using System.Text.Json;
using GerbilManagerWebAPI.Models;
using Microsoft.EntityFrameworkCore;

namespace GerbilManagerWebAPI.Import
{
    public sealed class IngestResolvedService
    {
        private readonly ApplicationContext _db;
        private readonly string _resolvedJsonPath;

        public IngestResolvedService(ApplicationContext db, IConfiguration config, IWebHostEnvironment env)
        {
            _db = db;
            var sourceDir = config["Import:SourcePath"]
                ?? Path.GetFullPath(Path.Combine(env.ContentRootPath, "..", "tools", "import", "output"));
            _resolvedJsonPath = Path.Combine(sourceDir, "resolved_import.json");
        }

        public async Task<string> RunAsync()
        {
            if (!File.Exists(_resolvedJsonPath))
            {
                return $"Error: Resolved import file not found at {_resolvedJsonPath}. Run resolve_import.py first.";
            }

            string jsonContent = await File.ReadAllTextAsync(_resolvedJsonPath);
            var jsonOptions = new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true
            };
            jsonOptions.Converters.Add(new System.Text.Json.Serialization.JsonStringEnumConverter());
            var data = JsonSerializer.Deserialize<ResolvedImportData>(jsonContent, jsonOptions);

            if (data == null)
            {
                return "Error: Failed to deserialize resolved_import.json.";
            }

            // 1. Provider-agnostic clean wipe of dependent tables to prevent duplicate keys
            if (_db.Database.ProviderName == "Microsoft.EntityFrameworkCore.InMemory")
            {
                // Break circular references first
                foreach (var l in _db.Litters)
                {
                    l.FatherId = null;
                    l.MotherId = null;
                }
                foreach (var g in _db.Gerbils)
                {
                    g.LitterId = null;
                }
                await _db.SaveChangesAsync();

                _db.GerbilPhotos.RemoveRange(_db.GerbilPhotos);
                _db.WeightRecords.RemoveRange(_db.WeightRecords);
                _db.HealthRecords.RemoveRange(_db.HealthRecords);
                _db.Gerbils.RemoveRange(_db.Gerbils);
                _db.Litters.RemoveRange(_db.Litters);
                await _db.SaveChangesAsync();
            }
            else
            {
                // Break circular references first using ExecuteUpdateAsync
                await _db.Litters.ExecuteUpdateAsync(s => s
                    .SetProperty(l => l.FatherId, (Guid?)null)
                    .SetProperty(l => l.MotherId, (Guid?)null));
                
                await _db.Gerbils.ExecuteUpdateAsync(s => s
                    .SetProperty(g => g.LitterId, (Guid?)null));

                await _db.GerbilPhotos.ExecuteDeleteAsync();
                await _db.WeightRecords.ExecuteDeleteAsync();
                await _db.HealthRecords.ExecuteDeleteAsync();
                await _db.Gerbils.ExecuteDeleteAsync();
                await _db.Litters.ExecuteDeleteAsync();
            }

            // 2. Import Contacts (Only add new ones to preserve manually entered contacts)
            var existingContactIds = await _db.Contacts.Select(c => c.Id).ToHashSetAsync();
            var addedContactIds = new HashSet<Guid>();
            int contactsAdded = 0;
            foreach (var c in data.Contacts)
            {
                if (!existingContactIds.Contains(c.Id) && addedContactIds.Add(c.Id))
                {
                    _db.Contacts.Add(c);
                    contactsAdded++;
                }
            }
            await _db.SaveChangesAsync();

            // 3. Pass 1: Insert all Litters with parent references set to null to avoid FK errors
            var littersToInsert = new List<Litter>();
            foreach (var l in data.Litters)
            {
                littersToInsert.Add(new Litter
                {
                    Id = l.Id,
                    Name = l.Name,
                    Date = l.Date,
                    TotalBorn = l.TotalBorn,
                    DeathsWithin8Weeks = l.DeathsWithin8Weeks,
                    FatherId = null, // Set in Pass 2
                    MotherId = null, // Set in Pass 2
                    ExpectedGoHomeDate = l.ExpectedGoHomeDate,
                    Notes = l.Notes,
                    PairingCode = l.PairingCode,
                    ExternalRef = l.ExternalRef,
                    LitterLetter = l.LitterLetter
                });
            }
            _db.Litters.AddRange(littersToInsert);
            await _db.SaveChangesAsync();

            // 4. Pass 1: Insert all Gerbils with LitterId set to null to avoid FK errors
            var gerbilsToInsert = new List<Gerbil>();
            foreach (var g in data.Gerbils)
            {
                gerbilsToInsert.Add(new Gerbil
                {
                    Id = g.Id,
                    Name = g.Name,
                    Gender = g.Gender,
                    Status = g.Status,
                    LitterId = null, // Set in Pass 2
                    OriginContactId = g.OriginContactId,
                    ReceiverContactId = g.ReceiverContactId,
                    EnclosureId = g.EnclosureId,
                    ColorVarietyId = g.ColorVarietyId,
                    DateOfBirth = g.DateOfBirth,
                    DateOfDeath = g.DateOfDeath,
                    CauseOfDeath = g.CauseOfDeath,
                    GoHomeDate = g.GoHomeDate,
                    Genotype = g.Genotype,
                    Notes = g.Notes,
                    ImportSource = g.ImportSource,
                    ExternalRef = g.ExternalRef,
                    RawImportData = g.RawImportData,
                    OriginBreeder = g.OriginBreeder,
                    NameSearch = g.NameSearch,
                    CharacterTraits = g.CharacterTraits,
                    CharacterNote = g.CharacterNote,
                    IsDeaf = g.IsDeaf,
                    IsResident = g.IsResident
                });
            }
            _db.Gerbils.AddRange(gerbilsToInsert);
            await _db.SaveChangesAsync();

            // 5. Pass 2: Set the actual foreign key relationships
            // Update Litters with their parent animal IDs
            var littersInDb = await _db.Litters.ToDictionaryAsync(l => l.Id);
            foreach (var l in data.Litters)
            {
                if (littersInDb.TryGetValue(l.Id, out var dbLitter))
                {
                    dbLitter.FatherId = l.FatherId;
                    dbLitter.MotherId = l.MotherId;
                }
            }

            // Update Gerbils with their actual LitterId
            var gerbilsInDb = await _db.Gerbils.ToDictionaryAsync(g => g.Id);
            foreach (var g in data.Gerbils)
            {
                if (gerbilsInDb.TryGetValue(g.Id, out var dbGerbil))
                {
                    dbGerbil.LitterId = g.LitterId;
                }
            }
            await _db.SaveChangesAsync();

            // 6. Insert all Photos
            foreach (var p in data.GerbilPhotos)
            {
                _db.GerbilPhotos.Add(p);
            }
            await _db.SaveChangesAsync();

            return $"Ingestion successful! Imported {contactsAdded} contacts, {data.Litters.Count} litters, {data.Gerbils.Count} gerbils, and {data.GerbilPhotos.Count} photos.";
        }
    }

    public class ResolvedImportData
    {
        public List<Contact> Contacts { get; set; } = new();
        public List<Litter> Litters { get; set; } = new();
        public List<Gerbil> Gerbils { get; set; } = new();
        public List<GerbilPhoto> GerbilPhotos { get; set; } = new();
    }
}