using BlueLaminate.EFCore.Data;
using BlueLaminate.EFCore.Entities;
using BlueLaminate.Scraper.Weapons;
using Microsoft.EntityFrameworkCore;

namespace BlueLaminate.Cli;

/// <param name="Skipped">True when the monthly throttle suppressed the run.</param>
/// <param name="LastRanAt">When the previous successful run happened, if any.</param>
public sealed record WeaponSyncResult(
    bool Skipped,
    DateTimeOffset? LastRanAt,
    int Scraped,
    int Inserted,
    int Updated);

/// <summary>
/// Fetches the CS2 weapon catalogue and upserts it into the database. The
/// catalogue changes rarely, so a run is throttled to at most once a month
/// unless explicitly forced.
/// </summary>
public sealed class WeaponSyncService
{
    public const string Source = "weapons";

    private readonly SkinTrackerDbContext _db;
    private readonly WeaponWikiScraper _scraper;

    public WeaponSyncService(SkinTrackerDbContext db, WeaponWikiScraper scraper)
    {
        _db = db;
        _scraper = scraper;
    }

    public async Task<WeaponSyncResult> SyncAsync(bool force = false, CancellationToken ct = default)
    {
        var now = DateTimeOffset.UtcNow;

        var lastRanAt = await _db.ScrapeRuns
            .Where(r => r.Source == Source)
            .OrderByDescending(r => r.RanAt)
            .Select(r => (DateTimeOffset?)r.RanAt)
            .FirstOrDefaultAsync(ct);

        if (!force && lastRanAt is { } last && last.AddMonths(1) > now)
            return new WeaponSyncResult(Skipped: true, last, Scraped: 0, Inserted: 0, Updated: 0);

        var scraped = await _scraper.ScrapeAsync(ct);

        var existing = await _db.Weapons.ToDictionaryAsync(w => w.Name, ct);
        var inserted = 0;
        var updated = 0;

        foreach (var s in scraped)
        {
            if (existing.TryGetValue(s.Name, out var weapon))
            {
                if (weapon.Type != s.Type || weapon.Team != s.Team)
                {
                    weapon.Type = s.Type;
                    weapon.Team = s.Team;
                    updated++;
                }
            }
            else
            {
                _db.Weapons.Add(new Weapon { Name = s.Name, Type = s.Type, Team = s.Team });
                inserted++;
            }
        }

        _db.ScrapeRuns.Add(new ScrapeRun { Source = Source, RanAt = now, ItemCount = scraped.Count });
        await _db.SaveChangesAsync(ct);

        return new WeaponSyncResult(Skipped: false, lastRanAt, scraped.Count, inserted, updated);
    }
}