/*
 * Copyright 2008 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;

namespace ZXing.OneD
{
    /// <summary>
    ///   <p>A reader that can read all available UPC/EAN formats. If a caller wants to try to
    /// read all such formats, it is most efficient to use this implementation rather than invoke
    /// individual readers.</p>
    ///   <author>Sean Owen</author>
    /// </summary>
    public sealed class MultiFormatUPCEANReader : OneDReader
    {
        private readonly UPCEANReader[] readers;

        /// <summary>
        /// Initializes a new instance of the <see cref="MultiFormatUPCEANReader"/> class.
        /// </summary>
        /// <param name="hints">The hints.</param>
        public MultiFormatUPCEANReader(IDictionary<DecodeHintType, object> hints)
        {
            var possibleFormats = hints == null || !hints.ContainsKey(DecodeHintType.POSSIBLE_FORMATS) ? null :
                (IList<BarcodeFormat>)hints[DecodeHintType.POSSIBLE_FORMATS];
            var readers = new List<UPCEANReader>();
            if (possibleFormats != null)
            {
                if (possibleFormats.Contains(BarcodeFormat.EAN_13) || possibleFormats.Contains(BarcodeFormat.All_1D))
                {
                    readers.Add(new EAN13Reader());
                }
                else if (possibleFormats.Contains(BarcodeFormat.UPC_A) || possibleFormats.Contains(BarcodeFormat.All_1D))
                {
                    readers.Add(new UPCAReader());
                }
                if (possibleFormats.Contains(BarcodeFormat.EAN_8) || possibleFormats.Contains(BarcodeFormat.All_1D))
                {
                    readers.Add(new EAN8Reader());
                }
                if (possibleFormats.Contains(BarcodeFormat.UPC_E) || possibleFormats.Contains(BarcodeFormat.All_1D))
                {
                    readers.Add(new UPCEReader());
                }
            }
            if (readers.Count == 0)
            {
                readers.Add(new EAN13Reader());
                // UPC-A is covered by EAN-13
                readers.Add(new EAN8Reader());
                readers.Add(new UPCEReader());
            }
            this.readers = readers.ToArray();
        }

        /// <summary>
        ///   <p>Attempts to decode a one-dimensional barcode format given a single row of
        /// an image.</p>
        /// </summary>
        /// <param name="rowNumber">row number from top of the row</param>
        /// <param name="row">the black/white pixel data of the row</param>
        /// <param name="hints">decode hints</param>
        /// <returns>
        ///   <see cref="Result"/>containing encoded string and start/end of barcode or null if an error occurs or barcode cannot be found
        /// </returns>
        override public Result decodeRow(int rowNumber,
                                BitArray row,
                                IDictionary<DecodeHintType, object> hints)
        {
            // Compute this location once and reuse it on multiple implementations
            int[] startGuardPattern = UPCEANReader.findStartGuardPattern(row);
            if (startGuardPattern == null)
                return null;

            foreach (UPCEANReader reader in readers)
            {
                Result result = reader.decodeRow(rowNumber, row, startGuardPattern, hints);
                if (result == null)
                    continue;

                // Special case: a 12-digit code encoded in UPC-A is identical to a "0"
                // followed by those 12 digits encoded as EAN-13. Each will recognize such a code,
                // UPC-A as a 12-digit string and EAN-13 as a 13-digit string starting with "0".
                // Individually these are correct and their readers will both read such a code
                // and correctly call it EAN-13, or UPC-A, respectively.
                //
                // In this case, if we've been looking for both types, we'd like to call it
                // a UPC-A code. But for efficiency we only run the EAN-13 decoder to also read
                // UPC-A. So we special case it here, and convert an EAN-13 result to a UPC-A
                // result if appropriate.
                //
                // But, don't return UPC-A if UPC-A was not a requested format!
                bool ean13MayBeUPCA =
                    result.BarcodeFormat == BarcodeFormat.EAN_13 &&
                        result.Text[0] == '0';
                var possibleFormats =
                    hints == null || !hints.ContainsKey(DecodeHintType.POSSIBLE_FORMATS) ? null : (IList<BarcodeFormat>)hints[DecodeHintType.POSSIBLE_FORMATS];
                bool canReturnUPCA = possibleFormats == null || possibleFormats.Contains(BarcodeFormat.UPC_A) || possibleFormats.Contains(BarcodeFormat.All_1D);

                if (ean13MayBeUPCA && canReturnUPCA)
                {
                    // Transfer the metadata across
                    var resultUPCA = new Result(result.Text.Substring(1),
                                                   result.RawBytes,
                                                   result.ResultPoints,
                                                   BarcodeFormat.UPC_A);
                    resultUPCA.putAllMetadata(result.ResultMetadata);
                    return resultUPCA;
                }
                return result;
            }

            return null;
        }

        /// <summary>
        /// Resets any internal state the implementation has after a decode, to prepare it
        /// for reuse.
        /// </summary>
        public override void reset()
        {
            foreach (Reader reader in readers)
            {
                reader.reset();
            }
        }
    }
}