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.Parser.Domain;
using Mirea.Tools.Schedule.WebParser;
using Mirea.Tools.Schedule.WebParser.Common.Domain;
using System;
using System.Collections.Concurrent;
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 (var 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
            });

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

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

        for (var 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);
    }

    private async Task Sync(Func<CancellationToken, Task<List<GroupResult>>> parseDataAsync, CancellationToken cancellationToken)
    {
        Stopwatch watch = new();
        watch.Start();

        try
        {
            logger.LogDebug("Start parsing schedule");
            var data = await parseDataAsync(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.");
            throw;
        }
        finally
        {
            maintenanceMode.DisableMaintenanceMode();
        }
    }

    public async Task StartSync(CancellationToken cancellationToken)
    {
        var pairPeriods = config.Value.ScheduleSettings?.PairPeriod
            .ToDictionary(x => x.Key, x => (x.Value.Start, x.Value.End));

        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;
        }

        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
        {
            await Sync(parser.ParseAsync, cancellationToken);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "An error occurred during synchronization.");
            throw;
        }
        finally
        {
            maintenanceMode.DisableMaintenanceMode();
        }
    }

    public async Task StartSync(List<(string File, string Campus)> files, CancellationToken cancellationToken)
    {
        await Task.Yield();
        var pairPeriods = config.Value.ScheduleSettings?.PairPeriod
            .ToDictionary(x => x.Key, x => (x.Value.Start, x.Value.End));

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

            return;
        }

        try
        {
            Task<List<GroupResult>> ParseTask(CancellationToken ctx)
            {
                var mappedData = new ConcurrentBag<GroupResult>();

                ParallelOptions options = new() { CancellationToken = ctx, MaxDegreeOfParallelism = Environment.ProcessorCount };
                Parallel.ForEach(files, options, (file) =>
                {
                    var parser = new Tools.Schedule.Parser.Parser();
                    var result = ConvertToGroupResults(parser.Parse(file.File, pairPeriods), file.Campus);

                    foreach (var item in result) mappedData.Add(item);
                });

                return Task.FromResult(mappedData.ToList());
            }

            await Sync(ParseTask, cancellationToken);
        }
        catch (Exception ex)
        {
            logger.LogError(ex, "An error occurred during synchronization.");
            throw;
        }
        finally
        {
            maintenanceMode.DisableMaintenanceMode();
        }
    }

    private static List<GroupResult> ConvertToGroupResults(IEnumerable<GroupInfo> groups, string campusDefault, CancellationToken cancellationToken = default)
    {
        var result = new List<GroupResult>();

        foreach (var group in groups)
        {
            cancellationToken.ThrowIfCancellationRequested();

            foreach (var day in group.Days)
            {
                foreach (var pair in day.Lessons)
                {
                    foreach (var lesson in pair.Value)
                    {
                        if (string.IsNullOrWhiteSpace(lesson.TypeOfOccupation))
                            continue;

                        var (weeks, isExclude) = ParseWeeks(lesson.Discipline);

                        var (lectureHalls, campuses) = ParseLectureHalls(lesson.LectureHall, campusDefault);

                        var groupResult = new GroupResult
                        {
                            Day = day.DayOfWeek,
                            Pair = pair.Key,
                            IsEven = lesson.IsEven,
                            Group = group.GroupName,
                            Discipline = NormalizeDiscipline(lesson.Discipline),
                            Professor = ParseProfessors(lesson.Professor),
                            TypeOfOccupation = lesson.TypeOfOccupation,
                            LectureHalls = lectureHalls,
                            Campuses = campuses,
                            SpecialWeek = weeks,
                            IsExclude = isExclude
                        };

                        result.Add(groupResult);
                    }
                }
            }
        }

        return result;
    }

    private static string[]? ParseProfessors(string? input)
    {
        if (string.IsNullOrWhiteSpace(input)) return null;

        var normalized = Regex.Replace(input
                .Replace("\n", " ")
                .Replace(",", " "),
            @"\s+", " ").Trim();

        return ProfessorFullName().Matches(normalized)
            .Select(m => $"{m.Groups["surname"].Value} {m.Groups["initials"].Value}".Trim())
            .Where(x => !string.IsNullOrEmpty(x))
            .ToArray();
    }

    private static (int[]? weeks, bool? isExclude) ParseWeeks(string discipline)
    {
        var match = ParseSpecificWeeks().Match(discipline);

        if (!match.Success) return (null, null);

        var numbers = new List<int>();
        var ranges = match.Groups[2].Value.Split(',');

        foreach (var range in ranges)
        {
            if (range.Contains('-'))
            {
                var parts = range.Split('-');
                if (int.TryParse(parts[0], out var start) &&
                    int.TryParse(parts[1], out var end))
                {
                    numbers.AddRange(Enumerable.Range(start, end - start + 1));
                }
            }
            else
                if (int.TryParse(range, out var num)) numbers.Add(num);
        }

        return (
            weeks: numbers.Distinct().OrderBy(x => x).ToArray(),
            isExclude: match.Groups[1].Success
        );
    }

    private static string NormalizeDiscipline(string input)
    {
        var normalized = Regex.Replace(input
                .Replace("\n", " ")
                .Replace("\r", " "),
            @"\s{2,}", " ");

        normalized = Regex.Replace(normalized,
            @"(\S+)\s(\S{3,})",
            "$1 $2");

        normalized = ParseSpecificWeeks().Replace(normalized, "");

        return normalized.Trim();
    }

    private static (string[]? lectureHalls, string[]? campuses) ParseLectureHalls(string? input, string defaultCampus)
    {
        if (string.IsNullOrWhiteSpace(input))
            return (null, null);

        var matches = ParseLectureCampus().Matches(input);
        var lectureHalls = new List<string>();
        var campuses = new List<string>();

        foreach (Match match in matches)
        {
            if (match.Groups["lectureWithCampus"].Success)
            {
                var raw = match.Value.Split('(');
                var campus = raw.LastOrDefault()?.Trim(')').Trim();
                var lecture = raw.FirstOrDefault()?.Trim();

                if (string.IsNullOrEmpty(campus) || string.IsNullOrEmpty(lecture))
                    continue;

                campuses.Add(campus);
                lectureHalls.Add(lecture);
            }
            else if (match.Groups["lecture"].Success)
            {
                var lecture = match.Value.Trim();
                if (string.IsNullOrEmpty(lecture))
                    continue;

                campuses.Add(defaultCampus);
                lectureHalls.Add(lecture);
            }
        }

        return (
            lectureHalls: lectureHalls.ToArray(),
            campuses: campuses.ToArray()
        );
    }



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

    [GeneratedRegex(@"(?<surname>[А-ЯЁ][а-яё]+(-[А-ЯЁ][а-яё]+)?)\s*(?<initials>[А-ЯЁ]\.[А-ЯЁ]?\.?)?", RegexOptions.IgnorePatternWhitespace)]
    private static partial Regex ProfessorFullName();

    [GeneratedRegex(@"([Кк]р\.?)?\s*((\d+-\d+|\d+)(,\s*\d+(-\d+)?)*)\s*[Нн]\.?", RegexOptions.IgnoreCase, "ru-RU")]
    private static partial Regex ParseSpecificWeeks();

    [GeneratedRegex(@"(?<lectureWithCampus>[^,.\n]+\s?\([А-Яа-яA-Za-z]+-?\d+\))|(?<lecture>[^,.\n]+)")]
    private static partial Regex ParseLectureCampus();
}