using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text.RegularExpressions;
using System.Threading;
using System.Threading.Tasks;
using CompatBot.Database;
using CompatBot.Database.Providers;
using CompatBot.EventHandlers;
using DSharpPlus.CommandsNext;
using PsnClient.POCOs;
using PsnClient.Utils;

namespace CompatBot.ThumbScrapper;

internal sealed class PsnScraper
{
    private static readonly PsnClient.Client Client = new();
    public static readonly Regex ContentIdMatcher = new(
        @"(?<content_id>(?<service_id>(?<service_letters>\w\w)(?<service_number>\d{4}))-(?<product_id>(?<product_letters>\w{4})(?<product_number>\d{5}))_(?<part>\d\d)-(?<label>\w{16}))",
        RegexOptions.Compiled | RegexOptions.IgnoreCase | RegexOptions.Singleline | RegexOptions.ExplicitCapture
    );
    private static readonly SemaphoreSlim LockObj = new(1, 1);
    private static List<string> psnStores = new();
    private static DateTime storeRefreshTimestamp = DateTime.MinValue;
    private static readonly SemaphoreSlim QueueLimiter = new(32, 32);

    public static async Task RunAsync(CancellationToken cancellationToken)
    {
        do
        {
            if (cancellationToken.IsCancellationRequested)
                break;

            await ScrapeStateProvider.CleanAsync(cancellationToken).ConfigureAwait(false);
            await RefreshStoresAsync(cancellationToken).ConfigureAwait(false);
            try
            {
                await DoScrapePassAsync(cancellationToken).ConfigureAwait(false);
            }
            catch (Exception e)
            {
                PrintError(e);
            }
            await Task.Delay(TimeSpan.FromHours(1), cancellationToken).ConfigureAwait(false);
        } while (!cancellationToken.IsCancellationRequested);
    }

    public static async void CheckContentIdAsync(CommandContext ctx, string contentId, CancellationToken cancellationToken)
    {
        if (string.IsNullOrEmpty(contentId))
            return;

        var match = ContentIdMatcher.Match(contentId);
        if (!match.Success)
            return;

        if (!QueueLimiter.Wait(0, cancellationToken))
            return;

        try
        {
            List<string> storesToScrape;
            contentId = match.Groups["content_id"].Value;
            await LockObj.WaitAsync(cancellationToken).ConfigureAwait(false);
            try
            {
                storesToScrape = new(psnStores);
            }
            finally
            {
                LockObj.Release();
            }

            foreach (var locale in storesToScrape)
            {
                var relatedContainer = await Client.ResolveContentAsync(locale, contentId, 1, cancellationToken).ConfigureAwait(false);
                if (relatedContainer == null)
                    continue;

                await ctx.Channel.SendMessageAsync($"Found {contentId} in {locale} store").ConfigureAwait(false);
                await ProcessIncludedGamesAsync(locale, relatedContainer, cancellationToken, false).ConfigureAwait(false);
                return;
            }
            await ctx.Channel.SendMessageAsync($"Didn't find {contentId} in any PSN store").ConfigureAwait(false);
        }
        catch (Exception e)
        {
            Config.Log.Error(e);
        }
        finally
        {
            QueueLimiter.Release();
        }
    }

    private static async Task RefreshStoresAsync(CancellationToken cancellationToken)
    {
        try
        {
            if (ScrapeStateProvider.IsFresh(storeRefreshTimestamp))
                return;

            var result = GetLocalesInPreferredOrder(PsnClient.Client.GetLocales());
            await LockObj.WaitAsync(cancellationToken).ConfigureAwait(false);
            try
            {
                if (ScrapeStateProvider.IsFresh(storeRefreshTimestamp))
                    return;

                psnStores = result;
                storeRefreshTimestamp = DateTime.UtcNow;
            }
            finally
            {
                LockObj.Release();
            }
        }
        catch (Exception e)
        {
            PrintError(e);
        }
    }

    private static async Task DoScrapePassAsync(CancellationToken cancellationToken)
    {
        List<string> storesToScrape;
        await LockObj.WaitAsync(cancellationToken).ConfigureAwait(false);
        try
        {
            storesToScrape = new(psnStores);
        }
        finally
        {
            LockObj.Release();
        }

        var percentPerStore = 1.0 / storesToScrape.Count;
        for (var storeIdx = 0; storeIdx < storesToScrape.Count; storeIdx++)
        {
            var locale = storesToScrape[storeIdx];
            if (cancellationToken.IsCancellationRequested)
                break;

            if (ScrapeStateProvider.IsFresh(locale))
            {
                //Config.Log.Debug($"Cache for {locale} PSN is fresh, skipping");
                continue;
            }

            Config.Log.Debug($"Scraping {locale} PSN for PS3 games...");
            var knownContainers = new HashSet<string>();
            // get containers from the left side navigation panel on the main page
            var containerIds = await Client.GetMainPageNavigationContainerIdsAsync(locale, cancellationToken).ConfigureAwait(false);
            // get all containers from all the menus
            var stores = await Client.GetStoresAsync(locale, cancellationToken).ConfigureAwait(false);
            if (!string.IsNullOrEmpty(stores?.Data.BaseUrl))
                containerIds?.Add(Path.GetFileName(stores.Data.BaseUrl));
            if (containerIds != null)
                foreach (var id in containerIds)
                {
                    if (cancellationToken.IsCancellationRequested)
                        return;

                    await ScrapeContainerIdsAsync(locale, id, knownContainers, cancellationToken).ConfigureAwait(false);
                }
            Config.Log.Debug($"\tFound {knownContainers.Count} containers");

            // now let's scrape for actual games in every container
            var defaultFilters = new Dictionary<string, string>
            {
                ["platform"] = "ps3",
                ["game_content_type"] = "games",
            };
            var take = 30;
            var returned = 0;
            var containersToScrape = knownContainers.ToList(); //.Where(c => c.Contains("FULL", StringComparison.InvariantCultureIgnoreCase)).ToList();
            var percentPerContainer = 1.0 / containersToScrape.Count;
            for (var containerIdx = 0; containerIdx < containersToScrape.Count; containerIdx++)
            {
                var containerId = containersToScrape[containerIdx];
                if (cancellationToken.IsCancellationRequested)
                    return;

                if (ScrapeStateProvider.IsFresh(locale, containerId))
                {
                    //Config.Log.Debug($"\tCache for {locale} container {containerId} is fresh, skipping");
                    continue;
                }

                var currentPercent = storeIdx * percentPerStore + containerIdx * percentPerStore * percentPerContainer;
                Config.Log.Debug($"\tScraping {locale} container {containerId} ({currentPercent*100:##0.00}%)...");
                var total = -1;
                var start = 0;
                do
                {
                    var tries = 0;
                    Container? container = null;
                    var error = false;
                    do
                    {
                        try
                        {
                            container = await Client.GetGameContainerAsync(locale, containerId, start, take, defaultFilters, cancellationToken).ConfigureAwait(false);
                        }
                        catch (Exception e)
                        {
                            PrintError(e);
                            error = true;
                        }
                        tries++;
                    } while (error && tries < 3 && !cancellationToken.IsCancellationRequested);
                    if (cancellationToken.IsCancellationRequested)
                        return;

                    if (container != null)
                    {
                        // this might've changed between the pages for some stupid reason
                        total = container.Data.Attributes.TotalResults;
                        var pages = (int)Math.Ceiling((double)total / take);
                        if (pages > 1)
                            Config.Log.Debug($"\t\tPage {start / take + 1} of {pages}");
                        returned = container.Data?.Relationships?.Children?.Data?.Count(i => i.Type == "game" || i.Type == "legacy-sku") ?? 0;
                        // included contains full data already, so it's wise to get it first
                        await ProcessIncludedGamesAsync(locale, container, cancellationToken).ConfigureAwait(false);

                        // returned items are just ids that need to be resolved
                        if (returned > 0)
                        {
                            foreach (var item in container.Data!.Relationships!.Children!.Data!)
                            {
                                if (cancellationToken.IsCancellationRequested)
                                    return;

                                if (item.Type == "game")
                                {
                                    if (!NeedLookup(item.Id))
                                        continue;
                                }
                                else if (item.Type != "legacy-sku")
                                    continue;

                                //need depth=1 in case it's a crossplay title, so ps3 id will be in entitlements instead
                                container = await Client.ResolveContentAsync(locale, item.Id, 1, cancellationToken).ConfigureAwait(false);
                                if (container == null)
                                    PrintError(new InvalidOperationException("No container for " + item.Id));
                                else
                                    await ProcessIncludedGamesAsync(locale, container, cancellationToken).ConfigureAwait(false);
                            }
                        }
                    }
                    start += take;
                } while ((returned > 0 || (total > -1 && start * take <= total)) && !cancellationToken.IsCancellationRequested);
                await ScrapeStateProvider.SetLastRunTimestampAsync(locale, containerId).ConfigureAwait(false);
                Config.Log.Debug($"\tFinished scraping {locale} container {containerId}, processed {start - take + returned} items");
            }
            await ScrapeStateProvider.SetLastRunTimestampAsync(locale).ConfigureAwait(false);
        }
        Config.Log.Debug("Finished scraping all the PSN stores");
    }

    private static List<string> GetLocalesInPreferredOrder(string[] locales)
    {
        /*
         * what we want here: only one language per country
         * prefer en, then ja language for the region if it has it
         * then order by language, so we get as much English titles as possible
         * then Japanese
         * then the rest
         * withing one language prefer US, then GB, then JP to cover the largest ones first
         */
        var en = new List<string>();
        var ja = new List<string>();
        foreach (var l in locales)
        {
            if (l.StartsWith("en"))
                en.Add(l);
            else if (l.StartsWith("ja"))
                ja.Add(l);
        }
        var orderedLocales = new[] {"en-US", "en-GB"}
            .Concat(en)
            .Concat(new[] {"ja-JP"})
            .Concat(ja)
            .Concat(locales);
        var countries = new HashSet<string>();
        var result = new List<string>(locales.Length);
        foreach (var locale in orderedLocales)
            if (countries.Add(locale.AsLocaleData().country))
                result.Add(locale);
        Config.Log.Debug($"Selected stores ({result.Count}): " + string.Join(' ', result));
        return result;
    }

    private static bool NeedLookup(string contentId)
    {
        using var db = new ThumbnailDb();
        if (db.Thumbnail.FirstOrDefault(t => t.ContentId == contentId) is Thumbnail thumbnail)
            if (!string.IsNullOrEmpty(thumbnail.Url))
                if (ScrapeStateProvider.IsFresh(new DateTime(thumbnail.Timestamp, DateTimeKind.Utc)))
                    return false;
        return true;
    }

    private static async Task ProcessIncludedGamesAsync(string locale, Container container, CancellationToken cancellationToken, bool resolveCrossplay = true)
    {
        if (container.Included?.Length > 0)
            foreach (var item in container.Included)
            {
                if (cancellationToken.IsCancellationRequested)
                    return;

                switch (item.Type)
                {
                    case "game":
                    case "game-related":
                        if (string.IsNullOrEmpty(item.Id))
                            continue;

                        await AddOrUpdateThumbnailAsync(item.Id, item.Attributes?.Name, item.Attributes?.ThumbnailUrlBase, cancellationToken).ConfigureAwait(false);
                        break;

                    case "legacy-sku":
                        if (!resolveCrossplay)
                            continue;

                        var relatedSkus = (item.Attributes?.Eligibilities ?? Enumerable.Empty<GameSkuRelation>())
                            .Concat(item.Attributes?.Entitlements ?? Enumerable.Empty<GameSkuRelation>())
                            .Select(sku => sku.Id)
                            .Distinct()
                            .Where(id => ProductCodeLookup.ProductCode.IsMatch(id) && NeedLookup(id))
                            .ToList();
                        foreach (var relatedSku in relatedSkus)
                        {
                            var relatedContainer = await Client.ResolveContentAsync(locale, relatedSku, 1, cancellationToken).ConfigureAwait(false);
                            if (relatedContainer != null)
                                await ProcessIncludedGamesAsync(locale, relatedContainer, cancellationToken, false).ConfigureAwait(false);
                        }
                        break;
                }
            }
    }

    private static async Task AddOrUpdateThumbnailAsync(string contentId, string? name, string? url, CancellationToken cancellationToken)
    {
        var match = ContentIdMatcher.Match(contentId);
        if (!match.Success)
            return;

        var productCode = match.Groups["product_id"].Value;
        if (!ProductCodeLookup.ProductCode.IsMatch(productCode))
            return;

        name = string.IsNullOrEmpty(name) ? null : name;
        await using var db = new ThumbnailDb();
        var savedItem = db.Thumbnail.FirstOrDefault(t => t.ProductCode == productCode);
        if (savedItem == null)
        {
            var newItem = new Thumbnail
            {
                ProductCode = productCode,
                ContentId = contentId,
                Name = name,
                Url = url,
                Timestamp = DateTime.UtcNow.Ticks,
            };
            await db.Thumbnail.AddAsync(newItem, cancellationToken).ConfigureAwait(false);
        }
        else if (!string.IsNullOrEmpty(url))
        {
            if (string.IsNullOrEmpty(savedItem.Url))
                savedItem.Url = url;
            if (string.IsNullOrEmpty(savedItem.Name) && !string.IsNullOrEmpty(name))
                savedItem.Name = name;
            if (!ScrapeStateProvider.IsFresh(savedItem.Timestamp))
            {
                if (savedItem.Url != url)
                {
                    savedItem.Url = url;
                    savedItem.EmbeddableUrl = null;
                }
                if (name != null && savedItem.Name != name)
                    savedItem.Name = name;
            }
            savedItem.ContentId = contentId;
            savedItem.Timestamp = DateTime.UtcNow.Ticks;
        }
        await db.SaveChangesAsync(cancellationToken).ConfigureAwait(false);
    }

    private static async Task ScrapeContainerIdsAsync(string locale, string containerId, HashSet<string> knownContainerIds, CancellationToken cancellationToken)
    {
        if (cancellationToken.IsCancellationRequested)
            return;

        if (string.IsNullOrEmpty(containerId))
            return;

        if (!knownContainerIds.Add(containerId))
            return;

        var navigation = await Client.GetStoreNavigationAsync(locale, containerId, cancellationToken).ConfigureAwait(false);
        if (navigation?.Data?.Attributes?.Navigation is StoreNavigationNavigation[] navs)
        {
            foreach (var nav in navs)
            {
                await ScrapeContainerIdsAsync(locale, nav.Id, knownContainerIds, cancellationToken).ConfigureAwait(false);
                if (nav.Submenu is StoreNavigationSubmenu[] submenus)
                    foreach (var submenu in submenus)
                        if (submenu.Items is StoreNavigationSubmenuItem[] items)
                            foreach (var item in items)
                                if (!item.IsSeparator && !string.IsNullOrEmpty(item.TargetContainerId))
                                {
                                    if (cancellationToken.IsCancellationRequested)
                                        return;

                                    await ScrapeContainerIdsAsync(locale, item.TargetContainerId, knownContainerIds, cancellationToken).ConfigureAwait(false);
                                }
            }
        }
        if (navigation?.Data?.Relationships?.Children?.Data is RelationshipsChildrenItem[] childItems)
            foreach (var item in childItems.Where(i => i.Type == "container"))
            {
                if (cancellationToken.IsCancellationRequested)
                    return;

                await ScrapeContainerIdsAsync(locale, item.Id, knownContainerIds, cancellationToken).ConfigureAwait(false);
            }
    }

    private static void PrintError(Exception e)
        => Config.Log.Error(e, "Error scraping thumbnails");
}