using System;
using System.Collections.Generic;
using System.Linq;
using NUnit.Framework;
using StardewModdingAPI.Framework.ModHelpers;
using StardewValley;

namespace StardewModdingAPI.Tests.Core
{
    /// <summary>Unit tests for <see cref="TranslationHelper"/> and <see cref="Translation"/>.</summary>
    [TestFixture]
    public class TranslationTests
    {
        /*********
        ** Data
        *********/
        /// <summary>Sample translation text for unit tests.</summary>
        public static string[] Samples = { null, "", "  ", "boop", "  boop  " };


        /*********
        ** Unit tests
        *********/
        /****
        ** Translation helper
        ****/
        [Test(Description = "Assert that the translation helper correctly handles no translations.")]
        public void Helper_HandlesNoTranslations()
        {
            // arrange
            var data = new Dictionary<string, IDictionary<string, string>>();

            // act
            ITranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
            Translation translation = helper.Get("key");
            Translation[] translationList = helper.GetTranslations()?.ToArray();

            // assert
            Assert.AreEqual("en", helper.Locale, "The locale doesn't match the input value.");
            Assert.AreEqual(LocalizedContentManager.LanguageCode.en, helper.LocaleEnum, "The locale enum doesn't match the input value.");
            Assert.IsNotNull(translationList, "The full list of translations is unexpectedly null.");
            Assert.AreEqual(0, translationList.Length, "The full list of translations is unexpectedly not empty.");

            Assert.IsNotNull(translation, "The translation helper unexpectedly returned a null translation.");
            Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value.");
        }

        [Test(Description = "Assert that the translation helper returns the expected translations correctly.")]
        public void Helper_GetTranslations_ReturnsExpectedText()
        {
            // arrange
            var data = this.GetSampleData();
            var expected = this.GetExpectedTranslations();

            // act
            var actual = new Dictionary<string, Translation[]>();
            TranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
            foreach (string locale in expected.Keys)
            {
                this.AssertSetLocale(helper, locale, LocalizedContentManager.LanguageCode.en);
                actual[locale] = helper.GetTranslations()?.ToArray();
            }

            // assert
            foreach (string locale in expected.Keys)
            {
                Assert.IsNotNull(actual[locale], $"The translations for {locale} is unexpectedly null.");
                Assert.That(actual[locale], Is.EquivalentTo(expected[locale]).Using<Translation, Translation>(this.CompareEquality), $"The translations for {locale} don't match the expected values.");
            }
        }

        [Test(Description = "Assert that the translations returned by the helper has the expected text.")]
        public void Helper_Get_ReturnsExpectedText()
        {
            // arrange
            var data = this.GetSampleData();
            var expected = this.GetExpectedTranslations();

            // act
            var actual = new Dictionary<string, Translation[]>();
            TranslationHelper helper = new TranslationHelper("ModID", "ModName", "en", LocalizedContentManager.LanguageCode.en).SetTranslations(data);
            foreach (string locale in expected.Keys)
            {
                this.AssertSetLocale(helper, locale, LocalizedContentManager.LanguageCode.en);

                List<Translation> translations = new List<Translation>();
                foreach (Translation translation in expected[locale])
                    translations.Add(helper.Get(translation.Key));
                actual[locale] = translations.ToArray();
            }

            // assert
            foreach (string locale in expected.Keys)
            {
                Assert.IsNotNull(actual[locale], $"The translations for {locale} is unexpectedly null.");
                Assert.That(actual[locale], Is.EquivalentTo(expected[locale]).Using<Translation, Translation>(this.CompareEquality), $"The translations for {locale} don't match the expected values.");
            }
        }

        /****
        ** Translation
        ****/
        [Test(Description = "Assert that HasValue returns the expected result for various inputs.")]
        [TestCase(null, ExpectedResult = false)]
        [TestCase("", ExpectedResult = false)]
        [TestCase("  ", ExpectedResult = true)]
        [TestCase("boop", ExpectedResult = true)]
        [TestCase("  boop  ", ExpectedResult = true)]
        public bool Translation_HasValue(string text)
        {
            return new Translation("ModName", "pt-BR", "key", text).HasValue();
        }

        [Test(Description = "Assert that the translation's ToString method returns the expected text for various inputs.")]
        public void Translation_ToString([ValueSource(nameof(TranslationTests.Samples))] string text)
        {
            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text);

            // assert
            if (translation.HasValue())
                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid input.");
            else
                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty input.");
        }

        [Test(Description = "Assert that the translation's implicit string conversion returns the expected text for various inputs.")]
        public void Translation_ImplicitStringConversion([ValueSource(nameof(TranslationTests.Samples))] string text)
        {
            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text);

            // assert
            if (translation.HasValue())
                Assert.AreEqual(text, (string)translation, "The translation returned an unexpected value given a valid input.");
            else
                Assert.AreEqual(this.GetPlaceholderText("key"), (string)translation, "The translation returned an unexpected value given a null or empty input.");
        }

        [Test(Description = "Assert that the translation returns the expected text given a use-placeholder setting.")]
        public void Translation_UsePlaceholder([Values(true, false)] bool value, [ValueSource(nameof(TranslationTests.Samples))] string text)
        {
            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text).UsePlaceholder(value);

            // assert
            if (translation.HasValue())
                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid input.");
            else if (!value)
                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a null or empty input with the placeholder disabled.");
            else
                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty input with the placeholder enabled.");
        }

        [Test(Description = "Assert that the translation's Assert method throws the expected exception.")]
        public void Translation_Assert([ValueSource(nameof(TranslationTests.Samples))] string text)
        {
            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text);

            // assert
            if (translation.HasValue())
                Assert.That(() => translation.Assert(), Throws.Nothing, "The assert unexpected threw an exception for a valid input.");
            else
                Assert.That(() => translation.Assert(), Throws.Exception.TypeOf<KeyNotFoundException>(), "The assert didn't throw an exception for invalid input.");
        }

        [Test(Description = "Assert that the translation returns the expected text after setting the default.")]
        public void Translation_Default([ValueSource(nameof(TranslationTests.Samples))] string text, [ValueSource(nameof(TranslationTests.Samples))] string @default)
        {
            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text).Default(@default);

            // assert
            if (!string.IsNullOrEmpty(text))
                Assert.AreEqual(text, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
            else if (!string.IsNullOrEmpty(@default))
                Assert.AreEqual(@default, translation.ToString(), "The translation returned an unexpected value given a null or empty base text, but valid default.");
            else
                Assert.AreEqual(this.GetPlaceholderText("key"), translation.ToString(), "The translation returned an unexpected value given a null or empty base and default text.");
        }

        /****
        ** Translation tokens
        ****/
        [Test(Description = "Assert that multiple translation tokens are replaced correctly regardless of the token structure.")]
        public void Translation_Tokens([Values("anonymous object", "class", "IDictionary<string, object>", "IDictionary<string, string>")] string structure)
        {
            // arrange
            string start = Guid.NewGuid().ToString("N");
            string middle = Guid.NewGuid().ToString("N");
            string end = Guid.NewGuid().ToString("N");
            const string input = "{{start}} tokens are properly replaced (including {{middle}} {{  MIDdlE}}) {{end}}";
            string expected = $"{start} tokens are properly replaced (including {middle} {middle}) {end}";

            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", input);
            switch (structure)
            {
                case "anonymous object":
                    translation = translation.Tokens(new { start, middle, end });
                    break;

                case "class":
                    translation = translation.Tokens(new TokenModel { Start = start, Middle = middle, End = end });
                    break;

                case "IDictionary<string, object>":
                    translation = translation.Tokens(new Dictionary<string, object> { ["start"] = start, ["middle"] = middle, ["end"] = end });
                    break;

                case "IDictionary<string, string>":
                    translation = translation.Tokens(new Dictionary<string, string> { ["start"] = start, ["middle"] = middle, ["end"] = end });
                    break;

                default:
                    throw new NotSupportedException($"Unknown structure '{structure}'.");
            }

            // assert
            Assert.AreEqual(expected, translation.ToString(), "The translation returned an unexpected text.");
        }

        [Test(Description = "Assert that the translation can replace tokens in all valid formats.")]
        [TestCase("{{value}}", "value")]
        [TestCase("{{ value }}", "value")]
        [TestCase("{{value       }}", "value")]
        [TestCase("{{ the_value }}", "the_value")]
        [TestCase("{{ the.value_here }}", "the.value_here")]
        [TestCase("{{ the_value-here.... }}", "the_value-here....")]
        [TestCase("{{ tHe_vALuE-HEre.... }}", "tHe_vALuE-HEre....")]
        public void Translation_Tokens_ValidFormats(string text, string key)
        {
            // arrange
            string value = Guid.NewGuid().ToString("N");

            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text).Tokens(new Dictionary<string, object> { [key] = value });

            // assert
            Assert.AreEqual(value, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
        }

        [Test(Description = "Assert that translation tokens are case-insensitive and surrounding-whitespace-insensitive.")]
        [TestCase("{{value}}", "value")]
        [TestCase("{{VaLuE}}", "vAlUe")]
        [TestCase("{{VaLuE   }}", "   vAlUe")]
        public void Translation_Tokens_KeysAreNormalised(string text, string key)
        {
            // arrange
            string value = Guid.NewGuid().ToString("N");

            // act
            Translation translation = new Translation("ModName", "pt-BR", "key", text).Tokens(new Dictionary<string, object> { [key] = value });

            // assert
            Assert.AreEqual(value, translation.ToString(), "The translation returned an unexpected value given a valid base text.");
        }


        /*********
        ** Private methods
        *********/
        /// <summary>Set a translation helper's locale and assert that it was set correctly.</summary>
        /// <param name="helper">The translation helper to change.</param>
        /// <param name="locale">The expected locale.</param>
        /// <param name="localeEnum">The expected game language code.</param>
        private void AssertSetLocale(TranslationHelper helper, string locale, LocalizedContentManager.LanguageCode localeEnum)
        {
            helper.SetLocale(locale, localeEnum);
            Assert.AreEqual(locale, helper.Locale, "The locale doesn't match the input value.");
            Assert.AreEqual(localeEnum, helper.LocaleEnum, "The locale enum doesn't match the input value.");
        }

        /// <summary>Get sample raw translations to input.</summary>
        private IDictionary<string, IDictionary<string, string>> GetSampleData()
        {
            return new Dictionary<string, IDictionary<string, string>>
            {
                ["default"] = new Dictionary<string, string>
                {
                    ["key A"] = "default A",
                    ["key C"] = "default C"
                },
                ["en"] = new Dictionary<string, string>
                {
                    ["key A"] = "en A",
                    ["key B"] = "en B"
                },
                ["en-US"] = new Dictionary<string, string>(),
                ["zzz"] = new Dictionary<string, string>
                {
                    ["key A"] = "zzz A"
                }
            };
        }

        /// <summary>Get the expected translation output given <see cref="TranslationTests.GetSampleData"/>, based on the expected locale fallback.</summary>
        private IDictionary<string, Translation[]> GetExpectedTranslations()
        {
            var expected = new Dictionary<string, Translation[]>
            {
                ["default"] = new[]
                {
                    new Translation(string.Empty, "default", "key A", "default A"),
                    new Translation(string.Empty, "default", "key C", "default C")
                },
                ["en"] = new[]
                {
                    new Translation(string.Empty, "en", "key A", "en A"),
                    new Translation(string.Empty, "en", "key B", "en B"),
                    new Translation(string.Empty, "en", "key C", "default C")
                },
                ["zzz"] = new[]
                {
                    new Translation(string.Empty, "zzz", "key A", "zzz A"),
                    new Translation(string.Empty, "zzz", "key C", "default C")
                }
            };
            expected["en-us"] = expected["en"].ToArray();
            return expected;
        }

        /// <summary>Get whether two translations have the same public values.</summary>
        /// <param name="a">The first translation to compare.</param>
        /// <param name="b">The second translation to compare.</param>
        private bool CompareEquality(Translation a, Translation b)
        {
            return a.Key == b.Key && a.ToString() == b.ToString();
        }

        /// <summary>Get the default placeholder text when a translation is missing.</summary>
        /// <param name="key">The translation key.</param>
        private string GetPlaceholderText(string key)
        {
            return string.Format(Translation.PlaceholderText, key);
        }


        /*********
        ** Test models
        *********/
        /// <summary>A model used to test token support.</summary>
        private class TokenModel
        {
            /// <summary>A sample token property.</summary>
            public string Start { get; set; }

            /// <summary>A sample token property.</summary>
            public string Middle { get; set; }

            /// <summary>A sample token field.</summary>
            public string End;
        }
    }
}