using System.Diagnostics;
using Dapper;
using Microsoft.Extensions.Logging;
using Npgsql;
using SatelliteProvider.Common.Configs;
using SatelliteProvider.Common.Utils;
using SatelliteProvider.DataAccess.Models;

namespace SatelliteProvider.DataAccess.Repositories;

public class TileRepository : ITileRepository
{
    private const int SlowQueryThresholdMs = 500;

    private const string ColumnList = @"id, tile_zoom as TileZoom, tile_x as TileX, tile_y as TileY,
                   latitude, longitude,
                   tile_size_meters as TileSizeMeters, tile_size_pixels as TileSizePixels,
                   image_type as ImageType, maps_version as MapsVersion, version,
                   file_path as FilePath, source, captured_at as CapturedAt,
                   created_at as CreatedAt, updated_at as UpdatedAt,
                   flight_id as FlightId, location_hash as LocationHash,
                   content_sha256 as ContentSha256, legacy_id as LegacyId";

    private readonly string _connectionString;
    private readonly ILogger<TileRepository> _logger;

    public TileRepository(string connectionString, ILogger<TileRepository> logger)
    {
        _connectionString = connectionString;
        _logger = logger;
    }

    public async Task<TileEntity?> GetByIdAsync(Guid id)
    {
        using var connection = new NpgsqlConnection(_connectionString);
        const string sql = $@"
            SELECT {ColumnList}
            FROM tiles
            WHERE id = @Id";

        return await connection.QuerySingleOrDefaultAsync<TileEntity>(sql, new { Id = id });
    }

    public async Task<TileEntity?> GetByTileCoordinatesAsync(int tileZoom, int tileX, int tileY)
    {
        using var connection = new NpgsqlConnection(_connectionString);
        // AZ-505 read-rewrite: filter by `location_hash` so the new
        // `tiles_leaflet_path` covering index drives the scan. Selection rule
        // is unchanged from AZ-484: most-recent across sources/flights with
        // deterministic tie-break on (captured_at DESC, updated_at DESC, id DESC).
        // Heap fetch is unavoidable here (the column list spans columns not in
        // the index INCLUDE list); the slim `SELECT file_path` Leaflet hot path
        // — which is what AC-3 measures — is index-only-scannable.
        var locationHash = Uuidv5.LocationHashForTile(tileZoom, tileX, tileY);
        const string sql = $@"
            SELECT {ColumnList}
            FROM tiles
            WHERE location_hash = @LocationHash
            ORDER BY captured_at DESC, updated_at DESC, id DESC
            LIMIT 1";

        return await connection.QuerySingleOrDefaultAsync<TileEntity>(sql, new { LocationHash = locationHash });
    }

    public async Task<IReadOnlyDictionary<Guid, TileEntity>> GetTilesByLocationHashesAsync(IReadOnlyList<Guid> locationHashes)
    {
        ArgumentNullException.ThrowIfNull(locationHashes);
        if (locationHashes.Count == 0)
        {
            return new Dictionary<Guid, TileEntity>();
        }

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

        // AZ-505: one-row-per-hash bulk lookup. `DISTINCT ON (location_hash)`
        // collapses the per-(z, x, y) cell to its most-recent variant across
        // sources/flights using the same tie-break as AZ-484. Caller dedupes
        // input + re-aligns response order; this query returns at most one
        // row per distinct hash.
        //
        // The query is intentionally NOT routed through Dapper: Dapper's
        // parameter expander rewrites any IEnumerable parameter (including
        // `Guid[]`) into `(@p0, @p1, ...)`, which would turn `ANY(@p)` into
        // `ANY((@p0, @p1, ...))` and break the SQL. Using NpgsqlParameter with
        // `Array | Uuid` lets Npgsql bind the array as a single `uuid[]`,
        // which is the form the AZ-505 spec query expects.
        const string sql = @"
            SELECT id, tile_zoom AS TileZoom, tile_x AS TileX, tile_y AS TileY,
                   latitude, longitude,
                   tile_size_meters AS TileSizeMeters, tile_size_pixels AS TileSizePixels,
                   image_type AS ImageType, maps_version AS MapsVersion, version,
                   file_path AS FilePath, source, captured_at AS CapturedAt,
                   created_at AS CreatedAt, updated_at AS UpdatedAt,
                   flight_id AS FlightId, location_hash AS LocationHash,
                   content_sha256 AS ContentSha256, legacy_id AS LegacyId
            FROM (
                SELECT DISTINCT ON (location_hash)
                       id, tile_zoom, tile_x, tile_y,
                       latitude, longitude,
                       tile_size_meters, tile_size_pixels,
                       image_type, maps_version, version,
                       file_path, source, captured_at,
                       created_at, updated_at,
                       flight_id, location_hash,
                       content_sha256, legacy_id
                FROM tiles
                WHERE location_hash = ANY(@LocationHashes)
                ORDER BY location_hash, captured_at DESC, updated_at DESC, id DESC
            ) most_recent";

        var distinctHashes = locationHashes.Distinct().ToArray();

        await using var cmd = new NpgsqlCommand(sql, connection);
        var arrayParam = new NpgsqlParameter("LocationHashes", NpgsqlTypes.NpgsqlDbType.Array | NpgsqlTypes.NpgsqlDbType.Uuid)
        {
            Value = distinctHashes
        };
        cmd.Parameters.Add(arrayParam);

        var stopwatch = Stopwatch.StartNew();
        var rows = new Dictionary<Guid, TileEntity>(distinctHashes.Length);
        await using (var reader = await cmd.ExecuteReaderAsync())
        {
            while (await reader.ReadAsync())
            {
                var tile = new TileEntity
                {
                    Id = reader.GetGuid(0),
                    TileZoom = reader.GetInt32(1),
                    TileX = reader.GetInt32(2),
                    TileY = reader.GetInt32(3),
                    Latitude = reader.GetDouble(4),
                    Longitude = reader.GetDouble(5),
                    TileSizeMeters = reader.GetDouble(6),
                    TileSizePixels = reader.GetInt32(7),
                    ImageType = reader.GetString(8),
                    MapsVersion = reader.IsDBNull(9) ? null : reader.GetString(9),
                    Version = reader.IsDBNull(10) ? null : reader.GetInt32(10),
                    FilePath = reader.GetString(11),
                    Source = reader.GetString(12),
                    CapturedAt = reader.GetDateTime(13),
                    CreatedAt = reader.GetDateTime(14),
                    UpdatedAt = reader.GetDateTime(15),
                    FlightId = reader.IsDBNull(16) ? null : reader.GetGuid(16),
                    LocationHash = reader.GetGuid(17),
                    ContentSha256 = reader.IsDBNull(18) ? null : (byte[])reader.GetValue(18),
                    LegacyId = reader.IsDBNull(19) ? null : reader.GetGuid(19)
                };
                rows[tile.LocationHash] = tile;
            }
        }
        stopwatch.Stop();

        if (stopwatch.ElapsedMilliseconds > SlowQueryThresholdMs)
        {
            _logger.LogWarning(
                "Slow GetTilesByLocationHashesAsync: {ElapsedMs} ms (threshold {ThresholdMs} ms) for {RequestedHashes} requested ({DistinctHashes} distinct) hashes",
                stopwatch.ElapsedMilliseconds, SlowQueryThresholdMs, locationHashes.Count, distinctHashes.Length);
        }

        return rows;
    }

    public async Task<IEnumerable<TileEntity>> GetTilesByRegionAsync(double latitude, double longitude, double sizeMeters, int zoomLevel)
    {
        using var connection = new NpgsqlConnection(_connectionString);

        var latRad = latitude * Math.PI / 180.0;
        var metersPerPixel = (GeoUtils.EarthEquatorialCircumferenceMeters * Math.Cos(latRad)) / (Math.Pow(2, zoomLevel) * MapConfig.DefaultTileSizePixels);
        var tileSizeMeters = metersPerPixel * MapConfig.DefaultTileSizePixels;

        var expandedSizeMeters = sizeMeters + (tileSizeMeters * 2);

        var latRange = expandedSizeMeters / GeoUtils.MetersPerDegreeLatitude;
        var lonRange = expandedSizeMeters / (GeoUtils.MetersPerDegreeLatitude * Math.Cos(latitude * Math.PI / 180.0));

        // AZ-484 selection rule: at most one row per (lat, lon, zoom, size) cell, picking
        // the most-recent across sources via DISTINCT ON, with deterministic tie-break on
        // (captured_at DESC, updated_at DESC, id DESC). The outer ORDER BY restores the
        // pre-AZ-484 caller-facing order (latitude DESC, longitude ASC); the pre-AZ-484
        // updated_at DESC tiebreak is unreachable here because DISTINCT ON already
        // guarantees one row per (latitude, longitude, ...) tuple.
        const string sql = $@"
            SELECT * FROM (
                SELECT DISTINCT ON (latitude, longitude, tile_zoom, tile_size_meters)
                       {ColumnList}
                FROM tiles
                WHERE latitude BETWEEN @MinLat AND @MaxLat
                  AND longitude BETWEEN @MinLon AND @MaxLon
                  AND tile_zoom = @TileZoom
                ORDER BY latitude, longitude, tile_zoom, tile_size_meters,
                         captured_at DESC, updated_at DESC, id DESC
            ) deduped
            ORDER BY latitude DESC, longitude ASC";

        var stopwatch = Stopwatch.StartNew();
        var tiles = await connection.QueryAsync<TileEntity>(sql, new
        {
            MinLat = latitude - latRange / 2,
            MaxLat = latitude + latRange / 2,
            MinLon = longitude - lonRange / 2,
            MaxLon = longitude + lonRange / 2,
            TileZoom = zoomLevel
        });
        stopwatch.Stop();

        if (stopwatch.ElapsedMilliseconds > SlowQueryThresholdMs)
        {
            _logger.LogWarning(
                "Slow GetTilesByRegionAsync: {ElapsedMs} ms (threshold {ThresholdMs} ms) for lat={Latitude}, lon={Longitude}, sizeMeters={SizeMeters}, zoom={ZoomLevel}",
                stopwatch.ElapsedMilliseconds, SlowQueryThresholdMs, latitude, longitude, sizeMeters, zoomLevel);
        }

        return tiles;
    }

    public async Task<Guid> InsertAsync(TileEntity tile)
    {
        using var connection = new NpgsqlConnection(_connectionString);
        // AZ-503: integer-keyed UPSERT with per-flight separation. The conflict key
        // is (tile_zoom, tile_x, tile_y, tile_size_meters, source, COALESCE(flight_id, '00...0')).
        // Two UAV flights uploading the same (z, x, y) cell coexist as distinct rows
        // because their flight_id values differ; legacy/google_maps rows collapse on
        // the zero-UUID coalesce, preserving AZ-484 single-row-per-cell semantics for
        // those producers. Float-based latitude/longitude is no longer part of the key
        // so independently-rounded center coords always converge on the same row.
        //
        // `id` is deliberately NOT updated on conflict — legacy random ids and AZ-503
        // deterministic ids both stay stable, matching AC-2 ("the `id` column is not
        // regenerated").
        const string sql = @"
            INSERT INTO tiles (id, tile_zoom, tile_x, tile_y, latitude, longitude, tile_size_meters,
                             tile_size_pixels, image_type, maps_version, version, file_path,
                             source, captured_at, created_at, updated_at,
                             flight_id, location_hash, content_sha256, legacy_id)
            VALUES (@Id, @TileZoom, @TileX, @TileY, @Latitude, @Longitude, @TileSizeMeters,
                    @TileSizePixels, @ImageType, @MapsVersion, @Version, @FilePath,
                    @Source, @CapturedAt, @CreatedAt, @UpdatedAt,
                    @FlightId, @LocationHash, @ContentSha256, @LegacyId)
            ON CONFLICT (tile_zoom, tile_x, tile_y, tile_size_meters, source,
                         COALESCE(flight_id, '00000000-0000-0000-0000-000000000000'::uuid))
            DO UPDATE SET
                file_path = EXCLUDED.file_path,
                latitude = EXCLUDED.latitude,
                longitude = EXCLUDED.longitude,
                captured_at = EXCLUDED.captured_at,
                updated_at = EXCLUDED.updated_at,
                content_sha256 = EXCLUDED.content_sha256
            RETURNING id";

        return await connection.ExecuteScalarAsync<Guid>(sql, tile);
    }

    public async Task<int> UpdateAsync(TileEntity tile)
    {
        using var connection = new NpgsqlConnection(_connectionString);
        const string sql = @"
            UPDATE tiles
            SET tile_zoom = @TileZoom,
                tile_x = @TileX,
                tile_y = @TileY,
                latitude = @Latitude,
                longitude = @Longitude,
                tile_size_meters = @TileSizeMeters,
                tile_size_pixels = @TileSizePixels,
                image_type = @ImageType,
                maps_version = @MapsVersion,
                version = @Version,
                file_path = @FilePath,
                source = @Source,
                captured_at = @CapturedAt,
                updated_at = @UpdatedAt,
                flight_id = @FlightId,
                location_hash = @LocationHash,
                content_sha256 = @ContentSha256
            WHERE id = @Id";

        return await connection.ExecuteAsync(sql, tile);
    }

    public async Task<int> DeleteAsync(Guid id)
    {
        using var connection = new NpgsqlConnection(_connectionString);
        const string sql = "DELETE FROM tiles WHERE id = @Id";
        return await connection.ExecuteAsync(sql, new { Id = id });
    }
}