handle.Result.Exports)
        {
            yield return new SymbolInfo(
                Name: export.Name,
                Address: export.Address,
                Size: 0, // Unknown size for exports
                Type: SymbolType.Function,
                Binding: SymbolBinding.Global,
                Section: DetermineSection(handle.Result.MemoryBlocks, export.Address));
        }
    }

    /// <inheritdoc />
    public IEnumerable<DisassembledInstruction> Disassemble(BinaryInfo binary, CodeRegion region)
    {
        ArgumentNullException.ThrowIfNull(binary);
        ArgumentNullException.ThrowIfNull(region);
        ObjectDisposedException.ThrowIf(_disposed, this);

        var handle = GetHandle(binary);

        _logger.LogDebug(
            "Disassembling region {Name} from 0x{Start:X} to 0x{End:X}",
            region.Name, region.VirtualAddress, region.VirtualAddress + region.Size);

        // Find functions within the region and return their instructions
        var regionEnd = region.VirtualAddress + region.Size;

        foreach (var func in handle.Result.Functions)
        {
            if (func.Address >= region.VirtualAddress && func.Address < regionEnd)
            {
                foreach (var instr in DisassembleFunctionInstructions(func, handle))
                {
                    if (instr.Address >= region.VirtualAddress && instr.Address < regionEnd)
                    {
                        yield return instr;
                    }
                }
            }
        }
    }

    /// <inheritdoc />
    public IEnumerable<DisassembledInstruction> Disassemble(BinaryInfo binary, ulong startAddress, ulong length)
    {
        var region = new CodeRegion(
            Name: $"0x{startAddress:X}",
            VirtualAddress: startAddress,
            FileOffset: startAddress,
            Size: length,
            IsExecutable: true,
            IsReadable: true,
            IsWritable: false);

        return Disassemble(binary, region);
    }

    /// <inheritdoc />
    public IEnumerable<DisassembledInstruction> DisassembleSymbol(BinaryInfo binary, SymbolInfo symbol)
    {
        ArgumentNullException.ThrowIfNull(binary);
        ArgumentNullException.ThrowIfNull(symbol);
        ObjectDisposedException.ThrowIf(_disposed, this);

        var handle = GetHandle(binary);

        // Find the function matching the symbol
        var func = handle.Result.Functions.FirstOrDefault(f =>
            f.Address == symbol.Address || f.Name.Equals(symbol.Name, StringComparison.Ordinal));

        if (func is null)
        {
            _logger.LogWarning(
                "Function not found for symbol {Name} at 0x{Address:X}",
                symbol.Name, symbol.Address);
            yield break;
        }

        foreach (var instr in DisassembleFunctionInstructions(func, handle))
        {
            yield return instr;
        }
    }

    #region Private Methods

    private async Task<GhidraAnalysisResult> RunGhidraAnalysisAsync(
        byte[] bytes,
        CpuArchitecture? archHint,
        BinaryFormat? formatHint,
        CancellationToken ct)
    {
        // Write bytes to temp file
        var tempPath = Path.Combine(
            _options.WorkDir,
            $"disasm_{_timeProvider.GetUtcNow():yyyyMMddHHmmssfff}_{Guid.NewGuid():N}.bin");

        try
        {
            Directory.CreateDirectory(Path.GetDirectoryName(tempPath)!);
            await File.WriteAllBytesAsync(tempPath, bytes, ct);

            var options = new GhidraAnalysisOptions
            {
                RunFullAnalysis = true,
                ExtractStrings = false, // Not needed for disassembly
                ExtractFunctions = true,
                ExtractDecompilation = false, // Can be expensive
                TimeoutSeconds = _options.DefaultTimeoutSeconds
            };

            // Add architecture hint if provided
            if (archHint.HasValue)
            {
                options = options with { ProcessorHint = MapToGhidraProcessor(archHint.Value) };
            }

            using var stream = File.OpenRead(tempPath);
            return await _ghidraService.AnalyzeAsync(stream, options, ct);
        }
        finally
        {
            TryDeleteFile(tempPath);
        }
    }

    private static IEnumerable<DisassembledInstruction> DisassembleFunctionInstructions(
        GhidraFunction func,
        GhidraBinaryHandle handle)
    {
        // Ghidra full analysis provides function boundaries but not individual instructions
        // We synthesize instruction info from the function's decompiled code or from the raw bytes

        // For now, return a synthetic instruction representing the function entry
        // A full implementation would require running a Ghidra script to export instructions

        // Calculate approximate instruction count based on function size and average instruction size
        // x86/x64 average instruction size is ~3-4 bytes
        var avgInstructionSize = handle.Result.Metadata.AddressSize == 64 ? 4 : 3;
        var estimatedInstructions = Math.Max(1, func.Size / avgInstructionSize);

        var address = func.Address;
        for (var i = 0; i < estimatedInstructions && i < 1000; i++) // Cap at 1000 instructions
        {
            // Without actual Ghidra instruction export, we create placeholder entries
            // Real implementation would parse Ghidra's instruction listing output
            var rawBytes = ExtractBytes(handle.Bytes, address, handle.Result.Metadata.ImageBase, avgInstructionSize);

            yield return new DisassembledInstruction(
                Address: address,
                RawBytes: rawBytes,
                Mnemonic: "GHIDRA", // Placeholder - real impl would have actual mnemonics
                OperandsText: $"; function {func.Name} + 0x{address - func.Address:X}",
                Kind: i == 0 ? InstructionKind.Call : InstructionKind.Unknown,
                Operands: []);

            address += (ulong)avgInstructionSize;
            if (address >= func.Address + (ulong)func.Size)
            {
                break;
            }
        }
    }

    private static ImmutableArray<byte> ExtractBytes(byte[] binary, ulong address, ulong imageBase, int count)
    {
        var offset = address - imageBase;
        if (offset >= (ulong)binary.Length)
        {
            return [];
        }

        var available = Math.Min(count, binary.Length - (int)offset);
        return binary.AsSpan((int)offset, available).ToArray().ToImmutableArray();
    }

    private static string? DetermineSection(ImmutableArray<GhidraMemoryBlock> blocks, ulong address)
    {
        foreach (var block in blocks)
        {
            if (address >= block.Start && address < block.End)
            {
                return block.Name;
            }
        }
        return null;
    }

    private static GhidraBinaryHandle GetHandle(BinaryInfo binary)
    {
        if (binary.Handle is not GhidraBinaryHandle handle)
        {
            throw new ArgumentException("Invalid binary handle - not a Ghidra handle", nameof(binary));
        }
        return handle;
    }

    private static BinaryFormat MapFormat(string ghidraFormat)
    {
        return ghidraFormat.ToUpperInvariant() switch
        {
            "ELF" or "ELF32" or "ELF64" => BinaryFormat.ELF,
            "PE" or "PE32" or "PE64" or "COFF" => BinaryFormat.PE,
            "MACHO" or "MACH-O" or "MACHO32" or "MACHO64" => BinaryFormat.MachO,
            "WASM" or "WEBASSEMBLY" => BinaryFormat.WASM,
            "RAW" or "BINARY" => BinaryFormat.Raw,
            _ => BinaryFormat.Unknown
        };
    }

    private static CpuArchitecture MapArchitecture(string ghidraArch, int addressSize)
    {
        var arch = ghidraArch.ToUpperInvariant();
        return arch switch
        {
            // Intel x86/x64
            "X86" or "X86:LE:32:DEFAULT" => CpuArchitecture.X86,
            "X86-64" or "X86:LE:64:DEFAULT" or "AMD64" => CpuArchitecture.X86_64,
            var x when x.StartsWith("X86", StringComparison.Ordinal) && addressSize == 32 => CpuArchitecture.X86,
            var x when x.StartsWith("X86", StringComparison.Ordinal) => CpuArchitecture.X86_64,

            // ARM
            "ARM" or "ARM:LE:32:V7" or "ARM:LE:32:V8" or "ARMV7" => CpuArchitecture.ARM32,
            "AARCH64" or "ARM:LE:64:V8A" or "ARM64" => CpuArchitecture.ARM64,
            var a when a.StartsWith("ARM", StringComparison.Ordinal) && addressSize == 32 => CpuArchitecture.ARM32,
            var a when a.StartsWith("ARM", StringComparison.Ordinal) || a.StartsWith("AARCH", StringComparison.Ordinal) => CpuArchitecture.ARM64,

            // MIPS
            "MIPS" or "MIPS:BE:32:DEFAULT" or "MIPS:LE:32:DEFAULT" => CpuArchitecture.MIPS32,
            "MIPS64" or "MIPS:BE:64:DEFAULT" or "MIPS:LE:64:DEFAULT" => CpuArchitecture.MIPS64,
            var m when m.StartsWith("MIPS", StringComparison.Ordinal) && addressSize == 64 => CpuArchitecture.MIPS64,
            var m when m.StartsWith("MIPS", StringComparison.Ordinal) => CpuArchitecture.MIPS32,

            // RISC-V
            "RISCV" or "RISCV:LE:64:RV64" or "RISCV64" => CpuArchitecture.RISCV64,
            var r when r.StartsWith("RISCV", StringComparison.Ordinal) => CpuArchitecture.RISCV64,

            // PowerPC
            "PPC" or "POWERPC" or "PPC:BE:32:DEFAULT" => CpuArchitecture.PPC32,
            "PPC64" or "POWERPC64" or "PPC:BE:64:DEFAULT" => CpuArchitecture.PPC64,
            var p when p.StartsWith("PPC", StringComparison.Ordinal) && addressSize == 64 => CpuArchitecture.PPC64,
            var p when p.StartsWith("PPC", StringComparison.Ordinal) || p.StartsWith("POWERPC", StringComparison.Ordinal) => CpuArchitecture.PPC32,

            // SPARC
            "SPARC" or "SPARC:BE:32:DEFAULT" => CpuArchitecture.SPARC,
            var s when s.StartsWith("SPARC", StringComparison.Ordinal) => CpuArchitecture.SPARC,

            // SuperH
            "SH4" or "SUPERH" or "SH:LE:32:SH4" => CpuArchitecture.SH4,
            var s when s.StartsWith("SH", StringComparison.Ordinal) || s.StartsWith("SUPERH", StringComparison.Ordinal) => CpuArchitecture.SH4,

            // AVR
            "AVR" or "AVR8:LE:16:DEFAULT" => CpuArchitecture.AVR,
            var a when a.StartsWith("AVR", StringComparison.Ordinal) => CpuArchitecture.AVR,

            // WASM
            "WASM" or "WEBASSEMBLY" => CpuArchitecture.WASM,

            // EVM (Ethereum)
            "EVM" => CpuArchitecture.EVM,

            _ => CpuArchitecture.Unknown
        };
    }

    private static string? MapToGhidraProcessor(CpuArchitecture arch)
    {
        return arch switch
        {
            CpuArchitecture.X86 => "x86:LE:32:default",
            CpuArchitecture.X86_64 => "x86:LE:64:default",
            CpuArchitecture.ARM32 => "ARM:LE:32:v7",
            CpuArchitecture.ARM64 => "AARCH64:LE:64:v8A",
            CpuArchitecture.MIPS32 => "MIPS:BE:32:default",
            CpuArchitecture.MIPS64 => "MIPS:BE:64:default",
            CpuArchitecture.RISCV64 => "RISCV:LE:64:RV64IC",
            CpuArchitecture.PPC32 => "PowerPC:BE:32:default",
            CpuArchitecture.PPC64 => "PowerPC:BE:64:default",
            CpuArchitecture.SPARC => "sparc:BE:32:default",
            CpuArchitecture.SH4 => "SuperH4:LE:32:default",
            CpuArchitecture.AVR => "avr8:LE:16:default",
            CpuArchitecture.WASM => "Wasm:LE:32:default",
            CpuArchitecture.EVM => "EVM:BE:256:default",
            _ => null
        };
    }

    private static string? DetectAbi(BinaryFormat format)
    {
        return format switch
        {
            BinaryFormat.ELF => "gnu",
            BinaryFormat.PE => "msvc",
            BinaryFormat.MachO => "darwin",
            _ => null
        };
    }

    private static void TryDeleteFile(string path)
    {
        try
        {
            if (File.Exists(path))
            {
                File.Delete(path);
            }
        }
        catch
        {
            // Ignore cleanup failures
        }
    }

    #endregion

    /// <summary>
    /// Disposes the plugin and releases resources.
    /// </summary>
    public void Dispose()
    {
        if (_disposed)
        {
            return;
        }
        _disposed = true;
    }
}

/// <summary>
/// Internal handle for Ghidra-analyzed binaries.
/// </summary>
/// <param name="Result">The Ghidra analysis result.</param>
/// <param name="Bytes">The original binary bytes.</param>
internal sealed record GhidraBinaryHandle(
    GhidraAnalysisResult Result,
    byte[] Bytes);