using System.Xml.Linq;
using CRIF.ACTion.Common;
using CRIF.ACTion.Common.Parsers;
using Serilog;
using Landmark.OLA.Models.Decisioning;
using Landmark.OLA.Models.Decisioning.Enums;

namespace CRIF.ACTion.Decisioning
{
    public class GetApplicationProductsResponseParser : IResponseParser<DecisioningDetails>
    {
        private string LoanApplicationId;

        private const string ApplicationsPath = "/actionAPI/getApplicationProducts/msg:appExportResponse/msg:applications/app:application";
        private const string AppDetailsPath = "/app:application/app:appDetails";
        private readonly XName AppDetailStatusesName = CrifNamespaces.App + "appDetailStatuses";
        private readonly XName AppDetailStatusName = CrifNamespaces.App + "appDetailStatus";
        private readonly XName StatusAttribute = CrifNamespaces.App + "statusType";
        private const string DecisionTypeValue = "DecisionStatus";
        private readonly XName DecisionResultName = CrifNamespaces.App + "status";
        private readonly XName AppDetailStipulationsName = CrifNamespaces.App + "appDetailStipulations";
        private readonly XName StipulationName = CrifNamespaces.App + "stipulation";
        private readonly XName StipulationIdName = CrifNamespaces.Common + "stipulationID";

        public GetApplicationProductsResponseParser()
        {
        }

        public void SetLoanId(string loanApplicationId)
        {
            LoanApplicationId = loanApplicationId;
        }

        public DecisioningDetails Parse(XElement xElement)
        {
            if (string.IsNullOrWhiteSpace(LoanApplicationId))
            {
                throw new ArgumentException("Must set valid LoanApplicationId with SetLoanId(loanApplicationId)");
            }

            var namespaceManager = CrifNamespaces.GetNamespaceManager(xElement);

            var applicationElement = xElement.XElementXPathSelectElement(ApplicationsPath, namespaceManager);

            if (applicationElement == null)
            {
                //CRIF didn't recognize this application ID
                throw new ArgumentException("The Application Id was not recognized by the decisioning system.");
            }

            if (!applicationElement.Attribute(CrifNamespaces.App + "applicationID").Value.Equals(LoanApplicationId))
            {
                Log.Fatal("CRIF XML does not match expected loan ID {loanId}", LoanApplicationId);
                throw new InvalidOperationException("Unexpected vendor response.");
            }

            var appDetailElements = applicationElement.XElementXPathSelectElement(AppDetailsPath, namespaceManager).Elements().ToList();

            for (int detailIndex = appDetailElements.Count - 1; detailIndex >= 0; detailIndex--)
            {
                var detail = appDetailElements[detailIndex];

                var statuses = GetElementFromElement(detail, AppDetailStatusesName);

                var decision = GetElementFromElementWithAttributeIdentifier(statuses, AppDetailStatusName, StatusAttribute, DecisionTypeValue);

                if (decision == null)
                {
                    appDetailElements.Remove(detail);
                    continue;
                }

                var decisionResult = GetAttributeFromElement(decision, DecisionResultName);

                var status = (DecisioningResult)Enum.Parse(typeof(DecisioningResult), decisionResult.Value);

                if (status == DecisioningResult.DecisionStatus_Cancelled)
                {
                    appDetailElements.Remove(detail);
                }
            }

            if (appDetailElements.Count != 1)
            {
                if (appDetailElements.Count == 0)
                {
                    return new DecisioningDetails()
                    {
                        DecisioningState = DecisioningState.Unknown
                    };
                }

                throw new ArgumentException($"Application contains {appDetailElements.Count} appDetail elements. An appDetailID is required.");
            }

            var appDetailStatuses = GetElementFromElement(appDetailElements.SingleOrDefault(), AppDetailStatusesName);

            var decisionStatus = GetElementFromElementWithAttributeIdentifier(appDetailStatuses, AppDetailStatusName, StatusAttribute, DecisionTypeValue);

            var stipulations = GetStipulations(appDetailElements.Single().Element(AppDetailStipulationsName));

            if (decisionStatus == null)
            {
                return new DecisioningDetails(stipulations)
                {
                    DecisioningState = DecisioningState.Unknown,
                };
            }
            else
            {
                var decisioningResult = GetAttributeFromElement(decisionStatus, DecisionResultName);

                var statusResult = (DecisioningResult)Enum.Parse(typeof(DecisioningResult), decisioningResult.Value);

                return new DecisioningDetails(stipulations)
                {
                    DecisioningState = DecisioningState.Ready,
                    DecisioningResult = statusResult,
                };
            }
        }

        private ICollection<int> GetStipulations(XElement appDetailStipulations)
        {
            var stipulations = new List<int>();

            if (appDetailStipulations is null)
            {
                return stipulations;
            }

            foreach (var stipulationElement in appDetailStipulations.Elements())
            {
                var appDetailStipulation = stipulationElement.Element(StipulationName);

                var stipulationIdString = appDetailStipulation.Attribute(StipulationIdName).Value;

                if (int.TryParse(stipulationIdString, out int stipulationId))
                {
                    if (CrifConstants.StipulationsToShow.ContainsKey(stipulationId))
                    {
                        stipulations.Add(stipulationId);
                    }
                }
            }

            return stipulations;
        }

        private static XElement GetElementFromElement(XElement element, XName elementToFind)
        {
            return element.Element(elementToFind);
        }

        private static XElement GetElementFromElementWithAttributeIdentifier(XElement element, XName elementToSearch, XName attribute, string identifier)
        {
            return element.Elements(elementToSearch).SingleOrDefault(x => x.Attribute(attribute).Value.Equals(identifier));
        }

        private static XAttribute GetAttributeFromElement(XElement element, XName attribute)
        {
            return element.Attribute(attribute);
        }
    }
}