using System.Drawing;
using System.Drawing.Imaging;
using System.Runtime.InteropServices;
using Poe2Trade.Core;
using OpenCvSharp.Extensions;
using Serilog;
using Region = Poe2Trade.Core.Region;

namespace Poe2Trade.Screen;

public class ScreenReader : IScreenReader
{
    private readonly DiffCropHandler _diffCrop = new();
    private readonly GridHandler _gridHandler = new();
    private readonly TemplateMatchHandler _templateMatch = new();
    private readonly EdgeCropHandler _edgeCrop = new();
    private readonly PythonOcrBridge _pythonBridge = new();
    private bool _initialized;

    public GridReader Grid { get; }

    public ScreenReader()
    {
        Grid = new GridReader(_gridHandler);
    }

    public Task Warmup()
    {
        if (!_initialized)
        {
            ScreenCapture.InitDpiAwareness();
            _initialized = true;
        }
        return Task.CompletedTask;
    }

    // -- Capture --

    public Task<byte[]> CaptureScreen()
    {
        return Task.FromResult(_diffCrop.HandleCapture());
    }

    public Task<byte[]> CaptureRegion(Region region)
    {
        return Task.FromResult(_diffCrop.HandleCapture(region));
    }

    // -- OCR --

    public Task<OcrResponse> Ocr(Region? region = null, string? preprocess = null)
    {
        using var bitmap = ScreenCapture.CaptureOrLoad(null, region);

        if (preprocess == "tophat")
        {
            using var processed = ImagePreprocessor.PreprocessForOcr(bitmap);
            return Task.FromResult(_pythonBridge.OcrFromBitmap(processed));
        }

        if (preprocess == "clahe")
        {
            using var processed = ImagePreprocessor.PreprocessClahe(bitmap);
            return Task.FromResult(_pythonBridge.OcrFromBitmap(processed));
        }

        return Task.FromResult(_pythonBridge.OcrFromBitmap(bitmap));
    }

    public async Task<(int X, int Y)?> FindTextOnScreen(string searchText, bool fuzzy = false)
    {
        var result = await Ocr();
        var pos = FindWordInOcrResult(result, searchText, fuzzy);
        if (pos.HasValue)
            Log.Information("Found text '{Text}' at ({X},{Y})", searchText, pos.Value.X, pos.Value.Y);
        else
            Log.Information("Text '{Text}' not found on screen", searchText);
        return pos;
    }

    public async Task<string> ReadFullScreen()
    {
        var result = await Ocr();
        return result.Text;
    }

    public async Task<(int X, int Y)?> FindTextInRegion(Region region, string searchText)
    {
        var result = await Ocr(region);
        var pos = FindWordInOcrResult(result, searchText);
        if (pos.HasValue)
            return (region.X + pos.Value.X, region.Y + pos.Value.Y);
        return null;
    }

    public async Task<string> ReadRegionText(Region region)
    {
        var result = await Ocr(region);
        return result.Text;
    }

    public async Task<bool> CheckForText(Region region, string searchText)
    {
        var pos = await FindTextInRegion(region, searchText);
        return pos.HasValue;
    }

    // -- Snapshot / Diff OCR --

    public Task Snapshot()
    {
        _diffCrop.HandleSnapshot();
        return Task.CompletedTask;
    }

    public Task<DiffOcrResponse> DiffOcr(string? savePath = null, Region? region = null)
    {
        var p = new DiffOcrParams();
        var cropResult = _diffCrop.DiffCrop(p.Crop, region: region);
        if (cropResult == null)
            return Task.FromResult(new DiffOcrResponse { Text = "", Lines = [] });

        var (cropped, refCropped, current, cropRegion) = cropResult.Value;
        using var _current = current;
        using var _cropped = cropped;
        using var _refCropped = refCropped;

        // Save raw crop if path is provided
        if (!string.IsNullOrEmpty(savePath))
        {
            var dir = Path.GetDirectoryName(savePath);
            if (!string.IsNullOrEmpty(dir) && !Directory.Exists(dir))
                Directory.CreateDirectory(dir);
            cropped.Save(savePath, ImageUtils.GetImageFormat(savePath));
        }

        // Preprocess with background subtraction
        var ocr = p.Ocr;
        using var processedBmp = ocr.UseBackgroundSub
            ? ImagePreprocessor.PreprocessWithBackgroundSub(cropped, refCropped, ocr.DimPercentile, ocr.TextThresh, 1, ocr.SoftThreshold)
            : ImagePreprocessor.PreprocessForOcr(cropped, ocr.KernelSize, 1);

        var ocrResult = _pythonBridge.OcrFromBitmap(processedBmp, ocr);

        // Offset coordinates to screen space
        foreach (var line in ocrResult.Lines)
            foreach (var word in line.Words)
            {
                word.X += cropRegion.X;
                word.Y += cropRegion.Y;
            }

        return Task.FromResult(new DiffOcrResponse
        {
            Text = ocrResult.Text,
            Lines = ocrResult.Lines,
            Region = cropRegion,
        });
    }

    // -- Template matching --

    public Task<TemplateMatchResult?> TemplateMatch(string templatePath, Region? region = null)
    {
        var result = _templateMatch.Match(templatePath, region);
        if (result != null)
            Log.Information("Template match found: ({X},{Y}) confidence={Conf:F3}", result.X, result.Y, result.Confidence);
        return Task.FromResult(result);
    }

    // -- Save --

    public Task SaveScreenshot(string path)
    {
        _diffCrop.HandleScreenshot(path);
        return Task.CompletedTask;
    }

    public Task SaveRegion(Region region, string path)
    {
        _diffCrop.HandleScreenshot(path, region);
        return Task.CompletedTask;
    }

    // -- Nameplate diff OCR --

    public Bitmap CaptureRawBitmap() => ScreenCapture.CaptureOrLoad(null, null);

    public Task<OcrResponse> NameplateDiffOcr(Bitmap reference, Bitmap current)
    {
        int w = Math.Min(reference.Width, current.Width);
        int h = Math.Min(reference.Height, current.Height);

        var refData = reference.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
        var curData = current.LockBits(new Rectangle(0, 0, w, h), ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
        byte[] refPx = new byte[refData.Stride * h];
        byte[] curPx = new byte[curData.Stride * h];
        Marshal.Copy(refData.Scan0, refPx, 0, refPx.Length);
        Marshal.Copy(curData.Scan0, curPx, 0, curPx.Length);
        int stride = refData.Stride;
        reference.UnlockBits(refData);
        current.UnlockBits(curData);

        // Build a binary mask of pixels that got significantly brighter (nameplates are bright text)
        const int brightThresh = 30;
        bool[] mask = new bool[w * h];
        Parallel.For(0, h, y =>
        {
            int rowOff = y * stride;
            for (int x = 0; x < w; x++)
            {
                int i = rowOff + x * 4;
                int brighter = (curPx[i] - refPx[i]) + (curPx[i + 1] - refPx[i + 1]) + (curPx[i + 2] - refPx[i + 2]);
                if (brighter > brightThresh)
                    mask[y * w + x] = true;
            }
        });

        // Find connected clusters via row-scan: collect bounding boxes of bright regions
        var boxes = FindBrightClusters(mask, w, h, minWidth: 40, minHeight: 10, maxGap: 8);
        Log.Information("NameplateDiff: found {Count} bright clusters", boxes.Count);

        if (boxes.Count == 0)
            return Task.FromResult(new OcrResponse { Text = "", Lines = [] });

        // OCR each cluster crop, accumulate results with screen-space coordinates
        var allLines = new List<OcrLine>();
        var allText = new List<string>();

        foreach (var box in boxes)
        {
            // Pad the crop slightly
            int pad = 4;
            int cx = Math.Max(0, box.X - pad);
            int cy = Math.Max(0, box.Y - pad);
            int cw = Math.Min(w - cx, box.Width + pad * 2);
            int ch = Math.Min(h - cy, box.Height + pad * 2);

            using var crop = current.Clone(new Rectangle(cx, cy, cw, ch), PixelFormat.Format32bppArgb);
            var ocrResult = _pythonBridge.OcrFromBitmap(crop);

            // Offset word coordinates to screen space
            foreach (var line in ocrResult.Lines)
            {
                foreach (var word in line.Words)
                {
                    word.X += cx;
                    word.Y += cy;
                }
                allLines.Add(line);
                allText.Add(line.Text);
            }
        }

        return Task.FromResult(new OcrResponse
        {
            Text = string.Join("\n", allText),
            Lines = allLines,
        });
    }

    private static List<Rectangle> FindBrightClusters(bool[] mask, int w, int h, int minWidth, int minHeight, int maxGap)
    {
        // Row density
        int[] rowCounts = new int[h];
        for (int y = 0; y < h; y++)
            for (int x = 0; x < w; x++)
                if (mask[y * w + x]) rowCounts[y]++;

        // Find horizontal bands of bright rows
        int rowThresh = 3;
        var bands = new List<(int Top, int Bottom)>();
        int bandStart = -1, lastActive = -1;
        for (int y = 0; y < h; y++)
        {
            if (rowCounts[y] >= rowThresh)
            {
                if (bandStart < 0) bandStart = y;
                lastActive = y;
            }
            else if (bandStart >= 0 && y - lastActive > maxGap)
            {
                if (lastActive - bandStart + 1 >= minHeight)
                    bands.Add((bandStart, lastActive));
                bandStart = -1;
            }
        }
        if (bandStart >= 0 && lastActive - bandStart + 1 >= minHeight)
            bands.Add((bandStart, lastActive));

        // For each band, find column extents to get individual nameplate boxes
        var boxes = new List<Rectangle>();
        foreach (var (top, bottom) in bands)
        {
            int[] colCounts = new int[w];
            for (int y = top; y <= bottom; y++)
                for (int x = 0; x < w; x++)
                    if (mask[y * w + x]) colCounts[x]++;

            int colThresh = 1;
            int colStart = -1, lastCol = -1;
            for (int x = 0; x < w; x++)
            {
                if (colCounts[x] >= colThresh)
                {
                    if (colStart < 0) colStart = x;
                    lastCol = x;
                }
                else if (colStart >= 0 && x - lastCol > maxGap)
                {
                    if (lastCol - colStart + 1 >= minWidth)
                        boxes.Add(new Rectangle(colStart, top, lastCol - colStart + 1, bottom - top + 1));
                    colStart = -1;
                }
            }
            if (colStart >= 0 && lastCol - colStart + 1 >= minWidth)
                boxes.Add(new Rectangle(colStart, top, lastCol - colStart + 1, bottom - top + 1));
        }

        return boxes;
    }

    public void Dispose() => _pythonBridge.Dispose();

    // -- OCR text matching --

    private static (int X, int Y)? FindWordInOcrResult(OcrResponse result, string needle, bool fuzzy = false)
    {
        var lower = needle.ToLowerInvariant();
        const double fuzzyThreshold = 0.55;

        if (lower.Contains(' '))
        {
            var needleNorm = Normalize(needle);
            foreach (var line in result.Lines)
            {
                if (line.Words.Count == 0) continue;
                if (line.Text.ToLowerInvariant().Contains(lower))
                    return LineBoundsCenter(line);

                if (fuzzy)
                {
                    var lineNorm = Normalize(line.Text);
                    var windowLen = needleNorm.Length;
                    for (var i = 0; i <= lineNorm.Length - windowLen + 2; i++)
                    {
                        var end = Math.Min(i + windowLen + 2, lineNorm.Length);
                        var window = lineNorm[i..end];
                        if (BigramSimilarity(needleNorm, window) >= fuzzyThreshold)
                            return LineBoundsCenter(line);
                    }
                }
            }
            return null;
        }

        var needleN = Normalize(needle);
        foreach (var line in result.Lines)
        {
            foreach (var word in line.Words)
            {
                if (word.Text.ToLowerInvariant().Contains(lower))
                    return (word.X + word.Width / 2, word.Y + word.Height / 2);

                if (fuzzy && BigramSimilarity(needleN, Normalize(word.Text)) >= fuzzyThreshold)
                    return (word.X + word.Width / 2, word.Y + word.Height / 2);
            }
        }
        return null;
    }

    private static (int X, int Y) LineBoundsCenter(OcrLine line)
    {
        var first = line.Words[0];
        var last = line.Words[^1];
        var x1 = first.X;
        var y1 = first.Y;
        var x2 = last.X + last.Width;
        var y2 = line.Words.Max(w => w.Y + w.Height);
        return ((x1 + x2) / 2, (y1 + y2) / 2);
    }

    private static string Normalize(string s) =>
        new(s.ToLowerInvariant().Where(char.IsLetterOrDigit).ToArray());

    private static double BigramSimilarity(string a, string b)
    {
        if (a.Length < 2 || b.Length < 2) return a == b ? 1 : 0;
        var bigramsA = new Dictionary<(char, char), int>();
        for (var i = 0; i < a.Length - 1; i++)
        {
            var bg = (a[i], a[i + 1]);
            bigramsA[bg] = bigramsA.GetValueOrDefault(bg) + 1;
        }
        var matches = 0;
        for (var i = 0; i < b.Length - 1; i++)
        {
            var bg = (b[i], b[i + 1]);
            if (bigramsA.TryGetValue(bg, out var count) && count > 0)
            {
                matches++;
                bigramsA[bg] = count - 1;
            }
        }
        return 2.0 * matches / (a.Length - 1 + b.Length - 1);
    }
}