using System.Collections.Immutable;
using System.Text.Json.Serialization;

namespace StellaOps.Scanner.SmartDiff;


/// <summary>
/// Smart-Diff predicate for DSSE attestation.
/// </summary>
public sealed record SmartDiffPredicate(
    [property: JsonPropertyName("schemaVersion")] string SchemaVersion,
    [property: JsonPropertyName("baseImage")] ImageReference BaseImage,
    [property: JsonPropertyName("targetImage")] ImageReference TargetImage,
    [property: JsonPropertyName("diff")] DiffPayload Diff,
    [property: JsonPropertyName("reachabilityGate")] ReachabilityGate ReachabilityGate,
    [property: JsonPropertyName("scanner")] ScannerInfo Scanner,
    [property: JsonPropertyName("context")] RuntimeContext? Context = null,
    [property: JsonPropertyName("suppressedCount")] int SuppressedCount = 0,
    [property: JsonPropertyName("materialChanges")] ImmutableArray<MaterialChange>? MaterialChanges = null)
{
    public const string PredicateType = "stellaops.dev/predicates/smart-diff@v1";
    public const string CurrentSchemaVersion = "1.0.0";
}

public sealed record ImageReference(
    [property: JsonPropertyName("digest")] string Digest,
    [property: JsonPropertyName("name")] string? Name = null,
    [property: JsonPropertyName("tag")] string? Tag = null);

public sealed record DiffPayload(
    [property: JsonPropertyName("filesAdded")] ImmutableArray<string>? FilesAdded = null,
    [property: JsonPropertyName("filesRemoved")] ImmutableArray<string>? FilesRemoved = null,
    [property: JsonPropertyName("filesChanged")] ImmutableArray<FileChange>? FilesChanged = null,
    [property: JsonPropertyName("packagesChanged")] ImmutableArray<PackageChange>? PackagesChanged = null,
    [property: JsonPropertyName("packagesAdded")] ImmutableArray<PackageRef>? PackagesAdded = null,
    [property: JsonPropertyName("packagesRemoved")] ImmutableArray<PackageRef>? PackagesRemoved = null);

public sealed record FileChange(
    [property: JsonPropertyName("path")] string Path,
    [property: JsonPropertyName("hunks")] ImmutableArray<DiffHunk>? Hunks = null,
    [property: JsonPropertyName("fromHash")] string? FromHash = null,
    [property: JsonPropertyName("toHash")] string? ToHash = null);

public sealed record DiffHunk(
    [property: JsonPropertyName("startLine")] int StartLine,
    [property: JsonPropertyName("lineCount")] int LineCount,
    [property: JsonPropertyName("content")] string? Content = null);

public sealed record PackageChange(
    [property: JsonPropertyName("name")] string Name,
    [property: JsonPropertyName("from")] string From,
    [property: JsonPropertyName("to")] string To,
    [property: JsonPropertyName("purl")] string? Purl = null,
    [property: JsonPropertyName("licenseDelta")] LicenseDelta? LicenseDelta = null);

public sealed record LicenseDelta(
    [property: JsonPropertyName("added")] ImmutableArray<string>? Added = null,
    [property: JsonPropertyName("removed")] ImmutableArray<string>? Removed = null);

public sealed record PackageRef(
    [property: JsonPropertyName("name")] string Name,
    [property: JsonPropertyName("version")] string Version,
    [property: JsonPropertyName("purl")] string? Purl = null);

public sealed record RuntimeContext(
    [property: JsonPropertyName("entrypoint")] ImmutableArray<string>? Entrypoint = null,
    [property: JsonPropertyName("env")] ImmutableDictionary<string, string>? Env = null,
    [property: JsonPropertyName("user")] UserContext? User = null);

public sealed record UserContext(
    [property: JsonPropertyName("uid")] int? Uid = null,
    [property: JsonPropertyName("gid")] int? Gid = null,
    [property: JsonPropertyName("caps")] ImmutableArray<string>? Caps = null);

/// <summary>
/// 3-bit reachability gate derived from the 7-state lattice.
/// </summary>
public sealed record ReachabilityGate(
    [property: JsonPropertyName("reachable")] bool? Reachable,
    [property: JsonPropertyName("configActivated")] bool? ConfigActivated,
    [property: JsonPropertyName("runningUser")] bool? RunningUser,
    [property: JsonPropertyName("class")] int Class,
    [property: JsonPropertyName("rationale")] string? Rationale = null)
{
    /// <summary>
    /// Computes the 3-bit class from the gate values.
    /// Returns -1 if any gate value is unknown (null).
    /// </summary>
    public static int ComputeClass(bool? reachable, bool? configActivated, bool? runningUser)
    {
        if (reachable is null || configActivated is null || runningUser is null)
        {
            return -1;
        }

        return (reachable.Value ? 4 : 0)
            + (configActivated.Value ? 2 : 0)
            + (runningUser.Value ? 1 : 0);
    }

    /// <summary>
    /// Creates a ReachabilityGate with auto-computed class.
    /// </summary>
    public static ReachabilityGate Create(
        bool? reachable,
        bool? configActivated,
        bool? runningUser,
        string? rationale = null)
        => new(
            reachable,
            configActivated,
            runningUser,
            ComputeClass(reachable, configActivated, runningUser),
            rationale);
}

public sealed record ScannerInfo(
    [property: JsonPropertyName("name")] string Name,
    [property: JsonPropertyName("version")] string Version,
    [property: JsonPropertyName("ruleset")] string? Ruleset = null);

public sealed record MaterialChange(
    [property: JsonPropertyName("findingKey")] FindingKey FindingKey,
    [property: JsonPropertyName("changeType")] MaterialChangeType ChangeType,
    [property: JsonPropertyName("reason")] string Reason,
    [property: JsonPropertyName("previousState")] RiskState? PreviousState = null,
    [property: JsonPropertyName("currentState")] RiskState? CurrentState = null,
    [property: JsonPropertyName("priorityScore")] int? PriorityScore = null);

public sealed record FindingKey(
    [property: JsonPropertyName("componentPurl")] string ComponentPurl,
    [property: JsonPropertyName("componentVersion")] string ComponentVersion,
    [property: JsonPropertyName("cveId")] string CveId);

[JsonConverter(typeof(JsonStringEnumConverter<MaterialChangeType>))]
public enum MaterialChangeType
{
    [JsonStringEnumMemberName("reachability_flip")]
    ReachabilityFlip,

    [JsonStringEnumMemberName("vex_flip")]
    VexFlip,

    [JsonStringEnumMemberName("range_boundary")]
    RangeBoundary,

    [JsonStringEnumMemberName("intelligence_flip")]
    IntelligenceFlip
}

public sealed record RiskState(
    [property: JsonPropertyName("reachable")] bool? Reachable = null,
    [property: JsonPropertyName("vexStatus")] VexStatusType VexStatus = VexStatusType.Unknown,
    [property: JsonPropertyName("inAffectedRange")] bool? InAffectedRange = null,
    [property: JsonPropertyName("kev")] bool Kev = false,
    [property: JsonPropertyName("epssScore")] double? EpssScore = null,
    [property: JsonPropertyName("policyFlags")] ImmutableArray<string>? PolicyFlags = null);

[JsonConverter(typeof(JsonStringEnumConverter<VexStatusType>))]
public enum VexStatusType
{
    [JsonStringEnumMemberName("affected")]
    Affected,

    [JsonStringEnumMemberName("not_affected")]
    NotAffected,

    [JsonStringEnumMemberName("fixed")]
    Fixed,

    [JsonStringEnumMemberName("under_investigation")]
    UnderInvestigation,

    [JsonStringEnumMemberName("unknown")]
    Unknown
}