using HyperBooru.ApiModels;
using Microsoft.EntityFrameworkCore;

namespace HyperBooru.Services;

public interface ITagService {
    public void AddTag(Guid obj, Guid tagDef);
    public void AddTag(HBObject obj, TagDefinition tagDef);
    public void RemoveTag(Guid obj, Guid tagDef);
    public void RemoveTag(HBObject obj, TagDefinition tagDef);
    public void SetImplicitTags(TagDefinition tagDef, TagDefinition[] implicitTagDefs);
    public void SetImplicitTags(Guid tagDef, Guid[] implicitTagDefs);
    public void AddImplicitTag(Guid tagDef, Guid implicitTagDef);
    public void AddImplicitTag(TagDefinition tagDef, TagDefinition implicitTagDef);
    public void RemoveImplicitTag(Guid tagDef, Guid implicitTagDef);
    public void RemoveImplicitTag(TagDefinition tagDef, TagDefinition implicitTagDef);
    public void CreateTagDefinition(string name, string? @namespace = null, string? alias = null);
    public void DeleteTagDefinition(Guid tagDef);
    public void DeleteTagDefinition(TagDefinition tagDef);
    public void UpdateTagDefinition(Guid tagDef, string name, string? @namespace = null, string? alias = null);
    public void UpdateTagDefinition(TagDefinition tagDef, string name, string? @namespace = null, string? alias = null);
    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(Guid obj);
    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(HBObject obj);
    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(TagDefinition tagDef);
    public TagDefinition[] TagsThatImply(Guid tagDef);
    public TagDefinition[] TagsThatImply(TagDefinition tagDef);
}

public class TagService : ITagService {
    private IDbContextFactory<HBContext> dbFactory;

    public TagService(IDbContextFactory<HBContext> dbFactory) =>
        this.dbFactory = dbFactory;

    public void AddTag(Guid obj, Guid tagDef) {
        using var db = dbFactory.CreateDbContext();

        var tag = db.TagDefinitions.First(td => td.Guid == tagDef);

        db.Objects
            .Include(o => o.Tags)
            .ThenInclude(t => t.TagDefinition)
            .Where(o => !o.Tags.Select(t => t.TagDefinition.Guid).Contains(tagDef))
            .FirstOrDefault(o => o.Guid == obj)?
            .Tags
            .Add(new(tag));

        db.SaveChanges();
    }

    public void AddTag(HBObject obj, TagDefinition tagDef) =>
        AddTag(obj.Guid, tagDef.Guid);

    public void RemoveTag(Guid obj, Guid tagDef) {
        using var db = dbFactory.CreateDbContext();

        db.Objects
            .Include(o => o.Tags)
            .ThenInclude(t => t.TagDefinition)
            .First(o => o.Guid == obj)
            .Tags
            .RemoveAll(t => t.TagDefinition.Guid == tagDef);

        db.SaveChanges();
    }

    public void RemoveTag(HBObject obj, TagDefinition tagDef) =>
        RemoveTag(obj.Guid, tagDef.Guid);

    public void SetImplicitTags(Guid tagDef, Guid[] implicitTagDefs) {
        using var db = dbFactory.CreateDbContext();
        using var transaction = db.Database.BeginTransaction();

        var tag = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .First(td => td.Guid == tagDef);

        tag.ImplicitTags.RemoveAll(td => !implicitTagDefs.Contains(td.Guid));
        tag.ImplicitTags.AddRange(
            db.TagDefinitions
                .Where(td => implicitTagDefs.Contains(td.Guid))
                .Where(td => !tag.ImplicitTags
                    .Select(td => td.Guid)
                    .Contains(td.Guid)));

        db.SaveChanges();
        transaction.Commit();
    }

    public void SetImplicitTags(TagDefinition tagDef, TagDefinition[] implicitTagDefs) =>
        SetImplicitTags(tagDef.Guid, implicitTagDefs.Select(td => td.Guid).ToArray());

    public void AddImplicitTag(Guid tagDef, Guid implicitTagDef) {
        using var db = dbFactory.CreateDbContext();

        var tag = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .First(td => td.Guid == tagDef);
        var implicitTag = db.TagDefinitions.First(td => td.Guid == implicitTagDef);

        tag.ImplicitTags.Add(implicitTag);
        db.SaveChanges();
    }

    public void AddImplicitTag(TagDefinition tagDef, TagDefinition implicitTagDef) =>
        AddImplicitTag(tagDef, implicitTagDef);

    public void RemoveImplicitTag(Guid tagDef, Guid implicitTagDef) {
        using var db = dbFactory.CreateDbContext();

        var tag = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .First(td => td.Guid == tagDef);

        tag.ImplicitTags.RemoveAll(td => td.Guid == implicitTagDef);
        db.SaveChanges();
    }

    public void RemoveImplicitTag(TagDefinition tagDef, TagDefinition implicitTagDef) =>
        RemoveImplicitTag(tagDef, implicitTagDef);

    public void CreateTagDefinition(string name, string? @namespace = null, string? alias = null) {
        using var db = dbFactory.CreateDbContext();

        if(string.IsNullOrEmpty(@namespace))
            @namespace = null;
        if(string.IsNullOrEmpty(alias))
            alias = null;

        // Remove leading and trailing whitespace
        name       = name.Trim();
        @namespace = @namespace?.Trim();
        alias      = alias?.Trim();

        TagDefinition tagDef = new() {
            Source    = TagSource.UserTag,
            Namespace = @namespace,
            Name      = name,
            Alias     = alias
        };

        bool nameExists  = db.TagDefinitions.Any(td => td.Name.ToLower() == name.ToLower());
        bool aliasExists = false;
        if(alias is not null)
            aliasExists = db.TagDefinitions
                .Where(td => td.Alias != null)
                .Any(td => td.Alias!.ToLower() == alias.ToLower());
        if(nameExists || aliasExists)
            throw new TagDuplicateException(nameExists, aliasExists);

        if(!db.TagDefinitions.Contains(tagDef))
            db.TagDefinitions.Add(tagDef);
        db.SaveChanges();
    }

    public void DeleteTagDefinition(Guid tagDef) {
        using var db = dbFactory.CreateDbContext();

        var tag = db.TagDefinitions.First(td => td.Guid == tagDef);

        using var transaction = db.Database.BeginTransaction();

        db.Tags.RemoveRange(
            db.Tags
                .Include(t => t.TagDefinition)
                .Where(t => t.TagDefinition.Guid == tagDef));
        db.TagDefinitions.Remove(tag);
        db.SaveChanges();

        transaction.Commit();
    }

    public void DeleteTagDefinition(TagDefinition tagDef) =>
        DeleteTagDefinition(tagDef.Guid);

    public void UpdateTagDefinition(Guid tagDef, string name, string? @namespace = null, string? alias = null) {
        using var db = dbFactory.CreateDbContext();

        if(string.IsNullOrEmpty(@namespace))
            @namespace = null;
        if(string.IsNullOrEmpty(alias))
            alias = null;

        // Remove leading and trailing whitespace
        name       = name.Trim();
        @namespace = @namespace?.Trim();
        alias      = alias?.Trim();

        var tag = db.TagDefinitions.First(td => td.Guid == tagDef);

        TagDefinition? nameExisting = db.TagDefinitions.FirstOrDefault(td => td.Name.ToLower() == name.ToLower());
        TagDefinition? aliasExisting = null;
        if(alias is not null)
            aliasExisting = db.TagDefinitions
                .Where(td => td.Alias != null)
                .FirstOrDefault(td => td.Alias!.ToLower() == alias.ToLower());
        bool nameExists  = nameExisting  is not null && nameExisting  != tag;
        bool aliasExists = aliasExisting is not null && aliasExisting != tag;
        if(nameExists || aliasExists)
            throw new TagDuplicateException(nameExists, aliasExists);

        tag.Name      = name;
        tag.Namespace = @namespace;
        tag.Alias     = alias;

        db.SaveChanges();
    }

    public void UpdateTagDefinition(TagDefinition tagDef, string name, string? @namespace = null, string? alias = null) =>
        UpdateTagDefinition(tagDef.Guid, name, @namespace, alias);

    private (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(IEnumerable<TagDefinition> tagDefs) {
        using var db = dbFactory.CreateDbContext();

        var tagGuids = tagDefs
            .Select(td => td.Guid)
            .ToArray();

        // Query all tag definitions
        var allTags = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .ToArray();

        var tags = new List<TagDefinition>(
            allTags.IntersectBy(
                tagGuids,
                td => td.Guid));

        while(true) {
            var toAdd = tags
                .SelectMany(td => td.ImplicitTags)
                .ExceptBy(tags.Select(td => td.Guid), td => td.Guid)
                .ToArray();

            if(toAdd.Count() == 0)
                break;

            tags.AddRange(toAdd);
        }

        return tags
            .Select(td => new ValueTuple<TagDefinition, bool>(td, !tagGuids.Contains(td.Guid)))
            .ToArray();
    }

    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(Guid obj) {
        using var db = dbFactory.CreateDbContext();

        // Query a list of tag GUIDs for this object
        var tags = db.Objects
            .Include(o => o.Tags)
            .ThenInclude(t => t.TagDefinition)
            .First(o => o.Guid == obj)
            .Tags
            .Select(t => t.TagDefinition)
            .ToArray();

        return GetAllTags(tags);
    }


    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(HBObject obj) =>
        GetAllTags(obj.Guid);

    public (TagDefinition tagDefinition, bool isImplicit)[] GetAllTags(TagDefinition tagDef) {
        using var db = dbFactory.CreateDbContext();

        var tags = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .First(td => td.Guid == tagDef.Guid)
            .ImplicitTags
            .ToArray();

        return GetAllTags(tags);
    }

    public TagDefinition[] TagsThatImply(Guid tagDef) {
        using var db = dbFactory.CreateDbContext();

        var tagDefs = db.TagDefinitions
            .Include(td => td.ImplicitTags)
            .ToArray();

        var tags = new List<TagDefinition>() {
            db.TagDefinitions.First(td => td.Guid == tagDef)
        };

        while(true) {
            var toAdd = tagDefs
                .Where(td => td.ImplicitTags.Select(it => it.Guid).Intersect(tags.Select(td => td.Guid)).Any())
                .ExceptBy(tags.Select(td => td.Guid), td => td.Guid)
                .ToArray();

            if(toAdd.Count() == 0)
                break;

            tags.AddRange(toAdd);
        }

        return tags.ToArray();
    }

    public TagDefinition[] TagsThatImply(TagDefinition tagDef) =>
        TagsThatImply(tagDef.Guid);
}