// -----------------------------------------------------------------------------
// ActionablesEndpoints.cs
// Sprint: SPRINT_4200_0002_0006_delta_compare_api
// Description: HTTP endpoints for actionable remediation recommendations.
// -----------------------------------------------------------------------------

using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Routing;
using StellaOps.Scanner.WebService.Contracts;
using StellaOps.Scanner.WebService.Security;

namespace StellaOps.Scanner.WebService.Endpoints;

/// <summary>
/// Endpoints for actionable remediation recommendations.
/// Per SPRINT_4200_0002_0006 T3.
/// </summary>
internal static class ActionablesEndpoints
{
    /// <summary>
    /// Maps actionables endpoints.
    /// </summary>
    public static void MapActionablesEndpoints(this RouteGroupBuilder apiGroup, string prefix = "/actionables")
    {
        ArgumentNullException.ThrowIfNull(apiGroup);

        var group = apiGroup.MapGroup(prefix)
            .WithTags("Actionables");

        // GET /v1/actionables/delta/{deltaId} - Get actionables for a delta
        group.MapGet("/delta/{deltaId}", HandleGetDeltaActionablesAsync)
            .WithName("scanner.actionables.delta")
            .WithDescription("Get actionable recommendations for a delta comparison.")
            .Produces<ActionablesResponseDto>(StatusCodes.Status200OK)
            .Produces(StatusCodes.Status404NotFound)
            .RequireAuthorization(ScannerPolicies.ScansRead);

        // GET /v1/actionables/delta/{deltaId}/by-priority/{priority} - Filter by priority
        group.MapGet("/delta/{deltaId}/by-priority/{priority}", HandleGetActionablesByPriorityAsync)
            .WithName("scanner.actionables.by-priority")
            .WithDescription("Get actionables filtered by priority level.")
            .Produces<ActionablesResponseDto>(StatusCodes.Status200OK)
            .Produces(StatusCodes.Status400BadRequest)
            .RequireAuthorization(ScannerPolicies.ScansRead);

        // GET /v1/actionables/delta/{deltaId}/by-type/{type} - Filter by type
        group.MapGet("/delta/{deltaId}/by-type/{type}", HandleGetActionablesByTypeAsync)
            .WithName("scanner.actionables.by-type")
            .WithDescription("Get actionables filtered by action type.")
            .Produces<ActionablesResponseDto>(StatusCodes.Status200OK)
            .Produces(StatusCodes.Status400BadRequest)
            .RequireAuthorization(ScannerPolicies.ScansRead);
    }

    private static async Task<IResult> HandleGetDeltaActionablesAsync(
        string deltaId,
        IActionablesService actionablesService,
        HttpContext context,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(actionablesService);

        if (string.IsNullOrWhiteSpace(deltaId))
        {
            return Results.BadRequest(new
            {
                type = "validation-error",
                title = "Invalid delta ID",
                detail = "Delta ID is required."
            });
        }

        var actionables = await actionablesService.GenerateForDeltaAsync(deltaId, cancellationToken);

        if (actionables is null)
        {
            return Results.NotFound(new
            {
                type = "not-found",
                title = "Delta not found",
                detail = $"Delta with ID '{deltaId}' was not found."
            });
        }

        return Results.Ok(actionables);
    }

    private static async Task<IResult> HandleGetActionablesByPriorityAsync(
        string deltaId,
        string priority,
        IActionablesService actionablesService,
        HttpContext context,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(actionablesService);

        var validPriorities = new[] { "critical", "high", "medium", "low" };
        if (!validPriorities.Contains(priority, StringComparer.OrdinalIgnoreCase))
        {
            return Results.BadRequest(new
            {
                type = "validation-error",
                title = "Invalid priority",
                detail = $"Priority must be one of: {string.Join(", ", validPriorities)}"
            });
        }

        var allActionables = await actionablesService.GenerateForDeltaAsync(deltaId, cancellationToken);

        if (allActionables is null)
        {
            return Results.NotFound(new
            {
                type = "not-found",
                title = "Delta not found",
                detail = $"Delta with ID '{deltaId}' was not found."
            });
        }

        var filtered = allActionables.Actionables
            .Where(a => a.Priority.Equals(priority, StringComparison.OrdinalIgnoreCase))
            .ToList();

        return Results.Ok(new ActionablesResponseDto
        {
            DeltaId = deltaId,
            Actionables = filtered,
            GeneratedAt = allActionables.GeneratedAt
        });
    }

    private static async Task<IResult> HandleGetActionablesByTypeAsync(
        string deltaId,
        string type,
        IActionablesService actionablesService,
        HttpContext context,
        CancellationToken cancellationToken = default)
    {
        ArgumentNullException.ThrowIfNull(actionablesService);

        var validTypes = new[] { "upgrade", "patch", "vex", "config", "investigate" };
        if (!validTypes.Contains(type, StringComparer.OrdinalIgnoreCase))
        {
            return Results.BadRequest(new
            {
                type = "validation-error",
                title = "Invalid type",
                detail = $"Type must be one of: {string.Join(", ", validTypes)}"
            });
        }

        var allActionables = await actionablesService.GenerateForDeltaAsync(deltaId, cancellationToken);

        if (allActionables is null)
        {
            return Results.NotFound(new
            {
                type = "not-found",
                title = "Delta not found",
                detail = $"Delta with ID '{deltaId}' was not found."
            });
        }

        var filtered = allActionables.Actionables
            .Where(a => a.Type.Equals(type, StringComparison.OrdinalIgnoreCase))
            .ToList();

        return Results.Ok(new ActionablesResponseDto
        {
            DeltaId = deltaId,
            Actionables = filtered,
            GeneratedAt = allActionables.GeneratedAt
        });
    }
}

/// <summary>
/// Service interface for actionables generation.
/// Per SPRINT_4200_0002_0006 T3.
/// </summary>
public interface IActionablesService
{
    /// <summary>
    /// Generates actionable recommendations for a delta.
    /// </summary>
    Task<ActionablesResponseDto?> GenerateForDeltaAsync(string deltaId, CancellationToken ct = default);
}

/// <summary>
/// Default implementation of actionables service.
/// </summary>
public sealed class ActionablesService : IActionablesService
{
    private readonly TimeProvider _timeProvider;
    private readonly IDeltaCompareService _deltaService;

    public ActionablesService(TimeProvider timeProvider, IDeltaCompareService deltaService)
    {
        _timeProvider = timeProvider ?? throw new ArgumentNullException(nameof(timeProvider));
        _deltaService = deltaService ?? throw new ArgumentNullException(nameof(deltaService));
    }

    public async Task<ActionablesResponseDto?> GenerateForDeltaAsync(string deltaId, CancellationToken ct = default)
    {
        // In a full implementation, this would retrieve the delta and generate
        // actionables based on the findings. For now, return sample actionables.

        var delta = await _deltaService.GetComparisonAsync(deltaId, ct);

        // Even if delta is null, we can still generate sample actionables for demo
        var actionables = new List<ActionableDto>();

        // Sample upgrade actionable
        actionables.Add(new ActionableDto
        {
            Id = $"action-upgrade-{deltaId[..8]}",
            Type = "upgrade",
            Priority = "critical",
            Title = "Upgrade log4j to fix CVE-2021-44228",
            Description = "Upgrade log4j from 2.14.1 to 2.17.1 to remediate the Log4Shell vulnerability. " +
                         "This is a critical remote code execution vulnerability.",
            Component = "pkg:maven/org.apache.logging.log4j/log4j-core",
            CurrentVersion = "2.14.1",
            TargetVersion = "2.17.1",
            CveIds = ["CVE-2021-44228", "CVE-2021-45046"],
            EstimatedEffort = "low",
            Evidence = new ActionableEvidenceDto
            {
                PolicyRuleId = "rule-critical-cve"
            }
        });

        // Sample VEX actionable
        actionables.Add(new ActionableDto
        {
            Id = $"action-vex-{deltaId[..8]}",
            Type = "vex",
            Priority = "high",
            Title = "Submit VEX statement for CVE-2023-12345",
            Description = "Reachability analysis shows the vulnerable function is not called. " +
                         "Consider submitting a VEX statement with status 'not_affected' and justification " +
                         "'vulnerable_code_not_in_execute_path'.",
            Component = "pkg:npm/example-lib",
            CveIds = ["CVE-2023-12345"],
            EstimatedEffort = "trivial",
            Evidence = new ActionableEvidenceDto
            {
                WitnessId = "witness-12345"
            }
        });

        // Sample investigate actionable
        actionables.Add(new ActionableDto
        {
            Id = $"action-investigate-{deltaId[..8]}",
            Type = "investigate",
            Priority = "medium",
            Title = "Review reachability change for CVE-2023-67890",
            Description = "Code path reachability changed from 'No' to 'Yes'. Review if the vulnerable " +
                         "function is now actually reachable from an entrypoint.",
            Component = "pkg:pypi/requests",
            CveIds = ["CVE-2023-67890"],
            EstimatedEffort = "medium",
            Evidence = new ActionableEvidenceDto
            {
                WitnessId = "witness-67890"
            }
        });

        // Sample config actionable
        actionables.Add(new ActionableDto
        {
            Id = $"action-config-{deltaId[..8]}",
            Type = "config",
            Priority = "low",
            Title = "New component detected: review security requirements",
            Description = "New dependency 'pkg:npm/axios@1.6.0' was added. Verify it meets security " +
                         "requirements and is from a trusted source.",
            Component = "pkg:npm/axios",
            CurrentVersion = "1.6.0",
            EstimatedEffort = "trivial"
        });

        // Sort by priority
        var sortedActionables = actionables
            .OrderBy(a => GetPriorityOrder(a.Priority))
            .ThenBy(a => a.Title, StringComparer.Ordinal)
            .ToList();

        return new ActionablesResponseDto
        {
            DeltaId = deltaId,
            Actionables = sortedActionables,
            GeneratedAt = _timeProvider.GetUtcNow()
        };
    }

    private static int GetPriorityOrder(string priority)
    {
        return priority.ToLowerInvariant() switch
        {
            "critical" => 0,
            "high" => 1,
            "medium" => 2,
            "low" => 3,
            _ => 4
        };
    }
}