package Torello.Java;

import java.util.regex.*;

import java.util.stream.IntStream;

import Torello.Browser.Debugger.scriptParsed;
import Torello.Java.Function.IntCharFunction;

import Torello.JavaDoc.StaticFunctional;
import Torello.JavaDoc.Excuse;
import Torello.JavaDoc.LinkJavaSource;

/**
 * A class for indenting, unindenting and trimming textual-strings.
 * 
 * <BR /><BR /><EMBED CLASS='external-html' DATA-FILE-ID=STRINDENT>
 */
@StaticFunctional
public class StrIndent
{
    private StrIndent() { }

    // This matches lines of text that contain only blank / white-space characters
    private static final Pattern EMPTY_LINE = Pattern.compile("^[ \t]+\n", Pattern.MULTILINE);

    /**
     * Replaces sub-strings that contain a newline character followed by only white-space with
     * only the new-line character itself.
     *
     * @param s Any Java {@code String}, but preferrably one which contains newline characters
     * ({@code '\n'}), and white-space characters immediately followng the newline, but not other
     * ASCII nor UNICODE.
     *
     * @return The same String with each instance of {@code ^[ \t]+\n} replaced by {@code '\n'}.
     */
    public static String trimWhiteSpaceOnlyLines(String s)
    {
        Matcher m = EMPTY_LINE.matcher(s);
        return m.replaceAll("\n");
    }

    /**
     * Will iterate through <I>each line of text</I> within the input {@code String}-parameter
     * {@code 's'}, and right-trim the lines.  "Right Trim" means to remove all white-space
     * characters that occur <I><B>after</I></B> the last non-white-space character on the line.
     * (Does not remove the new-line character ({@code '\n'}) itself).
     * 
     * <BR /><BR /><B>NOTE:</B> Any line of text which contains only white-space characters is
     * reduced to a single new-line character.
     * 
     * @param s Any Java {@code String}, preferrably one with several new-line characters.
     * 
     * @return The same text, but only after having any 'trailing white-space' characters removed
     * from each line of text.
     */
    @LinkJavaSource(handle="RightTrimAll")
    public static String rightTrimAll(String s)
    { return RightTrimAll.run(s); }

    /**
     * Will iterate through <I>each line of text</I> within the input {@code String}-parameter
     * {@code 's'}, and left-trim the lines.  "Left Trim" means to remove all white-space
     * characters that occur <I><B>before</I></B> the last non-white-space character on the line.
     * (Does not remove the new-line character ({@code '\n'}) itself).
     * 
     * <BR /><BR /><B>NOTE:</B> Any line of text which contains only white-space characters is
     * reduced to a single new-line character.
     * 
     * @param s Any Java {@code String}, preferrably one with several new-line characters.
     * 
     * @return The same text, but only after having any 'leading white-space' characters removed
     * from each line of text.
     */
    @LinkJavaSource(handle="LeftTrimAll")
    public static String leftTrimAll(String s)
    { return LeftTrimAll.run(s); }

    /**
     * This method expects to receive a method body, constructor body, or other callable body as a
     * {@code String}; it will remove the beginning and ending braces <CODE>('&#123;'</CODE> &amp;
     * <CODE>'&#125;')</CODE>, and beginning &amp; ending empty lines.  This is to prepare the
     * method for code hiliting, used internally by the package {@code Torello.JavaDoc}.
     * 
     * @param callableAsStr This should be a method body.  Make sure <B>**NOT TO INCLUDE**</B> the
     * method signature at the beginning of the method.  The first non-white-space character should
     * be the open braces character <CODE>('&#123;')</CODE>, and the last non-white-space should be
     * the closing braces character <CODE>('&amp;#125')</CODE>.
     * 
     * @return A method body {@code String} that can be hilited using the code-hiliting mechanism
     * of the "JavaDoc Package."
     * 
     * @throws CallableBodyException If the input parameter {@code String} does not begin and end
     * with the curly-braces.
     */
    @LinkJavaSource(handle="ChompCallableBraces")
    public static String chompCallableBraces(String callableAsStr)
    { return ChompCallableBraces.run(callableAsStr); }

    /**
     * Accepts a method body as a {@code String} and left-shifts or right-shifts each line
     * of text (each {@code 'Line of Code' - LOC}) so that the indentation is consistent with
     * the requested-indentation input-parameter.
     * 
     * <BR /><BR /><B>NOTE:</B> The lines of code contained by input-parameter {@code 'codeAsStr'}
     * must contain leading white-space <I><B STYLE='color: red;'>without any tab ({@code '\t'})
     * characters.</B></I>  The reasoning here is that tabs can be interpreted in many different
     * ways, and therefore it is required to replace them before invoking this method.  This method
     * merely adds or removes leading {@code ASCII 0x20} (space-bar characters) from the beginning
     * of each line of text.  A leading tab-character {@code ASCII 0x09} will generate an exception
     * throw.
     * 
     * @param codeAsStr A method body.  It is expected to be the internal part of a chunk of
     * source code.
     * 
     * @param requestedIndent The requested amount of indentation for the method-body.  The
     * line of code that contains the shortest amount of indentation (white-space) will be
     * calculated, and then all LOC's shall be left-shifted (or right-shifted) according to that
     * LOC which contained the least amount of leading white-space.
     * 
     * @return An updated method-body as a {@code String}.
     * 
     * @throws StringFormatException  This exception shall throw whenever a line of text contained
     * by the input {@code String} has a {@code '\t'} (tab-character) before the first 
     * non-white-space character on that line of text.  Code that contains tab-characters is
     * invariably "auto-indented" by the Code-Editor when loaded into the GUI, and the amount of
     * indentation applied for each tab-character is usually configurable.  Because there are many
     * variants of how tab's {@code '\t'} gets interpreted by the editor, it is required to replace
     * these characters first before invoking this method.
     */
    @LinkJavaSource(handle="SetCodeIndent")
    public static String setCodeIndent(String codeAsStr, int requestedIndent)
    { return SetCodeIndent.run(codeAsStr, requestedIndent); }

    /**
     * Convenience Method.
     * <BR />See Documentation: {@link #setCodeIndent(String, int)}
     * <BR />Converts: All {@code '\t'} to the specified number of spaces in parameter
     * {@code SPACES}.
     * <BR /><B STYLE='color: red'>NOTE:</B> Exception-Checking is <B STYLE='color: red'>NOT</B>
     * done on input
     */
    @LinkJavaSource(handle="SetCodeIndent")
    public static String setCodeIndent_WithTabsPolicyAbsolute
        (String codeAsStr, int requestedIndent, String SPACES)
    { return SetCodeIndent.run(codeAsStr.replace("\t", SPACES), requestedIndent); }

    /**
     * Adjusts code-indentation using a relative-sized tab-policy.  This method performs the
     * equivalent of shifting the entire text-block, proportionately, to the left or right.
     *
     * <BR /><BR />To do this, first, the number of spaces that preceed the
     * <B STYLE='color: red;'>least-indented</B> line is computed, and afterwards, every line in
     * the text is shifted by an identical number of space-characters.  The number of spaces that
     * are either added or removed from each line is dependent on whether the requested
     * indentation (parameter {@code 'requestedIndent'}) is greater-than or less-than the computed
     * least-indented line.
     * 
     * <EMBED CLASS='external-html' DATA-FILE-ID=SI_REL_TABS>
     * 
     * @param codeAsStr Any Java source-code block, as a {@code java.lang.String}
     * 
     * @param requestedIndent The number of spaces that the code should have as indentation.
     * Note, that in the JavaDoc Upgrader code, this number is always {@code '1'}.
     * 
     * @param spacesPerTab If tabs are found inside this {@code String}, then they are replaced
     * with an appropriate number of space characters, according to a relative tab-policy, as
     * described above.
     * 
     * @return A properly shifted-indented Java source-code block.
     */
    @LinkJavaSource(handle="SetCodeIndentTabsPolicy")
    public static String setCodeIndent_WithTabsPolicyRelative
        (String codeAsStr, int requestedIndent, int spacesPerTab)
    { return SetCodeIndentTabsPolicy.run(codeAsStr, requestedIndent, spacesPerTab); }

    /**
     * Helper Method for calculating the number of space characters to be used at the beginning
     * of a line of code, all the while obeying a particular tabs-policy.
     * 
     * <BR /><BR /><B STYLE='color: red;'>IMPORTANT:</B> None of the parameters to this method
     * will be checked for errors.  This method is often used inside of a loop, and improper 
     * input should be presumed to cause indeterminate results.
     * 
     * @param code A Java source-code {@code String}, that has been converted into a Java
     * {@code char[]}-Array.  The line of code whose leading white-space is being computed may be
     * located anywhere in the array.
     * 
     * <BR /><BR /><B>NOTE:</B> These types of arrays are easily creaated by invoking the
     * {@code java.lang.String} method {@code 'toCharArray()'}
     * 
     * @param lineFirstCharacterPos The array-index to be considered as the first character of
     * non-new-line character data.
     * 
     * @param spacesPerTab The number of spaces that a tab-character ({@code '\t'}) intends to
     * represent.
     * 
     * <BR /><BR />When {@code FALSE} is passed to this parameter, a tab-character will represent
     * a {@code String} of space-characters whose length is equal to the number of space-characters
     * that remain until the next modulo-{@code spacesPerTab} boundary.
     * 
     * @return The number of space-characters ({@code ' '}) that should preceede the line of source
     * code.
     * 
     * <BR /><BR /><B STYLE='color: red'>NOTE:</B> If this line of source-code is a white-space
     * <B STYLE='color: red;'>ONLY</B> line, then {@code -1} will be returned.
     */
    public static int computeEffectiveLeadingWhiteSpace
        (char[] code, int lineFirstCharacterPos, int spacesPerTab)
    {
        int ret = 0;
        int relativeCount = 0;

        for (int i=lineFirstCharacterPos; i < code.length; i++)

            if (! Character.isWhitespace(code[i])) return ret;

            else switch (code[i])
            {
                case ' ' : 
                    ret++;
                    relativeCount = (relativeCount + 1) % spacesPerTab;
                    break;

                case '\t' :
                    ret += (spacesPerTab - relativeCount);
                    relativeCount = 0;
                    break;

                case '\r' : 
                case '\f' : break;
                case '\n' : return -1;
                default: throw new UnreachableError();
            }

        return -1;
    }

    /**
     * Replaces tab-characters ({@code '\t'}) in a single-line of source-code with a
     * relative-number of space-characters ({@code ' '}).
     * 
     * <EMBED CLASS='external-html' DATA-FILE-ID=SI_REL_TABS>
     * 
     * <BR /><BR /><B STYLE='color: red;'>IMPORTANT:</B> None of the parameters to this method
     * will be checked for errors.  This method is often used inside of a loop, and improper 
     * input should be presumed to cause indeterminate results.
     * 
     * @param code This should be the source-code, converted to a character-array.  The specific
     * line in the source-code being properly space-adjusted may be located anywhere in this
     * array.
     * 
     * <BR /><BR /><B>NOTE:</B> These types of arrays are easily creaated by invoking the
     * {@code java.lang.String} method {@code 'toCharArray()'}
     * 
     * @param numLeadingSpaces The number of spaces that have been placed before the start of this
     * line of code.  This is needed because <B STYLE='color: red;'>relative</B>-tabs are computed
     * based on integral-multiples of the tab-width ({@code 'spacesPerTab'}).
     * 
     * <BR /><BR />This method is a helper &amp; example method that may be used in conjunction 
     * with properly indenting source-code.  Note that the number of leading-spaces may not be
     * identicaly to the actual number of white-space characters in the array.  <I>After converting
     * tab-characters ({@code '\t'}) to spaces ({@code ' '}), this number will often change.</I>
     * 
     * @param fcPos This parameter should contain the location of the first source-code character
     * in the line of code.  This parameter should be an array-index that
     * <B STYLE='color: red;'>does not</B> contain white-space.
     * 
     * @param spacesPerTab The number of spaces that are used to replaces tab-characters.  Since 
     * this method performs relative tab-replacement, this constitutes the
     * <B STYLE='color: red;'>maximum</B> number of space characters that will be used to replace 
     * a tab.
     * 
     * @return A line of code, as a {@code String}, without any leading white-space, and one in
     * which all tab-characters have been replaced by spaces.
     */
    @LinkJavaSource(handle="LOCAsStr")
    public static String lineOfCodeAsStr
        (char[] code, int numLeadingSpaces, int fcPos, int spacesPerTab)
    { return LOCAsStr.run(code, numLeadingSpaces, fcPos, spacesPerTab); }

    /**
     * This performs a variation of "indentation" on a Java {@code String} - simply put - it
     * replaces each new-line character ({@code '\n'}) with a {@code String} that begins with a
     * new-line, and is followed by {@code 'n'} blank white-space characters {@code ' '}.
     * 
     * If the input {@code String} parameter {@code 's'} is of zero-length, then the zero-length
     * {@code String} is returned.  If the final character in the input {@code String} is a 
     * new-line, that new-line is not padded.
     * 
     * @param s Any {@code java.lang.String} - preferably one that contains new-line characters.
     * 
     * @param n The number of white-space characters to use when pre-pending white-space to each
     * line of text in input-parameter {@code 's'}
     * 
     * @return A new {@code java.lang.String} where each line of text has been indented by
     * {@code 'n'} blank white-space characters.  If the text ends with a new-line, that line of
     * text is not indented.
     * 
     * @throws NException If parameter {@code 'n'} is less than one.
     */
    public static String indent(String s, int n)
    {
        if (n < 1) throw new NException(
            "The value passed to parameter 'n' was [" + n + "], but this is expected to be an " +
            "integer greater than or equal to 1."
        );

        if (s.length() == 0) return "";

        String  padding         = String.format("%1$" + n + "s", " ");
        boolean lastIsNewLine   = s.charAt(s.length() - 1) == '\n';

        s = padding + s.replace("\n", "\n" + padding);

        return lastIsNewLine
            ? s.substring(0, s.length() - padding.length())
            : s;
    }

    /**
     * Identical to {@link #indent(String, int)}, but pre-pends a {@code TAB} character {@code 'n'}
     * times, rather than a space-character {@code ' '}.
     * 
     * @param s Any {@code java.lang.String} - preferably one that contains new-line characters.
     * 
     * @param n The number of tab ({@code '\t'}) characters to use when pre-pending to each line of
     * text within input-parameter {@code 's'}
     * 
     * @return A new {@code java.lang.String} where each line of text has been indented by
     * {@code 'n'} tab characters.  If the text ends with a new-line, that line of text is not
     * indented.
     * 
     * @throws NException If parameter {@code 'n'} is less than one.
     */
    public static String indentTabs(String s, int n)
    {
        if (n < 1) throw new NException(
            "The value passed to parameter 'n' was [" + n + "], but this is expected to be an " +
            "integer greater than or equal to 1."
        );

        if (s.length() == 0) return "";

        String  padding         = String.format("%1$"+ n + "s", "\t");
        boolean lastIsNewLine   = s.charAt(s.length() - 1) == '\n';

        s = padding + s.replace("\n", "\n" + padding);

        return lastIsNewLine
            ? s.substring(0, s.length() - padding.length())
            : s;
    }

    /**
     * <EMBED CLASS='external-html' DATA-FILE-ID=SI_INDENT_DESC>
     * 
     * @param s Any {@code java.lang.String} - preferably one that contains new-line characters.
     * 
     * @param n The number of tab ({@code '\t'}) characters to use when pre-pending to each line of
     * text in input-parameter {@code 's'}
     * 
     * @param spaceOrTab When this parameter is passed <B>{@code TRUE}</B>, the space character
     * {@code ' '} is used for indentation.  When <B>{@code FALSE}</B>, the tab-character
     * {@code '\t'} is used.
     * 
     * @return <EMBED CLASS='external-html' DATA-FILE-ID=SI_INDENT_RET>
     * @throws NException If parameter {@code 'n'} is less than one.
     */
    @LinkJavaSource(handle="Indent")
    public static String indent
        (final String s, int n, boolean spaceOrTab, boolean trimBlankLines)
    { return Indent.run(s, n, spaceOrTab, trimBlankLines); }

    /**
     * Throws a new {@code ToDoException}
     * 
     * @return Will (one day) return an unindented String.
     */
    public static String unIndent(
            String s, int n,
            boolean trimBlankLines,
            boolean rightTrimLines,
            boolean throwOnTab, 
            boolean throwOnNotEnough,
            boolean dontThrowOnWhiteSpaceOnlyLines
        )
    {
        if (n < 1) throw new NException(
            "The value that was passed to parameter 'n' was [" + n + "], but unfortunately this " +
            "expected to be a positive integer, greater than zero."
        );

        char[] cArr = s.toCharArray();
        throw new ToDoException();
    }

    /**
     * Performs an indenting of {@code String} of text, but does not indent the first line.  This
     * is used quit frequently by code-generators that need to assign or invoke something, and want
     * to make sure that subsequent lines of piece of code are indented (after the first line of
     * text).
     * 
     * @param s Any instance of {@code java.lang.String}.
     * @param n The number of space-characters to insert after each newline {@code '\n'} character.
     * @param spaceOrTab When {@code TRUE}, then there shall be {@code 'n'}-number of space
     * characters ({@code ' '}) inserted at the beginning of each line of text.  When
     * {@code FALSE}, then this function will insert {@code 'n'} tab characters.
     * @param trimBlankLines When {@code TRUE}, requests that blank lines be trimmed to only
     * a single newline ({@code '\n'}) character.
     * @return The indented {@code String}
     */
    public static String indentAfter2ndLine
        (String s, int n, boolean spaceOrTab, boolean trimBlankLines)
    {
        int pos = s.indexOf('\n'); // If there are no newlines, then return the original string.
        if (pos == -1) return s;

        pos++;
        return // return the first string, as is, and then indent subsequent lines.
            s.substring(0, pos) + 
            indent(s.substring(pos), n, spaceOrTab, trimBlankLines);
    }

    /**
     * This will replaced leading tabs for each line of text in a source code file with a specified
     * number of spaces.  If tabs are supposed to represent {@code 4} spaces, then if a line in a
     * source-code file had three leading tab-characters, then those three leading
     * {@code char '\t'} would be replaced with {@code 12} leading space characters {@code ' '}.
     * 
     * @param javaSrcFileAsStr A Java Source-Code File, loaded as a {@code String}.
     * 
     * @param numSpacesPerTab This identifies the number of spaces a {@code char '\t'} is supposed
     * to represent in any source-code editor's settings.  In Google Cloud Server, the default
     * value is '4' spaces.
     */
    public static String tabsToSpace(String javaSrcFileAsStr, int numSpacesPerTab)
    {
        String spaces   = StringParse.nChars(' ', numSpacesPerTab);
        String[] lines  = javaSrcFileAsStr.split("\n");

        for (String line:lines) System.out.println("LINE: " + line);

        for (int i=0; i < lines.length; i++)
        {
            int numTabs = 0;

            while ((numTabs < lines[i].length()) && (lines[i].charAt(numTabs) == '\t'))
                numTabs++;

            if (numTabs == 0)
                lines[i] = lines[i] + '\n';
            else
                lines[i] = StringParse.nStrings(spaces, numTabs) +
                lines[i].substring(numTabs) + '\n';
        }

        StringBuilder sb = new StringBuilder();

        for (String line : lines) sb.append(line);

        return sb.toString();
    }
}