// Copyright (c) Microsoft Corporation
// The Microsoft Corporation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.

using System.Collections.Concurrent;

namespace PowerAccent.Common;

/// <summary>
/// Single source of truth for all Quick Accent character data.
/// <para>
/// <see cref="All"/> is the canonical registry of every language: its identity, group,
/// resource identifier, and character mappings. The Settings UI derives its language
/// list from this collection.
/// </para>
/// <para>
/// <see cref="DisplayOrder"/> and <see cref="GroupDisplayOrder"/> control the order
/// in which characters appear in the Quick Accent popup. These are intentionally
/// separate from <see cref="All"/> so that popup ordering is explicit and not an
/// accidental consequence of declaration order.
/// </para>
/// <para>
/// When adding a new language: add a <see cref="Language"/> enum value, a
/// <see cref="LanguageInfo"/> entry to <see cref="All"/>, a position in
/// <see cref="DisplayOrder"/>, and a resx string.
/// </para>
/// </summary>
public static class CharacterMappings
{
    /// <summary>
    /// The canonical registry of all languages. Each entry defines the language's
    /// identity, group, resource identifier, and character mappings.
    /// Declaration order here does not affect the popup or settings display order;
    /// see <see cref="DisplayOrder"/> and <see cref="GroupDisplayOrder"/> for that.
    /// </summary>
    public static readonly IReadOnlyList<LanguageInfo> All =
    [
        new(Language.SPECIAL, "Special", LanguageGroup.Special,  new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_0] = ["₀", "⁰", "°", "↉", "₎", "⁾"],
            [LetterKey.VK_1] = ["₁", "¹", "½", "⅓", "¼", "⅕", "⅙", "⅐", "⅛", "⅑", "⅒"],
            [LetterKey.VK_2] = ["₂", "²", "⅔", "⅖"],
            [LetterKey.VK_3] = ["₃", "³", "¾", "⅗", "⅜"],
            [LetterKey.VK_4] = ["₄", "⁴", "⅘"],
            [LetterKey.VK_5] = ["₅", "⁵", "⅚", "⅝"],
            [LetterKey.VK_6] = ["₆", "⁶"],
            [LetterKey.VK_7] = ["₇", "⁷", "⅞"],
            [LetterKey.VK_8] = ["₈", "⁸", "∞"],
            [LetterKey.VK_9] = ["₉", "⁹", "₍", "⁽"],
            [LetterKey.VK_A] = ["ȧ", "ǽ", "∀", "ᵃ", "ₐ"],
            [LetterKey.VK_B] = ["ḃ", "ᵇ"],
            [LetterKey.VK_C] = ["ċ", "°C", "©", "ℂ", "∁", "ᶜ"],
            [LetterKey.VK_D] = ["ḍ", "ḋ", "∂", "ᵈ"],
            [LetterKey.VK_E] = ["∈", "∃", "∄", "∉", "ĕ", "ᵉ", "ₑ"],
            [LetterKey.VK_F] = ["ḟ", "°F", "ᶠ"],
            [LetterKey.VK_G] = ["ģ", "ǧ", "ġ", "ĝ", "ǥ", "ᵍ"],
            [LetterKey.VK_H] = ["ḣ", "ĥ", "ħ", "ʰ", "ₕ"],
            [LetterKey.VK_I] = ["ⁱ", "ᵢ"],
            [LetterKey.VK_J] = ["ĵ", "ʲ", "ⱼ"],
            [LetterKey.VK_K] = ["ķ", "ǩ", "ᵏ", "ₖ"],
            [LetterKey.VK_L] = ["ļ", "₺", "ˡ", "ₗ"], // ₺ is in VK_T for other languages, but not VK_L, so we add it here.
            [LetterKey.VK_M] = ["ṁ", "ᵐ", "ₘ"],
            [LetterKey.VK_N] = ["ņ", "ṅ", "ⁿ", "ℕ", "№", "ₙ"],
            [LetterKey.VK_O] = ["ȯ", "∅", "⌀", "ᵒ", "ₒ"],
            [LetterKey.VK_P] = ["ṗ", "℗", "∏", "¶", "ᵖ", "ₚ", "‰", "‱"],
            [LetterKey.VK_Q] = ["ℚ", "𐞥"],
            [LetterKey.VK_R] = ["ṙ", "®", "ℝ", "ʳ", "ᵣ"],
            [LetterKey.VK_S] = ["ṡ", "§", "∑", "∫", "ˢ", "ₛ"],
            [LetterKey.VK_T] = ["ţ", "ṫ", "ŧ", "™", "ᵗ", "ₜ"],
            [LetterKey.VK_U] = ["ŭ", "ᵘ", "ᵤ"],
            [LetterKey.VK_V] = ["V̇", "ᵛ", "ᵥ"],
            [LetterKey.VK_W] = ["ẇ", "ʷ"],
            [LetterKey.VK_X] = ["ẋ", "×", "ˣ", "ₓ"],
            [LetterKey.VK_Y] = ["ẏ", "ꝡ", "ʸ"],
            [LetterKey.VK_Z] = ["ʒ", "ǯ", "ℤ", "ᶻ"],
            [LetterKey.VK_COMMA] = ["∙", "₋", "⁻", "–", "√", "‟", "⟪", "⟫", "‛", "⟨", "⟩", "″", "‴", "⁗"],
            [LetterKey.VK_PERIOD] = ["…", "⁝", "\u0300", "\u0301", "\u0302", "\u0303", "\u0304", "\u0308", "\u030B", "\u030C"],
            [LetterKey.VK_MINUS] = ["~", "‐", "‑", "‒", "–", "—", "―", "⁓", "−", "⸺", "⸻", "∓", "₋", "⁻"],
            [LetterKey.VK_SLASH_] = ["÷", "√", "‽", "⸘"],
            [LetterKey.VK_DIVIDE_] = ["÷", "√"],
            [LetterKey.VK_MULTIPLY_] = ["×", "⋅", "ˣ", "ₓ"],
            [LetterKey.VK_PLUS] = ["≤", "≥", "≠", "≈", "≙", "⊕", "⊗", "±", "≅", "≡", "₊", "⁺", "₌", "⁼"],
            [LetterKey.VK_BACKSLASH] = ["`", "~"],
        }),

        // Belarusian Latin
        new(Language.BE, "Belarusian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["ć", "č"],
            [LetterKey.VK_L] = ["ł"],
            [LetterKey.VK_N] = ["ń"],
            [LetterKey.VK_S] = ["ś", "š"],
            [LetterKey.VK_U] = ["ŭ"],
            [LetterKey.VK_Z] = ["ź", "ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "«", "»"],
        }),

        new(Language.BE_CYRL, "Belarusian_Cyrillic", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_E] = ["ё"],
            [LetterKey.VK_G] = ["ґ"],
            [LetterKey.VK_I] = ["і"],
            [LetterKey.VK_U] = ["ў"],
            [LetterKey.VK_COMMA] = ["’", "„", "“", "«", "»"],
        }),

        new(Language.BG, "Bulgarian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_I] = ["ѝ"],
            [LetterKey.VK_COMMA] = ["„", "“", "«", "»"],
        }),

        new(Language.CA, "Catalan", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_1] = ["¡"],
            [LetterKey.VK_A] = ["à", "á"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["è", "é", "€"],
            [LetterKey.VK_I] = ["ì", "í", "ï"],
            [LetterKey.VK_N] = ["ñ"],
            [LetterKey.VK_O] = ["ò", "ó"],
            [LetterKey.VK_U] = ["ù", "ú", "ü"],
            [LetterKey.VK_L] = ["·"],
            [LetterKey.VK_COMMA] = ["¿", "?", "¡", "!", "«", "»", "“", "”", "‘", "’"],
            [LetterKey.VK_SLASH_] = ["¿"],
        }),

        new(Language.CRH, "Crimean", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["â"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_G] = ["ğ"],
            [LetterKey.VK_H] = ["₴"],
            [LetterKey.VK_I] = ["ı", "İ"],
            [LetterKey.VK_N] = ["ñ"],
            [LetterKey.VK_O] = ["ö"],
            [LetterKey.VK_S] = ["ş"],
            [LetterKey.VK_T] = ["₺"],
            [LetterKey.VK_U] = ["ü"],
        }),

        // Currency symbols. This is a "special" language group as it's not a spoken
        // language, but rather a set of symbols used across languages.
        new(Language.CUR, "Currency", LanguageGroup.Special, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_B] = ["฿", "в"], // Bulgarian Lev (лв)
            [LetterKey.VK_C] = ["¢", "₡", "č"], // Czech Koruna (Kč)
            [LetterKey.VK_D] = ["₫"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_F] = ["ƒ"],
            [LetterKey.VK_H] = ["₴"],
            [LetterKey.VK_K] = ["₭"],
            [LetterKey.VK_L] = ["ł"], // Polish Złoty (zł)
            [LetterKey.VK_N] = ["л"], // Bulgarian Lev (лв)
            [LetterKey.VK_M] = ["₼"],
            [LetterKey.VK_P] = ["£", "₽", "₱"],
            [LetterKey.VK_R] = ["₹", "៛", "﷼"],
            [LetterKey.VK_S] = ["$", "₪"],
            [LetterKey.VK_T] = ["₮", "₺", "₸"],
            [LetterKey.VK_W] = ["₩"],
            [LetterKey.VK_Y] = ["¥"],
        }),

        new(Language.CY, "Welsh", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["â", "ä", "à", "á"],
            [LetterKey.VK_E] = ["ê", "ë", "è", "é"],
            [LetterKey.VK_I] = ["î", "ï", "ì", "í"],
            [LetterKey.VK_O] = ["ô", "ö", "ò", "ó"],
            [LetterKey.VK_P] = ["£"],
            [LetterKey.VK_U] = ["û", "ü", "ù", "ú"],
            [LetterKey.VK_Y] = ["ŷ", "ÿ", "ỳ", "ý"],
            [LetterKey.VK_W] = ["ŵ", "ẅ", "ẁ", "ẃ"],
            [LetterKey.VK_COMMA] = ["‘", "’", "“", "”"],
        }),

        new(Language.CZ, "Czech", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á"],
            [LetterKey.VK_C] = ["č"],
            [LetterKey.VK_D] = ["ď"],
            [LetterKey.VK_E] = ["ě", "é"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_N] = ["ň"],
            [LetterKey.VK_O] = ["ó"],
            [LetterKey.VK_R] = ["ř"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_T] = ["ť"],
            [LetterKey.VK_U] = ["ů", "ú"],
            [LetterKey.VK_Y] = ["ý"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "‘", "»", "«", "›", "‹"],
        }),

        new(Language.DK, "Danish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["å", "æ"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_O] = ["ø"],
            [LetterKey.VK_COMMA] = ["»", "«", "“", "”", "›", "‹", "‘", "’"],
        }),

        // Gaelic (Irish).
        new(Language.GA, "Gaeilge", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á"],
            [LetterKey.VK_E] = ["é", "€"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_O] = ["ó"],
            [LetterKey.VK_U] = ["ú"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’"],
        }),

        // Gaelic (Scottish).
        new(Language.GD, "Gaidhlig", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["à"],
            [LetterKey.VK_E] = ["è"],
            [LetterKey.VK_I] = ["ì"],
            [LetterKey.VK_O] = ["ò"],
            [LetterKey.VK_P] = ["£"],
            [LetterKey.VK_U] = ["ù"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’"],
        }),

        new(Language.DE, "German", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ä"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_O] = ["ö"],
            [LetterKey.VK_S] = ["ß"],
            [LetterKey.VK_U] = ["ü"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "‘", "»", "«", "›", "‹"],
        }),

        new(Language.EL, "Greek", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["α", "ά"],
            [LetterKey.VK_B] = ["β"],
            [LetterKey.VK_C] = ["χ"],
            [LetterKey.VK_D] = ["δ"],
            [LetterKey.VK_E] = ["ε", "έ", "η", "ή", "€"],
            [LetterKey.VK_F] = ["φ"],
            [LetterKey.VK_G] = ["γ"],
            [LetterKey.VK_I] = ["ι", "ί"],
            [LetterKey.VK_K] = ["κ"],
            [LetterKey.VK_L] = ["λ"],
            [LetterKey.VK_M] = ["μ"],
            [LetterKey.VK_N] = ["ν"],
            [LetterKey.VK_O] = ["ο", "ό", "ω", "ώ"],
            [LetterKey.VK_P] = ["π", "φ", "ψ"],
            [LetterKey.VK_R] = ["ρ"],
            [LetterKey.VK_S] = ["σ", "ς"],
            [LetterKey.VK_T] = ["τ", "θ", "ϑ"],
            [LetterKey.VK_U] = ["υ", "ύ"],
            [LetterKey.VK_X] = ["ξ"],
            [LetterKey.VK_Y] = ["υ"],
            [LetterKey.VK_Z] = ["ζ"],
            [LetterKey.VK_COMMA] = ["“", "”", "«", "»"],
        }),

        new(Language.EST, "Estonian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ä"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_O] = ["ö", "õ"],
            [LetterKey.VK_U] = ["ü"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_COMMA] = ["„", "“", "«", "»"],
        }),

        new(Language.EPO, "Esperanto", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["ĉ"],
            [LetterKey.VK_G] = ["ĝ"],
            [LetterKey.VK_H] = ["ĥ"],
            [LetterKey.VK_J] = ["ĵ"],
            [LetterKey.VK_S] = ["ŝ"],
            [LetterKey.VK_U] = ["ŭ"],
        }),

        new(Language.FI, "Finnish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ä", "å"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_O] = ["ö"],
            [LetterKey.VK_COMMA] = ["”", "’", "»"],
        }),

        new(Language.FR, "French", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["à", "â", "á", "ä", "ã", "æ"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["é", "è", "ê", "ë", "€"],
            [LetterKey.VK_I] = ["î", "ï", "í", "ì"],
            [LetterKey.VK_O] = ["ô", "ö", "ó", "ò", "õ", "œ"],
            [LetterKey.VK_U] = ["û", "ù", "ü", "ú"],
            [LetterKey.VK_Y] = ["ÿ", "ý"],
            [LetterKey.VK_COMMA] = ["«", "»", "‹", "›", "“", "”", "‘", "’"],
        }),

        new(Language.GRC, "Greek_Polytonic", LanguageGroup.Special, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["α", "ἀ", "ἁ", "ὰ", "ά", "ᾶ", "ᾱ", "ᾰ", "ἂ", "ἃ", "ἄ", "ἅ", "ἆ", "ἇ", "ᾳ", "ᾀ", "ᾁ", "ᾴ", "ᾲ", "ᾷ", "ᾄ", "ᾅ", "ᾂ", "ᾃ", "ᾆ", "ᾇ"],
            [LetterKey.VK_B] = ["β"],
            [LetterKey.VK_C] = ["χ", "ϲ"],
            [LetterKey.VK_D] = ["δ"],
            [LetterKey.VK_E] = ["ε", "ἐ", "ἑ", "ὲ", "έ", "ἒ", "ἓ", "ἔ", "ἕ"],
            [LetterKey.VK_F] = ["φ", "ϝ"],
            [LetterKey.VK_G] = ["γ"],
            [LetterKey.VK_H] = ["η", "ἠ", "ἡ", "ὴ", "ή", "ῆ", "ἢ", "ἣ", "ἤ", "ἥ", "ἦ", "ἧ", "ῃ", "ᾐ", "ᾑ", "ῄ", "ῂ", "ῇ", "ᾔ", "ᾕ", "ᾒ", "ᾓ", "ᾖ", "ᾗ"],
            [LetterKey.VK_I] = ["ι", "ἰ", "ἱ", "ὶ", "ί", "ῖ", "ῑ", "ῐ", "ἲ", "ἳ", "ἴ", "ἵ", "ἶ", "ἷ", "ϊ", "ΐ", "ῒ", "ῗ"],
            [LetterKey.VK_K] = ["κ"],
            [LetterKey.VK_L] = ["λ"],
            [LetterKey.VK_M] = ["μ"],
            [LetterKey.VK_N] = ["ν"],
            [LetterKey.VK_O] = ["ο", "ὀ", "ὁ", "ὸ", "ό", "ὂ", "ὃ", "ὄ", "ὅ"],
            [LetterKey.VK_P] = ["π", "φ", "ψ", "ρ"],
            [LetterKey.VK_Q] = ["ϙ", "ϟ"],
            [LetterKey.VK_R] = ["ρ", "ῤ", "ῥ"],
            [LetterKey.VK_S] = ["σ", "ς", "ϛ", "ϲ", "ϡ"],
            [LetterKey.VK_T] = ["τ", "θ", "ϑ"],
            [LetterKey.VK_U] = ["υ", "ὐ", "ὑ", "ὺ", "ύ", "ῦ", "ῡ", "ῠ", "ὒ", "ὓ", "ὔ", "ὕ", "ὖ", "ὗ", "ϋ", "ΰ", "ῢ", "ῧ"],
            [LetterKey.VK_V] = ["β", "ϝ"],
            [LetterKey.VK_W] = ["ω", "ὠ", "ὡ", "ὼ", "ώ", "ῶ", "ὢ", "ὣ", "ὤ", "ὥ", "ὦ", "ὧ", "ῳ", "ᾠ", "ᾡ", "ῴ", "ῲ", "ῷ", "ᾤ", "ᾥ", "ᾢ", "ᾣ", "ᾦ", "ᾧ"],
            [LetterKey.VK_X] = ["ξ", "χ"],
            [LetterKey.VK_Y] = ["υ", "ὐ", "ὑ", "ὺ", "ύ", "ῦ", "ῡ", "ῠ", "ὒ", "ὓ", "ὔ", "ὕ", "ὖ", "ὗ", "ϋ", "ΰ", "ῢ", "ῧ"],
            [LetterKey.VK_Z] = ["ζ"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’", ";", "`", "´"],
            [LetterKey.VK_PERIOD] = ["·"],
        }),

        new(Language.HR, "Croatian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["ć", "č"],
            [LetterKey.VK_D] = ["đ"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "»", "«"],
        }),

        new(Language.HE, "Hebrew", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["שׂ", "שׁ", "\u05b0"],
            [LetterKey.VK_B] = ["׆"],
            [LetterKey.VK_E] = ["\u05b8", "\u05b3", "\u05bb"],
            [LetterKey.VK_G] = ["ױ"],
            [LetterKey.VK_H] = ["ײ", "ײַ", "ׯ", "\u05b4"],
            [LetterKey.VK_M] = ["\u05b5"],
            [LetterKey.VK_N] = ["₪"],
            [LetterKey.VK_P] = ["\u05b7", "\u05b2"],
            [LetterKey.VK_S] = ["\u05bc"],
            [LetterKey.VK_T] = ["ﭏ"],
            [LetterKey.VK_U] = ["וֹ", "וּ", "װ", "\u05b9"],
            [LetterKey.VK_X] = ["\u05b6", "\u05b1"],
            [LetterKey.VK_Y] = ["ױ"],
            [LetterKey.VK_COMMA] = ["”", "’", "'", "״", "׳"],
            [LetterKey.VK_PERIOD] = ["\u05ab", "\u05bd", "\u05bf"],
            [LetterKey.VK_MINUS] = ["־"],
        }),

        new(Language.HU, "Hungarian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á"],
            [LetterKey.VK_E] = ["é"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_O] = ["ó", "ő", "ö"],
            [LetterKey.VK_U] = ["ú", "ű", "ü"],
            [LetterKey.VK_Y] = ["ÿ", "ý"],
            [LetterKey.VK_COMMA] = ["„", "”", "»", "«"],
        }),

        new(Language.IS, "Icelandic", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á", "æ"],
            [LetterKey.VK_D] = ["ð"],
            [LetterKey.VK_E] = ["é"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_O] = ["ó", "ö"],
            [LetterKey.VK_U] = ["ú"],
            [LetterKey.VK_Y] = ["ý"],
            [LetterKey.VK_T] = ["þ"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "‘"],
        }),

        // International Phonetic Alphabet. This is a "special" language group as it's not
        // a spoken language, but rather a set of symbols used across languages.
        new(Language.IPA, "IPA", LanguageGroup.Special,  new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ɑ", "æ", "ɒ", "ɐ"],
            [LetterKey.VK_B] = ["β", "ʙ", "ɓ", "ʘ"],
            [LetterKey.VK_C] = ["ç", "χ", "ǂ"],
            [LetterKey.VK_D] = ["ð", "ɗ", "ɖ", "ǀ"],
            [LetterKey.VK_E] = ["ə", "ɛ", "ɚ", "ɘ", "ɜ", "ɵ", "ɞ", "æ", "œ"],
            [LetterKey.VK_F] = ["ɸ"],
            [LetterKey.VK_G] = ["ɡ", "ɣ", "ɢ", "ɠ", "ʛ"],
            [LetterKey.VK_H] = ["ɦ", "ħ", "ɥ", "ʜ", "ɧ", "ʱ"],
            [LetterKey.VK_I] = ["ɪ", "ɨ"],
            [LetterKey.VK_J] = ["ɟ", "ʝ", "ʄ"],
            [LetterKey.VK_L] = ["ɫ", "ʎ", "ɬ", "ɮ", "ɭ", "ʟ", "ɺ", "ꞎ", "ǁ"],
            [LetterKey.VK_M] = ["ɱ"],
            [LetterKey.VK_N] = ["ŋ", "ɲ", "ɳ", "ɴ"],
            [LetterKey.VK_O] = ["ɔ", "ø", "œ", "ɤ", "ɶ", "ʘ"],
            [LetterKey.VK_R] = ["ɹ", "ɾ", "ʁ", "ʀ", "ɻ", "ɽ"],
            [LetterKey.VK_S] = ["ʃ", "ɕ", "ʂ"],
            [LetterKey.VK_T] = ["θ", "ʈ", "ǃ"],
            [LetterKey.VK_U] = ["ʊ", "ʉ"],
            [LetterKey.VK_V] = ["ʌ", "ʋ", "ⱱ"],
            [LetterKey.VK_W] = ["ʍ", "ɯ", "ɰ"],
            [LetterKey.VK_X] = ["χ"],
            [LetterKey.VK_Y] = ["ʎ", "ʏ"],
            [LetterKey.VK_Z] = ["ʒ", "ʐ", "ʑ"],
            [LetterKey.VK_COMMA] = ["ʔ", "ʕ", "ʡ", "ʢ"],
            [LetterKey.VK_PERIOD] = ["ˈ", "ˌ", "ː", "ʼ", "\u031D", "\u0325", "\u031A", "\u0361", "\u035C"],
            [LetterKey.VK_SLASH_] = ["ʔ"],
        }),

        new(Language.IT, "Italian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["à"],
            [LetterKey.VK_E] = ["è", "é", "ə", "€"],
            [LetterKey.VK_I] = ["ì", "í"],
            [LetterKey.VK_O] = ["ò", "ó"],
            [LetterKey.VK_U] = ["ù", "ú"],
            [LetterKey.VK_COMMA] = ["«", "»", "“", "”", "‘", "’"],
        }),

        new(Language.KU, "Kurdish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["ê", "€"],
            [LetterKey.VK_I] = ["î"],
            [LetterKey.VK_O] = ["ö", "ô"],
            [LetterKey.VK_L] = ["ł"],
            [LetterKey.VK_N] = ["ň"],
            [LetterKey.VK_R] = ["ř"],
            [LetterKey.VK_S] = ["ş"],
            [LetterKey.VK_U] = ["û", "ü"],
            [LetterKey.VK_COMMA] = ["«", "»", "“", "”"],
        }),

        new(Language.LT, "Lithuanian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ą"],
            [LetterKey.VK_C] = ["č"],
            [LetterKey.VK_E] = ["ę", "ė", "€"],
            [LetterKey.VK_I] = ["į"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_U] = ["ų", "ū"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "‘"],
        }),

        new(Language.MK, "Macedonian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_E] = ["ѐ"],
            [LetterKey.VK_I] = ["ѝ"],
            [LetterKey.VK_COMMA] = ["„", "“", "’", "‘"],
        }),

        new(Language.MT, "Maltese", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["à"],
            [LetterKey.VK_C] = ["ċ"],
            [LetterKey.VK_E] = ["è", "€"],
            [LetterKey.VK_G] = ["ġ"],
            [LetterKey.VK_H] = ["ħ"],
            [LetterKey.VK_I] = ["ì"],
            [LetterKey.VK_O] = ["ò"],
            [LetterKey.VK_U] = ["ù"],
            [LetterKey.VK_Z] = ["ż"],
        }),

        new(Language.MI, "Maori", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ā"],
            [LetterKey.VK_E] = ["ē"],
            [LetterKey.VK_I] = ["ī"],
            [LetterKey.VK_O] = ["ō"],
            [LetterKey.VK_S] = ["$"],
            [LetterKey.VK_U] = ["ū"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’"],
        }),

        new(Language.NL, "Dutch", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á", "à", "ä"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["é", "è", "ë", "ê", "€"],
            [LetterKey.VK_I] = ["í", "ï", "î"],
            [LetterKey.VK_N] = ["ñ"],
            [LetterKey.VK_O] = ["ó", "ö", "ô"],
            [LetterKey.VK_U] = ["ú", "ü", "û"],
            [LetterKey.VK_COMMA] = ["“", "„", "”", "‘", ",", "’"],
        }),

        new(Language.NO, "Norwegian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["å", "æ"],
            [LetterKey.VK_E] = ["€", "é"],
            [LetterKey.VK_O] = ["ø"],
            [LetterKey.VK_S] = ["$"],
            [LetterKey.VK_COMMA] = ["«", "»", ",", "‘", "’", "„", "“"],
        }),

        new(Language.PI, "Pinyin", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_1] = ["\u0304", "ˉ"],
            [LetterKey.VK_2] = ["\u0301", "ˊ"],
            [LetterKey.VK_3] = ["\u030c", "ˇ"],
            [LetterKey.VK_4] = ["\u0300", "ˋ"],
            [LetterKey.VK_5] = ["·"],
            [LetterKey.VK_A] = ["ā", "á", "ǎ", "à", "ɑ", "ɑ\u0304", "ɑ\u0301", "ɑ\u030c", "ɑ\u0300"],
            [LetterKey.VK_C] = ["ĉ"],
            [LetterKey.VK_E] = ["ē", "é", "ě", "è", "ê", "ê\u0304", "ế", "ê\u030c", "ề"],
            [LetterKey.VK_I] = ["ī", "í", "ǐ", "ì"],
            [LetterKey.VK_M] = ["m\u0304", "ḿ", "m\u030c", "m\u0300"],
            [LetterKey.VK_N] = ["n\u0304", "ń", "ň", "ǹ", "ŋ", "ŋ\u0304", "ŋ\u0301", "ŋ\u030c", "ŋ\u0300"],
            [LetterKey.VK_O] = ["ō", "ó", "ǒ", "ò"],
            [LetterKey.VK_S] = ["ŝ"],
            [LetterKey.VK_U] = ["ū", "ú", "ǔ", "ù", "ü", "ǖ", "ǘ", "ǚ", "ǜ"],
            [LetterKey.VK_V] = ["ü", "ǖ", "ǘ", "ǚ", "ǜ"],
            [LetterKey.VK_Y] = ["¥"],
            [LetterKey.VK_Z] = ["ẑ"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’", "「", "」", "『", "』"],
        }),

        // Proto-Indo-European. This is a "special" language group as it's not a spoken
        // language, but rather a reconstructed ancestor of many languages.
        new(Language.PIE, "Proto_Indo_European", LanguageGroup.Special,  new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ā"],
            [LetterKey.VK_E] = ["ē"],
            [LetterKey.VK_O] = ["ō"],
            [LetterKey.VK_K] = ["ḱ"],
            [LetterKey.VK_G] = ["ǵ"],
            [LetterKey.VK_R] = ["r̥"],
            [LetterKey.VK_L] = ["l̥"],
            [LetterKey.VK_M] = ["m̥"],
            [LetterKey.VK_N] = ["n̥"],
        }),

        new(Language.PL, "Polish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ą"],
            [LetterKey.VK_C] = ["ć"],
            [LetterKey.VK_E] = ["ę", "€"],
            [LetterKey.VK_L] = ["ł"],
            [LetterKey.VK_N] = ["ń"],
            [LetterKey.VK_O] = ["ó"],
            [LetterKey.VK_S] = ["ś"],
            [LetterKey.VK_Z] = ["ż", "ź"],
            [LetterKey.VK_COMMA] = ["„", "”", "‘", "’", "»", "«"],
        }),

        new(Language.PT, "Portuguese", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á", "à", "â", "ã", "ª"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["é", "ê", "€"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_O] = ["ô", "ó", "õ", "º"],
            [LetterKey.VK_S] = ["$"],
            [LetterKey.VK_U] = ["ú"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’", "«", "»"],
        }),

        // This language set covers both Pitjantjatjara and Yankunytjatjara dialects
        new(Language.PJT, "Pitjantjatjara", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_L] = ["ḻ"],
            [LetterKey.VK_N] = ["ṉ"],
            [LetterKey.VK_R] = ["ṟ"],
            [LetterKey.VK_T] = ["ṯ"],
        }),

        new(Language.RO, "Romanian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["ă", "â"],
            [LetterKey.VK_I] = ["î"],
            [LetterKey.VK_S] = ["ș"],
            [LetterKey.VK_T] = ["ț"],
            [LetterKey.VK_COMMA] = ["„", "”", "«", "»"],
        }),

        // Middle Eastern Romanization. This is a "special" language group as it's not a
        // spoken language, but rather a set of characters used to romanize various Middle
        // Eastern languages.
        new(Language.ROM, "Romanization", LanguageGroup.Special,  new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á", "â", "ă", "ā"],
            [LetterKey.VK_B] = ["ḇ"],
            [LetterKey.VK_C] = ["č", "ç"],
            [LetterKey.VK_D] = ["ḑ", "ḍ", "ḏ", "ḏ\u0323"],
            [LetterKey.VK_E] = ["ê", "ě", "ĕ", "ē", "é", "ə"],
            [LetterKey.VK_G] = ["ġ", "ǧ", "ğ", "ḡ", "g\u0303", "g\u0331"],
            [LetterKey.VK_H] = ["ḧ", "ḩ", "ḥ", "ḫ", "h\u0331"],
            [LetterKey.VK_I] = ["í", "ı", "î", "ī", "ı\u0307\u0304"],
            [LetterKey.VK_J] = ["ǰ", "j\u0331"],
            [LetterKey.VK_K] = ["ḳ", "ḵ"],
            [LetterKey.VK_L] = ["ł"],
            [LetterKey.VK_N] = ["ⁿ", "ñ"],
            [LetterKey.VK_O] = ["ó", "ô", "ö", "ŏ", "ō", "ȫ"],
            [LetterKey.VK_P] = ["p\u0304"],
            [LetterKey.VK_R] = ["ṙ", "ṛ"],
            [LetterKey.VK_S] = ["ś", "š", "ş", "ṣ", "s\u0331", "ṣ\u0304"],
            [LetterKey.VK_T] = ["ẗ", "ţ", "ṭ", "ṯ"],
            [LetterKey.VK_U] = ["ú", "û", "ü", "ū", "ǖ"],
            [LetterKey.VK_V] = ["v\u0307", "ṿ", "ᵛ"],
            [LetterKey.VK_Y] = ["̀y"],
            [LetterKey.VK_Z] = ["ż", "ž", "z\u0304", "z\u0327", "ẓ", "z\u0324", "ẕ"],
            [LetterKey.VK_PERIOD] = ["’", "ʾ", "ʿ", "′", "…"],
        }),

        new(Language.SK, "Slovak", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["á", "ä"],
            [LetterKey.VK_C] = ["č"],
            [LetterKey.VK_D] = ["ď"],
            [LetterKey.VK_E] = ["é", "€"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_L] = ["ľ", "ĺ"],
            [LetterKey.VK_N] = ["ň"],
            [LetterKey.VK_O] = ["ó", "ô"],
            [LetterKey.VK_R] = ["ŕ"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_T] = ["ť"],
            [LetterKey.VK_U] = ["ú"],
            [LetterKey.VK_Y] = ["ý"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "‘", "»", "«", "›", "‹"],
        }),

        new(Language.SL, "Slovenian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["č", "ć"],
            [LetterKey.VK_E] = ["€"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "»", "«"],
        }),

        new(Language.SP, "Spanish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_1] = ["¡"],
            [LetterKey.VK_A] = ["á"],
            [LetterKey.VK_E] = ["é", "€"],
            [LetterKey.VK_H] = ["ḥ"],
            [LetterKey.VK_I] = ["í"],
            [LetterKey.VK_L] = ["ḷ"],
            [LetterKey.VK_N] = ["ñ"],
            [LetterKey.VK_O] = ["ó"],
            [LetterKey.VK_U] = ["ú", "ü"],
            [LetterKey.VK_COMMA] = ["¿", "?", "¡", "!", "«", "»", "“", "”", "‘", "’"],
            [LetterKey.VK_SLASH_] = ["¿"],
        }),

        new(Language.SR, "Serbian", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_C] = ["ć", "č"],
            [LetterKey.VK_D] = ["đ"],
            [LetterKey.VK_S] = ["š"],
            [LetterKey.VK_Z] = ["ž"],
            [LetterKey.VK_COMMA] = ["„", "“", "‚", "’", "»", "«", "›", "‹"],
        }),

        new(Language.SR_CYRL, "Serbian_Cyrillic", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_D] = ["ђ", "џ"],
            [LetterKey.VK_L] = ["љ"],
            [LetterKey.VK_N] = ["њ"],
            [LetterKey.VK_C] = ["ћ"],
        }),

        new(Language.SV, "Swedish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["å", "ä"],
            [LetterKey.VK_E] = ["é"],
            [LetterKey.VK_O] = ["ö"],
            [LetterKey.VK_COMMA] = ["”", "’", "»", "«"],
        }),

        new(Language.TK, "Turkish", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["â"],
            [LetterKey.VK_C] = ["ç"],
            [LetterKey.VK_E] = ["ë", "€"],
            [LetterKey.VK_G] = ["ğ"],
            [LetterKey.VK_I] = ["ı", "İ", "î",],
            [LetterKey.VK_O] = ["ö", "ô"],
            [LetterKey.VK_S] = ["ş"],
            [LetterKey.VK_T] = ["₺"],
            [LetterKey.VK_U] = ["ü", "û"],
            [LetterKey.VK_COMMA] = ["“", "”", "‘", "’", "«", "»", "‹", "›"],
        }),

        new(Language.VI, "Vietnamese", LanguageGroup.Language, new Dictionary<LetterKey, string[]>
        {
            [LetterKey.VK_A] = ["à", "ả", "ã", "á", "ạ", "ă", "ằ", "ẳ", "ẵ", "ắ", "ặ", "â", "ầ", "ẩ", "ẫ", "ấ", "ậ"],
            [LetterKey.VK_D] = ["đ", "₫"],
            [LetterKey.VK_E] = ["è", "ẻ", "ẽ", "é", "ẹ", "ê", "ề", "ể", "ễ", "ế", "ệ"],
            [LetterKey.VK_I] = ["ì", "ỉ", "ĩ", "í", "ị"],
            [LetterKey.VK_O] = ["ò", "ỏ", "õ", "ó", "ọ", "ô", "ồ", "ổ", "ỗ", "ố", "ộ", "ơ", "ờ", "ở", "ỡ", "ớ", "ợ"],
            [LetterKey.VK_U] = ["ù", "ủ", "ũ", "ú", "ụ", "ư", "ừ", "ử", "ữ", "ứ", "ự"],
            [LetterKey.VK_Y] = ["ỳ", "ỷ", "ỹ", "ý", "ỵ"],
        }),
    ];

    /// <summary>
    /// O(1) lookup from <see cref="Language"/> to its <see cref="LanguageInfo"/>.
    /// Use this instead of searching <see cref="All"/> when you have a language identity.
    /// </summary>
    public static readonly IReadOnlyDictionary<Language, LanguageInfo> LanguageLookup =
        All.ToDictionary(x => x.Id);

    /// <summary>
    /// The order in which language groups appear in the Quick Accent popup.
    /// Groups listed first have their characters shown first.
    /// This is intentionally separate from the <see cref="LanguageGroup"/> enum order.
    /// </summary>
    public static readonly IReadOnlyList<LanguageGroup> GroupDisplayOrder =
    [
        LanguageGroup.UserDefined,
        LanguageGroup.Language,
        LanguageGroup.Special,
    ];

    /// <summary>
    /// The order in which individual languages appear within their group in the Quick
    /// Accent popup. Position in this list is the display order; position in
    /// <see cref="All"/> is irrelevant for popup ordering.
    /// Entries are sorted alphabetically by <see cref="Language"/> enum name.
    /// When adding a new language, insert it in alphabetical order.
    /// </summary>
    public static readonly IReadOnlyList<Language> DisplayOrder =
    [

        // Spoken languages.
        Language.BE,
        Language.BE_CYRL,
        Language.BG,
        Language.CA,
        Language.CRH,
        Language.CY,
        Language.CZ,
        Language.DE,
        Language.DK,
        Language.EL,
        Language.EPO,
        Language.EST,
        Language.FI,
        Language.FR,
        Language.GA,
        Language.GD,
        Language.HE,
        Language.HR,
        Language.HU,
        Language.IS,
        Language.IT,
        Language.KU,
        Language.LT,
        Language.MI,
        Language.MK,
        Language.MT,
        Language.NL,
        Language.NO,
        Language.PI,
        Language.PJT,
        Language.PL,
        Language.PT,
        Language.RO,
        Language.SK,
        Language.SL,
        Language.SP,
        Language.SR,
        Language.SR_CYRL,
        Language.SV,
        Language.TK,
        Language.VI,

        // Symbols, non-spoken languages, and non-language-specific characters.
        Language.CUR,
        Language.GRC,
        Language.IPA,
        Language.PIE,
        Language.ROM,
        Language.SPECIAL,
    ];

    // O(1) sort-key lookups derived from the display order lists above.
    private static readonly Dictionary<LanguageGroup, int> _groupOrder =
        GroupDisplayOrder.Select((g, i) => (g, i)).ToDictionary(x => x.g, x => x.i);

    private static readonly Dictionary<Language, int> _languageOrder =
        DisplayOrder.Select((l, i) => (l, i)).ToDictionary(x => x.l, x => x.i);

    private static readonly ConcurrentDictionary<LetterKey, string[]> _allLanguagesCache = new();

    /// <summary>
    /// Returns the deduplicated set of characters for the given key across the specified
    /// languages, ordered by <see cref="GroupDisplayOrder"/> then <see cref="DisplayOrder"/>.
    /// </summary>
    public static string[] GetCharacters(LetterKey letter, Language[] langs)
    {
        if (langs.Length == 0)
        {
            return [];
        }

        if (langs.Length == All.Count)
        {
            return _allLanguagesCache.GetOrAdd(letter, key => Collect(key, All));
        }

        return Collect(letter, langs.Select(lang => LanguageLookup[lang]));
    }

    private static string[] Collect(LetterKey letter, IEnumerable<LanguageInfo> maps)
    {
        var result = new List<string>();
        foreach (var map in maps
            .OrderBy(m => _groupOrder[m.Group])
            .ThenBy(m => _languageOrder[m.Id]))
        {
            if (map.Characters.TryGetValue(letter, out var chars))
            {
                result.AddRange(chars);
            }
        }

        return [.. result.Distinct()];
    }
}