using Backend.Interface;
using Npgsql;

namespace Backend.DatabaseHandler
{
	public sealed class PostgresNewsSentimentStore : INewsSentimentStore
	{
		private readonly string _connectionString;

		public PostgresNewsSentimentStore(IConfiguration configuration)
		{
			_connectionString = configuration.GetConnectionString("MarketDataDb")
				?? throw new InvalidOperationException("Missing connection string: MarketDataDb");
		}

		public async Task<List<NewsSentimentRecord>> GetByKeywordAsync(
			string keyword,
			CancellationToken cancellationToken = default)
		{
			var results = new List<NewsSentimentRecord>();

			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			const string sql = """
				SELECT source, keyword, published_at, title, score,
						sentiment_label, title_hash, publisher, url
				FROM news_sentiment_cache
				WHERE keyword = @keyword
				ORDER BY published_at DESC;
				""";

			await using var cmd = new NpgsqlCommand(sql, conn);
			cmd.Parameters.AddWithValue("keyword", keyword);

			await using var reader = await cmd.ExecuteReaderAsync(cancellationToken);
			while (await reader.ReadAsync(cancellationToken))
			{
				results.Add(new NewsSentimentRecord
				{
					Source = reader.GetString(0),
					Keyword = reader.GetString(1),
					PublishedAt = reader.GetFieldValue<DateTimeOffset>(2),
					Title = reader.GetString(3),
					Score = reader.GetDouble(4),
					SentimentLabel = reader.GetString(5),
					TitleHash = reader.GetString(6).TrimEnd(),
					Publisher = reader.GetString(7),
					Url = reader.GetString(8)
				});
			}

			return results;
		}

		public async Task<List<NewsSentimentRecord>> GetFeedAsync(
			IEnumerable<string> keywords,
			int limit,
			CancellationToken cancellationToken = default)
		{
			var keywordList = keywords.ToList();
			if (keywordList.Count == 0)
				return [];

			var results = new List<NewsSentimentRecord>();

			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			const string sql = """
				SELECT source, keyword, published_at, title, score,
						sentiment_label, title_hash, publisher, url
				FROM news_sentiment_cache
				WHERE keyword = ANY(@keywords)
				ORDER BY published_at DESC
				LIMIT @limit;
				""";

			await using var cmd = new NpgsqlCommand(sql, conn);
			cmd.Parameters.AddWithValue("keywords", keywordList.ToArray());
			cmd.Parameters.AddWithValue("limit", limit);

			await using var reader = await cmd.ExecuteReaderAsync(cancellationToken);
			while (await reader.ReadAsync(cancellationToken))
			{
				results.Add(new NewsSentimentRecord
				{
					Source = reader.GetString(0),
					Keyword = reader.GetString(1),
					PublishedAt = reader.GetFieldValue<DateTimeOffset>(2),
					Title = reader.GetString(3),
					Score = reader.GetDouble(4),
					SentimentLabel = reader.GetString(5),
					TitleHash = reader.GetString(6).TrimEnd(),
					Publisher = reader.GetString(7),
					Url = reader.GetString(8)
				});
			}

			return results;
		}

		public async Task InsertAsync(
			IEnumerable<NewsSentimentRecord> records,
			CancellationToken cancellationToken = default)
		{
			var recordList = records.ToList();
			if (recordList.Count == 0)
				return;

			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			await using var tx = await conn.BeginTransactionAsync(cancellationToken);

			const string sql = """
				INSERT INTO news_sentiment_cache
				(source, keyword, published_at, title, score,
				 sentiment_label, title_hash, publisher, url)
				VALUES
				(@source, @keyword, @published_at, @title, @score,
				 @sentiment_label, @title_hash, @publisher, @url)
				ON CONFLICT (title_hash) DO NOTHING;
				""";

			foreach (var record in recordList)
			{
				await using var cmd = new NpgsqlCommand(sql, conn, tx);
				cmd.Parameters.AddWithValue("source", record.Source);
				cmd.Parameters.AddWithValue("keyword", record.Keyword);
				cmd.Parameters.AddWithValue("published_at", record.PublishedAt);
				cmd.Parameters.AddWithValue("title", record.Title);
				cmd.Parameters.AddWithValue("score", record.Score);
				cmd.Parameters.AddWithValue("sentiment_label", record.SentimentLabel);
				cmd.Parameters.AddWithValue("title_hash", record.TitleHash);
				cmd.Parameters.AddWithValue("publisher", record.Publisher);
				cmd.Parameters.AddWithValue("url", record.Url);

				await cmd.ExecuteNonQueryAsync(cancellationToken);
			}

			await tx.CommitAsync(cancellationToken);
		}

		public async Task<HashSet<string>> GetExistingHashesAsync(
			string keyword,
			CancellationToken cancellationToken = default)
		{
			var hashes = new HashSet<string>();

			await using var conn = new NpgsqlConnection(_connectionString);
			await conn.OpenAsync(cancellationToken);

			const string sql = """
				SELECT title_hash
				FROM news_sentiment_cache
				WHERE keyword = @keyword;
				""";

			await using var cmd = new NpgsqlCommand(sql, conn);
			cmd.Parameters.AddWithValue("keyword", keyword);

			await using var reader = await cmd.ExecuteReaderAsync(cancellationToken);
			while (await reader.ReadAsync(cancellationToken))
			{
				hashes.Add(reader.GetString(0).TrimEnd());
			}

			return hashes;
		}
	}
}