using Disco.Data.Repository;
using Disco.Models.Repository;
using Disco.Plugins.ServiceTracker.Models;
using System;
using System.Collections.Generic;
using System.Linq;

namespace Disco.Plugins.ServiceTracker.Services
{
    /// <summary>
    /// Core service that combines Disco Job data with ServiceTracker metadata
    /// to produce the dashboard view model.
    /// </summary>
    public class ServiceTrackerService
    {
        private readonly DiscoDataContext _database;
        private readonly ServiceTrackerDataStore _dataStore;
        private readonly ServiceTrackerConfig _config;

        public ServiceTrackerService(DiscoDataContext database, ServiceTrackerDataStore dataStore)
        {
            _database = database;
            _dataStore = dataStore;
            _config = dataStore.LoadConfig();
        }

        public DashboardViewModel BuildDashboard(string filterPriority = null, string filterLocation = null,
            string filterStatus = null, string filterTech = null, string sortBy = "due")
        {
            // Get all open jobs from Disco
            var openJobs = _database.Jobs
                .Include("Device")
                .Include("Device.DeviceModel")
                .Include("User")
                .Include("OpenedTechUser")
                .Include("JobType")
                .Include("JobSubTypes")
                .Where(j => j.ClosedDate == null)
                .ToList();

            // Load all service tracker tickets
            var allTickets = _dataStore.LoadAllTickets();
            var ticketLookup = allTickets.ToDictionary(t => t.JobId, t => t);

            // Auto-create tickets for jobs that don't have one (if enabled)
            if (_config.AutoCreateTicketsForNewJobs)
            {
                foreach (var job in openJobs)
                {
                    if (!ticketLookup.ContainsKey(job.Id))
                    {
                        var newTicket = CreateDefaultTicket(job);
                        _dataStore.SaveTicket(newTicket);
                        ticketLookup[job.Id] = newTicket;
                    }
                }
            }

            // Build tiles
            var tiles = new List<DashboardTile>();
            foreach (var job in openJobs)
            {
                ServiceTicket ticket;
                ticketLookup.TryGetValue(job.Id, out ticket);
                tiles.Add(BuildTile(job, ticket));
            }

            // Apply filters
            if (!string.IsNullOrEmpty(filterPriority))
                tiles = tiles.Where(t => t.PriorityId == filterPriority).ToList();
            if (!string.IsNullOrEmpty(filterLocation))
                tiles = tiles.Where(t => t.LocationId == filterLocation).ToList();
            if (!string.IsNullOrEmpty(filterStatus))
                tiles = tiles.Where(t => t.StatusOverride == filterStatus).ToList();
            if (!string.IsNullOrEmpty(filterTech))
                tiles = tiles.Where(t => t.AssignedTechId == filterTech).ToList();

            // Sort
            switch (sortBy)
            {
                case "priority":
                    tiles = tiles.OrderBy(t => t.PrioritySortOrder).ThenBy(t => t.SortDate).ToList();
                    break;
                case "age":
                    tiles = tiles.OrderByDescending(t => t.AgeDays).ToList();
                    break;
                case "modified":
                    tiles = tiles.OrderByDescending(t => t.LastModifiedDate).ToList();
                    break;
                case "sla":
                    tiles = tiles.OrderBy(t => t.IsSlaBreached ? 0 : t.IsSlaWarning ? 1 : 2)
                                .ThenBy(t => t.SlaDeadline ?? DateTime.MaxValue).ToList();
                    break;
                case "due":
                default:
                    tiles = tiles.OrderBy(t => t.SortDate).ToList();
                    break;
            }

            // Build stats
            var stats = BuildStats(tiles);

            return new DashboardViewModel
            {
                Tiles = tiles,
                Stats = stats,
                Config = _config,
                CurrentFilter = filterPriority ?? filterLocation ?? filterStatus ?? "",
                SortBy = sortBy
            };
        }

        private DashboardTile BuildTile(Job job, ServiceTicket ticket)
        {
            var now = DateTime.Now;

            // Resolve priority
            var priorityId = ticket?.PriorityId ?? _config.DefaultPriorityId;
            var priority = _config.Priorities.FirstOrDefault(p => p.Id == priorityId)
                          ?? _config.Priorities.FirstOrDefault();

            // Resolve location
            var locationId = ticket?.LocationId ?? _config.DefaultLocationId;
            var location = _config.Locations.FirstOrDefault(l => l.Id == locationId)
                          ?? _config.Locations.FirstOrDefault();

            // Compute SLA
            var slaDeadline = ticket?.SlaDeadline;
            if (!slaDeadline.HasValue && priority != null && priority.SlaHours > 0)
            {
                slaDeadline = job.OpenedDate.AddHours(priority.SlaHours);
            }
            bool slaBreached = slaDeadline.HasValue && now > slaDeadline.Value;
            bool slaWarning = !slaBreached && slaDeadline.HasValue &&
                              priority != null && priority.SlaHours > 0 &&
                              now > slaDeadline.Value.AddHours(-priority.SlaHours * 0.25);

            // Compute age
            int ageDays = (int)(now - job.OpenedDate).TotalDays;
            string ageBadge;
            if (ageDays == 0) ageBadge = "Today";
            else if (ageDays == 1) ageBadge = "1 day";
            else if (ageDays < 7) ageBadge = ageDays + " days";
            else if (ageDays < 30) ageBadge = (ageDays / 7) + " wk" + (ageDays / 7 > 1 ? "s" : "");
            else ageBadge = (ageDays / 30) + " mo" + (ageDays / 30 > 1 ? "s" : "");

            // ETA display
            var eta = ticket?.EstimatedCompletion ?? job.ExpectedClosedDate;
            string etaDisplay = "—";
            if (eta.HasValue)
            {
                var etaDays = (int)(eta.Value - now).TotalDays;
                if (etaDays < 0) etaDisplay = Math.Abs(etaDays) + "d overdue";
                else if (etaDays == 0) etaDisplay = "Today";
                else if (etaDays == 1) etaDisplay = "Tomorrow";
                else etaDisplay = eta.Value.ToString("dd MMM");
            }

            // Sort date: use SLA deadline if breached, then ETA, then expected close, then opened
            DateTime sortDate = slaBreached && slaDeadline.HasValue ? slaDeadline.Value
                              : eta ?? job.ExpectedClosedDate ?? job.OpenedDate;

            // Determine Disco status string
            string discoStatus = "Open";
            if (job.WaitingForUserAction.HasValue) discoStatus = "Awaiting User Action";
            else if (job.DeviceHeld.HasValue && !job.DeviceReadyForReturn.HasValue) discoStatus = "Device Held";
            else if (job.DeviceReadyForReturn.HasValue && !job.DeviceReturnedDate.HasValue) discoStatus = "Ready for Return";

            // Latest note
            string latestNote = null;
            int noteCount = 0;
            if (ticket?.Notes != null && ticket.Notes.Count > 0)
            {
                noteCount = ticket.Notes.Count;
                var latest = ticket.Notes.OrderByDescending(n => n.Timestamp).First();
                latestNote = latest.Content;
                if (latestNote != null && latestNote.Length > 80)
                    latestNote = latestNote.Substring(0, 77) + "...";
            }

            return new DashboardTile
            {
                JobId = job.Id,
                JobTypeDescription = job.JobType != null ? job.JobType.Description : job.JobTypeId,
                DeviceSerialNumber = job.DeviceSerialNumber ?? "—",
                DeviceModelDescription = job.Device?.DeviceModel != null ? job.Device.DeviceModel.Description : null,
                DeviceComputerName = job.Device?.DeviceDomainId,
                UserId = job.UserId,
                UserDisplayName = job.User != null ? job.User.DisplayName : job.UserId,
                OpenedByTechId = job.OpenedTechUserId,
                OpenedByTechName = job.OpenedTechUser != null ? job.OpenedTechUser.DisplayName : job.OpenedTechUserId,
                OpenedDate = job.OpenedDate,
                ExpectedClosedDate = job.ExpectedClosedDate,
                DiscoStatus = discoStatus,
                PriorityId = priorityId,
                PriorityName = priority?.Name ?? "Unknown",
                PriorityColor = priority?.Color ?? "#999",
                PrioritySortOrder = priority?.SortOrder ?? 99,
                LocationId = locationId,
                LocationName = location?.Name ?? "Unknown",
                LocationIcon = location?.Icon ?? "",
                LocationColor = location?.Color ?? "#999",
                AssignedTechId = ticket?.AssignedTechId,
                AssignedTechName = ResolveUserName(ticket?.AssignedTechId),
                EstimatedCompletion = eta,
                SlaDeadline = slaDeadline,
                StatusOverride = ticket?.StatusOverride ?? discoStatus,
                Summary = ticket?.Summary,
                NoteCount = noteCount,
                LatestNote = latestNote,
                LastModifiedDate = ticket?.LastModifiedDate ?? job.OpenedDate,
                IsSlaBreached = slaBreached,
                IsSlaWarning = slaWarning,
                AgeBadge = ageBadge,
                AgeDays = ageDays,
                EtaDisplay = etaDisplay,
                SortDate = sortDate
            };
        }

        private DashboardStats BuildStats(List<DashboardTile> tiles)
        {
            var stats = new DashboardStats
            {
                TotalOpen = tiles.Count,
                SlaBreached = tiles.Count(t => t.IsSlaBreached),
                SlaWarning = tiles.Count(t => t.IsSlaWarning),
                AvgAgeDays = tiles.Count > 0 ? Math.Round(tiles.Average(t => t.AgeDays), 1) : 0,
                OldestJobDays = tiles.Count > 0 ? tiles.Max(t => t.AgeDays) : 0
            };

            // By priority
            foreach (var p in _config.Priorities)
            {
                stats.ByPriority[p.Id] = tiles.Count(t => t.PriorityId == p.Id);
            }
            stats.Critical = tiles.Count(t => t.PriorityId == "critical");
            stats.High = tiles.Count(t => t.PriorityId == "high");
            stats.Medium = tiles.Count(t => t.PriorityId == "medium");
            stats.Low = tiles.Count(t => t.PriorityId == "low");
            stats.Scheduled = tiles.Count(t => t.PriorityId == "scheduled");

            // By location
            foreach (var l in _config.Locations)
            {
                stats.ByLocation[l.Id] = tiles.Count(t => t.LocationId == l.Id);
            }
            stats.InItOffice = tiles.Count(t => t.LocationId == "it-office");
            stats.WithUser = tiles.Count(t => t.LocationId == "with-user");
            stats.AtRepairer = tiles.Count(t => t.LocationId == "at-repairer");

            // By status
            foreach (var tile in tiles)
            {
                var status = tile.StatusOverride ?? "Open";
                if (!stats.ByStatus.ContainsKey(status))
                    stats.ByStatus[status] = 0;
                stats.ByStatus[status]++;
            }

            // By tech
            foreach (var tile in tiles.Where(t => !string.IsNullOrEmpty(t.AssignedTechId)))
            {
                var tech = tile.AssignedTechName ?? tile.AssignedTechId;
                if (!stats.ByTech.ContainsKey(tech))
                    stats.ByTech[tech] = 0;
                stats.ByTech[tech]++;
            }

            return stats;
        }

        private ServiceTicket CreateDefaultTicket(Job job)
        {
            var priority = _config.Priorities.FirstOrDefault(p => p.Id == _config.DefaultPriorityId);
            DateTime? sla = null;
            if (priority != null && priority.SlaHours > 0)
                sla = job.OpenedDate.AddHours(priority.SlaHours);

            // Determine default location based on DeviceHeld
            string locationId = _config.DefaultLocationId;
            if (job.DeviceHeld.HasValue)
            {
                if (!string.IsNullOrEmpty(job.DeviceHeldLocation))
                {
                    // Try to match the Disco location to a configured location
                    var matchedLoc = _config.Locations.FirstOrDefault(
                        l => l.Name.Equals(job.DeviceHeldLocation, StringComparison.OrdinalIgnoreCase));
                    if (matchedLoc != null)
                        locationId = matchedLoc.Id;
                }
            }

            return new ServiceTicket
            {
                JobId = job.Id,
                PriorityId = _config.DefaultPriorityId,
                LocationId = locationId,
                AssignedTechId = job.OpenedTechUserId,
                EstimatedCompletion = job.ExpectedClosedDate,
                SlaDeadline = sla,
                StatusOverride = null,
                Summary = null,
                CreatedDate = DateTime.Now,
                LastModifiedDate = DateTime.Now
            };
        }

        private string ResolveUserName(string userId)
        {
            if (string.IsNullOrEmpty(userId)) return null;
            try
            {
                var user = _database.Users.FirstOrDefault(u => u.UserId == userId);
                return user != null ? user.DisplayName : userId;
            }
            catch
            {
                return userId;
            }
        }

        // --- CRUD operations for tickets ---

        public void UpdateTicket(int jobId, string priorityId, string locationId,
            string assignedTechId, DateTime? eta, string status, string summary, string modifiedBy)
        {
            var ticket = _dataStore.GetTicket(jobId);
            if (ticket == null)
            {
                ticket = new ServiceTicket { JobId = jobId };
            }

            if (priorityId != null) ticket.PriorityId = priorityId;
            if (locationId != null) ticket.LocationId = locationId;
            if (assignedTechId != null) ticket.AssignedTechId = assignedTechId;
            if (eta.HasValue) ticket.EstimatedCompletion = eta;
            if (status != null) ticket.StatusOverride = status;
            if (summary != null) ticket.Summary = summary;
            ticket.LastModifiedBy = modifiedBy;

            // Recalculate SLA if priority changed
            if (priorityId != null)
            {
                var priority = _config.Priorities.FirstOrDefault(p => p.Id == priorityId);
                if (priority != null && priority.SlaHours > 0)
                {
                    ticket.SlaDeadline = ticket.CreatedDate.AddHours(priority.SlaHours);
                }
                else
                {
                    ticket.SlaDeadline = null;
                }
            }

            _dataStore.SaveTicket(ticket);
        }

        public void AddNote(int jobId, string authorId, string authorName, string content, string noteType)
        {
            var note = new TicketNote
            {
                AuthorId = authorId,
                AuthorName = authorName,
                Content = content,
                NoteType = noteType ?? "general"
            };
            _dataStore.AddNote(jobId, note);
        }

        public ServiceTicket GetTicketDetail(int jobId)
        {
            return _dataStore.GetTicket(jobId);
        }
    }
}