// <copyright file="LegacyEvidencePropertyWriter.cs" company="StellaOps">
// Copyright (c) StellaOps. Licensed under the BUSL-1.1.
// </copyright>

using System.Collections.Immutable;
using System.Globalization;
using CycloneDX.Models;
using StellaOps.Scanner.Core.Contracts;

namespace StellaOps.Scanner.Emit.Evidence;

/// <summary>
/// Writes evidence data to legacy CycloneDX property format for backward compatibility.
/// Sprint: SPRINT_20260107_005_001 Task EV-009
/// </summary>
/// <remarks>
/// <para>Migration Support:</para>
/// <para>
/// During the migration period from property-based evidence to native CycloneDX 1.7 evidence fields,
/// this class provides dual-output capability - writing evidence both to native fields and legacy properties.
/// </para>
/// <para>Legacy Property Format:</para>
/// <list type="bullet">
/// <item>stellaops:evidence[n]:kind - Evidence kind (identity, occurrence, license, callstack)</item>
/// <item>stellaops:evidence[n]:source - Evidence source/analyzer</item>
/// <item>stellaops:evidence[n]:value - Evidence value</item>
/// <item>stellaops:evidence[n]:confidence - Confidence score (0.0-1.0)</item>
/// <item>stellaops:evidence[n]:methods - Reference to evidence.methods[] (CycloneDX 1.7)</item>
/// </list>
/// </remarks>
public sealed class LegacyEvidencePropertyWriter
{
    private const string PropertyPrefix = "stellaops:evidence";

    /// <summary>
    /// Writes component evidence to legacy property format.
    /// </summary>
    /// <param name="component">The CycloneDX component to add properties to.</param>
    /// <param name="evidence">The evidence collection from Scanner core.</param>
    /// <param name="options">Options controlling evidence output.</param>
    public void WriteEvidenceProperties(
        Component component,
        ImmutableArray<ComponentEvidence> evidence,
        LegacyEvidenceOptions options)
    {
        ArgumentNullException.ThrowIfNull(component);

        if (evidence.IsDefaultOrEmpty)
        {
            return;
        }

        component.Properties ??= [];

        int evidenceIndex = 0;
        foreach (var item in evidence)
        {
            WriteEvidenceItem(component.Properties, item, evidenceIndex, options);
            evidenceIndex++;
        }
    }

    /// <summary>
    /// Removes legacy evidence properties from a component.
    /// </summary>
    /// <param name="component">The CycloneDX component to clean.</param>
    public void RemoveLegacyProperties(Component component)
    {
        ArgumentNullException.ThrowIfNull(component);

        if (component.Properties == null)
        {
            return;
        }

        component.Properties.RemoveAll(p => p.Name?.StartsWith(PropertyPrefix, StringComparison.Ordinal) == true);
    }

    private void WriteEvidenceItem(
        List<Property> properties,
        ComponentEvidence evidence,
        int index,
        LegacyEvidenceOptions options)
    {
        var prefix = $"{PropertyPrefix}[{index.ToString(CultureInfo.InvariantCulture)}]";

        // Kind
        properties.Add(new Property
        {
            Name = $"{prefix}:kind",
            Value = evidence.Kind,
        });

        // Source
        if (!string.IsNullOrWhiteSpace(evidence.Source))
        {
            properties.Add(new Property
            {
                Name = $"{prefix}:source",
                Value = evidence.Source,
            });
        }

        // Value
        if (!string.IsNullOrWhiteSpace(evidence.Value))
        {
            properties.Add(new Property
            {
                Name = $"{prefix}:value",
                Value = evidence.Value,
            });
        }

        // Methods reference (CycloneDX 1.7 interop)
        if (options.IncludeMethodsReference)
        {
            var methodsReference = MapKindToMethodsReference(evidence.Kind);
            if (!string.IsNullOrWhiteSpace(methodsReference))
            {
                properties.Add(new Property
                {
                    Name = $"{prefix}:methods",
                    Value = methodsReference,
                });
            }
        }
    }

    private static string? MapKindToMethodsReference(string kind)
    {
        return kind.ToLowerInvariant() switch
        {
            "identity" => "evidence.identity",
            "occurrence" => "evidence.occurrences",
            "license" => "evidence.licenses",
            "callstack" => "evidence.callstack",
            "copyright" => "evidence.copyright",
            "hash" => "evidence.identity",
            "manifest" => "evidence.occurrences",
            "signature" => "evidence.identity",
            _ => null,
        };
    }
}

/// <summary>
/// Options for legacy evidence property output.
/// </summary>
public sealed class LegacyEvidenceOptions
{
    /// <summary>
    /// Gets or sets a value indicating whether to include references to CycloneDX 1.7 evidence.methods[].
    /// Default is true.
    /// </summary>
    public bool IncludeMethodsReference { get; set; } = true;

    /// <summary>
    /// Gets or sets a value indicating whether legacy properties should be written at all.
    /// When false, only native CycloneDX 1.7 evidence fields are used.
    /// Default is true during migration period.
    /// </summary>
    public bool EnableLegacyProperties { get; set; } = true;
}