using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.AspNetCore.Mvc;
using StellaOps.Auth.Abstractions;
using StellaOps.Policy.Engine.Services;
using StellaOps.Policy.Storage.Postgres.Models;
using StellaOps.Policy.Storage.Postgres.Repositories;

namespace StellaOps.Policy.Engine.Endpoints;

/// <summary>
/// Policy conflict detection and resolution endpoints.
/// Conflicts track policy rule overlaps and inconsistencies.
/// </summary>
internal static class ConflictEndpoints
{
    public static IEndpointRouteBuilder MapConflictsApi(this IEndpointRouteBuilder endpoints)
    {
        var group = endpoints.MapGroup("/api/policy/conflicts")
            .RequireAuthorization()
            .WithTags("Policy Conflicts");

        group.MapGet(string.Empty, ListOpenConflicts)
            .WithName("ListOpenPolicyConflicts")
            .WithSummary("List open policy conflicts sorted by severity.")
            .Produces<ConflictListResponse>(StatusCodes.Status200OK);

        group.MapGet("/{conflictId:guid}", GetConflict)
            .WithName("GetPolicyConflict")
            .WithSummary("Get a specific policy conflict by ID.")
            .Produces<ConflictResponse>(StatusCodes.Status200OK)
            .Produces<ProblemHttpResult>(StatusCodes.Status404NotFound);

        group.MapGet("/by-type/{conflictType}", GetConflictsByType)
            .WithName("GetPolicyConflictsByType")
            .WithSummary("Get conflicts filtered by type.")
            .Produces<ConflictListResponse>(StatusCodes.Status200OK);

        group.MapGet("/stats/by-severity", GetConflictStatsBySeverity)
            .WithName("GetPolicyConflictStatsBySeverity")
            .WithSummary("Get open conflict counts grouped by severity.")
            .Produces<ConflictStatsResponse>(StatusCodes.Status200OK);

        group.MapPost(string.Empty, CreateConflict)
            .WithName("CreatePolicyConflict")
            .WithSummary("Report a new policy conflict.")
            .Produces<ConflictResponse>(StatusCodes.Status201Created)
            .Produces<ProblemHttpResult>(StatusCodes.Status400BadRequest);

        group.MapPost("/{conflictId:guid}:resolve", ResolveConflict)
            .WithName("ResolvePolicyConflict")
            .WithSummary("Resolve an open conflict with a resolution description.")
            .Produces<ConflictActionResponse>(StatusCodes.Status200OK)
            .Produces<ProblemHttpResult>(StatusCodes.Status400BadRequest)
            .Produces<ProblemHttpResult>(StatusCodes.Status404NotFound);

        group.MapPost("/{conflictId:guid}:dismiss", DismissConflict)
            .WithName("DismissPolicyConflict")
            .WithSummary("Dismiss an open conflict without resolution.")
            .Produces<ConflictActionResponse>(StatusCodes.Status200OK)
            .Produces<ProblemHttpResult>(StatusCodes.Status404NotFound);

        return endpoints;
    }

    private static async Task<IResult> ListOpenConflicts(
        HttpContext context,
        [FromQuery] int limit,
        [FromQuery] int offset,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyRead);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var effectiveLimit = limit > 0 ? limit : 100;
        var effectiveOffset = offset > 0 ? offset : 0;

        var conflicts = await repository.GetOpenAsync(tenantId, effectiveLimit, effectiveOffset, cancellationToken)
            .ConfigureAwait(false);

        var items = conflicts.Select(c => new ConflictSummary(
            c.Id,
            c.ConflictType,
            c.Severity,
            c.Status,
            c.LeftRuleId,
            c.RightRuleId,
            c.AffectedScope,
            c.Description,
            c.CreatedAt
        )).ToList();

        return Results.Ok(new ConflictListResponse(items, effectiveLimit, effectiveOffset));
    }

    private static async Task<IResult> GetConflict(
        HttpContext context,
        [FromRoute] Guid conflictId,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyRead);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var conflict = await repository.GetByIdAsync(tenantId, conflictId, cancellationToken)
            .ConfigureAwait(false);

        if (conflict is null)
        {
            return Results.NotFound(new ProblemDetails
            {
                Title = "Conflict not found",
                Detail = $"Policy conflict '{conflictId}' was not found.",
                Status = StatusCodes.Status404NotFound
            });
        }

        return Results.Ok(new ConflictResponse(conflict));
    }

    private static async Task<IResult> GetConflictsByType(
        HttpContext context,
        [FromRoute] string conflictType,
        [FromQuery] string? status,
        [FromQuery] int limit,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyRead);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var effectiveLimit = limit > 0 ? limit : 100;

        var conflicts = await repository.GetByTypeAsync(tenantId, conflictType, status, effectiveLimit, cancellationToken)
            .ConfigureAwait(false);

        var items = conflicts.Select(c => new ConflictSummary(
            c.Id,
            c.ConflictType,
            c.Severity,
            c.Status,
            c.LeftRuleId,
            c.RightRuleId,
            c.AffectedScope,
            c.Description,
            c.CreatedAt
        )).ToList();

        return Results.Ok(new ConflictListResponse(items, effectiveLimit, 0));
    }

    private static async Task<IResult> GetConflictStatsBySeverity(
        HttpContext context,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyRead);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var stats = await repository.CountOpenBySeverityAsync(tenantId, cancellationToken)
            .ConfigureAwait(false);

        return Results.Ok(new ConflictStatsResponse(stats));
    }

    private static async Task<IResult> CreateConflict(
        HttpContext context,
        [FromBody] CreateConflictRequest request,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyEdit);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var actorId = ResolveActorId(context);

        var entity = new ConflictEntity
        {
            Id = Guid.NewGuid(),
            TenantId = tenantId,
            ConflictType = request.ConflictType,
            Severity = request.Severity,
            Status = "open",
            LeftRuleId = request.LeftRuleId,
            RightRuleId = request.RightRuleId,
            AffectedScope = request.AffectedScope,
            Description = request.Description,
            Metadata = request.Metadata ?? "{}",
            CreatedBy = actorId
        };

        try
        {
            var created = await repository.CreateAsync(entity, cancellationToken).ConfigureAwait(false);
            return Results.Created($"/api/policy/conflicts/{created.Id}", new ConflictResponse(created));
        }
        catch (Exception ex) when (ex is ArgumentException or InvalidOperationException)
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Failed to create conflict",
                Detail = ex.Message,
                Status = StatusCodes.Status400BadRequest
            });
        }
    }

    private static async Task<IResult> ResolveConflict(
        HttpContext context,
        [FromRoute] Guid conflictId,
        [FromBody] ResolveConflictRequest request,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyEdit);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var actorId = ResolveActorId(context) ?? "system";

        if (string.IsNullOrWhiteSpace(request.Resolution))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Resolution required",
                Detail = "A resolution description is required to resolve a conflict.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var resolved = await repository.ResolveAsync(tenantId, conflictId, request.Resolution, actorId, cancellationToken)
            .ConfigureAwait(false);

        if (!resolved)
        {
            return Results.NotFound(new ProblemDetails
            {
                Title = "Conflict not found or already resolved",
                Detail = $"Policy conflict '{conflictId}' was not found or is not in open status.",
                Status = StatusCodes.Status404NotFound
            });
        }

        return Results.Ok(new ConflictActionResponse(conflictId, "resolved", actorId));
    }

    private static async Task<IResult> DismissConflict(
        HttpContext context,
        [FromRoute] Guid conflictId,
        IConflictRepository repository,
        CancellationToken cancellationToken)
    {
        var scopeResult = ScopeAuthorization.RequireScope(context, StellaOpsScopes.PolicyEdit);
        if (scopeResult is not null)
        {
            return scopeResult;
        }

        var tenantId = ResolveTenantId(context);
        if (string.IsNullOrEmpty(tenantId))
        {
            return Results.BadRequest(new ProblemDetails
            {
                Title = "Tenant required",
                Detail = "Tenant ID must be provided.",
                Status = StatusCodes.Status400BadRequest
            });
        }

        var actorId = ResolveActorId(context) ?? "system";

        var dismissed = await repository.DismissAsync(tenantId, conflictId, actorId, cancellationToken)
            .ConfigureAwait(false);

        if (!dismissed)
        {
            return Results.NotFound(new ProblemDetails
            {
                Title = "Conflict not found or already resolved",
                Detail = $"Policy conflict '{conflictId}' was not found or is not in open status.",
                Status = StatusCodes.Status404NotFound
            });
        }

        return Results.Ok(new ConflictActionResponse(conflictId, "dismissed", actorId));
    }

    private static string? ResolveTenantId(HttpContext context)
    {
        if (context.Request.Headers.TryGetValue("X-Tenant-Id", out var tenantHeader) &&
            !string.IsNullOrWhiteSpace(tenantHeader))
        {
            return tenantHeader.ToString();
        }

        return context.User?.FindFirst("tenant_id")?.Value;
    }

    private static string? ResolveActorId(HttpContext context)
    {
        var user = context.User;
        return user?.FindFirst(System.Security.Claims.ClaimTypes.NameIdentifier)?.Value
            ?? user?.FindFirst("sub")?.Value;
    }
}

#region Request/Response DTOs

internal sealed record ConflictListResponse(
    IReadOnlyList<ConflictSummary> Conflicts,
    int Limit,
    int Offset);

internal sealed record ConflictSummary(
    Guid Id,
    string ConflictType,
    string Severity,
    string Status,
    string? LeftRuleId,
    string? RightRuleId,
    string? AffectedScope,
    string Description,
    DateTimeOffset CreatedAt);

internal sealed record ConflictResponse(ConflictEntity Conflict);

internal sealed record ConflictStatsResponse(Dictionary<string, int> CountBySeverity);

internal sealed record ConflictActionResponse(Guid ConflictId, string Action, string ActorId);

internal sealed record CreateConflictRequest(
    string ConflictType,
    string Severity,
    string? LeftRuleId,
    string? RightRuleId,
    string? AffectedScope,
    string Description,
    string? Metadata);

internal sealed record ResolveConflictRequest(string Resolution);

#endregion