using StitcherApi.Models;
using StitcherApi.Services.Utilities;

namespace StitcherApi.Services;

public class ImageService : IImageService
{
    private readonly ImageProcessor _processor;
    private const int TILE_SIZE = 720;

    public ImageService(IConfiguration configuration)
    {
        string assetPath =
            configuration["AssetPath"]
            ?? throw new InvalidOperationException("AssetPath is not configured.");
        _processor = new ImageProcessor(assetPath);
    }

    public async Task<byte[]> GenerateImageAsync(GenerateImageRequest request)
    {
        // 1. Delegate parsing to the CoordinateParser
        var (minRow, minCol, maxRow, maxCol) = CoordinateParser.ParseCanvasRect(request.CanvasRect);

        // 2. Perform high-level calculations
        var stitchedCanvasWidth = (maxCol - minCol + 1) * TILE_SIZE;
        var stitchedCanvasHeight = (maxRow - minRow + 1) * TILE_SIZE;

        int cropX = (int)(request.CropOffset[0] * stitchedCanvasWidth);
        int cropY = (int)(request.CropOffset[1] * stitchedCanvasHeight);
        int cropW = (int)(request.CropSize[0] * stitchedCanvasWidth);
        int cropH = (int)(request.CropSize[1] * stitchedCanvasHeight);

        if (cropW <= 0 || cropH <= 0)
        {
            throw new ArgumentException("Calculated crop dimensions are invalid.");
        }

        var startTileCol = minCol + (cropX / TILE_SIZE);
        var endTileCol = minCol + ((cropX + cropW - 1) / TILE_SIZE);
        var startTileRow = minRow + (cropY / TILE_SIZE);
        var endTileRow = minRow + ((cropY + cropH - 1) / TILE_SIZE);

        // 3. Create a parameter object for the processor
        var stitchRequest = new StitchRequest(
            minRow,
            minCol,
            startTileRow,
            startTileCol,
            endTileRow,
            endTileCol,
            cropX,
            cropY,
            cropW,
            cropH,
            request.OutputScale
        );

        // 4. Delegate image processing work
        return await _processor.StitchAndCropAsync(stitchRequest);
    }
}