using Microsoft.AspNetCore.Mvc;
using StellaOps.Notifier.Worker.Correlation;

namespace StellaOps.Notifier.WebService.Endpoints;

/// <summary>
/// API endpoints for throttle configuration management.
/// </summary>
public static class ThrottleEndpoints
{
    /// <summary>
    /// Maps throttle configuration endpoints.
    /// </summary>
    public static IEndpointRouteBuilder MapThrottleEndpoints(this IEndpointRouteBuilder app)
    {
        var group = app.MapGroup("/api/v2/throttles")
            .WithTags("Throttles")
            .WithOpenApi();

        group.MapGet("/config", GetConfigurationAsync)
            .WithName("GetThrottleConfiguration")
            .WithSummary("Get throttle configuration")
            .WithDescription("Returns the throttle configuration for the tenant.");

        group.MapPut("/config", UpdateConfigurationAsync)
            .WithName("UpdateThrottleConfiguration")
            .WithSummary("Update throttle configuration")
            .WithDescription("Creates or updates the throttle configuration for the tenant.");

        group.MapDelete("/config", DeleteConfigurationAsync)
            .WithName("DeleteThrottleConfiguration")
            .WithSummary("Delete throttle configuration")
            .WithDescription("Deletes the throttle configuration for the tenant, reverting to defaults.");

        group.MapPost("/evaluate", EvaluateAsync)
            .WithName("EvaluateThrottle")
            .WithSummary("Evaluate throttle duration")
            .WithDescription("Returns the effective throttle duration for an event kind.");

        return app;
    }

    private static async Task<IResult> GetConfigurationAsync(
        [FromHeader(Name = "X-Tenant-Id")] string? tenantId,
        [FromServices] IThrottleConfigurationService throttleService,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(tenantId))
        {
            return Results.BadRequest(new { error = "X-Tenant-Id header is required." });
        }

        var config = await throttleService.GetConfigurationAsync(tenantId, cancellationToken);

        if (config is null)
        {
            return Results.Ok(new ThrottleConfigurationApiResponse
            {
                TenantId = tenantId,
                DefaultDurationSeconds = 900, // 15 minutes default
                Enabled = true,
                EventKindOverrides = new Dictionary<string, int>(),
                IsDefault = true
            });
        }

        return Results.Ok(MapToApiResponse(config));
    }

    private static async Task<IResult> UpdateConfigurationAsync(
        [FromBody] ThrottleConfigurationApiRequest request,
        [FromHeader(Name = "X-Tenant-Id")] string? tenantIdHeader,
        [FromHeader(Name = "X-Actor")] string? actor,
        [FromServices] IThrottleConfigurationService throttleService,
        CancellationToken cancellationToken)
    {
        var tenantId = request.TenantId ?? tenantIdHeader;
        if (string.IsNullOrWhiteSpace(tenantId))
        {
            return Results.BadRequest(new { error = "Tenant ID is required via X-Tenant-Id header or request body." });
        }

        if (request.DefaultDurationSeconds is <= 0)
        {
            return Results.BadRequest(new { error = "Default duration must be a positive value in seconds." });
        }

        var config = new ThrottleConfiguration
        {
            TenantId = tenantId,
            DefaultDuration = TimeSpan.FromSeconds(request.DefaultDurationSeconds ?? 900),
            EventKindOverrides = request.EventKindOverrides?
                .ToDictionary(kvp => kvp.Key, kvp => TimeSpan.FromSeconds(kvp.Value)),
            MaxEventsPerWindow = request.MaxEventsPerWindow,
            BurstWindowDuration = request.BurstWindowDurationSeconds.HasValue
                ? TimeSpan.FromSeconds(request.BurstWindowDurationSeconds.Value)
                : null,
            Enabled = request.Enabled ?? true
        };

        var updated = await throttleService.UpsertConfigurationAsync(config, actor, cancellationToken);

        return Results.Ok(MapToApiResponse(updated));
    }

    private static async Task<IResult> DeleteConfigurationAsync(
        [FromHeader(Name = "X-Tenant-Id")] string? tenantId,
        [FromHeader(Name = "X-Actor")] string? actor,
        [FromServices] IThrottleConfigurationService throttleService,
        CancellationToken cancellationToken)
    {
        if (string.IsNullOrWhiteSpace(tenantId))
        {
            return Results.BadRequest(new { error = "X-Tenant-Id header is required." });
        }

        var deleted = await throttleService.DeleteConfigurationAsync(tenantId, actor, cancellationToken);

        if (!deleted)
        {
            return Results.NotFound(new { error = "No throttle configuration exists for this tenant." });
        }

        return Results.NoContent();
    }

    private static async Task<IResult> EvaluateAsync(
        [FromBody] ThrottleEvaluateApiRequest request,
        [FromHeader(Name = "X-Tenant-Id")] string? tenantIdHeader,
        [FromServices] IThrottleConfigurationService throttleService,
        CancellationToken cancellationToken)
    {
        var tenantId = request.TenantId ?? tenantIdHeader;
        if (string.IsNullOrWhiteSpace(tenantId))
        {
            return Results.BadRequest(new { error = "Tenant ID is required via X-Tenant-Id header or request body." });
        }

        if (string.IsNullOrWhiteSpace(request.EventKind))
        {
            return Results.BadRequest(new { error = "Event kind is required." });
        }

        var duration = await throttleService.GetEffectiveThrottleDurationAsync(
            tenantId,
            request.EventKind,
            cancellationToken);

        return Results.Ok(new ThrottleEvaluateApiResponse
        {
            EventKind = request.EventKind,
            EffectiveDurationSeconds = (int)duration.TotalSeconds
        });
    }

    private static ThrottleConfigurationApiResponse MapToApiResponse(ThrottleConfiguration config) => new()
    {
        TenantId = config.TenantId,
        DefaultDurationSeconds = (int)config.DefaultDuration.TotalSeconds,
        EventKindOverrides = config.EventKindOverrides?
            .ToDictionary(kvp => kvp.Key, kvp => (int)kvp.Value.TotalSeconds)
            ?? new Dictionary<string, int>(),
        MaxEventsPerWindow = config.MaxEventsPerWindow,
        BurstWindowDurationSeconds = config.BurstWindowDuration.HasValue
            ? (int)config.BurstWindowDuration.Value.TotalSeconds
            : null,
        Enabled = config.Enabled,
        CreatedAt = config.CreatedAt,
        CreatedBy = config.CreatedBy,
        UpdatedAt = config.UpdatedAt,
        UpdatedBy = config.UpdatedBy,
        IsDefault = false
    };
}

#region API Request/Response Models

/// <summary>
/// Request to create or update throttle configuration.
/// </summary>
public sealed class ThrottleConfigurationApiRequest
{
    public string? TenantId { get; set; }
    public int? DefaultDurationSeconds { get; set; }
    public Dictionary<string, int>? EventKindOverrides { get; set; }
    public int? MaxEventsPerWindow { get; set; }
    public int? BurstWindowDurationSeconds { get; set; }
    public bool? Enabled { get; set; }
}

/// <summary>
/// Request to evaluate throttle duration.
/// </summary>
public sealed class ThrottleEvaluateApiRequest
{
    public string? TenantId { get; set; }
    public string? EventKind { get; set; }
}

/// <summary>
/// Response for throttle configuration.
/// </summary>
public sealed class ThrottleConfigurationApiResponse
{
    public required string TenantId { get; set; }
    public required int DefaultDurationSeconds { get; set; }
    public required Dictionary<string, int> EventKindOverrides { get; set; }
    public int? MaxEventsPerWindow { get; set; }
    public int? BurstWindowDurationSeconds { get; set; }
    public required bool Enabled { get; set; }
    public DateTimeOffset CreatedAt { get; set; }
    public string? CreatedBy { get; set; }
    public DateTimeOffset UpdatedAt { get; set; }
    public string? UpdatedBy { get; set; }
    public bool IsDefault { get; set; }
}

/// <summary>
/// Response for throttle evaluation.
/// </summary>
public sealed class ThrottleEvaluateApiResponse
{
    public required string EventKind { get; set; }
    public required int EffectiveDurationSeconds { get; set; }
}

#endregion