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

namespace GerbilManagerWebAPI.Import
{
    /// <summary>
    /// FEAT-8d docx loader. Consumes tools/import/output/docx_litters.json +
    /// docx_animals.json (produced by extract_docx.py) and enriches OR CREATES animals.
    ///
    /// Load policy (IDEMPOTENT NACHZUG after main WIPE+REIMPORT):
    ///   Match order per docx row:
    ///     1. ExternalRef "docx-…" (previously created by this loader) → enrich (fill-NULL-only)
    ///     2. normalize(name)+litterDob in Gerbils (from main import) → enrich (fill-NULL-only)
    ///     3. No match → CREATE: abgegebene Jungtiere that never appeared in the pedigree charts.
    ///
    ///   Created animals: Status=GivenAway (or Deceased), IsResident=false,
    ///   OriginBreeder='Zucht der Kleinen Chaoten', ImportSource="docx",
    ///   ExternalRef = stable "docx-{ws}-{normname}-{litterDob}" key (idempotent).
    ///
    ///   NEVER overwrites a manually-set non-null value (fill-NULL-only for all fields).
    ///
    /// Idempotent: running multiple times is safe. Each run resolves whatever is still null.
    /// Execute is gated by the endpoint; this service only acts when asked.
    /// </summary>
    public sealed class ImportDocxService
    {
        private static readonly JsonSerializerOptions Json = new() { PropertyNameCaseInsensitive = true };

        private readonly ApplicationContext _db;
        private readonly string _sourceDir;

        public ImportDocxService(ApplicationContext db, IConfiguration config, IWebHostEnvironment env)
            : this(db,
                   config["Import:SourcePath"]
                       ?? Path.GetFullPath(Path.Combine(env.ContentRootPath, "..", "tools", "import", "output")))
        { }

        public ImportDocxService(ApplicationContext db, string sourceDir)
        {
            _db = db;
            _sourceDir = sourceDir;
        }

        public async Task<ImportDocxReport> RunAsync(bool execute)
        {
            var notes = new List<string>();

            var docxLitters = Load<List<DocxLitter>>("docx_litters.json") ?? new();
            var docxAnimals = Load<List<DocxAnimal>>("docx_animals.json") ?? new();

            if (docxLitters.Count == 0 && docxAnimals.Count == 0)
            {
                notes.Add($"Keine Quelldaten in {_sourceDir} (docx_litters.json/docx_animals.json). " +
                          "extract_docx.py zuerst ausführen.");
                return new ImportDocxReport(false, 0, 0, 0, 0, 0, 0, 0, notes);
            }

            // PairingCode → Litters (WS-code normalised: spaces removed)
            var littersInDb = await _db.Litters
                .Where(l => l.PairingCode != null)
                .Select(l => new { l.Id, l.Date, l.PairingCode })
                .ToListAsync();
            var litterByWs = littersInDb
                .GroupBy(l => l.PairingCode!.Replace(" ", ""))
                .ToDictionary(g => g.Key, g => g.ToList());

            // normalize(name)+litterDob → Gerbil snapshot (main-import enrich path)
            var gerbilsInDb = await _db.Gerbils
                .Select(g => new { g.Id, g.Name, g.DateOfBirth, g.LitterId,
                                   g.ReceiverContactId, g.GoHomeDate, g.DateOfDeath, g.CauseOfDeath,
                                   g.ExternalRef })
                .ToListAsync();
            var gerbilByKey = gerbilsInDb
                .Where(g => g.DateOfBirth is not null)
                .GroupBy(g => NameDobKey(g.Name, g.DateOfBirth!.Value))
                .ToDictionary(g => g.Key, g => g.ToList());

            // ExternalRef → snapshot for previously docx-created animals (idempotency across runs)
            var docxExternalRefs = gerbilsInDb
                .Where(g => g.ExternalRef?.StartsWith("docx-") == true)
                .ToDictionary(g => g.ExternalRef!,
                              g => new { g.Id, g.LitterId, g.GoHomeDate, g.DateOfDeath, g.ReceiverContactId });

            // Contact lookup: normalized name → existing Contact.Id
            var contactsInDb = await _db.Contacts
                .Select(c => new { c.Id, c.Name })
                .ToListAsync();
            var contactByNorm = contactsInDb
                .GroupBy(c => NormalizeName(c.Name))
                .ToDictionary(g => g.Key, g => g.First().Id);

            // ColorVariety lookup: normalized name → Id (for CREATE path Farbschlag matching)
            var colorVarietyByName = (await _db.ColorVarieties
                .Select(cv => new { cv.Id, cv.Name })
                .ToListAsync())
                .GroupBy(cv => NormalizeName(cv.Name))
                .ToDictionary(g => g.Key, g => g.First().Id);

            int animalsCreated = 0, litterLinked = 0, goHomeFilled = 0, deathFilled = 0;
            int ownerLinked = 0, ownerCreated = 0, skipped = 0;

            foreach (var da in docxAnimals)
            {
                if (string.IsNullOrWhiteSpace(da.Name)) { skipped++; continue; }

                var externalRef = DocxExternalRef(da);

                // Resolve litter by WS-code + approximate birth date
                Guid? litterId = null;
                if (!string.IsNullOrWhiteSpace(da.WsCode) && !string.IsNullOrWhiteSpace(da.LitterDob))
                {
                    var litterDob = ParseDate(da.LitterDob);
                    if (litterDob is not null && litterByWs.TryGetValue(da.WsCode.Replace(" ", ""), out var cands))
                    {
                        var match = cands.FirstOrDefault(l =>
                            Math.Abs(l.Date.DayNumber - litterDob.Value.DayNumber) <= 5);
                        litterId = match?.Id;
                    }
                }

                // Animal DOB = litter birth date (docx has no per-animal DOB)
                var animalDob = litterId is not null
                    ? (await _db.Litters.Where(l => l.Id == litterId).Select(l => (DateOnly?)l.Date).FirstOrDefaultAsync())
                    : ParseDate(da.LitterDob);

                if (animalDob is null) { skipped++; continue; }

                var goHomeDate = ParseDate(da.AbgabeDate);
                var deathDate  = ParseDate(da.DeathDate);

                // Resolve receiver contact (lookup-or-create; shared by all paths)
                Guid? receiverId = null;
                if (!string.IsNullOrWhiteSpace(da.Owner))
                {
                    var normOwner = NormalizeName(da.Owner);
                    if (contactByNorm.TryGetValue(normOwner, out var existingContactId))
                    {
                        receiverId = existingContactId;
                        ownerLinked++;
                    }
                    else
                    {
                        ownerCreated++;
                        if (execute)
                        {
                            var newContact = new Contact { Id = Guid.NewGuid(), Name = da.Owner.Trim() };
                            _db.Contacts.Add(newContact);
                            await _db.SaveChangesAsync();   // persist before any Gerbil FK reference
                            receiverId = newContact.Id;
                            contactByNorm[normOwner] = receiverId.Value;
                        }
                    }
                }

                // ── PATH 1: previously docx-created animal (idempotent re-run) ──────────
                if (docxExternalRefs.TryGetValue(externalRef, out var prevSnap))
                {
                    bool willLink  = litterId is not null && prevSnap.LitterId is null;
                    bool willHome  = goHomeDate is not null && prevSnap.GoHomeDate is null;
                    bool willDeath = deathDate  is not null && prevSnap.DateOfDeath is null;

                    if (willLink)  litterLinked++;
                    if (willHome)  goHomeFilled++;
                    if (willDeath) deathFilled++;

                    if (execute)
                    {
                        var row = await _db.Gerbils.FirstOrDefaultAsync(g => g.Id == prevSnap.Id);
                        if (row is null) continue;
                        if (willLink)  row.LitterId = litterId;
                        if (receiverId is not null && row.ReceiverContactId is null) row.ReceiverContactId = receiverId;
                        if (willHome)  row.GoHomeDate = goHomeDate;
                        if (willDeath)
                        {
                            row.DateOfDeath = deathDate;
                            if (!string.IsNullOrWhiteSpace(da.DeathCause) && row.CauseOfDeath is null)
                                row.CauseOfDeath = da.DeathCause.Trim();
                        }
                    }
                    continue;
                }

                // ── PATH 2: main-import animal matched by name+dob ───────────────────────
                var nameKey = NameDobKey(da.Name, animalDob.Value);
                if (gerbilByKey.TryGetValue(nameKey, out var gerbilCands))
                {
                    var gerbilSnap = gerbilCands.FirstOrDefault(g => g.LitterId == null)
                                  ?? gerbilCands.First();

                    bool willLink  = litterId is not null && gerbilSnap.LitterId is null;
                    bool willHome  = goHomeDate is not null && gerbilSnap.GoHomeDate is null;
                    bool willDeath = deathDate  is not null && gerbilSnap.DateOfDeath is null;

                    if (willLink)  litterLinked++;
                    if (willHome)  goHomeFilled++;
                    if (willDeath) deathFilled++;

                    if (execute)
                    {
                        var row = await _db.Gerbils.FirstOrDefaultAsync(g => g.Id == gerbilSnap.Id);
                        if (row is null) continue;
                        if (willLink)  row.LitterId = litterId;
                        if (receiverId is not null && row.ReceiverContactId is null) row.ReceiverContactId = receiverId;
                        if (willHome)  row.GoHomeDate = goHomeDate;
                        if (willDeath)
                        {
                            row.DateOfDeath = deathDate;
                            if (!string.IsNullOrWhiteSpace(da.DeathCause) && row.CauseOfDeath is null)
                                row.CauseOfDeath = da.DeathCause.Trim();
                        }
                    }
                    continue;
                }

                // ── PATH 3: no match → CREATE ────────────────────────────────────────────
                animalsCreated++;
                if (litterId is not null) litterLinked++;
                if (goHomeDate is not null) goHomeFilled++;
                if (deathDate  is not null) deathFilled++;

                if (execute)
                {
                    colorVarietyByName.TryGetValue(NormalizeName(da.Farbschlag ?? ""), out var cvId);

                    _db.Gerbils.Add(new Gerbil
                    {
                        Id                = Guid.NewGuid(),
                        Name              = da.Name.Trim(),
                        DateOfBirth       = animalDob,
                        Gender            = ParseGender(da.Gender),
                        Status            = deathDate is not null ? GerbilStatus.Deceased : GerbilStatus.GivenAway,
                        LitterId          = litterId,
                        ReceiverContactId = receiverId,
                        GoHomeDate        = goHomeDate,
                        DateOfDeath       = deathDate,
                        CauseOfDeath      = string.IsNullOrWhiteSpace(da.DeathCause) ? null : da.DeathCause.Trim(),
                        ColorVarietyId    = cvId == default ? null : cvId,
                        OriginBreeder     = "Zucht der Kleinen Chaoten",
                        IsResident        = false,
                        ImportSource      = "docx",
                        ExternalRef       = externalRef,
                    });
                }
            }

            if (execute && (animalsCreated + litterLinked + goHomeFilled + deathFilled + ownerCreated) > 0)
                await _db.SaveChangesAsync();

            notes.Add($"Quelle: {docxLitters.Count} Würfe, {docxAnimals.Count} Tier-Zeilen aus der docx.");
            notes.Add($"Neu angelegt: {animalsCreated} Jungtiere (abgegeben, nicht in Stammbäumen).");
            notes.Add($"Litter-Links: {litterLinked} Tiere einem Wurf zugeordnet.");
            notes.Add($"Abnehmer: {ownerLinked} bestehende Kontakte verknüpft, {ownerCreated} neue Kontakte angelegt.");
            notes.Add($"GoHomeDate: {goHomeFilled} Abgabe-Daten nachgetragen.");
            notes.Add($"Tod-Datum: {deathFilled} Todesdaten nachgetragen.");
            notes.Add($"Übersprungen: {skipped} Zeilen (kein Name oder kein Datum).");
            if (!execute) notes.Add("DRY-RUN: nichts gespeichert. /import/docx/execute schreibt die Änderungen.");

            return new ImportDocxReport(execute, animalsCreated, litterLinked, ownerLinked + ownerCreated,
                goHomeFilled, deathFilled, ownerCreated, skipped, notes);
        }

        private T? Load<T>(string file)
        {
            var path = Path.Combine(_sourceDir, file);
            if (!File.Exists(path)) return default;
            using var fs = File.OpenRead(path);
            return JsonSerializer.Deserialize<T>(fs, Json);
        }

        private static DateOnly? ParseDate(string? s)
        {
            if (string.IsNullOrWhiteSpace(s)) return null;
            var m = System.Text.RegularExpressions.Regex.Match(s,
                @"(\d{1,2})\.(\d{1,2})\.(\d{2,4})");
            if (!m.Success) return null;
            int d = int.Parse(m.Groups[1].Value), mo = int.Parse(m.Groups[2].Value);
            int y = int.Parse(m.Groups[3].Value);
            if (y < 100) y += 2000;
            try { return new DateOnly(y, mo, d); } catch { return null; }
        }

        private static string NameDobKey(string name, DateOnly dob)
        {
            var n = System.Text.RegularExpressions.Regex.Replace(
                (name ?? "").ToLowerInvariant(), @"[^a-z0-9äöüß]", "");
            return $"{n}|{dob:yyyy-MM-dd}";
        }

        private static string NormalizeName(string name)
        {
            var n = (name ?? "").ToLowerInvariant();
            n = System.Text.RegularExpressions.Regex.Replace(n, @"\s+", " ").Trim();
            return n;
        }

        /// <summary>
        /// Stable ExternalRef key for a docx animal row — used for idempotency across re-runs.
        /// Format: "docx-{wsCode}-{normname}-{litterDob}" (lowercased, spaces/punctuation stripped).
        /// </summary>
        internal static string DocxExternalRef(DocxAnimal da)
        {
            var ws   = da.WsCode.Replace(" ", "").ToLowerInvariant();
            var name = System.Text.RegularExpressions.Regex.Replace(
                (da.Name ?? "").ToLowerInvariant(), @"[^a-z0-9äöüß]", "");
            return $"docx-{ws}-{name}-{da.LitterDob}";
        }

        private static Gender ParseGender(string? s)
        {
            if (string.IsNullOrWhiteSpace(s)) return Gender.unknown;
            var lower = s.ToLowerInvariant();
            if (lower == "male"   || lower == "m" || lower.Contains("männ")) return Gender.male;
            if (lower == "female" || lower == "f" || lower == "w" || lower.Contains("weibl")) return Gender.female;
            return Gender.unknown;
        }
    }

    // ---- Source shapes (from extract_docx.py output) ----

    public sealed class DocxLitter
    {
        public string LitterId { get; set; } = "";
        public string Dob { get; set; } = "";
        public string MotherName { get; set; } = "";
        public string FatherName { get; set; } = "";
        public string WsCode { get; set; } = "";
        public string Note { get; set; } = "";
    }

    public sealed class DocxAnimal
    {
        public string WsCode { get; set; } = "";
        public string LitterDob { get; set; } = "";
        public string Name { get; set; } = "";
        public string Farbschlag { get; set; } = "";
        public string Gender { get; set; } = "";
        public string Owner { get; set; } = "";
        public string AbgabeDate { get; set; } = "";
        public string AbgabeWeight { get; set; } = "";
        public string DeathDate { get; set; } = "";
        public string DeathCause { get; set; } = "";
        public string PartnerName { get; set; } = "";
        public string PartnerDob { get; set; } = "";
    }

    // ---- Report ----

    public sealed record ImportDocxReport(
        bool Executed,
        int Created,
        int LitterLinked,
        int OwnerLinked,
        int GoHomeFilled,
        int DeathFilled,
        int ContactsCreated,
        int Skipped,
        IReadOnlyList<string> Notes);
}