// Scintilla source code edit control
/** @file LexPython.cxx
 ** Lexer for Python.
 **/
// Copyright 1998-2002 by Neil Hodgson <neilh@scintilla.org>
// The License.txt file describes the conditions under which this software may be distributed.

#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stdarg.h>
#include <assert.h>
#include <ctype.h>

#include "ILexer.h"
#include "Scintilla.h"
#include "SciLexer.h"

#include "WordList.h"
#include "LexAccessor.h"
#include "Accessor.h"
#include "StyleContext.h"
#include "CharacterSet.h"
#include "LexerModule.h"

#ifdef SCI_NAMESPACE
using namespace Scintilla;
#endif

/* kwCDef, kwCTypeName only used for Cython */
enum kwType { kwOther, kwClass, kwDef, kwImport, kwCDef, kwCTypeName, kwCPDef };

static const int indicatorWhitespace = 1;

static bool IsPyComment(Accessor &styler, int pos, int len) {
    return len > 0 && styler[pos] == '#';
}

enum literalsAllowed { litNone=0, litU=1, litB=2};

static bool IsPyStringTypeChar(int ch, literalsAllowed allowed) {
    return
        ((allowed & litB) && (ch == 'b' || ch == 'B')) ||
        ((allowed & litU) && (ch == 'u' || ch == 'U'));
}

static bool IsPyStringStart(int ch, int chNext, int chNext2, literalsAllowed allowed) {
    if (ch == '\'' || ch == '"')
        return true;
    if (IsPyStringTypeChar(ch, allowed)) {
        if (chNext == '"' || chNext == '\'')
            return true;
        if ((chNext == 'r' || chNext == 'R') && (chNext2 == '"' || chNext2 == '\''))
            return true;
    }
    if ((ch == 'r' || ch == 'R') && (chNext == '"' || chNext == '\''))
        return true;

    return false;
}

/* Return the state to use for the string starting at i; *nextIndex will be set to the first index following the quote(s) */
static int GetPyStringState(Accessor &styler, int i, unsigned int *nextIndex, literalsAllowed allowed) {
    char ch = styler.SafeGetCharAt(i);
    char chNext = styler.SafeGetCharAt(i + 1);

    // Advance beyond r, u, or ur prefix (or r, b, or br in Python 3.0), but bail if there are any unexpected chars
    if (ch == 'r' || ch == 'R') {
        i++;
        ch = styler.SafeGetCharAt(i);
        chNext = styler.SafeGetCharAt(i + 1);
    } else if (IsPyStringTypeChar(ch, allowed)) {
        if (chNext == 'r' || chNext == 'R')
            i += 2;
        else
            i += 1;
        ch = styler.SafeGetCharAt(i);
        chNext = styler.SafeGetCharAt(i + 1);
    }

    if (ch != '"' && ch != '\'') {
        *nextIndex = i + 1;
        return SCE_P_DEFAULT;
    }

    if (ch == chNext && ch == styler.SafeGetCharAt(i + 2)) {
        *nextIndex = i + 3;

        if (ch == '"')
            return SCE_P_TRIPLEDOUBLE;
        else
            return SCE_P_TRIPLE;
    } else {
        *nextIndex = i + 1;

        if (ch == '"')
            return SCE_P_STRING;
        else
            return SCE_P_CHARACTER;
    }
}

static inline bool IsAWordChar(int ch) {
    return (ch < 0x80) && (isalnum(ch) || ch == '.' || ch == '_');
}

static inline bool IsAWordStart(int ch) {
    return (ch < 0x80) && (isalnum(ch) || ch == '_');
}

static void ColourisePyDoc(unsigned int startPos, int length, int initStyle,
        WordList *keywordlists[], Accessor &styler) {

    int endPos = startPos + length;

    // Backtrack to previous line in case need to fix its tab whinging
    int lineCurrent = styler.GetLine(startPos);
    if (startPos > 0) {
        if (lineCurrent > 0) {
            lineCurrent--;
            // Look for backslash-continued lines
            while (lineCurrent > 0) {
                int eolPos = styler.LineStart(lineCurrent) - 1;
                int eolStyle = styler.StyleAt(eolPos);
                if (eolStyle == SCE_P_STRING
                    || eolStyle == SCE_P_CHARACTER
                    || eolStyle == SCE_P_STRINGEOL) {
                    lineCurrent -= 1;
                } else {
                    break;
                }
            }
            startPos = styler.LineStart(lineCurrent);
        }
        initStyle = startPos == 0 ? SCE_P_DEFAULT : styler.StyleAt(startPos - 1);
    }

    WordList &keywords = *keywordlists[0];
    WordList &keywords2 = *keywordlists[1];

    // property tab.timmy.whinge.level
    //  For Python code, checks whether indenting is consistent.
    //  The default, 0 turns off indentation checking,
    //  1 checks whether each line is potentially inconsistent with the previous line,
    //  2 checks whether any space characters occur before a tab character in the indentation,
    //  3 checks whether any spaces are in the indentation, and
    //  4 checks for any tab characters in the indentation.
    //  1 is a good level to use.
    const int whingeLevel = styler.GetPropertyInt("tab.timmy.whinge.level");

    // property lexer.python.literals.binary
    //  Set to 0 to not recognise Python 3 binary and octal literals: 0b1011 0o712.
    bool base2or8Literals = styler.GetPropertyInt("lexer.python.literals.binary", 1) != 0;

    // property lexer.python.strings.u
    //  Set to 0 to not recognise Python Unicode literals u"x" as used before Python 3.
    literalsAllowed allowedLiterals = (styler.GetPropertyInt("lexer.python.strings.u", 1)) ? litU : litNone;

    // property lexer.python.strings.b
    //  Set to 0 to not recognise Python 3 bytes literals b"x".
    if (styler.GetPropertyInt("lexer.python.strings.b", 1))
        allowedLiterals = static_cast<literalsAllowed>(allowedLiterals | litB);

    // property lexer.python.strings.over.newline
    //      Set to 1 to allow strings to span newline characters.
    bool stringsOverNewline = styler.GetPropertyInt("lexer.python.strings.over.newline") != 0;

    // property lexer.python.keywords2.no.sub.identifiers
    //  When enabled, it will not style keywords2 items that are used as a sub-identifier.
    //      Example: when set, will not highlight "foo.open" when "open" is a keywords2 item.
    const bool keywords2NoSubIdentifiers = styler.GetPropertyInt("lexer.python.keywords2.no.sub.identifiers") != 0;

    initStyle = initStyle & 31;
    if (initStyle == SCE_P_STRINGEOL) {
        initStyle = SCE_P_DEFAULT;
    }

    kwType kwLast = kwOther;
    int spaceFlags = 0;
    styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
    bool base_n_number = false;

    StyleContext sc(startPos, endPos - startPos, initStyle, styler);

    bool indentGood = true;
    int startIndicator = sc.currentPos;
    bool inContinuedString = false;

    for (; sc.More(); sc.Forward()) {

        if (sc.atLineStart) {
            styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
            indentGood = true;
            if (whingeLevel == 1) {
                indentGood = (spaceFlags & wsInconsistent) == 0;
            } else if (whingeLevel == 2) {
                indentGood = (spaceFlags & wsSpaceTab) == 0;
            } else if (whingeLevel == 3) {
                indentGood = (spaceFlags & wsSpace) == 0;
            } else if (whingeLevel == 4) {
                indentGood = (spaceFlags & wsTab) == 0;
            }
            if (!indentGood) {
                styler.IndicatorFill(startIndicator, sc.currentPos, indicatorWhitespace, 0);
                startIndicator = sc.currentPos;
            }
        }

        if (sc.atLineEnd) {
            if ((sc.state == SCE_P_DEFAULT) ||
                    (sc.state == SCE_P_TRIPLE) ||
                    (sc.state == SCE_P_TRIPLEDOUBLE)) {
                // Perform colourisation of white space and triple quoted strings at end of each line to allow
                // tab marking to work inside white space and triple quoted strings
                sc.SetState(sc.state);
            }
            lineCurrent++;
            if ((sc.state == SCE_P_STRING) || (sc.state == SCE_P_CHARACTER)) {
                if (inContinuedString || stringsOverNewline) {
                    inContinuedString = false;
                } else {
                    sc.ChangeState(SCE_P_STRINGEOL);
                    sc.ForwardSetState(SCE_P_DEFAULT);
                }
            }
            if (!sc.More())
                break;
        }

        bool needEOLCheck = false;

        // Check for a state end
        if (sc.state == SCE_P_OPERATOR) {
            kwLast = kwOther;
            sc.SetState(SCE_P_DEFAULT);
        } else if (sc.state == SCE_P_NUMBER) {
            if (!IsAWordChar(sc.ch) &&
                    !(!base_n_number && ((sc.ch == '+' || sc.ch == '-') && (sc.chPrev == 'e' || sc.chPrev == 'E')))) {
                sc.SetState(SCE_P_DEFAULT);
            }
        } else if (sc.state == SCE_P_IDENTIFIER) {
            if ((sc.ch == '.') || (!IsAWordChar(sc.ch))) {
                char s[100];
                sc.GetCurrent(s, sizeof(s));
                int style = SCE_P_IDENTIFIER;
                if ((kwLast == kwImport) && (strcmp(s, "as") == 0)) {
                    style = SCE_P_WORD;
                } else if (keywords.InList(s)) {
                    style = SCE_P_WORD;
                } else if (kwLast == kwClass) {
                    style = SCE_P_CLASSNAME;
                } else if (kwLast == kwDef) {
                    style = SCE_P_DEFNAME;
                } else if (kwLast == kwCDef || kwLast == kwCPDef) {
                    int pos = sc.currentPos;
                    unsigned char ch = styler.SafeGetCharAt(pos, '\0');
                    while (ch != '\0') {
                        if (ch == '(') {
                            style = SCE_P_DEFNAME;
                            break;
                        } else if (ch == ':') {
                            style = SCE_P_CLASSNAME;
                            break;
                        } else if (ch == ' ' || ch == '\t' || ch == '\n' || ch == '\r') {
                            pos++;
                            ch = styler.SafeGetCharAt(pos, '\0');
                        } else {
                            break;
                        }
                    }
                } else if (keywords2.InList(s)) {
                    if (keywords2NoSubIdentifiers) {
                        // We don't want to highlight keywords2
                        // that are used as a sub-identifier,
                        // i.e. not open in "foo.open".
                        int pos = styler.GetStartSegment() - 1;
                        if (pos < 0 || (styler.SafeGetCharAt(pos, '\0') != '.'))
                            style = SCE_P_WORD2;
                    } else {
                        style = SCE_P_WORD2;
                    }
                }
                sc.ChangeState(style);
                sc.SetState(SCE_P_DEFAULT);
                if (style == SCE_P_WORD) {
                    if (0 == strcmp(s, "class"))
                        kwLast = kwClass;
                    else if (0 == strcmp(s, "def"))
                        kwLast = kwDef;
                    else if (0 == strcmp(s, "import"))
                        kwLast = kwImport;
                    else if (0 == strcmp(s, "cdef"))
                        kwLast = kwCDef;
                    else if (0 == strcmp(s, "cpdef"))
                        kwLast = kwCPDef;
                    else if (0 == strcmp(s, "cimport"))
                        kwLast = kwImport;
                    else if (kwLast != kwCDef && kwLast != kwCPDef)
                        kwLast = kwOther;
                } else if (kwLast != kwCDef && kwLast != kwCPDef) {
                    kwLast = kwOther;
                }
            }
        } else if ((sc.state == SCE_P_COMMENTLINE) || (sc.state == SCE_P_COMMENTBLOCK)) {
            if (sc.ch == '\r' || sc.ch == '\n') {
                sc.SetState(SCE_P_DEFAULT);
            }
        } else if (sc.state == SCE_P_DECORATOR) {
            if (!IsAWordChar(sc.ch)) {
                sc.SetState(SCE_P_DEFAULT);
            }
        } else if ((sc.state == SCE_P_STRING) || (sc.state == SCE_P_CHARACTER)) {
            if (sc.ch == '\\') {
                if ((sc.chNext == '\r') && (sc.GetRelative(2) == '\n')) {
                    sc.Forward();
                }
                if (sc.chNext == '\n' || sc.chNext == '\r') {
                    inContinuedString = true;
                } else {
                    // Don't roll over the newline.
                    sc.Forward();
                }
            } else if ((sc.state == SCE_P_STRING) && (sc.ch == '\"')) {
                sc.ForwardSetState(SCE_P_DEFAULT);
                needEOLCheck = true;
            } else if ((sc.state == SCE_P_CHARACTER) && (sc.ch == '\'')) {
                sc.ForwardSetState(SCE_P_DEFAULT);
                needEOLCheck = true;
            }
        } else if (sc.state == SCE_P_TRIPLE) {
            if (sc.ch == '\\') {
                sc.Forward();
            } else if (sc.Match("\'\'\'")) {
                sc.Forward();
                sc.Forward();
                sc.ForwardSetState(SCE_P_DEFAULT);
                needEOLCheck = true;
            }
        } else if (sc.state == SCE_P_TRIPLEDOUBLE) {
            if (sc.ch == '\\') {
                sc.Forward();
            } else if (sc.Match("\"\"\"")) {
                sc.Forward();
                sc.Forward();
                sc.ForwardSetState(SCE_P_DEFAULT);
                needEOLCheck = true;
            }
        }

        if (!indentGood && !IsASpaceOrTab(sc.ch)) {
            styler.IndicatorFill(startIndicator, sc.currentPos, indicatorWhitespace, 1);
            startIndicator = sc.currentPos;
            indentGood = true;
        }

        // One cdef or cpdef line, clear kwLast only at end of line
        if ((kwLast == kwCDef || kwLast == kwCPDef) && sc.atLineEnd) {
            kwLast = kwOther;
        }

        // State exit code may have moved on to end of line
        if (needEOLCheck && sc.atLineEnd) {
            lineCurrent++;
            styler.IndentAmount(lineCurrent, &spaceFlags, IsPyComment);
            if (!sc.More())
                break;
        }

        // Check for a new state starting character
        if (sc.state == SCE_P_DEFAULT) {
            if (IsADigit(sc.ch) || (sc.ch == '.' && IsADigit(sc.chNext))) {
                if (sc.ch == '0' && (sc.chNext == 'x' || sc.chNext == 'X')) {
                    base_n_number = true;
                    sc.SetState(SCE_P_NUMBER);
                } else if (sc.ch == '0' &&
                    (sc.chNext == 'o' || sc.chNext == 'O' || sc.chNext == 'b' || sc.chNext == 'B')) {
                    if (base2or8Literals) {
                        base_n_number = true;
                        sc.SetState(SCE_P_NUMBER);
                    } else {
                        sc.SetState(SCE_P_NUMBER);
                        sc.ForwardSetState(SCE_P_IDENTIFIER);
                    }
                } else {
                    base_n_number = false;
                    sc.SetState(SCE_P_NUMBER);
                }
            } else if ((isascii(sc.ch) && isoperator(static_cast<char>(sc.ch))) || sc.ch == '`') {
                sc.SetState(SCE_P_OPERATOR);
            } else if (sc.ch == '#') {
                sc.SetState(sc.chNext == '#' ? SCE_P_COMMENTBLOCK : SCE_P_COMMENTLINE);
            } else if (sc.ch == '@') {
                sc.SetState(SCE_P_DECORATOR);
            } else if (IsPyStringStart(sc.ch, sc.chNext, sc.GetRelative(2), allowedLiterals)) {
                unsigned int nextIndex = 0;
                sc.SetState(GetPyStringState(styler, sc.currentPos, &nextIndex, allowedLiterals));
                while (nextIndex > (sc.currentPos + 1) && sc.More()) {
                    sc.Forward();
                }
            } else if (IsAWordStart(sc.ch)) {
                sc.SetState(SCE_P_IDENTIFIER);
            }
        }
    }
    styler.IndicatorFill(startIndicator, sc.currentPos, indicatorWhitespace, 0);
    sc.Complete();
}

static bool IsCommentLine(int line, Accessor &styler) {
    int pos = styler.LineStart(line);
    int eol_pos = styler.LineStart(line + 1) - 1;
    for (int i = pos; i < eol_pos; i++) {
        char ch = styler[i];
        if (ch == '#')
            return true;
        else if (ch != ' ' && ch != '\t')
            return false;
    }
    return false;
}

static bool IsQuoteLine(int line, Accessor &styler) {
    int style = styler.StyleAt(styler.LineStart(line)) & 31;
    return ((style == SCE_P_TRIPLE) || (style == SCE_P_TRIPLEDOUBLE));
}


static void FoldPyDoc(unsigned int startPos, int length, int /*initStyle - unused*/,
                      WordList *[], Accessor &styler) {
    const int maxPos = startPos + length;
    const int maxLines = (maxPos == styler.Length()) ? styler.GetLine(maxPos) : styler.GetLine(maxPos - 1); // Requested last line
    const int docLines = styler.GetLine(styler.Length());   // Available last line

    // property fold.quotes.python
    //  This option enables folding multi-line quoted strings when using the Python lexer.
    const bool foldQuotes = styler.GetPropertyInt("fold.quotes.python") != 0;

    const bool foldCompact = styler.GetPropertyInt("fold.compact") != 0;

    // Backtrack to previous non-blank line so we can determine indent level
    // for any white space lines (needed esp. within triple quoted strings)
    // and so we can fix any preceding fold level (which is why we go back
    // at least one line in all cases)
    int spaceFlags = 0;
    int lineCurrent = styler.GetLine(startPos);
    int indentCurrent = styler.IndentAmount(lineCurrent, &spaceFlags, NULL);
    while (lineCurrent > 0) {
        lineCurrent--;
        indentCurrent = styler.IndentAmount(lineCurrent, &spaceFlags, NULL);
        if (!(indentCurrent & SC_FOLDLEVELWHITEFLAG) &&
                (!IsCommentLine(lineCurrent, styler)) &&
                (!IsQuoteLine(lineCurrent, styler)))
            break;
    }
    int indentCurrentLevel = indentCurrent & SC_FOLDLEVELNUMBERMASK;

    // Set up initial loop state
    startPos = styler.LineStart(lineCurrent);
    int prev_state = SCE_P_DEFAULT & 31;
    if (lineCurrent >= 1)
        prev_state = styler.StyleAt(startPos - 1) & 31;
    int prevQuote = foldQuotes && ((prev_state == SCE_P_TRIPLE) || (prev_state == SCE_P_TRIPLEDOUBLE));

    // Process all characters to end of requested range or end of any triple quote
    //that hangs over the end of the range.  Cap processing in all cases
    // to end of document (in case of unclosed quote at end).
    while ((lineCurrent <= docLines) && ((lineCurrent <= maxLines) || prevQuote)) {

        // Gather info
        int lev = indentCurrent;
        int lineNext = lineCurrent + 1;
        int indentNext = indentCurrent;
        int quote = false;
        if (lineNext <= docLines) {
            // Information about next line is only available if not at end of document
            indentNext = styler.IndentAmount(lineNext, &spaceFlags, NULL);
            int lookAtPos = (styler.LineStart(lineNext) == styler.Length()) ? styler.Length() - 1 : styler.LineStart(lineNext);
            int style = styler.StyleAt(lookAtPos) & 31;
            quote = foldQuotes && ((style == SCE_P_TRIPLE) || (style == SCE_P_TRIPLEDOUBLE));
        }
        const int quote_start = (quote && !prevQuote);
        const int quote_continue = (quote && prevQuote);
        if (!quote || !prevQuote)
            indentCurrentLevel = indentCurrent & SC_FOLDLEVELNUMBERMASK;
        if (quote)
            indentNext = indentCurrentLevel;
        if (indentNext & SC_FOLDLEVELWHITEFLAG)
            indentNext = SC_FOLDLEVELWHITEFLAG | indentCurrentLevel;

        if (quote_start) {
            // Place fold point at start of triple quoted string
            lev |= SC_FOLDLEVELHEADERFLAG;
        } else if (quote_continue || prevQuote) {
            // Add level to rest of lines in the string
            lev = lev + 1;
        }

        // Skip past any blank lines for next indent level info; we skip also
        // comments (all comments, not just those starting in column 0)
        // which effectively folds them into surrounding code rather
        // than screwing up folding.

        while (!quote &&
                (lineNext < docLines) &&
                ((indentNext & SC_FOLDLEVELWHITEFLAG) ||
                 (lineNext <= docLines && IsCommentLine(lineNext, styler)))) {

            lineNext++;
            indentNext = styler.IndentAmount(lineNext, &spaceFlags, NULL);
        }

        const int levelAfterComments = indentNext & SC_FOLDLEVELNUMBERMASK;
        const int levelBeforeComments = Maximum(indentCurrentLevel,levelAfterComments);

        // Now set all the indent levels on the lines we skipped
        // Do this from end to start.  Once we encounter one line
        // which is indented more than the line after the end of
        // the comment-block, use the level of the block before

        int skipLine = lineNext;
        int skipLevel = levelAfterComments;

        while (--skipLine > lineCurrent) {
            int skipLineIndent = styler.IndentAmount(skipLine, &spaceFlags, NULL);

            if (foldCompact) {
                if ((skipLineIndent & SC_FOLDLEVELNUMBERMASK) > levelAfterComments)
                    skipLevel = levelBeforeComments;

                int whiteFlag = skipLineIndent & SC_FOLDLEVELWHITEFLAG;

                styler.SetLevel(skipLine, skipLevel | whiteFlag);
            } else {
                if ((skipLineIndent & SC_FOLDLEVELNUMBERMASK) > levelAfterComments &&
                    !(skipLineIndent & SC_FOLDLEVELWHITEFLAG) &&
                    !IsCommentLine(skipLine, styler))
                    skipLevel = levelBeforeComments;

                styler.SetLevel(skipLine, skipLevel);
            }
        }

        // Set fold header on non-quote line
        if (!quote && !(indentCurrent & SC_FOLDLEVELWHITEFLAG)) {
            if ((indentCurrent & SC_FOLDLEVELNUMBERMASK) < (indentNext & SC_FOLDLEVELNUMBERMASK))
                lev |= SC_FOLDLEVELHEADERFLAG;
        }

        // Keep track of triple quote state of previous line
        prevQuote = quote;

        // Set fold level for this line and move to next line
        styler.SetLevel(lineCurrent, foldCompact ? lev : lev & ~SC_FOLDLEVELWHITEFLAG);
        indentCurrent = indentNext;
        lineCurrent = lineNext;
    }

    // NOTE: Cannot set level of last line here because indentCurrent doesn't have
    // header flag set; the loop above is crafted to take care of this case!
    //styler.SetLevel(lineCurrent, indentCurrent);
}

static const char *const pythonWordListDesc[] = {
    "Keywords",
    "Highlighted identifiers",
    0
};

LexerModule lmPython(SCLEX_PYTHON, ColourisePyDoc, "python", FoldPyDoc,
                     pythonWordListDesc);

