using System.Text.Json;
using System.Text.RegularExpressions;
using Shouldly;

namespace ClawdDotNet.Web.Tests;

/// <summary>
/// #764 / #661: The WebUI texts come from language packs (<c>wwwroot/i18n/en.json</c> and
/// <c>de.json</c>). A key missing in one pack shows up as the bare key on screen — in the
/// language nobody tested in. So every run checks the packs, not a person after each change.
/// </summary>
public sealed partial class LanguagePackTests
{
    private static readonly string WwwRoot = Path.Combine(
        FindRepositoryRoot(), "src", "ClawdDotNet.Manager.Web", "wwwroot");

    private static string FindRepositoryRoot()
    {
        for (var dir = new DirectoryInfo(AppContext.BaseDirectory); dir is not null; dir = dir.Parent)
        {
            if (File.Exists(Path.Combine(dir.FullName, "ClawdDotNet.slnx")))
                return dir.FullName;
        }

        throw new InvalidOperationException("Repository root not found above " + AppContext.BaseDirectory);
    }

    private static Dictionary<string, string> Pack(string language)
        => JsonSerializer.Deserialize<Dictionary<string, string>>(
            File.ReadAllText(Path.Combine(WwwRoot, "i18n", language + ".json")))!;

    [GeneratedRegex(@"\{(\w+)\}")]
    private static partial Regex Placeholder();

    // t("key" … — but not erstelleElement("div": the t must stand on its own.
    [GeneratedRegex(@"(?<![\w.])t\(\s*[""']([\w.]+)[""']")]
    private static partial Regex TranslateCall();

    [Fact]
    public void Both_packs_have_the_same_keys()
    {
        var en = Pack("en").Keys.ToHashSet();
        var de = Pack("de").Keys.ToHashSet();

        en.Except(de).ShouldBeEmpty("missing in de.json");
        de.Except(en).ShouldBeEmpty("missing in en.json");
    }

    [Fact]
    public void A_text_keeps_its_placeholders_in_both_languages()
    {
        // "{name} saved" in English and "Gespeichert" in German would drop the name silently.
        var en = Pack("en");
        var de = Pack("de");

        var mismatches = en.Keys.Intersect(de.Keys)
            // Shows the trigger syntax itself ("{field}" / "{feld}" stands for any field name) and
            // is called without arguments — the braces are text for the reader, not placeholders.
            .Where(k => k != "trigger.instructionHint")
            .Where(k => !Placeholder().Matches(en[k]).Select(m => m.Value).ToHashSet()
                .SetEquals(Placeholder().Matches(de[k]).Select(m => m.Value)))
            .ToList();

        mismatches.ShouldBeEmpty();
    }

    [Fact]
    public void Every_key_the_code_asks_for_exists()
    {
        var en = Pack("en");

        var missing = Directory.EnumerateFiles(WwwRoot, "*.js", SearchOption.AllDirectories)
            .Where(f => !f.Contains(Path.DirectorySeparatorChar + "vendor" + Path.DirectorySeparatorChar))
            .SelectMany(f => TranslateCall().Matches(File.ReadAllText(f))
                .Select(m => (File: Path.GetFileName(f), Key: m.Groups[1].Value)))
            .Where(x => !en.ContainsKey(x.Key))
            // The example in the doc comment of i18n.js.
            .Where(x => x.Key != "runs.count")
            .Select(x => $"{x.File}: {x.Key}")
            .Distinct()
            .ToList();

        missing.ShouldBeEmpty();
    }

    [Fact]
    public void No_text_is_empty()
    {
        foreach (var language in new[] { "en", "de" })
            Pack(language).Where(p => string.IsNullOrWhiteSpace(p.Value)).Select(p => p.Key).ShouldBeEmpty(language);
    }
}