using System.CommandLine;
using System.CommandLine.Invocation;
using Microsoft.Extensions.Logging;

namespace StellaOps.Cli.Commands.Proof;

/// <summary>
/// Command group for proof chain operations.
/// Implements advisory §15 CLI commands.
/// </summary>
public class ProofCommandGroup
{
    private readonly ILogger<ProofCommandGroup> _logger;

    public ProofCommandGroup(ILogger<ProofCommandGroup> logger)
    {
        _logger = logger;
    }

    /// <summary>
    /// Build the proof command tree.
    /// </summary>
    public Command BuildCommand()
    {
        var proofCommand = new Command("proof", "Proof chain operations");

        proofCommand.AddCommand(BuildVerifyCommand());
        proofCommand.AddCommand(BuildSpineCommand());

        return proofCommand;
    }

    private Command BuildVerifyCommand()
    {
        var artifactArg = new Argument<string>(
            name: "artifact",
            description: "Artifact digest (sha256:...) or PURL");

        var sbomOption = new Option<FileInfo?>(
            aliases: ["-s", "--sbom"],
            description: "Path to SBOM file");

        var vexOption = new Option<FileInfo?>(
            aliases: ["--vex"],
            description: "Path to VEX file");

        var anchorOption = new Option<Guid?>(
            aliases: ["-a", "--anchor"],
            description: "Trust anchor ID");

        var offlineOption = new Option<bool>(
            name: "--offline",
            description: "Offline mode (skip Rekor verification)");

        var outputOption = new Option<string>(
            name: "--output",
            getDefaultValue: () => "text",
            description: "Output format: text, json");

        var verboseOption = new Option<int>(
            aliases: ["-v", "--verbose"],
            getDefaultValue: () => 0,
            description: "Verbose output level (use -vv for very verbose)");

        var verifyCommand = new Command("verify", "Verify an artifact's proof chain")
        {
            artifactArg,
            sbomOption,
            vexOption,
            anchorOption,
            offlineOption,
            outputOption,
            verboseOption
        };

        verifyCommand.SetHandler(async (context) =>
        {
            var artifact = context.ParseResult.GetValueForArgument(artifactArg);
            var sbomFile = context.ParseResult.GetValueForOption(sbomOption);
            var vexFile = context.ParseResult.GetValueForOption(vexOption);
            var anchorId = context.ParseResult.GetValueForOption(anchorOption);
            var offline = context.ParseResult.GetValueForOption(offlineOption);
            var output = context.ParseResult.GetValueForOption(outputOption) ?? "text";
            var verbose = context.ParseResult.GetValueForOption(verboseOption);

            context.ExitCode = await VerifyAsync(
                artifact,
                sbomFile,
                vexFile,
                anchorId,
                offline,
                output,
                verbose,
                context.GetCancellationToken());
        });

        return verifyCommand;
    }

    private Command BuildSpineCommand()
    {
        var spineCommand = new Command("spine", "Proof spine operations");

        // stellaops proof spine create
        var createCommand = new Command("create", "Create a proof spine for an artifact");
        var artifactArg = new Argument<string>("artifact", "Artifact digest or PURL");
        createCommand.AddArgument(artifactArg);
        createCommand.SetHandler(async (context) =>
        {
            var artifact = context.ParseResult.GetValueForArgument(artifactArg);
            context.ExitCode = await CreateSpineAsync(artifact, context.GetCancellationToken());
        });

        // stellaops proof spine show
        var showCommand = new Command("show", "Show proof spine details");
        var bundleArg = new Argument<string>("bundleId", "Proof bundle ID");
        showCommand.AddArgument(bundleArg);
        showCommand.SetHandler(async (context) =>
        {
            var bundleId = context.ParseResult.GetValueForArgument(bundleArg);
            context.ExitCode = await ShowSpineAsync(bundleId, context.GetCancellationToken());
        });

        spineCommand.AddCommand(createCommand);
        spineCommand.AddCommand(showCommand);

        return spineCommand;
    }

    private async Task<int> VerifyAsync(
        string artifact,
        FileInfo? sbomFile,
        FileInfo? vexFile,
        Guid? anchorId,
        bool offline,
        string output,
        int verbose,
        CancellationToken ct)
    {
        try
        {
            if (verbose > 0)
            {
                _logger.LogDebug("Starting proof verification for {Artifact}", artifact);
            }

            // Validate artifact format
            if (!IsValidArtifactId(artifact))
            {
                _logger.LogError("Invalid artifact format: {Artifact}", artifact);
                return ProofExitCodes.SystemError;
            }

            if (verbose > 0)
            {
                _logger.LogDebug("Artifact format valid: {Artifact}", artifact);
            }

            // TODO: Implement actual verification using IVerificationPipeline
            // 1. Load SBOM if provided
            // 2. Load VEX if provided
            // 3. Find or use specified trust anchor
            // 4. Run verification pipeline
            // 5. Check Rekor inclusion (unless offline)
            // 6. Generate receipt

            if (verbose > 0)
            {
                _logger.LogDebug("Verification pipeline not yet implemented");
            }

            if (output == "json")
            {
                Console.WriteLine("{");
                Console.WriteLine($"  \"artifact\": \"{artifact}\",");
                Console.WriteLine("  \"status\": \"pass\",");
                Console.WriteLine("  \"message\": \"Verification successful (stub)\"");
                Console.WriteLine("}");
            }
            else
            {
                Console.WriteLine("StellaOps Scan Summary");
                Console.WriteLine("══════════════════════");
                Console.WriteLine($"Artifact: {artifact}");
                Console.WriteLine("Status: PASS (stub - verification not yet implemented)");
            }

            return ProofExitCodes.Success;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Verification failed for {Artifact}", artifact);
            return ProofExitCodes.SystemError;
        }
    }

    private async Task<int> CreateSpineAsync(string artifact, CancellationToken ct)
    {
        try
        {
            _logger.LogInformation("Creating proof spine for {Artifact}", artifact);

            // TODO: Implement spine creation using IProofSpineAssembler
            Console.WriteLine($"Creating proof spine for: {artifact}");
            Console.WriteLine("Spine creation not yet implemented");

            return ProofExitCodes.Success;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to create spine for {Artifact}", artifact);
            return ProofExitCodes.SystemError;
        }
    }

    private async Task<int> ShowSpineAsync(string bundleId, CancellationToken ct)
    {
        try
        {
            _logger.LogInformation("Showing proof spine {BundleId}", bundleId);

            // TODO: Implement spine retrieval
            Console.WriteLine($"Proof spine: {bundleId}");
            Console.WriteLine("Spine display not yet implemented");

            return ProofExitCodes.Success;
        }
        catch (Exception ex)
        {
            _logger.LogError(ex, "Failed to show spine {BundleId}", bundleId);
            return ProofExitCodes.SystemError;
        }
    }

    private static bool IsValidArtifactId(string artifact)
    {
        if (string.IsNullOrWhiteSpace(artifact))
            return false;

        // sha256:<64-hex>
        if (artifact.StartsWith("sha256:", StringComparison.OrdinalIgnoreCase))
        {
            var hash = artifact[7..];
            return hash.Length == 64 && hash.All(c => "0123456789abcdef".Contains(char.ToLowerInvariant(c)));
        }

        // pkg:type/...
        if (artifact.StartsWith("pkg:", StringComparison.OrdinalIgnoreCase))
        {
            return artifact.Length > 5; // Minimal PURL validation
        }

        return false;
    }
}