using Backend.Domain;
using Backend.Services;
using Microsoft.EntityFrameworkCore;

namespace Backend.Data;

public static partial class SeedDataBootstrapper
{
    private static async Task EnsureCategoriesAsync(AwardsDbContext db, Season season)
    {
        var categories = await db.Categories
            .Where(item => item.SeasonId == season.Id)
            .ToListAsync();
        var templates = SeedCatalog.DefaultSubcategoryTemplates
            .Select((item, index) => item with { SortOrder = index + 1 })
            .ToArray();
        var usedCategories = new HashSet<Category>();

        season.SubcategoryTemplatesJson = SeasonSubcategoryTemplateSettings.Serialize(templates);

        var nextSortOrder = 1;
        foreach (var award in SeedCatalog.AwardCategorySeeds.OrderBy(item => item.SortOrder))
        {
            foreach (var template in templates)
            {
                var category = FindReusableCategory(categories, award, template, usedCategories)
                    ?? new Category { SeasonId = season.Id };
                usedCategories.Add(category);

                category.GroupName = award.Name;
                category.Name = template.Name;
                category.Slug = BuildCategorySlug(award.Slug, template.Slug);
                category.Description = award.Description;
                category.SortOrder = nextSortOrder++;
                category.MaxNomineesPerUser = 3;
                category.ViewerRangeMin = template.ViewerRangeMin;
                category.ViewerRangeMax = template.ViewerRangeMax;

                if (category.Id == 0 && !db.Categories.Local.Any(item => ReferenceEquals(item, category)))
                {
                    db.Categories.Add(category);
                    categories.Add(category);
                }
            }
        }

        var staleCategories = categories
            .Where(item => item.Id > 0 && !usedCategories.Contains(item))
            .ToArray();
        await RemoveStaleCategoryDataAsync(db, staleCategories);
        await db.SaveChangesAsync();
    }

    private static async Task RemoveStaleCategoryDataAsync(AwardsDbContext db, Category[] staleCategories)
    {
        if (staleCategories.Length == 0)
        {
            return;
        }

        var staleCategoryIds = staleCategories.Select(item => item.Id).ToArray();
        var staleCandidateIds = await db.Candidates
            .Where(item => staleCategoryIds.Contains(item.CategoryId))
            .Select(item => item.Id)
            .ToArrayAsync();

        var staleVoteEntries = await db.VoteEntries
            .Where(item => staleCategoryIds.Contains(item.CategoryId) || staleCandidateIds.Contains(item.CandidateId))
            .ToArrayAsync();
        db.VoteEntries.RemoveRange(staleVoteEntries);

        var staleResults = await db.Results
            .Where(item => staleCategoryIds.Contains(item.CategoryId) || staleCandidateIds.Contains(item.CandidateId))
            .ToArrayAsync();
        db.Results.RemoveRange(staleResults);

        var affectedClips = await db.ClipSubmissions
            .Where(item =>
                (item.CategoryId != null && staleCategoryIds.Contains(item.CategoryId.Value))
                || (item.CandidateId != null && staleCandidateIds.Contains(item.CandidateId.Value)))
            .ToArrayAsync();
        foreach (var clip in affectedClips)
        {
            if (clip.CategoryId != null && staleCategoryIds.Contains(clip.CategoryId.Value))
            {
                clip.CategoryId = null;
            }

            if (clip.CandidateId != null && staleCandidateIds.Contains(clip.CandidateId.Value))
            {
                clip.CandidateId = null;
            }
        }

        var affectedNominations = await db.Nominations
            .Where(item =>
                (item.CategoryId != null && staleCategoryIds.Contains(item.CategoryId.Value))
                || (item.SuggestedCategoryId != null && staleCategoryIds.Contains(item.SuggestedCategoryId.Value))
                || (item.CandidateId != null && staleCandidateIds.Contains(item.CandidateId.Value)))
            .ToArrayAsync();
        foreach (var nomination in affectedNominations)
        {
            if (nomination.CategoryId != null && staleCategoryIds.Contains(nomination.CategoryId.Value))
            {
                nomination.CategoryId = null;
            }

            if (nomination.SuggestedCategoryId != null && staleCategoryIds.Contains(nomination.SuggestedCategoryId.Value))
            {
                nomination.SuggestedCategoryId = null;
            }

            if (nomination.CandidateId != null && staleCandidateIds.Contains(nomination.CandidateId.Value))
            {
                nomination.CandidateId = null;
            }
        }

        var staleCandidates = await db.Candidates
            .Where(item => staleCandidateIds.Contains(item.Id))
            .ToArrayAsync();
        db.Candidates.RemoveRange(staleCandidates);
        db.Categories.RemoveRange(staleCategories);
    }

    private static Category? FindReusableCategory(
        List<Category> categories,
        AwardCategorySeed award,
        SeasonSubcategoryTemplateSetting template,
        HashSet<Category> usedCategories)
    {
        var targetSlug = BuildCategorySlug(award.Slug, template.Slug);

        return categories.FirstOrDefault(item => !usedCategories.Contains(item)
                && string.Equals(item.Slug, targetSlug, StringComparison.OrdinalIgnoreCase))
            ?? categories.FirstOrDefault(item => !usedCategories.Contains(item)
                && string.Equals(item.GroupName, award.Name, StringComparison.OrdinalIgnoreCase)
                && string.Equals(item.Name, template.Name, StringComparison.OrdinalIgnoreCase))
            ?? categories.FirstOrDefault(item => !usedCategories.Contains(item)
                && string.Equals(item.GroupName, award.LegacyGroupName, StringComparison.OrdinalIgnoreCase)
                && string.Equals(item.Name, template.Name, StringComparison.OrdinalIgnoreCase));
    }

    private static async Task EnsureCandidatesAsync(AwardsDbContext db, Season season, CandidateSeed[] seeds)
    {
        var categories = await db.Categories
            .Where(item => item.SeasonId == season.Id)
            .ToDictionaryAsync(item => item.Slug, StringComparer.OrdinalIgnoreCase);
        var existing = await db.Candidates
            .Where(item => item.SeasonId == season.Id)
            .Select(item => new { item.CategoryId, item.DisplayName, item.ChannelSlug })
            .ToArrayAsync();
        var existingKeys = existing
            .Select(item => $"{item.CategoryId}|{item.DisplayName}|{item.ChannelSlug}".ToLowerInvariant())
            .ToHashSet();

        foreach (var seed in seeds)
        {
            if (!categories.TryGetValue(seed.CategorySlug, out var category))
            {
                continue;
            }

            var key = $"{category.Id}|{seed.DisplayName}|{seed.ChannelSlug}".ToLowerInvariant();
            if (existingKeys.Contains(key))
            {
                continue;
            }

            db.Candidates.Add(new Candidate
            {
                SeasonId = season.Id,
                CategoryId = category.Id,
                DisplayName = seed.DisplayName,
                ChannelSlug = seed.ChannelSlug,
                Platform = seed.Platform,
            });
        }

        await db.SaveChangesAsync();
    }

    private static async Task EnsureWinnersAsync(AwardsDbContext db, Season season, WinnerSeed[] seeds)
    {
        var categories = await db.Categories
            .Where(item => item.SeasonId == season.Id)
            .ToDictionaryAsync(item => item.Slug, StringComparer.OrdinalIgnoreCase);
        var candidates = await db.Candidates
            .Where(item => item.SeasonId == season.Id)
            .ToArrayAsync();
        var existingResults = await db.Results
            .Where(item => item.SeasonId == season.Id)
            .ToArrayAsync();
        foreach (var result in existingResults)
        {
            if (categories.Values.FirstOrDefault(item => item.Id == result.CategoryId) is { } category
                && result.CategoryName != category.Name)
            {
                result.CategoryName = category.Name;
            }
        }

        var existingResultCategoryIds = existingResults.Select(item => item.CategoryId).ToHashSet();

        foreach (var seed in seeds)
        {
            if (!categories.TryGetValue(seed.CategorySlug, out var category) || existingResultCategoryIds.Contains(category.Id))
            {
                continue;
            }

            var candidate = candidates.FirstOrDefault(item =>
                item.CategoryId == category.Id
                && string.Equals(item.DisplayName, seed.DisplayName, StringComparison.OrdinalIgnoreCase));
            if (candidate is null)
            {
                continue;
            }

            db.Results.Add(new AwardResult
            {
                SeasonId = season.Id,
                CategoryId = category.Id,
                CandidateId = candidate.Id,
                CategoryName = category.Name,
            });
        }
    }

    private static string BuildCategorySlug(string awardSlug, string templateSlug) =>
        $"{SeasonSubcategoryTemplateSettings.Slugify(awardSlug)}-{SeasonSubcategoryTemplateSettings.Slugify(templateSlug)}";
}