using LocationsApi.Models;
using MongoDB.Driver;

namespace LocationsApi.Services;

public class ResourceService
{
    private readonly IMongoCollection<PlayerResources> _resources;
    private readonly int _startingGold;
    private readonly int _headquartersGoldPerMinute;

    public ResourceService(IConfiguration cfg)
    {
        var connectionString = cfg["MongoDB:ConnectionString"] ?? "mongodb://127.0.0.1:27017";
        var databaseName = cfg["MongoDB:DatabaseName"] ?? "territory-autobattler";
        var client = new MongoClient(connectionString);
        var database = client.GetDatabase(databaseName);
        _resources = database.GetCollection<PlayerResources>("PlayerResources");
        _startingGold = int.TryParse(cfg["Resources:StartingGold"], out var startingGold) ? Math.Max(0, startingGold) : 100;
        _headquartersGoldPerMinute = int.TryParse(cfg["Resources:HeadquartersGoldPerMinute"], out var goldPerMinute)
            ? Math.Max(0, goldPerMinute)
            : 10;

        _resources.Indexes.CreateOne(new CreateIndexModel<PlayerResources>(
            Builders<PlayerResources>.IndexKeys.Ascending(x => x.Username),
            new CreateIndexOptions { Unique = true }));
    }

    public async Task<PlayerResources> EnsureAsync(string username)
    {
        var now = DateTime.UtcNow;
        var update = Builders<PlayerResources>.Update
            .SetOnInsert(x => x.Username, username)
            .SetOnInsert(x => x.Gold, _startingGold)
            .SetOnInsert(x => x.CreatedAtUtc, now)
            .SetOnInsert(x => x.LastGoldGeneratedAtUtc, now)
            .Set(x => x.GoldPerMinute, _headquartersGoldPerMinute)
            .Set(x => x.UpdatedAtUtc, now);

        var resources = await _resources.FindOneAndUpdateAsync(
            x => x.Username == username,
            update,
            new FindOneAndUpdateOptions<PlayerResources>
            {
                IsUpsert = true,
                ReturnDocument = ReturnDocument.After
            });

        return await ApplyGoldGenerationAsync(resources);
    }

    public async Task<PlayerResources> GetAsync(string username)
    {
        var resources = await EnsureAsync(username);
        return await ApplyGoldGenerationAsync(resources);
    }

    private async Task<PlayerResources> ApplyGoldGenerationAsync(PlayerResources resources)
    {
        if (resources.GoldPerMinute <= 0)
        {
            return resources;
        }

        var now = DateTime.UtcNow;
        var elapsed = now - resources.LastGoldGeneratedAtUtc;
        var elapsedMinutes = (int)Math.Floor(elapsed.TotalMinutes);
        if (elapsedMinutes <= 0)
        {
            return resources;
        }

        var generatedGold = elapsedMinutes * resources.GoldPerMinute;
        var generationTimestamp = resources.LastGoldGeneratedAtUtc.AddMinutes(elapsedMinutes);
        var update = Builders<PlayerResources>.Update
            .Inc(x => x.Gold, generatedGold)
            .Set(x => x.GoldPerMinute, _headquartersGoldPerMinute)
            .Set(x => x.LastGoldGeneratedAtUtc, generationTimestamp)
            .Set(x => x.UpdatedAtUtc, now);

        return await _resources.FindOneAndUpdateAsync(
            x => x.Username == resources.Username,
            update,
            new FindOneAndUpdateOptions<PlayerResources>
            {
                ReturnDocument = ReturnDocument.After
            });
    }
}