zedseven/Romanization.NET

using Romanization.Internal;
using System;
using System.Collections.Generic;
using System.Diagnostics.Contracts;
using System.Linq;

// ReSharper disable CheckNamespace
// ReSharper disable CommentTypo
// ReSharper disable IdentifierTypo
// ReSharper disable StringLiteralTypo
// ReSharper disable InconsistentNaming

namespace Romanization
{
    public static partial class Chinese
    {
        /// <summary>
        /// The Hànyǔ Pīnyīn Chinese romanization system.<br />
        /// For more information, visit:
        /// <a href='https://en.wikipedia.org/wiki/Hanyu_Pinyin'>https://en.wikipedia.org/wiki/Hanyu_Pinyin</a>
        /// </summary>
        public sealed class HanyuPinyin : IReadingsSystem<HanyuPinyin.ReadingTypes>
        {
            /// <inheritdoc />
            public SystemType Type => SystemType.PhonemicTranscription;

            /// <summary>
            /// The supported reading types for Hànyǔ Pīnyīn.
            /// </summary>
            [Flags]
            public enum ReadingTypes
            {
                /// <summary>
                /// Standard Hànyǔ Pīnyīn.
                /// </summary>
                HanyuPinyin = 1,
                /// <summary>
                /// Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Pínlǜ Cídiǎn.
                /// </summary>
                HanyuPinlu = 1 << 1,
                /// <summary>
                /// Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Cídiǎn.
                /// </summary>
                XHC = 1 << 2
            }

            private const string HanyuPinyinFileName = "HanziHanyuPinyin.csv";
            private const string HanyuPinluFileName  = "HanziHanyuPinlu.csv";
            private const string XhcFileName         = "HanziXHC.csv";

            private readonly Dictionary<string, string[]> HanyuPinyinReadings = new Dictionary<string, string[]>();
            private readonly Dictionary<string, string[]> HanyuPinluReadings  = new Dictionary<string, string[]>();
            private readonly Dictionary<string, string[]> XhcReadings         = new Dictionary<string, string[]>();

            /// <summary>
            /// Instantiates a copy of the system to process romanizations.
            /// </summary>
            public HanyuPinyin()
            {
                CsvLoader.LoadCharacterMap(HanyuPinyinFileName, HanyuPinyinReadings, k => k, v => v.Split(' '));
                CsvLoader.LoadCharacterMap(HanyuPinluFileName,  HanyuPinluReadings,  k => k, v => v.Split(' '));
                CsvLoader.LoadCharacterMap(XhcFileName,         XhcReadings,         k => k, v => v.Split(' '));
            }

            /// <summary>
            /// Performs Hànyǔ Pīnyīn romanization on the given text.<br />
            /// Uses the first (oft-most-common) reading of the character - standard Hànyǔ Pīnyīn first if available, then Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Pínlǜ Cídiǎn, then as it appeared in Xiàndài Hànyǔ Cídiǎn.<br />
            /// If more readings are required, use <see cref="ProcessWithReadings(string, ReadingTypes)"/> instead.
            /// </summary>
            /// <param name="text">The text to romanize.</param>
            /// <param name="readingsToUse">The reading types to use.</param>
            /// <returns>A romanized version of the text, leaving unrecognized characters untouched. Note that all romanized text will be lowercase.</returns>
            [Pure]
            public string Process(string text, ReadingTypes readingsToUse)
                => string.Join("", ProcessWithReadings(text, readingsToUse).Characters
                    .Select(c => c.Readings.Length > 0 ? c.Readings[0].Value : c.Character));

            /// <summary>
            /// Performs Hànyǔ Pīnyīn romanization on the given text.<br />
            /// Uses the first (oft-most-common) reading of the character - standard Hànyǔ Pīnyīn first if available, then Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Pínlǜ Cídiǎn, then as it appeared in Xiàndài Hànyǔ Cídiǎn.<br />
            /// If more readings are required, use <see cref="ProcessWithReadings(string)"/> instead.
            /// </summary>
            /// <param name="text">The text to romanize.</param>
            /// <returns>A romanized version of the text, leaving unrecognized characters untouched. Note that all romanized text will be lowercase.</returns>
            [Pure]
            public string Process(string text)
                => string.Join("", ProcessWithReadings(text).Characters
                    .Select(c => c.Readings.Length > 0 ? c.Readings[0].Value : c.Character));

            /// <summary>
            /// Performs Hànyǔ Pīnyīn romanization on the given text.<br />
            /// Returns a collection of all the characters in <paramref name="text"/>, but with all readings (pronunciations) of each.<br />
            /// Returns the following readings for characters if in <paramref name="readingsToUse"/> and they exist: standard Hànyǔ Pīnyīn, Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Pínlǜ Cídiǎn, and Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Cídiǎn.
            /// </summary>
            /// <param name="text">The text to romanize.</param>
            /// <param name="readingsToUse">The reading types to use.</param>
            /// <returns>A <see cref="ReadingsString{ReadingTypes}"/> with all readings for each character in <paramref name="text"/>.</returns>
            [Pure]
            public ReadingsString<ReadingTypes> ProcessWithReadings(string text, ReadingTypes readingsToUse)
                => new ReadingsString<ReadingTypes>(text.SplitIntoSurrogatePairs()
                    .Select(c =>
                    {
                        List<Reading<ReadingTypes>> readings = new List<Reading<ReadingTypes>>(text.Length);

                        if (readingsToUse.HasFlag(ReadingTypes.HanyuPinyin) && HanyuPinyinReadings.TryGetValue(c, out string[] rawHanyuPinyinReadings))
                            readings.AddRange(rawHanyuPinyinReadings.Select(r => new Reading<ReadingTypes>(ReadingTypes.HanyuPinyin, r)));
                        if (readingsToUse.HasFlag(ReadingTypes.HanyuPinlu) && HanyuPinluReadings.TryGetValue(c, out string[] rawHanyuPinluReadings))
                            readings.AddRange(rawHanyuPinluReadings.Select(r => new Reading<ReadingTypes>(ReadingTypes.HanyuPinlu, r)));
                        if (readingsToUse.HasFlag(ReadingTypes.XHC) && XhcReadings.TryGetValue(c, out string[] rawXhcReadings))
                            readings.AddRange(rawXhcReadings.Select(r => new Reading<ReadingTypes>(ReadingTypes.XHC, r)));

                        return new ReadingCharacter<ReadingTypes>(c, readings);
                    })
                    .ToArray());

            /// <summary>
            /// Performs Hànyǔ Pīnyīn romanization on the given text.<br />
            /// Returns a collection of all the characters in <paramref name="text"/>, but with all readings (pronunciations) of each.<br />
            /// Returns the following readings for characters if they exist: standard Hànyǔ Pīnyīn, Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Pínlǜ Cídiǎn, and Hànyǔ Pīnyīn as it appeared in Xiàndài Hànyǔ Cídiǎn.
            /// </summary>
            /// <param name="text">The text to romanize.</param>
            /// <returns>A <see cref="ReadingsString{ReadingTypes}"/> with all readings for each character in <paramref name="text"/>.</returns>
            [Pure]
            public ReadingsString<ReadingTypes> ProcessWithReadings(string text)
                => ProcessWithReadings(text, ReadingTypes.HanyuPinyin | ReadingTypes.HanyuPinlu | ReadingTypes.XHC);
        }
    }
}