using DataModel.Database;
using DataModel.Database.Common;
using Microsoft.EntityFrameworkCore;

namespace Processor;

public static class TextElementProcessor
{
    public static Task<IAsyncEnumerable<TextElement>> GetTextElements(DataContext db, Section section)
    {
        return Task.FromResult(db.TextElements.Where(n => n.Section == section).AsAsyncEnumerable());
    }

    public static async Task<ProcessorResult<TextElement>> AddTextElement(DataContext db, string? currentSectionKey, string elementName)
    {
        if(string.IsNullOrWhiteSpace(currentSectionKey))
            throw new ArgumentOutOfRangeException(nameof(currentSectionKey));
        
        var currentSection = await db.Sections.FirstOrDefaultAsync(n => n.DataKey == currentSectionKey);
        if (currentSection is null)
            throw new ArgumentOutOfRangeException(nameof(currentSectionKey));

        // Remove any whitespaces from the element name, regardless of how many e.g. spaces the user typed:
        var code = string.Join('_', elementName.Split(' ', StringSplitOptions.TrimEntries | StringSplitOptions.RemoveEmptyEntries)).ToUpperInvariant();
        
        // Check, if this key already exists:
        if (await db.TextElements.AnyAsync(n => n.Section == currentSection && n.Code == code))
        {
            var rng = new Random();
            while (await db.TextElements.AnyAsync(n => n.Section == currentSection && n.Code == code))
            {
                // Add a random number to the end of the key:
                code += $"_{rng.Next(1, 10_000)}";
            }
        }
        
        var textElement = new TextElement
        {
            Name = elementName,
            Code = code,
            Section = currentSection,
        };
        
        // Add the new element to the database:
        await db.TextElements.AddAsync(textElement);

        try
        {
            // Save the changes:
            await db.SaveChangesAsync();
            return new ProcessorResult<TextElement>(textElement);
        }
        catch (DbUpdateException updateException)
        {
            return updateException.ToProcessorResult<TextElement>();
        }
    }
}