using System;
using System.IO;

namespace ExcelLateBinding
{
    public class ExcelWriter
    {
        // Champs
        private object m_Application;
        private object m_Workbook;
        private object m_Worksheet;
        private object _mis = Type.Missing;
        private int m_ColumnCount;
        private int m_ColumnIndex;
        private int m_RowCount;
        private int m_RowIndex;
        private bool m_StreamEnded;
        private string m_filename;

        // Constructeur
        public ExcelWriter()
        {
            m_StreamEnded = false;
            m_ColumnCount = -1;
            m_ColumnIndex = -1;
            m_RowCount = -1;
            m_RowIndex = -1;
        }

        // Propriétés

        public object Application
        {
            get { return m_Application; }
        }

        public object Workbook
        {
            get { return m_Workbook; }
        }

        public object Worksheet
        {
            get { return m_Worksheet; }
        }

        public bool StreamEnded
        {
            get { return m_StreamEnded; }
        }

        public string Version
        {
            get { return (string)LateBindings.Get(m_Application, "Version"); }
        }

        // Méthodes

        // Ferme le processus Excel
        public void Close()
        {
            if (m_Workbook != null)
            {
                LateBindings.Invoke(m_Workbook, "Close", new object[3] { false, _mis, _mis });
                m_Workbook = null;
            }
            if (m_Application != null)
            {
                LateBindings.Set(m_Application, "DisplayAlerts", true);
                LateBindings.Invoke(m_Application, "Quit");
                LateBindings.ReleaseInstance(m_Application);
                m_Application = null;
            }
        }

        // Supprime le contenu de toute la feuille
        public void Clear()
        {
            LateBindings.Invoke(LateBindings.Get(m_Worksheet, "Cells"), "Clear");
        }

        // Enregistre le fichier
        public void Save()
        {
            if (File.Exists(m_filename))
                LateBindings.Invoke(m_Workbook, "Save");
            else
            {
                int fileFormat =
                    string.Compare("11.0", this.Version) < 0 &&
                    m_filename.EndsWith(".xlsx", StringComparison.CurrentCultureIgnoreCase) ?
                    51 : -4143;
                object[] param =
                    new object[8] { m_filename, fileFormat, string.Empty, string.Empty, false, false, 1, 1 };
                LateBindings.Invoke(m_Workbook, "SaveAs", param);
            }
        }

        // Ouvre le processus Excel et le fichier donné (surchargé)
        public void Open(string filename)
        {
            Open(filename, null);
        }

        public void Open(string filename, string worksheetName)
        {
            m_Application = LateBindings.GetOrCreateInstance("Excel.Application");

            LateBindings.Set(m_Application, "DisplayAlerts", false);

            object workbooks = LateBindings.Get(m_Application, "Workbooks");

            m_filename = filename;
            if (File.Exists(filename))
                m_Workbook = LateBindings.Invoke(workbooks, "Open", filename);
            else
                m_Workbook = LateBindings.Invoke(workbooks, "Add", _mis);

            if (string.IsNullOrEmpty(worksheetName))
                m_Worksheet = LateBindings.Get(m_Workbook, "Activesheet");
            else
                m_Worksheet = GetWorksheet(worksheetName);

            SetWorksheetAttributes();
        }

        // Change de ligne
        public void NewLine()
        {
            if (m_StreamEnded)
                throw new EndOfStreamException();
            if (m_RowIndex < m_RowCount)
            {
                m_RowIndex++;
                m_ColumnIndex = 1;
            }
            else
                m_StreamEnded = true;

        }

        // Ecrit la valeur donnée dans la cellule courante et avance d'une cellule 
        // ou change de ligne s'il arrive à la fin d'une ligne.
        public void Write(object value)
        {
            if (m_StreamEnded)
                throw new EndOfStreamException();
            object cells = LateBindings.Get(m_Worksheet, "Cells");
            object range = LateBindings.Get(cells, "Item", new object[2] { m_RowIndex, m_ColumnIndex });
            if (value is String)
                LateBindings.Set(range, "NumberFormat", "@");
            LateBindings.Set(range, "Value2", value);
            if (m_ColumnIndex == m_ColumnCount)
            {
                if (m_RowIndex < m_RowCount)
                {
                    m_RowIndex++;
                    m_ColumnIndex = 1;
                }
                else
                    m_StreamEnded = true;
            }
            else
                m_ColumnIndex++;
        }

        // Ecrit un ensemble de valeurs donné sous forme de tableau dans des cellules,
        // puis change de ligne à la fin.
        public void WriteLine(object[] values)
        {
            if (m_StreamEnded)
                throw new EndOfStreamException();
            foreach (object val in values)
            {
                if (m_ColumnIndex <= m_ColumnCount)
                {
                    object range = LateBindings.Get(m_Worksheet, "Cells");
                    object cell = LateBindings.Get(range, "Item", new object[2] { m_RowIndex, m_ColumnIndex });
                    if (val is String)
                        LateBindings.Set(cell, "NumberFormat", "@");
                    LateBindings.Set(cell, "Value2", val);
                    if (m_ColumnIndex < m_ColumnCount)
                        m_ColumnIndex++;
                }
            }
            if (m_RowIndex < m_RowCount)
            {
                m_RowIndex++;
                m_ColumnIndex = 1;
            }
        }

        // Colle le contenu du presse papier dans la feuille courante
        public void PasteFromClipboard()
        {
            object cells = LateBindings.Get(m_Worksheet, "Cells", new object[2] { 1, 1 });
            LateBindings.Invoke(m_Worksheet, "Paste", new object[2] { cells, false });
        }

        // Met à jour les nombres de lignes et de colonnes et la position du lecteur.
        private void SetWorksheetAttributes()
        {
            m_RowIndex = 1;
            m_ColumnIndex = 1;
            object rows = LateBindings.Get(m_Worksheet, "Rows");
            m_RowCount = (int)LateBindings.Get(rows, "Count");
            object cols = LateBindings.Get(m_Worksheet, "Columns");
            m_ColumnCount = (int)LateBindings.Get(cols, "Count");
        }

        // Retourne l'instance de la feuille donnée en paramètre, l'ajoute si elle n'existe pas.
        private object GetWorksheet(string worksheetName)
        {
            object worksheets = LateBindings.Get(m_Workbook, "Worksheets");
            try
            {
                return LateBindings.Get(worksheets, "Item", worksheetName);
            }
            catch
            {
                object ws = LateBindings.Invoke(worksheets, "Add", _mis);
                LateBindings.Set(ws, "Name", worksheetName);
                return ws;
            }
        }
    }
}