// SPDX-License-Identifier: BUSL-1.1
// Copyright (c) 2025 StellaOps
// Sprint: SPRINT_20260122_041_Policy_interop_import_export_rego
// Task: TASK-07 - Platform API Endpoints

using Microsoft.AspNetCore.Builder;
using Microsoft.AspNetCore.Http;
using Microsoft.AspNetCore.Mvc;
using Microsoft.AspNetCore.Routing;
using StellaOps.Auth.ServerIntegration.Tenancy;
using StellaOps.Platform.WebService.Constants;
using StellaOps.Platform.WebService.Contracts;
using StellaOps.Platform.WebService.Services;

namespace StellaOps.Platform.WebService.Endpoints;

/// <summary>
/// Policy import/export interop API endpoints.
/// Provides bidirectional policy exchange between JSON (PolicyPack v2) and OPA/Rego formats.
/// </summary>
public static class PolicyInteropEndpoints
{
    /// <summary>
    /// Maps policy interop endpoints under /api/v1/policy/interop.
    /// </summary>
    public static IEndpointRouteBuilder MapPolicyInteropEndpoints(this IEndpointRouteBuilder app)
    {
        var interop = app.MapGroup("/api/v1/policy/interop")
            .WithTags("PolicyInterop")
            .RequireAuthorization(PlatformPolicies.PolicyRead)
            .RequireTenant();

        MapExportEndpoint(interop);
        MapImportEndpoint(interop);
        MapValidateEndpoint(interop);
        MapEvaluateEndpoint(interop);
        MapFormatsEndpoint(interop);

        return app;
    }

    private static void MapExportEndpoint(IEndpointRouteBuilder group)
    {
        // POST /api/v1/policy/interop/export
        group.MapPost("/export", async Task<IResult> (
            HttpContext context,
            PlatformRequestContextResolver resolver,
            IPolicyInteropService service,
            [FromBody] PolicyExportApiRequest request,
            CancellationToken cancellationToken) =>
        {
            if (!TryResolveContext(context, resolver, out var requestContext, out var failure))
            {
                return failure!;
            }

            var result = await service.ExportAsync(
                requestContext!,
                request,
                cancellationToken).ConfigureAwait(false);

            if (!result.Success)
            {
                return Results.BadRequest(new { error = "export_failed", diagnostics = result.Diagnostics });
            }

            return Results.Ok(new PlatformItemResponse<PolicyExportApiResponse>(
                requestContext!.TenantId,
                requestContext.ActorId,
                DateTimeOffset.UtcNow,
                false,
                0,
                result));
        })
        .WithName("ExportPolicy")
        .WithSummary("Export policy to format")
        .WithDescription("Exports a PolicyPack v2 document to JSON or OPA/Rego format with optional environment-specific thresholds and remediation hints.")
        .RequireAuthorization(PlatformPolicies.PolicyRead);

        // POST /api/v1/policy/interop/import
    }

    private static void MapImportEndpoint(IEndpointRouteBuilder group)
    {
        group.MapPost("/import", async Task<IResult> (
            HttpContext context,
            PlatformRequestContextResolver resolver,
            IPolicyInteropService service,
            [FromBody] PolicyImportApiRequest request,
            CancellationToken cancellationToken) =>
        {
            if (!TryResolveContext(context, resolver, out var requestContext, out var failure))
            {
                return failure!;
            }

            var result = await service.ImportAsync(
                requestContext!,
                request,
                cancellationToken).ConfigureAwait(false);

            if (!result.Success)
            {
                return Results.BadRequest(new { error = "import_failed", diagnostics = result.Diagnostics });
            }

            return Results.Ok(new PlatformItemResponse<PolicyImportApiResponse>(
                requestContext!.TenantId,
                requestContext.ActorId,
                DateTimeOffset.UtcNow,
                false,
                0,
                result));
        })
        .WithName("ImportPolicy")
        .WithSummary("Import policy from format")
        .WithDescription("Imports a policy from JSON or OPA/Rego format into the native PolicyPack v2 model. Unknown Rego patterns are preserved for OPA evaluation.")
        .RequireAuthorization(PlatformPolicies.PolicyWrite);
    }

    private static void MapValidateEndpoint(IEndpointRouteBuilder group)
    {
        // POST /api/v1/policy/interop/validate
        group.MapPost("/validate", async Task<IResult> (
            HttpContext context,
            PlatformRequestContextResolver resolver,
            IPolicyInteropService service,
            [FromBody] PolicyValidateApiRequest request,
            CancellationToken cancellationToken) =>
        {
            if (!TryResolveContext(context, resolver, out var requestContext, out var failure))
            {
                return failure!;
            }

            var result = await service.ValidateAsync(
                requestContext!,
                request,
                cancellationToken).ConfigureAwait(false);

            return Results.Ok(new PlatformItemResponse<PolicyValidateApiResponse>(
                requestContext!.TenantId,
                requestContext.ActorId,
                DateTimeOffset.UtcNow,
                false,
                0,
                result));
        })
        .WithName("ValidatePolicy")
        .WithSummary("Validate policy document")
        .WithDescription("Validates a policy document against the PolicyPack v2 schema or checks Rego syntax via embedded OPA.")
        .RequireAuthorization(PlatformPolicies.PolicyRead);
    }

    private static void MapEvaluateEndpoint(IEndpointRouteBuilder group)
    {
        // POST /api/v1/policy/interop/evaluate
        group.MapPost("/evaluate", async Task<IResult> (
            HttpContext context,
            PlatformRequestContextResolver resolver,
            IPolicyInteropService service,
            [FromBody] PolicyEvaluateApiRequest request,
            CancellationToken cancellationToken) =>
        {
            if (!TryResolveContext(context, resolver, out var requestContext, out var failure))
            {
                return failure!;
            }

            var result = await service.EvaluateAsync(
                requestContext!,
                request,
                cancellationToken).ConfigureAwait(false);

            var statusCode = result.Decision switch
            {
                "allow" => StatusCodes.Status200OK,
                "warn" => StatusCodes.Status200OK,
                "block" => StatusCodes.Status200OK,
                _ => StatusCodes.Status200OK
            };

            return Results.Ok(new PlatformItemResponse<PolicyEvaluateApiResponse>(
                requestContext!.TenantId,
                requestContext.ActorId,
                DateTimeOffset.UtcNow,
                false,
                0,
                result));
        })
        .WithName("EvaluatePolicy")
        .WithSummary("Evaluate policy against input")
        .WithDescription("Evaluates a policy (JSON or Rego) against evidence input and returns allow/warn/block decision with remediation hints.")
        .RequireAuthorization(PlatformPolicies.PolicyEvaluate);
    }

    private static void MapFormatsEndpoint(IEndpointRouteBuilder group)
    {
        // GET /api/v1/policy/interop/formats
        group.MapGet("/formats", (
            HttpContext context,
            PlatformRequestContextResolver resolver) =>
        {
            if (!TryResolveContext(context, resolver, out var requestContext, out var failure))
            {
                return failure!;
            }

            var formats = new PolicyFormatsApiResponse
            {
                Formats =
                [
                    new PolicyFormatInfo("json", "PolicyPack v2 (JSON)", "policy.stellaops.io/v2", true, true),
                    new PolicyFormatInfo("rego", "OPA/Rego", "package stella.release", true, true)
                ]
            };

            return Results.Ok(new PlatformItemResponse<PolicyFormatsApiResponse>(
                requestContext!.TenantId,
                requestContext.ActorId,
                DateTimeOffset.UtcNow,
                true,
                3600,
                formats));
        })
        .WithName("ListPolicyFormats")
        .WithSummary("List supported policy formats")
        .WithDescription("Returns the list of supported policy import/export formats.")
        .RequireAuthorization(PlatformPolicies.PolicyRead);
    }

    private static bool TryResolveContext(
        HttpContext context,
        PlatformRequestContextResolver resolver,
        out PlatformRequestContext? requestContext,
        out IResult? failure)
    {
        if (resolver.TryResolve(context, out requestContext, out var error))
        {
            failure = null;
            return true;
        }

        failure = Results.BadRequest(new { error = error ?? "tenant_missing" });
        return false;
    }
}