using Microsoft.Office.Interop.Word;
/* Importer.cs
 * part of zaaReloaded2
 * 
 * Copyright 2015-2017 Daniel Kraus
 * 
 * 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;
using System.Collections.Generic;
using System.Linq;
using System.Text;

namespace zaaReloaded2.Medication
{
    /// <summary>
    /// Imports prescriptions from a physician's letter.
    /// </summary>
    public class Importer
    {
        #region Static methods

        /// <summary>
        /// Attempts to automatically detect a block of prescriptions
        /// in a document. The document is screened from end to start.
        /// The detected block is selected.
        /// </summary>
        /// <returns>True if a block was detected, false if not.</returns>
        /// <remarks>
        /// <para>
        /// Autodetection works by examining the document paragraph by
        /// paragraph, starting at the end of the document. The first
        /// block of at least two lines that are identified as prescription
        /// lines is selected.
        /// </para>
        /// <para>
        /// It should be noted that every paragraph (a.k.a. line) may
        /// be regarded as one of three things:
        /// </para>
        /// <list type="ol">
        /// <item>A typical prescription line (in the form "Ramipril 5 mg 1-0-0")</item>
        /// <item>A typical non-prescription text line</item>
        /// <item>Something inbetween, e.g. a line with tab stops as in
        /// "Ramipril 5 mg \t alle zwei Tage" or in "Prof. B. Oss \t Dr. A. Sistent"
        /// </item>
        /// </list>
        /// <para>
        /// It is the third type of line that may cause confusion. If such a line
        /// is encountered at the start of a putative block of prescriptions, we
        /// therefore enter a "fuzzy" state in the detection algorithm and take
        /// it from there, i.e. disregard the block if there are no lines that
        /// are clearly prescriptions lines, or accept the block if we do detect
        /// adjacent lines with unequivocal prescriptions.
        /// </para>
        /// 
        /// </remarks>
        public static bool AutoDetect(Document document)
        {
            Paragraph start = null;
            Paragraph end = null;
            bool insideBlock = false;
            bool fuzzy = false;
            bool result = false;
            int i = document.Paragraphs.Count;

            while (i > 1)
            {
                string line = document.Paragraphs[i].Range.Text;

                if (Prescription.IsCanonicalPrescriptionLine(line))
                {
                    // The current line is unequivocally a prescription line:
                    // If we're not inside a block already, mark the bottom
                    // of the block.
                    // If we are inside a block already, make sure to leave
                    // the 'fuzzy' state because this clearly now is a prescription
                    // block.
                    if (insideBlock)
                    {
                        fuzzy = false;
                    }
                    else
                    {
                        end = document.Paragraphs[i];
                        insideBlock = true;
                    }
                }
                else if (Prescription.IsPotentialPrescriptionLine(line))
                {
                    // The current line is a putative prescription line:
                    // If we're not inside a block already, enter the
                    // "fuzzy" state.
                    // If we are inside a block, no special action is
                    // needed, we can continue with the next paragraph.
                    if (!insideBlock)
                    {
                        fuzzy = true;
                        insideBlock = true;
                        end = document.Paragraphs[i];
                    }
                }
                else
                {
                    // The current line is not a prescription line:
                    // If we are currently in a definitive block of prescriptions,
                    // mark the line below the current line as the start of the block.
                    // If we're in a putative block, discard the information
                    // about the bottom end of the block and reset all flags.
                    if (insideBlock)
                    {
                        if (!fuzzy)
	                    {
                            start = document.Paragraphs[i + 1];
                            break;
	                    }
                        else
                        {
                            fuzzy = false;
                            insideBlock = false;
                            end = null;
                        }
                    }
                }

                i--;
            }

            if (end != null)
	        {
                // If we don't have a start paragraph,
                // but do have an end paragraph, we set the start paragraph to the
                // first paragraph of the document.
                if (start == null)
                {
                    start = document.Paragraphs[1];
                }
                document.Range(start.Range.Start, end.Range.End).Select();
                result = true;
	        }
            return result;
        }

        #endregion

        #region Properties

        public List<Prescription> Prescriptions { get; protected set; }

        #endregion

        #region Constructor

        public Importer() { }

        public Importer(string text)
            : this()
        {
            Import(text);
        }

        #endregion

        #region Private methods

        protected virtual void Import(string text)
        {
            List<Prescription> list = new List<Prescription>();
            IList<Prescription> addition;
            int columns = 1;
            string[] lines = Helpers.SplitParagraphs(text);
            foreach (string line in lines)
            {
                if (Prescription.IsPotentialPrescriptionLine(line))
                {
                    addition = Prescription.ManyFromLine(line);
                    columns = System.Math.Max(columns, addition.Count);
                    list.AddRange(addition);
                }
            }

            // If the input had several columns, sort the prescriptions by
            // column.
            // TODO: Make this more generic so it works with 3 or 4 columns as well.
            if (columns == 2)
            {
                var firstCol = list.Where((item, index) => index % 2 == 0);
                var secondCol = list.Where((item, index) => index % 2 != 0);
                Prescriptions = firstCol.Concat(secondCol).ToList();
            }
            else
            {
                Prescriptions = list;
            }
        }
        
        #endregion
    }
}