namespace LehrerApp.Templating;

public enum PlaceholderType { Text, Multiline, Date, Number, Image, Table, Chart }

public abstract record PlaceholderValue(PlaceholderType Type);
public sealed record TextValue(string Value) : PlaceholderValue(PlaceholderType.Text);
public sealed record MultilineValue(string Value) : PlaceholderValue(PlaceholderType.Multiline);
public sealed record DateValue(DateOnly Value) : PlaceholderValue(PlaceholderType.Date);
public sealed record NumberValue(decimal Value) : PlaceholderValue(PlaceholderType.Number);
public sealed record ImageValue(byte[] Data, string MimeType) : PlaceholderValue(PlaceholderType.Image);
public sealed record ImageMetadata(int Width, int Height);
public sealed record TableValue(IReadOnlyList<string> Columns, IReadOnlyList<IReadOnlyList<string>> Rows)
    : PlaceholderValue(PlaceholderType.Table);
public sealed record ChartPoint(string X, decimal Y);
public sealed record ChartSeries(string Label, IReadOnlyList<ChartPoint> Points);
public sealed record ChartValue(IReadOnlyList<ChartSeries> Series) : PlaceholderValue(PlaceholderType.Chart);

public interface ITemplateDataProvider
{
    IReadOnlyDictionary<string, PlaceholderValue> GetValues();
}

public sealed record PageSizeDefinition(float Width, float Height, string Unit = "mm");
public sealed record PlaceholderDefinition(string Name, PlaceholderType Type, bool Required = false);

public sealed class TemplateManifest
{
    public int SchemaVersion { get; set; } = 1;
    public string Id { get; set; } = "neue-vorlage";
    public string Name { get; set; } = "Neue Vorlage";
    public string Description { get; set; } = "";
    public PageSizeDefinition PageSize { get; set; } = new(210, 297);
    public string LayoutFile { get; set; } = "layout.tpl";
    public List<PlaceholderDefinition> Placeholders { get; set; } = [];
}

public abstract record TemplateElement(int Line, float X, float Y, float Width, float Height,
    IReadOnlyDictionary<string, string> Attributes);
public sealed record BackgroundElement(int Line, string Path)
    : TemplateElement(Line, 0, 0, 0, 0, EmptyAttributes.Value);
public sealed record ImageElement(int Line, string Path, float X, float Y, float Width, float Height,
    IReadOnlyDictionary<string, string> Attributes)
    : TemplateElement(Line, X, Y, Width, Height, Attributes);
public sealed record TextElement(int Line, float X, float Y, string Content, string? Placeholder,
    string? Format, IReadOnlyDictionary<string, string> Attributes)
    : TemplateElement(Line, X, Y, 0, 0, Attributes);
public sealed record TextBoxElement(int Line, float X, float Y, float Width, float Height,
    string Content, string? Placeholder, string? Format, IReadOnlyDictionary<string, string> Attributes)
    : TemplateElement(Line, X, Y, Width, Height, Attributes);
public sealed record TableElement(int Line, float X, float Y, float Width, float Height,
    string Placeholder, IReadOnlyDictionary<string, string> Attributes)
    : TemplateElement(Line, X, Y, Width, Height, Attributes);
public sealed record ChartElement(int Line, float X, float Y, float Width, float Height,
    string Placeholder, string ChartType, IReadOnlyDictionary<string, string> Attributes)
    : TemplateElement(Line, X, Y, Width, Height, Attributes);

internal static class EmptyAttributes
{
    public static readonly IReadOnlyDictionary<string, string> Value =
        new Dictionary<string, string>();
}

public sealed record TemplateLayout(float Width, float Height, string Unit,
    IReadOnlyList<TemplateElement> Elements);

public sealed record LoadedTemplate(TemplateManifest Manifest, TemplateLayout Layout,
    IReadOnlyDictionary<string, byte[]> Assets, string SourceName = "");

public enum ValidationSeverity { Warning, Error }
public sealed record ValidationIssue(ValidationSeverity Severity, string Message, int? Line = null);
public sealed record ValidationResult(IReadOnlyList<ValidationIssue> Issues)
{
    public bool IsValid => Issues.All(x => x.Severity != ValidationSeverity.Error);
    public static ValidationResult Success { get; } = new([]);
}

public sealed class TemplateValidationException(ValidationResult result)
    : Exception(string.Join(Environment.NewLine, result.Issues.Select(x => x.Message)))
{
    public ValidationResult Result { get; } = result;
}

public interface ITemplateRenderer
{
    byte[] RenderToPdf(LoadedTemplate template, ITemplateDataProvider data);
}

public interface ITemplatePreviewRenderer
{
    byte[] RenderFirstPageToPng(LoadedTemplate template, ITemplateDataProvider data, int dpi = 120);
}

public interface ITemplateLoader
{
    LoadedTemplate LoadFromPackage(string packagePath);
    LoadedTemplate LoadFromPackage(Stream package, string sourceName = "");
    ValidationResult Validate(LoadedTemplate template,
        IReadOnlyDictionary<string, PlaceholderType> providedTypes);
}

public interface ITemplateMigrator
{
    int SourceVersion { get; }
    TemplateManifest Migrate(TemplateManifest manifest);
}