// -----------------------------------------------------------------------------
// RiskBudgetEndpoints.cs
// Sprint: SPRINT_20251226_002_BE_budget_enforcement
// Task: BUDGET-04 - Budget consumption API
// Description: API endpoints for risk budget management
// -----------------------------------------------------------------------------

using Microsoft.AspNetCore.Http.HttpResults;
using Microsoft.AspNetCore.Mvc;
using StellaOps.Policy.Gates;

namespace StellaOps.Policy.Engine.Endpoints;

/// <summary>
/// API endpoints for risk budget management.
/// </summary>
internal static class RiskBudgetEndpoints
{
    public static IEndpointRouteBuilder MapRiskBudgets(this IEndpointRouteBuilder endpoints)
    {
        var group = endpoints.MapGroup("/api/v1/policy/budget")
            .RequireAuthorization()
            .WithTags("Risk Budgets");

        group.MapGet("/status/{serviceId}", GetBudgetStatus)
            .WithName("GetRiskBudgetStatus")
            .WithSummary("Get current risk budget status for a service.")
            .Produces<RiskBudgetStatusResponse>(StatusCodes.Status200OK);

        group.MapPost("/consume", ConsumeBudget)
            .WithName("ConsumeRiskBudget")
            .WithSummary("Record budget consumption after a release.")
            .Produces<BudgetConsumeResponse>(StatusCodes.Status200OK)
            .Produces<ProblemHttpResult>(StatusCodes.Status400BadRequest);

        group.MapPost("/check", CheckRelease)
            .WithName("CheckRelease")
            .WithSummary("Check if a release can proceed given current budget.")
            .Produces<ReleaseCheckResponse>(StatusCodes.Status200OK);

        group.MapGet("/history/{serviceId}", GetBudgetHistory)
            .WithName("GetBudgetHistory")
            .WithSummary("Get budget consumption history for a service.")
            .Produces<BudgetHistoryResponse>(StatusCodes.Status200OK);

        group.MapPost("/adjust", AdjustBudget)
            .WithName("AdjustBudget")
            .WithSummary("Adjust budget allocation (earned capacity or manual override).")
            .Produces<RiskBudgetStatusResponse>(StatusCodes.Status200OK)
            .Produces<ProblemHttpResult>(StatusCodes.Status400BadRequest);

        group.MapGet("/list", ListBudgets)
            .WithName("ListRiskBudgets")
            .WithSummary("List all risk budgets with optional filtering.")
            .Produces<BudgetListResponse>(StatusCodes.Status200OK);

        return endpoints;
    }

    private static async Task<Ok<RiskBudgetStatusResponse>> GetBudgetStatus(
        string serviceId,
        [FromQuery] string? window,
        IBudgetLedger ledger,
        CancellationToken ct)
    {
        var budget = await ledger.GetBudgetAsync(serviceId, window, ct);

        return TypedResults.Ok(new RiskBudgetStatusResponse(
            budget.BudgetId,
            budget.ServiceId,
            budget.Tier.ToString(),
            budget.Window,
            budget.Allocated,
            budget.Consumed,
            budget.Remaining,
            budget.PercentageUsed,
            budget.Status.ToString().ToLowerInvariant(),
            budget.UpdatedAt));
    }

    private static async Task<Results<Ok<BudgetConsumeResponse>, ProblemHttpResult>> ConsumeBudget(
        [FromBody] BudgetConsumeRequest request,
        IBudgetLedger ledger,
        CancellationToken ct)
    {
        if (request.RiskPoints <= 0)
        {
            return TypedResults.Problem(
                "Risk points must be greater than 0.",
                statusCode: StatusCodes.Status400BadRequest);
        }

        var result = await ledger.ConsumeAsync(
            request.ServiceId,
            request.RiskPoints,
            request.ReleaseId,
            ct);

        if (!result.IsSuccess)
        {
            return TypedResults.Problem(
                result.Error ?? "Budget consumption failed.",
                statusCode: StatusCodes.Status400BadRequest);
        }

        return TypedResults.Ok(new BudgetConsumeResponse(
            result.IsSuccess,
            result.Entry?.EntryId,
            result.Budget.Remaining,
            result.Budget.PercentageUsed,
            result.Budget.Status.ToString().ToLowerInvariant(),
            result.Error));
    }

    private static async Task<Ok<ReleaseCheckResponse>> CheckRelease(
        [FromBody] ReleaseCheckRequest request,
        IBudgetConstraintEnforcer enforcer,
        CancellationToken ct)
    {
        var input = new ReleaseCheckInput
        {
            ServiceId = request.ServiceId,
            Tier = Enum.Parse<ServiceTier>(request.Tier, ignoreCase: true),
            DiffCategory = Enum.Parse<DiffCategory>(request.DiffCategory, ignoreCase: true),
            Context = new OperationalContext
            {
                // Map request properties to actual OperationalContext properties
                InRestrictedWindow = request.ChangeFreeze || !request.DeploymentWindow,
                HasRecentIncident = request.IncidentActive,
                ErrorBudgetBelow50Percent = false, // Would come from budget ledger
                HighOnCallLoad = false // Would come from external system
            },
            Mitigations = new MitigationFactors
            {
                HasFeatureFlag = request.HasFeatureFlag,
                HasCanaryDeployment = request.CanaryPercentage > 0,
                HasBackwardCompatibleMigration = request.HasRollbackPlan,
                HasHighTestCoverage = false, // Would come from CI metadata
                HasPermissionBoundary = request.IsNonProduction
            }
        };

        var result = await enforcer.CheckReleaseAsync(input, ct);

        return TypedResults.Ok(new ReleaseCheckResponse(
            result.CanProceed,
            result.RequiredGate.ToString().ToLowerInvariant(),
            result.RiskPoints,
            result.BudgetBefore.Remaining,
            result.BudgetAfter.Remaining,
            result.BudgetBefore.Status.ToString().ToLowerInvariant(),
            result.BudgetAfter.Status.ToString().ToLowerInvariant(),
            result.BlockReason,
            result.Requirements,
            result.Recommendations));
    }

    private static async Task<Ok<BudgetHistoryResponse>> GetBudgetHistory(
        string serviceId,
        [FromQuery] string? window,
        IBudgetLedger ledger,
        CancellationToken ct)
    {
        var entries = await ledger.GetHistoryAsync(serviceId, window, ct);

        var items = entries.Select(e => new BudgetEntryDto(
            e.EntryId,
            e.ReleaseId,
            e.RiskPoints,
            e.ConsumedAt)).ToList();

        return TypedResults.Ok(new BudgetHistoryResponse(
            serviceId,
            window ?? GetCurrentWindow(),
            items));
    }

    private static async Task<Results<Ok<RiskBudgetStatusResponse>, ProblemHttpResult>> AdjustBudget(
        [FromBody] BudgetAdjustRequest request,
        IBudgetLedger ledger,
        CancellationToken ct)
    {
        if (request.Adjustment == 0)
        {
            return TypedResults.Problem(
                "Adjustment must be non-zero.",
                statusCode: StatusCodes.Status400BadRequest);
        }

        var budget = await ledger.AdjustAllocationAsync(
            request.ServiceId,
            request.Adjustment,
            request.Reason,
            ct);

        return TypedResults.Ok(new RiskBudgetStatusResponse(
            budget.BudgetId,
            budget.ServiceId,
            budget.Tier.ToString(),
            budget.Window,
            budget.Allocated,
            budget.Consumed,
            budget.Remaining,
            budget.PercentageUsed,
            budget.Status.ToString().ToLowerInvariant(),
            budget.UpdatedAt));
    }

    private static Ok<BudgetListResponse> ListBudgets(
        [FromQuery] string? status,
        [FromQuery] string? window,
        [FromQuery] int limit = 50)
    {
        // This would query from PostgresBudgetStore.GetBudgetsByStatusAsync or GetBudgetsByWindowAsync
        // For now, return empty list - implementation would need to inject the store
        return TypedResults.Ok(new BudgetListResponse([], 0));
    }

    private static string GetCurrentWindow() =>
        DateTimeOffset.UtcNow.ToString("yyyy-MM");
}

#region DTOs

/// <summary>Response containing risk budget status.</summary>
public sealed record RiskBudgetStatusResponse(
    string BudgetId,
    string ServiceId,
    string Tier,
    string Window,
    int Allocated,
    int Consumed,
    int Remaining,
    decimal PercentageUsed,
    string Status,
    DateTimeOffset UpdatedAt);

/// <summary>Request to consume budget.</summary>
public sealed record BudgetConsumeRequest(
    string ServiceId,
    int RiskPoints,
    string ReleaseId,
    string? Reason = null);

/// <summary>Response from budget consumption.</summary>
public sealed record BudgetConsumeResponse(
    bool IsSuccess,
    string? EntryId,
    int Remaining,
    decimal PercentageUsed,
    string Status,
    string? Error);

/// <summary>Request to check if release can proceed.</summary>
public sealed record ReleaseCheckRequest(
    string ServiceId,
    string Tier,
    string DiffCategory,
    bool ChangeFreeze = false,
    bool IncidentActive = false,
    bool DeploymentWindow = true,
    bool HasFeatureFlag = false,
    int CanaryPercentage = 0,
    bool HasRollbackPlan = false,
    bool IsNonProduction = false);

/// <summary>Response from release check.</summary>
public sealed record ReleaseCheckResponse(
    bool CanProceed,
    string RequiredGate,
    int RiskPoints,
    int BudgetRemainingBefore,
    int BudgetRemainingAfter,
    string StatusBefore,
    string StatusAfter,
    string? BlockReason,
    IReadOnlyList<string> Requirements,
    IReadOnlyList<string> Recommendations);

/// <summary>Budget entry DTO.</summary>
public sealed record BudgetEntryDto(
    string EntryId,
    string ReleaseId,
    int RiskPoints,
    DateTimeOffset ConsumedAt);

/// <summary>Response containing budget history.</summary>
public sealed record BudgetHistoryResponse(
    string ServiceId,
    string Window,
    IReadOnlyList<BudgetEntryDto> Entries);

/// <summary>Request to adjust budget.</summary>
public sealed record BudgetAdjustRequest(
    string ServiceId,
    int Adjustment,
    string Reason);

/// <summary>Response containing budget list.</summary>
public sealed record BudgetListResponse(
    IReadOnlyList<RiskBudgetStatusResponse> Budgets,
    int TotalCount);

#endregion