using System.Text.Json.Serialization;

namespace StellaOps.Policy.Engine.Domain;

/// <summary>
/// Request for a policy decision with source evidence summaries (POLICY-ENGINE-40-003).
/// </summary>
public sealed record PolicyDecisionRequest(
    [property: JsonPropertyName("snapshot_id")] string SnapshotId,
    [property: JsonPropertyName("tenant_id")] string? TenantId = null,
    [property: JsonPropertyName("component_purl")] string? ComponentPurl = null,
    [property: JsonPropertyName("advisory_id")] string? AdvisoryId = null,
    [property: JsonPropertyName("include_evidence")] bool IncludeEvidence = true,
    [property: JsonPropertyName("max_sources")] int MaxSources = 5);

/// <summary>
/// Response containing policy decisions with source evidence summaries.
/// </summary>
public sealed record PolicyDecisionResponse(
    [property: JsonPropertyName("snapshot_id")] string SnapshotId,
    [property: JsonPropertyName("decisions")] IReadOnlyList<PolicyDecisionItem> Decisions,
    [property: JsonPropertyName("summary")] PolicyDecisionSummary Summary);

/// <summary>
/// A single policy decision with associated evidence.
/// </summary>
public sealed record PolicyDecisionItem(
    [property: JsonPropertyName("tenant_id")] string TenantId,
    [property: JsonPropertyName("component_purl")] string ComponentPurl,
    [property: JsonPropertyName("advisory_id")] string AdvisoryId,
    [property: JsonPropertyName("severity_fused")] string SeverityFused,
    [property: JsonPropertyName("score")] decimal Score,
    [property: JsonPropertyName("status")] string Status,
    [property: JsonPropertyName("top_sources")] IReadOnlyList<PolicyDecisionSource> TopSources,
    [property: JsonPropertyName("evidence")] PolicyDecisionEvidence? Evidence,
    [property: JsonPropertyName("conflict_count")] int ConflictCount,
    [property: JsonPropertyName("reason_codes")] IReadOnlyList<string> ReasonCodes);

/// <summary>
/// Top severity source information for a decision.
/// </summary>
public sealed record PolicyDecisionSource(
    [property: JsonPropertyName("source")] string Source,
    [property: JsonPropertyName("weight")] decimal Weight,
    [property: JsonPropertyName("severity")] string Severity,
    [property: JsonPropertyName("score")] decimal Score,
    [property: JsonPropertyName("rank")] int Rank);

/// <summary>
/// Evidence summary for a policy decision.
/// </summary>
public sealed record PolicyDecisionEvidence(
    [property: JsonPropertyName("headline")] string Headline,
    [property: JsonPropertyName("severity")] string Severity,
    [property: JsonPropertyName("locator")] PolicyDecisionLocator Locator,
    [property: JsonPropertyName("signals")] IReadOnlyList<string> Signals);

/// <summary>
/// Evidence locator information.
/// </summary>
public sealed record PolicyDecisionLocator(
    [property: JsonPropertyName("file_path")] string FilePath,
    [property: JsonPropertyName("digest")] string? Digest);

/// <summary>
/// Summary statistics for the decision response.
/// </summary>
public sealed record PolicyDecisionSummary(
    [property: JsonPropertyName("total_decisions")] int TotalDecisions,
    [property: JsonPropertyName("total_conflicts")] int TotalConflicts,
    [property: JsonPropertyName("severity_counts")] IReadOnlyDictionary<string, int> SeverityCounts,
    [property: JsonPropertyName("top_severity_sources")] IReadOnlyList<PolicyDecisionSourceRank> TopSeveritySources);

/// <summary>
/// Aggregated source rank across all decisions.
/// </summary>
public sealed record PolicyDecisionSourceRank(
    [property: JsonPropertyName("source")] string Source,
    [property: JsonPropertyName("total_weight")] decimal TotalWeight,
    [property: JsonPropertyName("decision_count")] int DecisionCount,
    [property: JsonPropertyName("average_score")] decimal AverageScore);