using AutoMapper;
using Mws.Application.Common;
using Mws.Application.Permissions;
using Mws.Domain.Roles;

namespace Mws.Application.Roles;

public class RoleService(IUnitOfWork uow, IMapper mapper) : IRoleService
{
    public async Task<List<RoleDto>> GetRolesAsync(CancellationToken ct = default)
    {
        var roles = await uow.Roles.GetAllWithPermissionsAsync(ct);
        return mapper.Map<List<RoleDto>>(roles);
    }

    public async Task<RoleDto> GetRoleAsync(Guid id, CancellationToken ct = default)
    {
        var role = await uow.Roles.GetByIdWithPermissionsAsync(id, ct)
            ?? throw new NotFoundException("Role not found");
        return mapper.Map<RoleDto>(role);
    }

    public async Task<RoleDto> CreateRoleAsync(SaveRoleRequest request, CancellationToken ct = default)
    {
        var name = request.Name.Trim();
        if (string.IsNullOrWhiteSpace(name))
        {
            throw new BadRequestException("Role name is required");
        }

        if (await uow.Roles.ExistsByNameAsync(name, null, ct))
        {
            throw new BadRequestException("Role name already exists");
        }

        var now = DateTime.UtcNow;
        var role = new Role
        {
            Id = Guid.NewGuid(),
            Name = name,
            IsSystem = false,
            CreatedAt = now,
            UpdatedAt = now,
            Permissions = BuildPermissions(request.Permissions),
        };

        uow.Roles.Add(role);
        await uow.SaveChangesAsync(ct);
        return mapper.Map<RoleDto>(role);
    }

    public async Task<RoleDto> UpdateRoleAsync(Guid id, SaveRoleRequest request, CancellationToken ct = default)
    {
        var role = await uow.Roles.GetByIdWithPermissionsAsync(id, ct)
            ?? throw new NotFoundException("Role not found");

        var name = request.Name.Trim();
        if (string.IsNullOrWhiteSpace(name))
        {
            throw new BadRequestException("Role name is required");
        }

        if (await uow.Roles.ExistsByNameAsync(name, id, ct))
        {
            throw new BadRequestException("Role name already exists");
        }

        role.Name = name;
        role.UpdatedAt = DateTime.UtcNow;

        uow.Roles.RemovePermissions(role.Permissions.ToList());
        role.Permissions = BuildPermissions(request.Permissions);
        foreach (var p in role.Permissions)
        {
            p.RoleId = role.Id;
        }

        await uow.SaveChangesAsync(ct);
        return mapper.Map<RoleDto>(role);
    }

    public async Task DeleteRoleAsync(Guid id, CancellationToken ct = default)
    {
        var role = await uow.Roles.GetByIdAsync(id, ct)
            ?? throw new NotFoundException("Role not found");

        if (role.IsSystem)
        {
            throw new BadRequestException("Cannot delete a system role");
        }

        if (await uow.Users.ExistsByRoleIdAsync(id, ct))
        {
            throw new BadRequestException("Cannot delete a role that is assigned to accounts");
        }

        uow.Roles.Remove(role);
        await uow.SaveChangesAsync(ct);
    }

    private static List<RolePermission> BuildPermissions(List<PermissionEntryDto> entries)
    {
        var byScreen = entries.Where(e => ScreenCatalog.Keys.Contains(e.Screen)).ToDictionary(e => e.Screen);

        return ScreenCatalog.Keys.Select(key =>
        {
            byScreen.TryGetValue(key, out var entry);
            return new RolePermission
            {
                Screen = key,
                CanView = entry?.CanView ?? false,
                CanCreate = entry?.CanCreate ?? false,
                CanEdit = entry?.CanEdit ?? false,
                CanDelete = entry?.CanDelete ?? false,
            };
        }).ToList();
    }
}