using Core.Entities;
using Core.Utility;
using Data;
using Microsoft.EntityFrameworkCore;

namespace WebApp.Services;

/// <summary>
/// Service for handling EventDefinition-related operations
/// </summary>
public class EventDefinitionService
{
    private readonly AppDbContext _context;

    public EventDefinitionService(AppDbContext context)
    {
        _context = context;
    }

    /// <summary>
    /// Processes and normalizes related careers for an EventDefinition.
    /// Matches existing careers by normalized name (case-insensitive) or creates new ones.
    /// </summary>
    /// <param name="eventDefinition">The EventDefinition to process careers for</param>
    public async Task ProcessRelatedCareersAsync(EventDefinition eventDefinition)
    {
        if (string.IsNullOrWhiteSpace(eventDefinition.RelatedCareersText))
        {
            eventDefinition.RelatedCareers.Clear();
            return;
        }

        var normalizedNames = CareerNormalizer.NormalizeCareerNames(eventDefinition.RelatedCareersText).ToList();
        
        if (!normalizedNames.Any())
        {
            eventDefinition.RelatedCareers.Clear();
            return;
        }

        // Get all existing careers from database (case-insensitive lookup)
        var existingCareers = await _context.Careers
            .Where(c => !string.IsNullOrWhiteSpace(c.Name))
            .ToListAsync();
        
        // Build lookup dictionary, handling potential duplicates by taking the first occurrence
        var careerLookup = new Dictionary<string, Career>(StringComparer.OrdinalIgnoreCase);
        foreach (var career in existingCareers)
        {
            var normalizedKey = CareerNormalizer.GetNormalizedKey(career.Name);
            if (!careerLookup.ContainsKey(normalizedKey))
            {
                careerLookup[normalizedKey] = career;
            }
        }

        var careersToAdd = new List<Career>();

        foreach (var normalizedName in normalizedNames)
        {
            var normalizedKey = CareerNormalizer.GetNormalizedKey(normalizedName);
            
            if (careerLookup.TryGetValue(normalizedKey, out var existingCareer))
            {
                // Use existing career (preserve original capitalization)
                careersToAdd.Add(existingCareer);
            }
            else
            {
                // Create new career with the normalized name (preserving capitalization from input)
                var newCareer = new Career { Name = normalizedName };
                _context.Careers.Add(newCareer);
                careersToAdd.Add(newCareer);
                careerLookup[normalizedKey] = newCareer;
            }
        }

        // Replace the collection
        eventDefinition.RelatedCareers = careersToAdd;
    }
}