using System;
using System.Collections.Generic;
using System.IO;
using System.Text.Encodings.Web;
using System.Text.Json;
using System.Text.Json.Serialization;

namespace XLAB2
{
    internal sealed class DocumentNumberDirectory
    {
        public DocumentNumberDirectory(IReadOnlyList<GroupOption> accountingBooks, IReadOnlyList<GroupOption> documentTypes)
        {
            AccountingBooks = accountingBooks ?? Array.Empty<GroupOption>();
            DocumentTypes = documentTypes ?? Array.Empty<GroupOption>();
        }

        public IReadOnlyList<GroupOption> AccountingBooks { get; private set; }

        public IReadOnlyList<GroupOption> DocumentTypes { get; private set; }
    }

    internal sealed class DocumentNumberDirectoryService
    {
        private readonly string _filePath;

        public DocumentNumberDirectoryService(string filePath)
        {
            _filePath = filePath;
        }

        public DocumentNumberDirectory LoadDirectory()
        {
            var configuration = LoadConfiguration();

            return new DocumentNumberDirectory(
                NormalizeEntries(configuration.AccountingBooks, "книг учета"),
                NormalizeEntries(configuration.DocumentTypes, "типов документов"));
        }

        public IReadOnlyList<GroupOption> LoadAccountingBooks()
        {
            return LoadDirectory().AccountingBooks;
        }

        public void SaveAccountingBooks(IReadOnlyList<GroupOption> accountingBooks)
        {
            var configuration = LoadConfiguration();
            var normalizedAccountingBooks = NormalizeWritableEntries(accountingBooks, "книг учета");
            var normalizedDocumentTypes = NormalizeEntries(configuration.DocumentTypes, "типов документов");

            configuration.AccountingBooks = ToConfigurationEntries(normalizedAccountingBooks);
            configuration.DocumentTypes = ToConfigurationEntries(normalizedDocumentTypes);

            SaveConfiguration(configuration);
        }

        private static IReadOnlyList<GroupOption> NormalizeEntries(IEnumerable<DocumentNumberDirectoryEntry> entries, string sectionName)
        {
            var items = new List<GroupOption>();
            var seenKeys = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

            foreach (var entry in entries ?? Array.Empty<DocumentNumberDirectoryEntry>())
            {
                if (entry == null)
                {
                    continue;
                }

                var key = DocumentNumberFormatter.NormalizePart(entry.Key);
                var title = DocumentNumberFormatter.NormalizePart(entry.Title);
                if (key == null || title == null || !seenKeys.Add(key))
                {
                    continue;
                }

                items.Add(new GroupOption
                {
                    Key = key,
                    Title = title
                });
            }

            if (items.Count == 0)
            {
                throw new InvalidOperationException(string.Format("Справочник номеров документов не содержит {0}.", sectionName));
            }

            return items;
        }

        private static IReadOnlyList<GroupOption> NormalizeWritableEntries(IEnumerable<GroupOption> entries, string sectionName)
        {
            var items = new List<GroupOption>();
            var seenKeys = new HashSet<string>(StringComparer.OrdinalIgnoreCase);
            var seenTitles = new HashSet<string>(StringComparer.OrdinalIgnoreCase);

            foreach (var entry in entries ?? Array.Empty<GroupOption>())
            {
                if (entry == null)
                {
                    continue;
                }

                var key = DocumentNumberFormatter.NormalizePart(entry.Key);
                if (key == null)
                {
                    throw new InvalidOperationException("Не задан ключ книги учета.");
                }

                var title = DocumentNumberFormatter.NormalizePart(entry.Title);
                if (title == null)
                {
                    throw new InvalidOperationException("Не задан номер книги учета.");
                }

                if (!seenKeys.Add(key))
                {
                    throw new InvalidOperationException(string.Format("Ключ книги учета \"{0}\" повторяется.", key));
                }

                if (!seenTitles.Add(title))
                {
                    throw new InvalidOperationException(string.Format("Номер книги учета \"{0}\" повторяется.", title));
                }

                items.Add(new GroupOption
                {
                    Key = key,
                    Title = title
                });
            }

            if (items.Count == 0)
            {
                throw new InvalidOperationException(string.Format("Справочник номеров документов не содержит {0}.", sectionName));
            }

            return items;
        }

        private DocumentNumberDirectoryConfiguration LoadConfiguration()
        {
            if (string.IsNullOrWhiteSpace(_filePath))
            {
                throw new InvalidOperationException("Не задан путь к справочнику номеров документов.");
            }

            if (!File.Exists(_filePath))
            {
                throw new InvalidOperationException(string.Format("Не найден справочник номеров документов: {0}.", _filePath));
            }

            using (var stream = File.OpenRead(_filePath))
            {
                var configuration = JsonSerializer.Deserialize<DocumentNumberDirectoryConfiguration>(stream, CreateReadSerializerOptions());
                if (configuration == null)
                {
                    throw new InvalidOperationException("Справочник номеров документов пуст или поврежден.");
                }

                return configuration;
            }
        }

        private void SaveConfiguration(DocumentNumberDirectoryConfiguration configuration)
        {
            var directoryPath = Path.GetDirectoryName(_filePath);
            if (!string.IsNullOrWhiteSpace(directoryPath))
            {
                Directory.CreateDirectory(directoryPath);
            }

            var json = JsonSerializer.Serialize(configuration, CreateWriteSerializerOptions());
            File.WriteAllText(_filePath, json);
        }

        private static List<DocumentNumberDirectoryEntry> ToConfigurationEntries(IEnumerable<GroupOption> entries)
        {
            var items = new List<DocumentNumberDirectoryEntry>();

            foreach (var entry in entries ?? Array.Empty<GroupOption>())
            {
                if (entry == null)
                {
                    continue;
                }

                items.Add(new DocumentNumberDirectoryEntry
                {
                    Key = entry.Key,
                    Title = entry.Title
                });
            }

            return items;
        }

        private static JsonSerializerOptions CreateReadSerializerOptions()
        {
            return new JsonSerializerOptions
            {
                PropertyNameCaseInsensitive = true
            };
        }

        private static JsonSerializerOptions CreateWriteSerializerOptions()
        {
            return new JsonSerializerOptions
            {
                Encoder = JavaScriptEncoder.UnsafeRelaxedJsonEscaping,
                PropertyNamingPolicy = JsonNamingPolicy.CamelCase,
                WriteIndented = true
            };
        }
    }

    internal static class DocumentNumberFormatter
    {
        public const int MaxLength = 60;

        public static string Build(string documentTypeTitle, string accountingBookTitle, string documentSequenceNumber)
        {
            var normalizedDocumentTypeTitle = NormalizePart(documentTypeTitle);
            var normalizedAccountingBookTitle = NormalizePart(accountingBookTitle);
            var normalizedDocumentSequenceNumber = NormalizePart(documentSequenceNumber);

            if (normalizedDocumentTypeTitle == null
                || normalizedAccountingBookTitle == null
                || normalizedDocumentSequenceNumber == null)
            {
                return string.Empty;
            }

            return string.Format("{0} № {1}-{2}", normalizedDocumentTypeTitle, normalizedAccountingBookTitle, normalizedDocumentSequenceNumber);
        }

        public static string NormalizePart(string value)
        {
            return string.IsNullOrWhiteSpace(value) ? null : value.Trim();
        }
    }

    internal sealed class DocumentNumberDirectoryConfiguration
    {
        public List<DocumentNumberDirectoryEntry> AccountingBooks { get; set; }

        public List<DocumentNumberDirectoryEntry> DocumentTypes { get; set; }

        [JsonExtensionData]
        public Dictionary<string, JsonElement> ExtensionData { get; set; }
    }

    internal sealed class DocumentNumberDirectoryEntry
    {
        public string Key { get; set; }

        public string Title { get; set; }
    }
}