/*
 * Copyright 2011 ZXing authors
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

using System.Collections.Generic;

using ZXing.Common;
using ZXing.Maxicode.Internal;

namespace ZXing.Maxicode
{
    /// <summary>
    /// This implementation can detect and decode a MaxiCode in an image.
    /// </summary>
    public sealed class MaxiCodeReader : Reader
    {
        private static readonly ResultPoint[] NO_POINTS = new ResultPoint[0];
        private const int MATRIX_WIDTH = 30;
        private const int MATRIX_HEIGHT = 33;

        private readonly Decoder decoder = new Decoder();

        /// <summary>
        /// Locates and decodes a MaxiCode in an image.
        ///
        /// <returns>a String representing the content encoded by the MaxiCode</returns>
        /// <exception cref="FormatException">if a MaxiCode cannot be decoded</exception>
        /// </summary>
        public Result decode(BinaryBitmap image)
        {
            return decode(image, null);
        }

        /// <summary>
        /// Locates and decodes a MaxiCode within an image. This method also accepts
        /// hints, each possibly associated to some data, which may help the implementation decode.
        /// </summary>
        /// <param name="image">image of barcode to decode</param>
        /// <param name="hints">passed as a <see cref="IDictionary{TKey, TValue}"/> from <see cref="DecodeHintType"/>
        /// to arbitrary data. The
        /// meaning of the data depends upon the hint type. The implementation may or may not do
        /// anything with these hints.</param>
        /// <returns>
        /// String which the barcode encodes
        /// </returns>
        public Result decode(BinaryBitmap image, IDictionary<DecodeHintType, object> hints)
        {
            // Note that MaxiCode reader effectively always assumes PURE_BARCODE mode
            // and can't detect it in an image
            var bits = extractPureBits(image.BlackMatrix);
            if (bits == null)
                return null;
            var decoderResult = decoder.decode(bits, hints);
            if (decoderResult == null)
                return null;

            var result = new Result(decoderResult.Text, decoderResult.RawBytes, NO_POINTS, BarcodeFormat.MAXICODE);

            var ecLevel = decoderResult.ECLevel;
            if (ecLevel != null)
            {
                result.putMetadata(ResultMetadataType.ERROR_CORRECTION_LEVEL, ecLevel);
            }
            return result;
        }
        /// <summary>
        /// does nothing here
        /// </summary>
        public void reset()
        {
            // do nothing
        }

        /// <summary>
        /// This method detects a code in a "pure" image -- that is, pure monochrome image
        /// which contains only an unrotated, unskewed, image of a code, with some white border
        /// around it. This is a specialized method that works exceptionally fast in this special
        /// case.
        ///
        /// <seealso cref="ZXing.Datamatrix.DataMatrixReader.extractPureBits(BitMatrix)" />
        /// <seealso cref="ZXing.QrCode.QRCodeReader.extractPureBits(BitMatrix)" />
        /// </summary>
        private static BitMatrix extractPureBits(BitMatrix image)
        {

            int[] enclosingRectangle = image.getEnclosingRectangle();
            if (enclosingRectangle == null)
            {
                return null;
            }

            int left = enclosingRectangle[0];
            int top = enclosingRectangle[1];
            int width = enclosingRectangle[2];
            int height = enclosingRectangle[3];

            // correct corner cases: the enclosing rectangle borders the right or bottom edge
            if (left + width >= image.Width)
                width = image.Width - left - 1;
            if (top + height >= image.Height)
                height = image.Height - top - 1;

            // Now just read off the bits
            BitMatrix bits = new BitMatrix(MATRIX_WIDTH, MATRIX_HEIGHT);
            for (int y = 0; y < MATRIX_HEIGHT; y++)
            {
                int iy = top + (y * height + height / 2) / MATRIX_HEIGHT;
                for (int x = 0; x < MATRIX_WIDTH; x++)
                {
                    int ix = left + (x * width + width / 2 + (y & 0x01) * width / 2) / MATRIX_WIDTH;
                    if (image[ix, iy])
                    {
                        bits[x, y] = true;
                    }
                }
            }
            return bits;
        }
    }
}