using System.Text.RegularExpressions;
using BigRegister.Api.Contracts;
using BigRegister.Api.Data;
using BigRegister.Domain.Letters;

namespace BigRegister.Tests;

/// <summary>
/// WP-25's fence against drift between the backend renderer and the FE letter
/// canvas: a golden-file snapshot of a fixed brief + template, and a class-parity
/// check that every `letter`-prefixed class the renderer emits exists in the
/// shared `public/letter.css` contract. Neither test launches a browser.
/// </summary>
public class LetterHtmlTests
{
  private static BriefEntity FixtureBrief() => new()
  {
    BriefId = "golden-brief-1",
    Owner = "golden",
    Beroep = "arts",
    TemplateId = "besluit-arts",
    DrafterId = BriefStore.DrafterId,
    Placeholders = new[]
    {
      new PlaceholderDefDto("naam_zorgverlener", "Naam zorgverlener", true),
      new PlaceholderDefDto("datum", "Datum", true),
      new PlaceholderDefDto("reden_besluit", "Reden besluit", false),
    },
    Sections = new()
    {
      new("aanhef", "Aanhef", true, new List<LetterBlockDto>
      {
        new("freeText", "aanhef-1", new RichTextBlockDto(new[]
        {
          new ParagraphDto(new[]
          {
            new RichTextNodeDto("text", Text: "Geachte heer/mevrouw "),
            new RichTextNodeDto("placeholder", Key: "naam_zorgverlener"),
            new RichTextNodeDto("text", Text: ","),
          }),
        })),
      }, Locked: true),
      new("kern", "Kern van het besluit", true, new List<LetterBlockDto>
      {
        new("freeText", "kern-1", new RichTextBlockDto(new[]
        {
          new ParagraphDto(new[] { new RichTextNodeDto("text", Text: "Op ") }),
          new ParagraphDto(new RichTextNodeDto[]
          {
            new("text", Text: "Eerste punt: "),
            new("placeholder", Key: "reden_besluit"),
          }, List: "bullet"),
          new ParagraphDto(new RichTextNodeDto[]
          {
            new("text", Text: "Tweede punt"),
          }, List: "bullet"),
        })),
      }),
      new("slot", "Slot", false, new List<LetterBlockDto>
      {
        new("freeText", "slot-1", new RichTextBlockDto(new[]
        {
          new ParagraphDto(new[] { new RichTextNodeDto("text", Text: "Met vriendelijke groet,") }),
        })),
      }, Locked: true),
    },
    Status = new BriefStatusDto("draft"),
  };

  private static readonly OrgTemplateDto Template = new(
      "cibg-registers", "BIG-register",
      "Retouradres: Postbus 00000, 2500 AA Den Haag",
      LogoDocumentId: null,
      "BIG-register · Postbus 00000, 2500 AA Den Haag · 070 000 00 00 · info@voorbeeld.example",
      "Dit is een gegenereerd voorbeelddocument uit de register-reference PoC. Alle gegevens zijn fictief.",
      "A. de Vries", "Hoofd Registratie, BIG-register", "Met vriendelijke groet,",
      new MarginsDto(25, 20, 20, 25), Version: 1);

  private const string At = "2026-07-05T12:00:00.0000000+00:00";

  private static readonly string GoldenPath = Path.Combine(AppContext.BaseDirectory, "LetterHtml.golden.html");

  // A minimal brief whose body renders the "datum" placeholder — the golden-file
  // fixture above never uses it in the body, only in the letterhead, so it cannot
  // exercise ResolveAuto's "datum" case (TE-007).
  private static BriefEntity FixtureBriefWithDatumInBody() => new()
  {
    BriefId = "datum-brief-1",
    Owner = "golden",
    Beroep = "arts",
    TemplateId = "besluit-arts",
    DrafterId = BriefStore.DrafterId,
    Placeholders = new[]
    {
      new PlaceholderDefDto("datum", "Datum", true),
    },
    Sections = new()
    {
      new("kern", "Kern van het besluit", true, new List<LetterBlockDto>
      {
        new("freeText", "kern-1", new RichTextBlockDto(new[]
        {
          new ParagraphDto(new[] { new RichTextNodeDto("placeholder", Key: "datum") }),
        })),
      }),
    },
    Status = new BriefStatusDto("draft"),
  };

  private static string ExtractLetterheadDate(string html) =>
      Regex.Match(html, "<dt>Datum</dt><dd>([^<]+)</dd>").Groups[1].Value;

  private static string ExtractBodyDatumParagraph(string html)
  {
    var bodyStart = html.IndexOf("<div class=\"letter__body\">", StringComparison.Ordinal);
    var bodyEnd = html.IndexOf("<div class=\"letter__signature\">", StringComparison.Ordinal);
    var body = html[bodyStart..bodyEnd];
    return Regex.Match(body, "<p>([^<]+)</p>").Groups[1].Value;
  }

  [Fact]
  public void Render_matches_the_golden_file()
  {
    var html = LetterHtml.Render(FixtureBrief(), Template, At, watermark: true);
    var golden = File.ReadAllText(GoldenPath);
    Assert.Equal(golden, html);
  }

  [Fact]
  public void Render_resolves_the_body_datum_placeholder_from_the_given_at_not_the_wall_clock()
  {
    const string historicalAt = "2019-03-14T08:00:00.0000000+00:00";

    var html = LetterHtml.Render(FixtureBriefWithDatumInBody(), Template, historicalAt, watermark: false);

    Assert.Equal("14 maart 2019", ExtractBodyDatumParagraph(html));
  }

  [Fact]
  public void Render_keeps_the_letterhead_date_and_the_body_datum_in_agreement_for_a_historical_at()
  {
    // A historical `at` (an archive re-render, a back-dated letter) is the case
    // where the letterhead and the body datum placeholder could disagree within
    // one document, if the body still read the wall clock (TE-007).
    const string historicalAt = "2019-03-14T08:00:00.0000000+00:00";

    var html = LetterHtml.Render(FixtureBriefWithDatumInBody(), Template, historicalAt, watermark: false);

    Assert.Equal(ExtractLetterheadDate(html), ExtractBodyDatumParagraph(html));
  }

  [Fact]
  public void Every_letter_prefixed_class_exists_in_letter_css()
  {
    var html = LetterHtml.Render(FixtureBrief(), Template, At, watermark: true);
    var classes = Regex.Matches(html, "class=\"([^\"]+)\"")
        .SelectMany(m => m.Groups[1].Value.Split(' '))
        .Where(c => c.StartsWith("letter"))
        .Distinct();
    Assert.NotEmpty(classes);
    Assert.All(classes, c => Assert.Contains($".{c}", LetterHtml.StyleSheet));
  }
}