/*  Starshatter: The Open Source Project
    Copyright (c) 2021-2022, Starshatter: The Open Source Project Contributors
    Copyright (c) 2011-2012, Starshatter OpenSource Distribution Contributors
    Copyright (c) 1997-2006, Destroyer Studios LLC.

     AUTHOR:       John DiCamillo


     OVERVIEW
     ========
     Scanner class implementation
*/

#include "Token.h"
#include "Reader.h"
#include "Text.h"

#include <ctype.h>

// +-------------------------------------------------------------------+

bool        Token::hidecom   = true;
char        Token::combeg[3] = "//";
char        Token::comend[3] = "\n";
char        Token::altbeg[3] = "/*";
char        Token::altend[3] = "*/";
Dictionary<int>   Token::keymap;

// +-------------------------------------------------------------------+

Token::Token()
    : mType(Undefined), mKey(0), mLine(0), mColumn(0)
{
    mLength    = 0;
    mSymbol[0] = '\0';
}

Token::Token(const Token& rhs)
    : mType(rhs.mType), mKey(rhs.mKey), mLine(rhs.mLine), mColumn(rhs.mColumn)
{
    mLength = rhs.mLength;
    if (mLength < 8) {
        strcpy_s(mSymbol, rhs.mSymbol);
    }
    else {
        mFullSymbol = new char[mLength + 1];
        strcpy(mFullSymbol, rhs.mFullSymbol);
    }
}

Token::Token(int t)
    : mType(t), mKey(0), mLine(0), mColumn(0)
{
    mLength    = 0;
    mSymbol[0] = '\0';
}

Token::Token(const char* s, int t, int k, int l, int c)
    : mType(t), mKey(k), mLine(l), mColumn(c)
{
    mLength = strlen(s);
    if (mLength < 8) {
        strcpy_s(mSymbol, s);
    }
    else {
        mFullSymbol = new char[mLength + 1];
        strcpy(mFullSymbol, s);
    }
}

Token::Token(const Text& s, int t, int k, int l, int c)
    : mType(t), mKey(k), mLine(l), mColumn(c)
{
    mLength = s.length();
    if (mLength < 8) {
        strcpy_s(mSymbol, s.data());
    }
    else {
        mFullSymbol = new char[mLength + 1];
        strcpy(mFullSymbol, s.data());
    }
}

Token::~Token()
{
    if (mLength >= 8)
        delete [] mFullSymbol;
}

// +-------------------------------------------------------------------+

void
Token::close()
{
    keymap.clear();
}

// +-------------------------------------------------------------------+

Token&
Token::operator = (const Token& rhs)
{
    if (mLength >= 8)
        delete [] mFullSymbol;

    mLength = rhs.mLength;
    if (mLength < 8) {
        strcpy_s(mSymbol, rhs.mSymbol);
    }
    else {
        mFullSymbol = new char[mLength + 1];
        strcpy(mFullSymbol, rhs.mFullSymbol);
    }

    mType   = rhs.mType;
    mKey    = rhs.mKey;
    mLine   = rhs.mLine;
    mColumn = rhs.mColumn;

    return *this;
}

// +-------------------------------------------------------------------+

bool
Token::match(const Token& ref) const
{
    if (mType == ref.mType) {                    // if types match
        if (ref.mLength == 0)                     // if no symbol to match
            return true;                           // match!

        else if (mLength == ref.mLength) {        // else if symbols match
            if (mLength < 8) {
                if (!strcmp(mSymbol, ref.mSymbol))
                    return true;                     // match!
            }
            else {
                if (!strcmp(mFullSymbol, ref.mFullSymbol))
                    return true;                     // match!
            }
        }
    }

    return false;
}

// +-------------------------------------------------------------------+

Text
Token::symbol() const
{
    if (mLength < 8)
        return Text(mSymbol);
    else
        return Text(mFullSymbol);
}

// +-------------------------------------------------------------------+

void
Token::addKey(const Text& k, int v)
{
    keymap.insert(k, v);
}

// +-------------------------------------------------------------------+

void
Token::addKeys(Dictionary<int>& keys)
{
    DictionaryIter<int> iter = keys;
    while (++iter)
        keymap.insert(iter.key(), iter.value());
}

// +-------------------------------------------------------------------+

bool
Token::findKey(const Text& k, int& v)
{
    if (keymap.contains(k)) {
        v = keymap.find(k, 0);
        return true;
    }
    else
        return false;
}

// +-------------------------------------------------------------------+

void
Token::comments(const Text& begin, const Text& end)
{
    combeg[0] = begin(0);
    if (begin.length() > 1) combeg[1] = begin(1);
    else                    combeg[1] = '\0';

    comend[0] = end(0);
    if (end.length() > 1)   comend[1] = end(1);
    else                    comend[1] = '\0';
}

// +-------------------------------------------------------------------+

void
Token::altComments(const Text& begin, const Text& end)
{
    altbeg[0] = begin(0);
    if (begin.length() > 1) altbeg[1] = begin(1);
    else                    altbeg[1] = '\0';

    altend[0] = end(0);
    if (end.length() > 1)   altend[1] = end(1);
    else                    altend[1] = '\0';
}

// +-------------------------------------------------------------------+

Text
Token::typestr() const
{
    Text t = "Unknown";
    switch (type()) {
    case Undefined:      t = "Undefined"; break;
    case Keyword:        t = "Keyword"; break;
    case AlphaIdent:     t = "AlphaIdent"; break;
    case SymbolicIdent:  t = "SymbolicIdent"; break;
    case Comment:        t = "Comment"; break;
    case IntLiteral:     t = "IntLiteral"; break;
    case FloatLiteral:   t = "FloatLiteral"; break;
    case StringLiteral:  t = "StringLiteral"; break;
    case CharLiteral:    t = "CharLiteral"; break;
    case Dot:            t = "Dot"; break;
    case Comma:          t = "Comma"; break;
    case Colon:          t = "Colon"; break;
    case Semicolon:      t = "Semicolon"; break;
    case LParen:         t = "LParen"; break;
    case RParen:         t = "RParen"; break;
    case LBracket:       t = "LBracket"; break;
    case RBracket:       t = "RBracket"; break;
    case LBrace:         t = "LBrace"; break;
    case RBrace:         t = "RBrace"; break;
    case EOT:            t = "EOT"; break;
    case LastTokenType:  t = "LastTokenType"; break;
    }

    return t;
}

// +-------------------------------------------------------------------+

Text
Token::describe(const Text& tok)
{
    Text d;

    switch (tok(0)) {
    case '.' : d = "Token::Dot"; break;
    case ',' : d = "Token::Comma"; break;
    case ';' : d = "Token::Semicolon"; break;
    case '(' : d = "Token::LParen"; break;
    case ')' : d = "Token::RParen"; break;
    case '[' : d = "Token::LBracket"; break;
    case ']' : d = "Token::RBracket"; break;
    case '{' : d = "Token::LBrace"; break;
    case '}' : d = "Token::RBrace"; break;
    default  :               break;
    }

    if (d.length() == 0) {
        if (isalpha(tok(0)))
            d = "\"" + tok + "\", Token::AlphaIdent";
        else if (isdigit(tok(0))) {
            if (tok.contains("."))
                d = "\"" + tok + "\", Token::FloatLiteral";
            else
                d = "\"" + tok + "\", Token::IntLiteral";
        }
        else
            d = "\"" + tok + "\", Token::SymbolicIdent";
    }

    return d;
}

// +-------------------------------------------------------------------+

Scanner::Scanner(Reader* r)
    : reader(r), str(0), index(0), old_index(0),
      length(0), line(0), old_line(0), lineStart(0)
{ }

Scanner::Scanner(const Scanner& rhs)
    : index(rhs.index), old_index(rhs.old_index), length(rhs.length),
      reader(rhs.reader),
      line(rhs.line), old_line(0), lineStart(rhs.lineStart)
{
    str = new char [strlen(rhs.str) + 1];
    strcpy(str, rhs.str);
}

Scanner::Scanner(const Text& s)
    : reader(0), index(0), old_index(0), length(s.length()), line(0),
      old_line(0), lineStart(0)
{
    str = new char [s.length() + 1];
    strcpy(str, s.data());
}

Scanner::~Scanner()
{
    delete [] str;
}

// +-------------------------------------------------------------------+

Scanner&
Scanner::operator = (const Scanner& rhs)
{
    delete [] str;
    str = new char [strlen(rhs.str) + 1];
    strcpy(str, rhs.str);

    index     = rhs.index;
    old_index = rhs.old_index;
    length    = rhs.length;
    line      = rhs.line;
    old_line  = rhs.old_line;
    lineStart = rhs.lineStart;

    return *this;
}

// +-------------------------------------------------------------------+

void
Scanner::Load(const Text& s)
{
    delete [] str;
    str = new char [s.length() + 1];
    strcpy(str, s.data());

    index       = 0;
    old_index   = 0;
    best        = Token();
    length      = s.length();
    line        = 0;
    old_line    = 0;
    lineStart   = 0;
}

// +-------------------------------------------------------------------+

Token
Scanner::Get(Need need)
{
    int   type = Token::EOT;
    old_index  = index;
    old_line   = line;

    eos = str + length;
    p   = str + index;

    if (p >= eos) {
        if (need == Demand && reader) {
            Load(reader->more());
            if (length > 0)
                return Get(need);
        }
        return Token("", type, 0, line, 0);
    }

    while (isspace(*p) && p < eos) { // skip initial white space
        if (*p == '\n') {
            line++;
            lineStart = p - str;
        }
        p++;
    }

    if (p >= eos) {
        if (need == Demand && reader) {
            Load(reader->more());
            if (length > 0)
                return Get(need);
        }
        return Token("", type, 0, line, 0);
    }

    Token  result;
    size_t start = p - str;

    if (*p == '"' || *p == '\'') {   // special case for quoted tokens

        if (*p == '"') type = Token::StringLiteral;
        else           type = Token::CharLiteral;

        char match = *p;
        while (++p < eos) {
            if (*p == match) {         // find matching quote
                if (*(p-1) != '\\') {   // if not escaped
                    p++;                 // token includes matching quote
                    break;
                }
            }
        }
    }

    // generic delimited comments
    else if (*p == Token::comBeg(0) &&
                     (!Token::comBeg(1) || *(p+1) == Token::comBeg(1))) {
        type = Token::Comment;
        while (++p < eos) {
            if (*p == Token::comEnd(0) &&
                      (!Token::comEnd(1) || *(p+1) == Token::comEnd(1))) {
                p++; if (Token::comEnd(1)) p++;
                break;
            }
        }
    }

    // alternate form delimited comments
    else if (*p == Token::altBeg(0) &&
                     (!Token::altBeg(1) || *(p+1) == Token::altBeg(1))) {
        type = Token::Comment;
        while (++p < eos) {
            if (*p == Token::altEnd(0) &&
                      (!Token::altEnd(1) || *(p+1) == Token::altEnd(1))) {
                p++; if (Token::altEnd(1)) p++;
                break;
            }
        }
    }

    else if (*p == '.')  type = Token::Dot;
    else if (*p == ',')  type = Token::Comma;
    else if (*p == ';')  type = Token::Semicolon;
    else if (*p == '(')  type = Token::LParen;
    else if (*p == ')')  type = Token::RParen;
    else if (*p == '[')  type = Token::LBracket;
    else if (*p == ']')  type = Token::RBracket;
    else if (*p == '{')  type = Token::LBrace;
    else if (*p == '}')  type = Token::RBrace;

    // use lexical sub-parser for ints and floats
    else if (isdigit(*p))
        type = GetNumeric();

    else if (IsSymbolic(*p)) {
        type = Token::SymbolicIdent;
        while (IsSymbolic(*p)) p++;
    }

    else {
        type = Token::AlphaIdent;
        while (IsAlpha(*p)) p++;
    }

    size_t extent = (p - str) - start;

    if (extent < 1) extent = 1;      // always get at least one character

    index  = start + extent;         // advance the cursor
    int col = start - lineStart;
    if (line == 0) col++;

    char* buf = new char [extent + 1];
    strncpy(buf, str + start, extent);
    buf[extent] = '\0';

    if (type == Token::Comment && Token::hidecom) {
        delete [] buf;
        if (Token::comEnd(0) == '\n') {
            line++;
            lineStart = p - str;
        }
        return Get(need);
    }

    if (type == Token::AlphaIdent || // check for keyword
         type == Token::SymbolicIdent) {
         int val;
         if (Token::findKey(Text(buf), val))
            result = Token(buf, Token::Keyword, val, line+1, col);
    }

    if (result.mType != Token::Keyword)
        result = Token(buf, type, 0, line+1, col);

    if (line+1 >  (size_t) best.mLine ||
        (line+1 == (size_t) best.mLine && col > best.mColumn))
        best = result;

    delete [] buf;
    return result;
}

// +-------------------------------------------------------------------+

int
Scanner::GetNumeric()
{
    int type = Token::IntLiteral;             // assume int

    if (*p == '0' && *(p+1) == 'x') {         // check for hex:
        p += 2;
        while (isxdigit(*p)) p++;
        return type;
    }

    while (isdigit(*p) || *p == '_') p++;     // whole number part

    if (*p == '.') { p++;                     // optional fract part
        type = Token::FloatLiteral;            // implies float

        while (isdigit(*p) || *p == '_') p++;  // fractional part
    }

    if (*p == 'E' || *p == 'e') {  p++;       // optional exponent
        if (*p == '+' || *p == '-') p++;       // which may be signed
        while (isdigit(*p)) p++;

        type = Token::FloatLiteral;            // implies float
    }

    return type;
}

// +-------------------------------------------------------------------+

bool
Scanner::IsAlpha(char c)
{
    return (isalpha(*p) || isdigit(*p) || (*p == '_'))?true:false;
}

// +-------------------------------------------------------------------+

bool
Scanner::IsSymbolic(char c)
{
    const char* s = "+-*/\\<=>~!@#$%^&|:";
    return strchr(s, c)?true:false;
}