using Microsoft.EntityFrameworkCore;
using Microsoft.Extensions.Logging;
using Microsoft.Extensions.Options;
using Mirea.Api.DataAccess.Domain.Schedule;
using Mirea.Api.DataAccess.Persistence;
using Mirea.Api.Endpoint.Common.Interfaces;
using Mirea.Api.Endpoint.Configuration.Model;
using Mirea.Api.Endpoint.Sync.Common;
using Mirea.Tools.Schedule.WebParser;
using Mirea.Tools.Schedule.WebParser.Common.Domain;
using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using Group = Mirea.Api.DataAccess.Domain.Schedule.Group;

namespace Mirea.Api.Endpoint.Sync;

internal partial class ScheduleSynchronizer(UberDbContext dbContext, IOptionsSnapshot<GeneralConfig> config, ILogger<ScheduleSynchronizer> logger, IMaintenanceModeService maintenanceMode)
{
    private readonly DataRepository<Campus> _campuses = new([.. dbContext.Campuses]);
    private readonly DataRepository<Discipline> _disciplines = new([.. dbContext.Disciplines]);
    private readonly DataRepository<Faculty> _faculties = new([.. dbContext.Faculties]);
    private readonly DataRepository<Group> _groups = new([.. dbContext.Groups]);
    private readonly DataRepository<LectureHall> _lectureHalls = new([.. dbContext.LectureHalls]);
    private readonly DataRepository<Lesson> _lessons = new([]);
    private readonly DataRepository<LessonAssociation> _lessonAssociation = new([]);
    private readonly DataRepository<Professor> _professors = new([.. dbContext.Professors]);
    private readonly DataRepository<TypeOfOccupation> _typeOfOccupations = new([.. dbContext.TypeOfOccupations]);
    private readonly DataRepository<SpecificWeek> _specificWeeks = new([]);

    // todo: transfer data to storage
    private static string GetFaculty(char c) =>
        c switch
        {
            'У' => "ИТУ",
            'Б' => "ИКБ",
            'Х' => "ИТХТ",
            'Э' => "ИПТИП",
            'Т' => "ИПТИП",
            'Р' => "ИРИ",
            'К' => "ИИИ",
            'И' => "ИИТ",
            'П' => "ИИТ",
            _ => throw new ArgumentOutOfRangeException(nameof(c), c, null)
        };

    private void ParallelSync(GroupResult groupInfo)
    {
        var facultyName = GetFaculty(groupInfo.Group[0]);

        var faculty = _faculties.GetOrCreate(
            f => f.Name.Equals(facultyName, StringComparison.OrdinalIgnoreCase),
            () => new Faculty
            {
                Name = facultyName
            });

        var groupName = OnlyGroupName().Match(groupInfo.Group.ToUpper()).Value;

        var group = _groups.GetOrCreate(
            g => g.Name.Equals(groupName, StringComparison.OrdinalIgnoreCase),
            () => new Group
            {
                Name = groupName,
                Faculty = faculty
            });

        var typeOfOccupation = _typeOfOccupations.GetOrCreate(
            t => t.ShortName.Equals(groupInfo.TypeOfOccupation.Trim(), StringComparison.OrdinalIgnoreCase),
            () => new TypeOfOccupation
            {
                ShortName = groupInfo.TypeOfOccupation.ToUpper()
            });

        List<Professor>? professor = [];
        if (groupInfo.Professor != null)
        {
            foreach (var prof in groupInfo.Professor)
            {
                var professorParts = prof.Split(' ').ToList();

                string? altName = null;

                if (professorParts is { Count: >= 2 })
                {
                    altName = professorParts.ElementAtOrDefault(0);

                    if (professorParts.ElementAtOrDefault(1) != null)
                        altName += $" {professorParts.ElementAtOrDefault(1)?[0]}.";

                    if (professorParts.ElementAtOrDefault(2) != null)
                        altName += $"{professorParts.ElementAtOrDefault(2)?[0]}.";
                }

                if (string.IsNullOrEmpty(altName))
                    continue;

                var profDb = _professors.GetOrCreate(x =>
                        (x.AltName == null || x.AltName.Equals(prof, StringComparison.OrdinalIgnoreCase)) &&
                        x.Name.Equals(altName, StringComparison.OrdinalIgnoreCase),
                    () => new Professor
                    {
                        AltName = prof,
                        Name = altName
                    });

                professor.Add(profDb);
            }
        }
        else
            professor = null;

        List<LectureHall>? hall = null;
        List<Campus>? campuses;
        if (groupInfo.Campuses != null && groupInfo.Campuses.Length != 0)
        {
            hall = [];
            campuses = [];
            for (int i = 0; i < groupInfo.Campuses.Length; i++)
            {
                var campus = groupInfo.Campuses[i];
                campuses.Add(_campuses.GetOrCreate(
                    c => c.CodeName.Equals(campus, StringComparison.OrdinalIgnoreCase),
                    () => new Campus
                    {
                        CodeName = campus.ToUpper()
                    }));
                if (groupInfo.LectureHalls == null || groupInfo.LectureHalls.Length <= i)
                    continue;
                var lectureHall = groupInfo.LectureHalls[i];

                hall.Add(_lectureHalls.GetOrCreate(l =>
                        l.Name.Equals(lectureHall, StringComparison.OrdinalIgnoreCase) &&
                        string.Equals(l.Campus?.CodeName, campuses[^1].CodeName, StringComparison.CurrentCultureIgnoreCase),
                    () => new LectureHall
                    {
                        Name = lectureHall,
                        Campus = campuses[^1]
                    }));
            }
        }

        var discipline = _disciplines.GetOrCreate(
            d => d.Name.Equals(groupInfo.Discipline, StringComparison.OrdinalIgnoreCase),
            () => new Discipline
            {
                Name = groupInfo.Discipline
            });

        var lesson = _lessons.GetOrCreate(l =>
                l.IsEven == groupInfo.IsEven &&
                l.DayOfWeek == groupInfo.Day &&
                l.PairNumber == groupInfo.Pair &&
                l.Discipline?.Name == discipline.Name,
            () =>
            {
                var lesson = new Lesson
                {
                    IsEven = groupInfo.IsEven,
                    DayOfWeek = groupInfo.Day,
                    PairNumber = groupInfo.Pair,
                    Discipline = discipline,
                    Group = group,
                    IsExcludedWeeks = groupInfo.IsExclude
                };

                if (groupInfo.SpecialWeek == null)
                    return lesson;

                foreach (var week in groupInfo.SpecialWeek)
                    _specificWeeks.Create(() => new SpecificWeek
                    {
                        Lesson = lesson,
                        WeekNumber = week
                    });

                return lesson;
            });

        int maxValue = int.Max(int.Max(professor?.Count ?? -1, hall?.Count ?? -1), 1);

        for (int i = 0; i < maxValue; i++)
        {
            var prof = professor?.ElementAtOrDefault(i);
            var lectureHall = hall?.ElementAtOrDefault(i);
            _lessonAssociation.Create(() => new LessonAssociation
            {
                Professor = prof,
                Lesson = lesson,
                LectureHall = lectureHall,
                TypeOfOccupation = typeOfOccupation
            });
        }
    }

    private async Task SaveChanges(CancellationToken cancellationToken)
    {
        foreach (var group in _groups.GetAll())
        {
            var existingGroup = await dbContext.Groups.FirstOrDefaultAsync(g => g.Id == group.Id, cancellationToken);
            if (existingGroup != null)
                dbContext.Remove(existingGroup);
        }

        await dbContext.Disciplines.BulkSynchronizeAsync(_disciplines.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
        await dbContext.Professors.BulkSynchronizeAsync(_professors.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
        await dbContext.TypeOfOccupations.BulkSynchronizeAsync(_typeOfOccupations.GetAll(), bulkOperation => bulkOperation.BatchSize = 100, cancellationToken);
        await dbContext.Faculties.BulkSynchronizeAsync(_faculties.GetAll(), bulkOperation => bulkOperation.BatchSize = 100, cancellationToken);
        await dbContext.Campuses.BulkSynchronizeAsync(_campuses.GetAll(), bulkOperation => bulkOperation.BatchSize = 10, cancellationToken);
        await dbContext.LectureHalls.BulkSynchronizeAsync(_lectureHalls.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
        await dbContext.Groups.BulkSynchronizeAsync(_groups.GetAll(), bulkOperation => bulkOperation.BatchSize = 100, cancellationToken);
        await dbContext.Lessons.BulkSynchronizeAsync(_lessons.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
        await dbContext.SpecificWeeks.BulkSynchronizeAsync(_specificWeeks.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
        await dbContext.LessonAssociations.BulkSynchronizeAsync(_lessonAssociation.GetAll(), bulkOperation => bulkOperation.BatchSize = 1000, cancellationToken);
    }

    public async Task StartSync(CancellationToken cancellationToken)
    {
        var pairPeriods = config.Value.ScheduleSettings?.PairPeriod;
        var startTerm = config.Value.ScheduleSettings?.StartTerm;

        if (pairPeriods == null || startTerm == null)
        {
            logger.LogWarning("It is not possible to synchronize the schedule due to the fact that the {Arg1} or {Arg2} variable is not initialized.", nameof(pairPeriods), nameof(startTerm));

            return;
        }

        Stopwatch watch = new();
        watch.Start();

        var parser = new Parser
        {
            Pairs = pairPeriods
                .ToDictionary(x => x.Key,
                    x => (x.Value.Start, x.Value.End)),
            TermStart = startTerm.Value.ToDateTime(new TimeOnly(0, 0, 0))
        };

        try
        {
            logger.LogDebug("Start parsing schedule");
            var data = await parser.ParseAsync(cancellationToken);

            watch.Stop();
            var parsingTime = watch.ElapsedMilliseconds;
            watch.Restart();

            ParallelOptions options = new()
            {
                CancellationToken = cancellationToken,
                MaxDegreeOfParallelism = Environment.ProcessorCount
            };

            logger.LogDebug("Start mapping parsed data");
            Parallel.ForEach(data, options, ParallelSync);

            watch.Stop();
            var mappingTime = watch.ElapsedMilliseconds;
            watch.Restart();

            maintenanceMode.EnableMaintenanceMode();

            logger.LogDebug("Start saving changing");
            await SaveChanges(cancellationToken);

            maintenanceMode.DisableMaintenanceMode();

            watch.Stop();

            logger.LogInformation("Parsing time: {ParsingTime}ms Mapping time: {MappingTime}ms Saving time: {SavingTime}ms Total time: {TotalTime}ms",
                parsingTime, mappingTime, watch.ElapsedMilliseconds, parsingTime + mappingTime + watch.ElapsedMilliseconds);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "An error occurred during synchronization.");
            maintenanceMode.DisableMaintenanceMode();
            throw;
        }
    }

    [GeneratedRegex(@"\w{4}-\d{2}-\d{2}(?=\s?\d?\s?[Пп]/?[Гг]\s?\d?)?")]
    private static partial Regex OnlyGroupName();
}