using FastEndpoints;
using Microsoft.EntityFrameworkCore;
using Socialize.Api.Data;
using Socialize.Api.Infrastructure.Security;
using Socialize.Api.Modules.Approvals.Data;
using Socialize.Api.Modules.Approvals.Services;
using Socialize.Api.Modules.Workspaces.Data;

namespace Socialize.Api.Modules.Workspaces.Handlers;

public record UpdateApprovalStepConfigurationRequest(
    string Name,
    int SortOrder,
    string TargetType,
    string TargetValue,
    int RequiredApproverCount);

public record UpdateWorkspaceRequest(
    string Name,
    string TimeZone,
    string? ApprovalMode,
    bool? SchedulePostsAutomaticallyOnApproval,
    bool? LockContentAfterApproval,
    bool? SendAutomaticApprovalReminders,
    IReadOnlyCollection<UpdateApprovalStepConfigurationRequest>? ApprovalSteps);

public class UpdateWorkspaceRequestValidator
    : Validator<UpdateWorkspaceRequest>
{
    private static readonly string[] AllowedApprovalModes = ["None", "Optional", "Required", "Multi-level"];

    public UpdateWorkspaceRequestValidator()
    {
        RuleFor(x => x.Name).NotEmpty().MaximumLength(256);
        RuleFor(x => x.TimeZone).NotEmpty().MaximumLength(128);
        RuleFor(x => x.ApprovalMode)
            .Must(mode => string.IsNullOrWhiteSpace(mode) || AllowedApprovalModes.Contains(mode.Trim()))
            .WithMessage("A valid approval mode should be specified.");
        RuleFor(x => x.ApprovalSteps)
            .Must(steps => steps is null || steps.Select(step => step.SortOrder).Distinct().Count() == steps.Count)
            .WithMessage("Approval step sort orders must be unique.");
        RuleForEach(x => x.ApprovalSteps).ChildRules(step =>
        {
            step.RuleFor(x => x.Name).NotEmpty().MaximumLength(128);
            step.RuleFor(x => x.TargetType)
                .Must(ApprovalStepConfigurationRules.IsValidTargetType)
                .WithMessage("A valid approval step target type should be specified.");
            step.RuleFor(x => x.TargetValue).NotEmpty().MaximumLength(128);
            step.RuleFor(x => x.RequiredApproverCount).GreaterThanOrEqualTo(1);
        });
    }
}

public class UpdateWorkspaceHandler(
    AppDbContext dbContext,
    AccessScopeService accessScopeService)
    : Endpoint<UpdateWorkspaceRequest, WorkspaceDto>
{
    public override void Configure()
    {
        Put("/api/workspaces/{id}");
        Options(o => o.WithTags("Workspaces"));
    }

    public override async Task HandleAsync(UpdateWorkspaceRequest request, CancellationToken ct)
    {
        Guid id = Route<Guid>("id");

        Workspace? workspace = await dbContext.Workspaces.SingleOrDefaultAsync(candidate => candidate.Id == id, ct);
        if (workspace is null)
        {
            await SendNotFoundAsync(ct);
            return;
        }

        if (!await accessScopeService.CanManageWorkspaceAsync(User, workspace.Id, ct))
        {
            await SendForbiddenAsync(ct);
            return;
        }

        string nextApprovalMode = string.IsNullOrWhiteSpace(request.ApprovalMode)
            ? workspace.ApprovalMode
            : request.ApprovalMode.Trim();
        List<UpdateApprovalStepConfigurationRequest>? requestedApprovalSteps = request.ApprovalSteps?.ToList();

        if (nextApprovalMode == ApprovalModes.MultiLevel)
        {
            bool hasConfiguredSteps = requestedApprovalSteps is null
                ? await dbContext.WorkspaceApprovalStepConfigurations.AnyAsync(step => step.WorkspaceId == workspace.Id, ct)
                : requestedApprovalSteps.Count > 0;

            if (!hasConfiguredSteps)
            {
                AddError(request => request.ApprovalSteps, "Multi-level approval requires at least one approval step.");
                await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
                return;
            }
        }

        if (requestedApprovalSteps is not null &&
            !await ValidateApprovalStepsAsync(workspace.Id, requestedApprovalSteps, ct))
        {
            await SendErrorsAsync(StatusCodes.Status400BadRequest, ct);
            return;
        }

        workspace.Name = request.Name.Trim();
        workspace.TimeZone = request.TimeZone.Trim();
        workspace.ApprovalMode = nextApprovalMode;
        workspace.SchedulePostsAutomaticallyOnApproval = request.SchedulePostsAutomaticallyOnApproval ?? workspace.SchedulePostsAutomaticallyOnApproval;
        workspace.LockContentAfterApproval = request.LockContentAfterApproval ?? workspace.LockContentAfterApproval;
        workspace.SendAutomaticApprovalReminders = request.SendAutomaticApprovalReminders ?? workspace.SendAutomaticApprovalReminders;

        if (requestedApprovalSteps is not null)
        {
            List<WorkspaceApprovalStepConfiguration> existingSteps = await dbContext.WorkspaceApprovalStepConfigurations
                .Where(step => step.WorkspaceId == workspace.Id)
                .ToListAsync(ct);
            dbContext.WorkspaceApprovalStepConfigurations.RemoveRange(existingSteps);

            List<WorkspaceApprovalStepConfiguration> replacementSteps = requestedApprovalSteps
                .OrderBy(step => step.SortOrder)
                .Select(step => new WorkspaceApprovalStepConfiguration
                {
                    Id = Guid.NewGuid(),
                    WorkspaceId = workspace.Id,
                    Name = step.Name.Trim(),
                    SortOrder = step.SortOrder,
                    TargetType = step.TargetType.Trim(),
                    TargetValue = NormalizeTargetValue(step),
                    RequiredApproverCount = step.RequiredApproverCount,
                    CreatedAt = DateTimeOffset.UtcNow,
                })
                .ToList();

            dbContext.WorkspaceApprovalStepConfigurations.AddRange(replacementSteps);
        }

        await dbContext.SaveChangesAsync(ct);

        List<ApprovalStepConfigurationDto> approvalSteps = await dbContext.WorkspaceApprovalStepConfigurations
            .Where(step => step.WorkspaceId == workspace.Id)
            .OrderBy(step => step.SortOrder)
            .ThenBy(step => step.Name)
            .Select(step => new ApprovalStepConfigurationDto(
                step.Id,
                step.WorkspaceId,
                step.Name,
                step.SortOrder,
                step.TargetType,
                step.TargetValue,
                step.RequiredApproverCount,
                step.CreatedAt))
            .ToListAsync(ct);

        WorkspaceDto dto = WorkspaceDto.FromWorkspace(workspace, approvalSteps);

        await SendOkAsync(dto, ct);
    }

    private async Task<bool> ValidateApprovalStepsAsync(
        Guid workspaceId,
        IReadOnlyCollection<UpdateApprovalStepConfigurationRequest> steps,
        CancellationToken ct)
    {
        foreach (UpdateApprovalStepConfigurationRequest step in steps)
        {
            string targetType = step.TargetType.Trim();
            string targetValue = step.TargetValue.Trim();

            if (targetType == ApprovalStepTargetTypes.Role &&
                !ApprovalStepConfigurationRules.IsValidRoleTarget(targetValue))
            {
                AddError(request => request.ApprovalSteps, $"'{targetValue}' is not a supported approval role target.");
                return false;
            }

            if (targetType == ApprovalStepTargetTypes.Membership &&
                !ApprovalStepConfigurationRules.IsValidMembershipTarget(targetValue))
            {
                AddError(request => request.ApprovalSteps, $"'{targetValue}' is not a supported approval membership target.");
                return false;
            }

            if (targetType == ApprovalStepTargetTypes.Member)
            {
                IReadOnlyCollection<Guid> memberUserIds = ApprovalWorkflowRules.ParseMemberTargetIds(targetValue);

                if (memberUserIds.Count == 0)
                {
                    AddError(request => request.ApprovalSteps, "Member approval step targets must reference at least one valid user id.");
                    return false;
                }

                if (memberUserIds.Count < step.RequiredApproverCount)
                {
                    AddError(request => request.ApprovalSteps, "Member approval step targets must include at least as many members as required approvers.");
                    return false;
                }

                string workspaceClaimValue = workspaceId.ToString();
                int workspaceMemberCount = await dbContext.UserClaims
                    .Where(claim => memberUserIds.Contains(claim.UserId) &&
                                    claim.ClaimType == KnownClaims.WorkspaceScope &&
                                    claim.ClaimValue == workspaceClaimValue)
                    .Select(claim => claim.UserId)
                    .Distinct()
                    .CountAsync(ct);

                if (workspaceMemberCount != memberUserIds.Count)
                {
                    AddError(request => request.ApprovalSteps, "Member approval step targets must reference users with access to the workspace.");
                    return false;
                }
            }
        }

        return true;
    }

    private static string NormalizeTargetValue(UpdateApprovalStepConfigurationRequest step)
    {
        string targetValue = step.TargetValue.Trim();
        return step.TargetType.Trim() == ApprovalStepTargetTypes.Member
            ? ApprovalWorkflowRules.FormatMemberTargetValue(ApprovalWorkflowRules.ParseMemberTargetIds(targetValue))
            : targetValue;
    }
}