package de.hs_mannheim.informatik.spreadsheet;

import java.io.File;
import java.io.FileNotFoundException;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Scanner;
import java.util.regex.Matcher;
import java.util.regex.Pattern;

/**
 * A simplified spreadsheet class for the PR1 programming lab at Hochschule Mannheim.
 * One aspect worth mentioning is that it only supports long numbers, not doubles.
 *
 * @author  Oliver Hummel
 */
public class Spreadsheet {
	Cell[][] cells;

	/**
	 * Constructor that creates a Spreadsheet of size rows * cols.
	 *
	 * @param rows number of rows
	 * @param cols number of columns
	 */
	public Spreadsheet(int rows, int cols) {

		if(rows>99)
			rows = 99;
		else if(rows<1)
			rows = 1;
		if(cols < 1)
			cols = 1;
		else if(cols > 26)
			cols = 26;

		cells = new Cell[rows][cols];

		for (int r = 0; r < rows; r++)
			for (int c = 0; c < cols; c++)
				cells[r][c] = new Cell();
	}

	// -----
	// retrieve or change values of cells

	private String get(int row, int col) {
		return cells[row][col].getValue();
	}

	public String get(String cellName) {
		cellName = cellName.toUpperCase();
		return get(getRow(cellName), getCol(cellName));
	}

	private void put(int row, int col, String value) {
		if (!value.startsWith("="))
			cells[row][col].setValue(value);
		else {
			cells[row][col].setFormula(value);
			evaluateCell(row, col);
		}
	}

	public void put(String cellName, String value) {
		cellName = cellName.toUpperCase();
		put(getRow(cellName), getCol(cellName), value);
	}

	private int getCol(String cellName) {
		return cellName.charAt(0) - 'A';
	}

	private int getRow(String cellName) {
		if(cellName.length()>2)
			return Integer.parseInt(""+cellName.charAt(1)+cellName.charAt(2)) - 1;
		return cellName.charAt(1) - '1';
	}

	// -----
	// business logic

	/**
	 * A method for reading in data from a CSV file.
	 *
	 * @param path         The file to read.
	 * @param separator    The char used to split up the input, e.g. a comma or a semicolon.
	 * @param starCellName The upper left cell where data from the CSV file should be inserted.
	 * @return Nothing.
	 * @throws IOException If path does not exist.
	 */
	public void readCsv(String path, char separator, String startCellName) throws FileNotFoundException {
		Scanner sc = new Scanner(new File(path));
		ArrayList<String> memList = new ArrayList<>();

		while (sc.hasNextLine()) {
			memList.add(sc.nextLine());
		}

		String[][] memArr = new String[memList.size()][];
		for(int i = 0; i < memList.size(); i++)
			memArr[i] = (memList.get(i)).split(String.valueOf(separator));

		for (int r = getRow(startCellName); r < memList.size(); r++)
			for (int c = getCol(startCellName); c < memList.get(0).length(); c++)
				if(c<memArr[r].length)
					put(r, c, memArr[r][c]);

		sc.close();
	}

	/**
	 * A method for saving data to a CSV file.
	 *
	 * @param path The file to write.
	 * @return Nothing.
	 * @throws IOException If path does not exist.
	 */
	public void saveCsv(String path) throws FileNotFoundException {
		PrintWriter out = new PrintWriter(path);

		for (Cell[] row : cells) {
			for (Cell cell : row) {
				if (!cell.getFormula().isEmpty())
					out.print("=" + cell.getFormula());
				else
					out.print(cell.getValue());

				if (cell != row[cells[0].length - 1])
					out.print(",");
			}
			out.println();
		}

		out.close();
	}

	/**
	 * This method does the actual evaluation/calcluation of a specific cell
	 *
	 * @param cellName the name of the cell to be evaluated
	 * @return Nothing.
	 */
	private void evaluateCell(int row, int col) {
		String formula = cells[row][col].getFormula();
		String result = "";

		if (formula.startsWith("SUMME("))  // e.g. SUMME(A3:A8)
			result = "" + sum(formula.substring(6, 8), formula.substring(9, 11));  // TODO adapt to cells with two digits
		else if (formula.startsWith("PRODUKT("))  // e.g. PRODUKT(A3:B9)
			result = "TODO"; // TODO
		else if (formula.startsWith("MITTELWERT("))  // e.g. MITTELWERT(A3:A5)
			result = "TODO"; // TODO
		else if (formula.startsWith("STABW("))  // e.g. STABW(C6:D8) -> Standardabweichung
			result = "TODO"; // TODO
		else if (formula.startsWith("MIN("))  // e.g. MIN(C13:H13) -> größter Wert
			result = "TODO"; // TODO
		else if (formula.startsWith("MAX("))  // e.g. MAX(A1:A10) -> Standardabweichung
			result = "TODO"; // TODO
		else if (!formula.isEmpty()) {
			try {
				result = "" + calculate(formula);
			} catch (ArithmeticException ae) {
				result = "exc.";
			}
		}

		cells[row][col].setValue("" + result);
	}

	/**
	 * Method for calculating the sum of a rectangular block of cells, such as from A1 to B3.
	 *
	 * @param startCellName The name of the cell in the upper left corner of the rectangle.
	 * @param endCellName   The name of the cell in the lower right corner of the rectangle.
	 * @return The sum calculated.
	 */
	private long sum(String startCellName, String endCellName) {
		// TODO implement

		return 0;
	}

	/**
	 * This method calculates the result of a "normal" algebraic expression. It only needs to support
	 * expressions like =B4 or =2+A3-B2, i.e. only with int numbers and other cells and with plus,
	 * minus, times, split only. An expression always starts with either a number or a cell name. If it
	 * continues, it is guaranteed that this is followed by an operator and either a number or a
	 * cell name again. It is NOT required to implement dot before dash or parentheses in formulas.
	 *
	 * @param formula The expression to be evaluated.
	 * @return The result calculated.
	 */
	private long calculate(String formula) throws ArithmeticException {
		Matcher m = Pattern.compile("([A-Z][0-9]*)|[-\\+\\*/]|[0-9]*").matcher(formula);

		long res = 0;

		// TODO implement

		// uncomment the following to see an example how the elements of a formula can be accessed
		while (m.find()) {        // m.find() must always be used before m.group()
			String s = m.group();
			if (!s.isEmpty()) {
				System.out.println(s);
			}
		}

		return res;
	}

	// -----

	public String toString() {
		StringBuilder sb = new StringBuilder();

		sb.append(System.lineSeparator());
		sb.append("     |");
		for (int i = 0; i < cells[0].length; i++) {
			sb.append("       " + (char) ('A' + i) + "       |");
		}
		int rc = 1;
		for (Cell[] r : cells) {
			sb.append(System.lineSeparator());
			for (int i = 0; i < cells[0].length; i++) {
				sb.append("----------------");
			}
			sb.append("------");
			sb.append(System.lineSeparator());
			sb.append(String.format(" " + "%2s", rc++) + "  |");

			for (Cell c : r) {
				sb.append(" " + String.format("%13s", c) + " |");
			}

		}
		sb.append(System.lineSeparator());
		for (int i = 0; i < cells[0].length; i++) {
			sb.append("----------------");
		}
		sb.append("------");
		sb.append(System.lineSeparator());
		return sb.toString();


	}
}