// Scintilla source code edit control
/** @file LexPowerShell.cxx
 ** Lexer for PowerShell scripts.
 **/
// Copyright 2008 by Tim Gerundt <tim@gerundt.de>
// 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 <string>
#include <string_view>

#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"

using namespace Lexilla;

// Extended to accept accented characters
static inline bool IsAWordChar(int ch) noexcept {
	return ch >= 0x80 || isalnum(ch) || ch == '-' || ch == '_';
}

static bool IsNumericLiteral(int chPrev, int ch, int chNext) {
	// integers
	if (ch >= '0' && ch <= '9') {
		return true;
	}
	// hex 0x or a-f
	if ((ch == 'x' && chPrev == '0') || (ch >= 'a' && ch <= 'f')) {
		return true;
	}
	// decimal point
	if (ch == '.' && chNext != '.') {
		return true;
	}
	// optional -/+ sign after exponent
	if ((ch == '+' || ch == '-') && chPrev == 'e') {
		return true;
	}
	// suffix
	switch (ch) {
	//case 'b': see hex
	case 'g':
	case 'k':
	case 'l':
	case 'm':
	case 'n':
	case 'p':
	case 's':
	case 't':
	case 'u':
	case 'y':
		return true;
	}
	return false;
}

static void ColourisePowerShellDoc(Sci_PositionU startPos, Sci_Position length, int initStyle,
				   WordList *keywordlists[], Accessor &styler) {

	const WordList &keywords = *keywordlists[0];
	const WordList &keywords2 = *keywordlists[1];
	const WordList &keywords3 = *keywordlists[2];
	const WordList &keywords4 = *keywordlists[3];
	const WordList &keywords5 = *keywordlists[4];
	const WordList &keywords6 = *keywordlists[5];

	styler.StartAt(startPos);

	StyleContext sc(startPos, length, initStyle, styler);

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

		if (sc.state == SCE_POWERSHELL_COMMENT) {
			if (sc.MatchLineEnd()) {
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_COMMENTSTREAM) {
			if (sc.atLineStart) {
				while (IsASpaceOrTab(sc.ch)) {
					sc.Forward();
				}
				if (sc.ch == '.' && IsAWordChar(sc.chNext)) {
					sc.SetState(SCE_POWERSHELL_COMMENTDOCKEYWORD);
				}
			}
			if (sc.ch == '>' && sc.chPrev == '#') {
				sc.ForwardSetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_COMMENTDOCKEYWORD) {
			if (!IsAWordChar(sc.ch)) {
				char s[100];
				sc.GetCurrentLowered(s, sizeof(s));
				if (!keywords6.InList(s + 1)) {
					sc.ChangeState(SCE_POWERSHELL_COMMENTSTREAM);
				}
				sc.SetState(SCE_POWERSHELL_COMMENTSTREAM);
			}
		} else if (sc.state == SCE_POWERSHELL_STRING) {
			// This is a doubles quotes string
			if (sc.ch == '\"') {
				sc.ForwardSetState(SCE_POWERSHELL_DEFAULT);
			} else if (sc.ch == '`') {
				sc.Forward(); // skip next escaped character
			}
		} else if (sc.state == SCE_POWERSHELL_CHARACTER) {
			// This is a single quote string
			if (sc.ch == '\'') {
				sc.ForwardSetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_HERE_STRING) {
			// This is a doubles quotes here-string
			if (sc.atLineStart && sc.ch == '\"' && sc.chNext == '@') {
				sc.Forward(2);
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_HERE_CHARACTER) {
			// This is a single quote here-string
			if (sc.atLineStart && sc.ch == '\'' && sc.chNext == '@') {
				sc.Forward(2);
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_NUMBER) {
			if (!IsNumericLiteral(MakeLowerCase(sc.chPrev),
					      MakeLowerCase(sc.ch),
					      MakeLowerCase(sc.chNext))) {
				if (sc.MatchLineEnd() || IsASpaceOrTab(sc.ch) || isoperator(sc.ch)) {
					sc.SetState(SCE_POWERSHELL_DEFAULT);
				} else {
					sc.ChangeState(SCE_POWERSHELL_IDENTIFIER);
				}
			}
		} else if (sc.state == SCE_POWERSHELL_VARIABLE) {
			if (!IsAWordChar(sc.ch)) {
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_OPERATOR) {
			if (!isoperator(sc.ch)) {
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		} else if (sc.state == SCE_POWERSHELL_IDENTIFIER) {
			if (!IsAWordChar(sc.ch)) {
				char s[100];
				sc.GetCurrentLowered(s, sizeof(s));

				if (keywords.InList(s)) {
					sc.ChangeState(SCE_POWERSHELL_KEYWORD);
				} else if (keywords2.InList(s)) {
					sc.ChangeState(SCE_POWERSHELL_CMDLET);
				} else if (keywords3.InList(s)) {
					sc.ChangeState(SCE_POWERSHELL_ALIAS);
				} else if (keywords4.InList(s)) {
					sc.ChangeState(SCE_POWERSHELL_FUNCTION);
				} else if (keywords5.InList(s)) {
					sc.ChangeState(SCE_POWERSHELL_USER1);
				}
				sc.SetState(SCE_POWERSHELL_DEFAULT);
			}
		}

		// Determine if a new state should be entered.
		if (sc.state == SCE_POWERSHELL_DEFAULT) {
			if (sc.ch == '#') {
				sc.SetState(SCE_POWERSHELL_COMMENT);
			} else if (sc.ch == '<' && sc.chNext == '#') {
				sc.SetState(SCE_POWERSHELL_COMMENTSTREAM);
			} else if (sc.ch == '\"') {
				sc.SetState(SCE_POWERSHELL_STRING);
			} else if (sc.ch == '\'') {
				sc.SetState(SCE_POWERSHELL_CHARACTER);
			} else if (sc.ch == '@' && sc.chNext == '\"') {
				sc.SetState(SCE_POWERSHELL_HERE_STRING);
			} else if (sc.ch == '@' && sc.chNext == '\'') {
				sc.SetState(SCE_POWERSHELL_HERE_CHARACTER);
			} else if (sc.ch == '$') {
				sc.SetState(SCE_POWERSHELL_VARIABLE);
			} else if (IsADigit(sc.ch) || (sc.chPrev != '.' && sc.ch == '.' && IsADigit(sc.chNext))) {
				sc.SetState(SCE_POWERSHELL_NUMBER);
			} else if (isoperator(sc.ch)) {
				sc.SetState(SCE_POWERSHELL_OPERATOR);
			} else if (IsAWordChar(sc.ch)) {
				sc.SetState(SCE_POWERSHELL_IDENTIFIER);
			} else if (sc.ch == '`') {
				sc.Forward(); // skip next escaped character
			}
		}
	}
	sc.Complete();
}

// Store both the current line's fold level and the next lines in the
// level store to make it easy to pick up with each increment
// and to make it possible to fiddle the current level for "} else {".
static void FoldPowerShellDoc(Sci_PositionU startPos, Sci_Position length, int initStyle,
			      WordList *[], Accessor &styler) {
	const bool foldComment = styler.GetPropertyInt("fold.comment") != 0;
	const bool foldCompact = styler.GetPropertyInt("fold.compact", 1) != 0;
	const bool foldAtElse = styler.GetPropertyInt("fold.at.else", 0) != 0;
	const Sci_PositionU endPos = startPos + length;
	int visibleChars = 0;
	Sci_Position lineCurrent = styler.GetLine(startPos);
	int levelCurrent = SC_FOLDLEVELBASE;
	if (lineCurrent > 0)
		levelCurrent = styler.LevelAt(lineCurrent-1) >> 16;
	int levelMinCurrent = levelCurrent;
	int levelNext = levelCurrent;
	char chNext = styler[startPos];
	int styleNext = styler.StyleAt(startPos);
	int style = initStyle;
	for (Sci_PositionU i = startPos; i < endPos; i++) {
		const char ch = chNext;
		chNext = styler.SafeGetCharAt(i + 1);
		const int stylePrev = style;
		style = styleNext;
		styleNext = styler.StyleAt(i + 1);
		const bool atEOL = (ch == '\r' && chNext != '\n') || (ch == '\n');
		if (style == SCE_POWERSHELL_OPERATOR) {
			if (ch == '{') {
				// Measure the minimum before a '{' to allow
				// folding on "} else {"
				if (levelMinCurrent > levelNext) {
					levelMinCurrent = levelNext;
				}
				levelNext++;
			} else if (ch == '}') {
				levelNext--;
			}
		} else if (foldComment && style == SCE_POWERSHELL_COMMENTSTREAM) {
			if (stylePrev != SCE_POWERSHELL_COMMENTSTREAM && stylePrev != SCE_POWERSHELL_COMMENTDOCKEYWORD) {
				levelNext++;
			} else if (styleNext != SCE_POWERSHELL_COMMENTSTREAM && styleNext != SCE_POWERSHELL_COMMENTDOCKEYWORD) {
				levelNext--;
			}
		} else if (foldComment && style == SCE_POWERSHELL_COMMENT) {
			if (ch == '#') {
				Sci_PositionU j = i + 1;
				while ((j < endPos) && IsASpaceOrTab(styler.SafeGetCharAt(j))) {
					j++;
				}
				if (styler.Match(j, "region")) {
					levelNext++;
				} else if (styler.Match(j, "endregion")) {
					levelNext--;
				}
			}
		}
		if (!IsASpace(ch))
			visibleChars++;
		if (atEOL || (i == endPos-1)) {
			int levelUse = levelCurrent;
			if (foldAtElse) {
				levelUse = levelMinCurrent;
			}
			int lev = levelUse | levelNext << 16;
			if (visibleChars == 0 && foldCompact)
				lev |= SC_FOLDLEVELWHITEFLAG;
			if (levelUse < levelNext)
				lev |= SC_FOLDLEVELHEADERFLAG;
			if (lev != styler.LevelAt(lineCurrent)) {
				styler.SetLevel(lineCurrent, lev);
			}
			lineCurrent++;
			levelCurrent = levelNext;
			levelMinCurrent = levelCurrent;
			visibleChars = 0;
		}
	}
}

static const char *const powershellWordLists[] = {
	"Commands",
	"Cmdlets",
	"Aliases",
	"Functions",
	"User1",
	"DocComment",
	0
};

extern const LexerModule lmPowerShell(SCLEX_POWERSHELL, ColourisePowerShellDoc, "powershell", FoldPowerShellDoc, powershellWordLists);