namespace StellaOps.Signals.Services;

/// <summary>
/// Symbol canonicalization service interface.
/// Sprint: SPRINT_20251226_010_SIGNALS_runtime_stack
/// Task: STACK-06
///
/// Resolves program counter addresses to canonical (Build-ID, function, offset) tuples.
/// </summary>
public interface ISymbolCanonicalizationService
{
    /// <summary>
    /// Resolves a program counter address to a canonical symbol.
    /// </summary>
    /// <param name="address">The program counter address.</param>
    /// <param name="buildId">The ELF Build-ID of the binary.</param>
    /// <param name="binaryPath">Optional path to the binary for symbol lookup.</param>
    /// <param name="cancellationToken">Cancellation token.</param>
    /// <returns>The resolved symbol, or null if resolution failed.</returns>
    Task<CanonicalSymbol?> ResolveAsync(
        ulong address,
        string? buildId,
        string? binaryPath = null,
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Resolves multiple addresses in batch for efficiency.
    /// </summary>
    Task<IReadOnlyList<CanonicalSymbol?>> ResolveBatchAsync(
        IReadOnlyList<SymbolResolutionRequest> requests,
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Resolves a Java frame using JVMTI metadata.
    /// </summary>
    Task<CanonicalSymbol?> ResolveJavaFrameAsync(
        ulong address,
        JavaFrameMetadata metadata,
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Resolves a .NET frame using DAC (Data Access Component).
    /// </summary>
    Task<CanonicalSymbol?> ResolveDotNetFrameAsync(
        ulong address,
        DotNetFrameMetadata metadata,
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Resolves a Python frame using interpreter symbols.
    /// </summary>
    Task<CanonicalSymbol?> ResolvePythonFrameAsync(
        ulong address,
        PythonFrameMetadata metadata,
        CancellationToken cancellationToken = default);

    /// <summary>
    /// Checks if a Build-ID is in the local symbol cache.
    /// </summary>
    Task<bool> IsInCacheAsync(string buildId, CancellationToken cancellationToken = default);

    /// <summary>
    /// Adds symbols for a Build-ID to the cache.
    /// </summary>
    Task CacheSymbolsAsync(
        string buildId,
        IReadOnlyList<SymbolEntry> symbols,
        CancellationToken cancellationToken = default);
}

/// <summary>
/// Request for symbol resolution.
/// </summary>
public sealed record SymbolResolutionRequest
{
    /// <summary>
    /// Program counter address.
    /// </summary>
    public required ulong Address { get; init; }

    /// <summary>
    /// ELF Build-ID of the binary.
    /// </summary>
    public string? BuildId { get; init; }

    /// <summary>
    /// Path to the binary file.
    /// </summary>
    public string? BinaryPath { get; init; }

    /// <summary>
    /// Runtime type hint for managed runtimes.
    /// </summary>
    public RuntimeType RuntimeType { get; init; } = RuntimeType.Native;
}

/// <summary>
/// Runtime type for symbol resolution hints.
/// </summary>
public enum RuntimeType
{
    /// <summary>
    /// Native code (C, C++, Rust, Go, etc.).
    /// </summary>
    Native,

    /// <summary>
    /// Java Virtual Machine.
    /// </summary>
    Java,

    /// <summary>
    /// .NET Common Language Runtime.
    /// </summary>
    DotNet,

    /// <summary>
    /// Python interpreter.
    /// </summary>
    Python,

    /// <summary>
    /// Node.js / V8.
    /// </summary>
    NodeJs,

    /// <summary>
    /// Ruby interpreter.
    /// </summary>
    Ruby,
}

/// <summary>
/// Canonical symbol representation.
/// </summary>
public sealed record CanonicalSymbol
{
    /// <summary>
    /// Original address that was resolved.
    /// </summary>
    public required ulong Address { get; init; }

    /// <summary>
    /// ELF Build-ID of the containing binary.
    /// </summary>
    public required string BuildId { get; init; }

    /// <summary>
    /// Demangled function name.
    /// </summary>
    public required string FunctionName { get; init; }

    /// <summary>
    /// Offset within the function.
    /// </summary>
    public required ulong Offset { get; init; }

    /// <summary>
    /// Module or binary name.
    /// </summary>
    public string? ModuleName { get; init; }

    /// <summary>
    /// Source file path (if debug info available).
    /// </summary>
    public string? SourceFile { get; init; }

    /// <summary>
    /// Source line number.
    /// </summary>
    public int? SourceLine { get; init; }

    /// <summary>
    /// Whether this symbol is from a trusted source.
    /// </summary>
    public bool IsTrusted { get; init; }

    /// <summary>
    /// Resolution method used.
    /// </summary>
    public SymbolResolutionMethod ResolutionMethod { get; init; }

    /// <summary>
    /// Returns the canonical string format.
    /// </summary>
    public string ToCanonicalString()
    {
        return $"{BuildId[..Math.Min(16, BuildId.Length)]}:{FunctionName}+0x{Offset:x}";
    }

    /// <summary>
    /// Parses a canonical string format.
    /// </summary>
    public static CanonicalSymbol? Parse(string canonical)
    {
        if (string.IsNullOrWhiteSpace(canonical))
            return null;

        // Format: "buildid:function+0xoffset"
        var colonIdx = canonical.IndexOf(':');
        if (colonIdx < 0)
            return null;

        var buildId = canonical[..colonIdx];
        var rest = canonical[(colonIdx + 1)..];

        var plusIdx = rest.LastIndexOf('+');
        if (plusIdx < 0)
            return null;

        var functionName = rest[..plusIdx];
        var offsetStr = rest[(plusIdx + 1)..];

        if (!offsetStr.StartsWith("0x", StringComparison.OrdinalIgnoreCase))
            return null;

        if (!ulong.TryParse(offsetStr[2..], System.Globalization.NumberStyles.HexNumber, null, out var offset))
            return null;

        return new CanonicalSymbol
        {
            Address = 0, // Not recoverable from canonical string
            BuildId = buildId,
            FunctionName = functionName,
            Offset = offset,
            ResolutionMethod = SymbolResolutionMethod.Parsed,
        };
    }
}

/// <summary>
/// Method used to resolve the symbol.
/// </summary>
public enum SymbolResolutionMethod
{
    /// <summary>
    /// Resolved from ELF symbol table.
    /// </summary>
    ElfSymtab,

    /// <summary>
    /// Resolved from DWARF debug info.
    /// </summary>
    DwarfDebugInfo,

    /// <summary>
    /// Resolved from local symbol cache.
    /// </summary>
    LocalCache,

    /// <summary>
    /// Resolved from debuginfod server.
    /// </summary>
    Debuginfod,

    /// <summary>
    /// Resolved from JIT metadata (Java/V8/etc).
    /// </summary>
    JitMetadata,

    /// <summary>
    /// Resolved from runtime-specific mechanism.
    /// </summary>
    RuntimeSpecific,

    /// <summary>
    /// Parsed from canonical string format.
    /// </summary>
    Parsed,

    /// <summary>
    /// Could not resolve, using address only.
    /// </summary>
    Unresolved,
}

/// <summary>
/// Symbol entry for cache storage.
/// </summary>
public sealed record SymbolEntry
{
    /// <summary>
    /// Start address of the symbol.
    /// </summary>
    public required ulong StartAddress { get; init; }

    /// <summary>
    /// Size of the symbol in bytes.
    /// </summary>
    public required ulong Size { get; init; }

    /// <summary>
    /// Symbol name (demangled).
    /// </summary>
    public required string Name { get; init; }

    /// <summary>
    /// Symbol type.
    /// </summary>
    public SymbolType Type { get; init; } = SymbolType.Function;
}

/// <summary>
/// Type of symbol.
/// </summary>
public enum SymbolType
{
    Function,
    Object,
    Unknown,
}

/// <summary>
/// Metadata for Java frame resolution.
/// </summary>
public sealed record JavaFrameMetadata
{
    /// <summary>
    /// Class name.
    /// </summary>
    public string? ClassName { get; init; }

    /// <summary>
    /// Method name.
    /// </summary>
    public string? MethodName { get; init; }

    /// <summary>
    /// Method signature.
    /// </summary>
    public string? Signature { get; init; }

    /// <summary>
    /// Bytecode index.
    /// </summary>
    public int? BytecodeIndex { get; init; }

    /// <summary>
    /// Whether this is a JIT-compiled frame.
    /// </summary>
    public bool IsJit { get; init; }
}

/// <summary>
/// Metadata for .NET frame resolution.
/// </summary>
public sealed record DotNetFrameMetadata
{
    /// <summary>
    /// Type name.
    /// </summary>
    public string? TypeName { get; init; }

    /// <summary>
    /// Method name.
    /// </summary>
    public string? MethodName { get; init; }

    /// <summary>
    /// Method token.
    /// </summary>
    public uint? MethodToken { get; init; }

    /// <summary>
    /// IL offset.
    /// </summary>
    public int? IlOffset { get; init; }

    /// <summary>
    /// Assembly name.
    /// </summary>
    public string? AssemblyName { get; init; }
}

/// <summary>
/// Metadata for Python frame resolution.
/// </summary>
public sealed record PythonFrameMetadata
{
    /// <summary>
    /// Module name.
    /// </summary>
    public string? ModuleName { get; init; }

    /// <summary>
    /// Function name.
    /// </summary>
    public string? FunctionName { get; init; }

    /// <summary>
    /// Source file path.
    /// </summary>
    public string? SourceFile { get; init; }

    /// <summary>
    /// Line number.
    /// </summary>
    public int? LineNumber { get; init; }

    /// <summary>
    /// Python version.
    /// </summary>
    public string? PythonVersion { get; init; }
}