#include "tokenizer.h"
#include <ctype.h>
#include <math.h>

static StringView StringViewOfNumberTillNextNonDigit(StringView* source) {
	StringView stringViewOfNumber = StringView_Slice(*source, 0, 0);
	while (source->length != 0 && isdigit(source->source[0])) {
		*source = StringView_Drop(*source, 1);
		stringViewOfNumber.length ++;
	}
	return stringViewOfNumber;
}

static int64_t* _StringView_FoldInt64(char c, int64_t* i)
{
	*i = *i * 10 + (c - '0');
	return i;
}

static double* _StringView_FoldDouble(char c, double* d)
{
	*d = *d * 10 + (c - '0');
	return d;
}

static Token _Tokenizer_ParseInt64(bool negative, StringView integerPart)
{
	int64_t theInt64 = 0;
	StringView_FoldLeft(integerPart, &theInt64, (StringViewFoldFunction) _StringView_FoldInt64);

	return (Token) {
		.type = TOKENTYPE_INTEGER,
		.get = {
			.integer = theInt64 * (negative ? -1 : 1)
		}
	};
}

static Token _Tokenizer_ParseDouble(bool negative, StringView integerPart, StringView decimalPart)
{
	double theDouble = 0.0;
	StringView_FoldLeft(integerPart, &theDouble, (StringViewFoldFunction) _StringView_FoldDouble);
	double theDecimal = 0.0;
	StringView_FoldLeft(decimalPart, &theDecimal, (StringViewFoldFunction) _StringView_FoldDouble);

	double result = (negative ? -1 : 1) * (theDouble + theDecimal / pow(10.0, decimalPart.length));

	return (Token) {
		.type = TOKENTYPE_DOUBLE,
		.get = {
			.decimal = result
		}
	};
}

static Token _Tokenizer_NumberToken(StringView* source)
{
	bool negative = false;
	if (StringView_StartsWith(*source, StringView_FromString("-"))) {
		negative = true;
		*source = StringView_Drop(*source, 1);
	}

	StringView integerPart = StringViewOfNumberTillNextNonDigit(source);
	bool has_point = false;
	if (source->length != 0 && source->source[0] == '.') {
		*source = StringView_Drop(*source, 1);
		has_point = true;
	}
	StringView decimalPart = StringViewOfNumberTillNextNonDigit(source);

	if (has_point) {
		return _Tokenizer_ParseDouble(negative, integerPart, decimalPart);
	} else {
		return _Tokenizer_ParseInt64(negative, integerPart);
	}
}

static bool _Tokenizer_IdentifierLetter(char c)
{
	return isalnum(c);
}

static Token _Tokenizer_IdentifierToken(StringView* source)
{
	StringView identifier = StringView_TakeWhile(*source, _Tokenizer_IdentifierLetter);
	*source = StringView_Drop(*source, identifier.length);

	return (Token) {
		.type = TOKENTYPE_IDENTIFIER,
		.get = {
			.identifier = identifier,
		}
	};
}

static Token _Tokenizer_SimpleToken(StringView* source)
{
	const char* literal_table[] = { "{", "}", "&", ":", "+", "->", "-", "*", "/", "|", "==", "!=", "<", "<=", ">", ">=", ",", ";" };
	const enum TokenType type_table[] = { 
		TOKENTYPE_LEFT_BRACE,
		TOKENTYPE_RIGHT_BRACE,
		TOKENTYPE_AMPERSAND,
		TOKENTYPE_COLON,
		TOKENTYPE_PLUS,
		TOKENTYPE_ARROW,
		TOKENTYPE_MINUS,
		TOKENTYPE_MULTIPLY,
		TOKENTYPE_DIVIDE,
		TOKENTYPE_PIPE,
		TOKENTYPE_EQUALITY,
		TOKENTYPE_INEQUALITY,
		TOKENTYPE_LESSTHAN,
		TOKENTYPE_LESSEQUAL,
		TOKENTYPE_GREATERTHAN,
		TOKENTYPE_GREATEREQUAL,
		TOKENTYPE_COMMA,
		TOKENTYPE_SEMICOLON,
	};

	for (size_t i = 0; i < sizeof(literal_table) / sizeof(literal_table[0]); i++) {
		StringView literal_view = StringView_FromString(literal_table[i]);
		if (StringView_StartsWith(*source, literal_view)) {
			*source = StringView_Drop(*source, literal_view.length);
			return (Token) {
				.type = type_table[i],
				.get = { .identifier = STRINGVIEW_NONE }
			};
		}
	}
	return TOKEN_NONE;
}

Token Tokenizer_NextToken(StringView* source)
{
	while (source->length != 0 && isspace(source->source[0])) {
		0[source] = StringView_Slice(*source, 1, source->length);
	}

	if (source->length == 0) {
		return TOKEN_NONE;
	}

	{
		Token simple_token = _Tokenizer_SimpleToken(source);
		if (simple_token.type != TOKENTYPE_NONE) {
			return simple_token;
		}
	}

	if (isdigit(source->source[0]) || StringView_StartsWith(*source, StringView_FromString("-"))) {
		// parse int/double
		return _Tokenizer_NumberToken(source);
	} else if (isalpha(source->source[0])) {
		// parse name
		return _Tokenizer_IdentifierToken(source);
	} else {
		return (Token) {.type = TOKENTYPE_ERROR, .get = {.error = *source } };
	}
}

const char* TokenType_ToString(enum TokenType type)
{
	switch (type) {
		case TOKENTYPE_NONE:
			return "TOKENTYPE_NONE";
		case TOKENTYPE_INTEGER:
			return "TOKENTYPE_INTEGER";
		case TOKENTYPE_DOUBLE:
			return "TOKENTYPE_DOUBLE";
		case TOKENTYPE_IDENTIFIER:
			return "TOKENTYPE_IDENTIFIER";
		case TOKENTYPE_LEFT_BRACE:
			return "TOKENTYPE_LEFT_BRACE";
		case TOKENTYPE_RIGHT_BRACE:
			return "TOKENTYPE_RIGHT_BRACE";
		case TOKENTYPE_AMPERSAND:
			return "TOKENTYPE_AMPERSAND";
		case TOKENTYPE_PLUS:
			return "TOKENTYPE_PLUS";
		case TOKENTYPE_MINUS:
			return "TOKENTYPE_MINUS";
		case TOKENTYPE_MULTIPLY:
			return "TOKENTYPE_MULTIPLY";
		case TOKENTYPE_DIVIDE:
			return "TOKENTYPE_DIVIDE";
		case TOKENTYPE_PIPE:
			return "TOKENTYPE_PIPE";
		case TOKENTYPE_ARROW:
			return "TOKENTYPE_ARROW";
		case TOKENTYPE_COLON:
			return "TOKENTYPE_COLON";
		case TOKENTYPE_ERROR:
			return "TOKENTYPE_ERROR";
		case TOKENTYPE_EQUALITY:
			return "TOKENTYPE_EQUALITY";
		case TOKENTYPE_INEQUALITY:
			return "TOKENTYPE_INEQUALITY";
		case TOKENTYPE_LESSTHAN:
			return "TOKENTYPE_LESSTHAN";
		case TOKENTYPE_LESSEQUAL:
			return "TOKENTYPE_LESSEQUAL";
		case TOKENTYPE_GREATERTHAN:
			return "TOKENTYPE_GREATERTHAN";
		case TOKENTYPE_GREATEREQUAL:
			return "TOKENTYPE_GREATEREQUAL";
		case TOKENTYPE_COMMA:
			return "TOKENTYPE_COMMA";
		case TOKENTYPE_SEMICOLON:
			return "TOKENTYPE_SEMICOLON";

	}

	return "INVALID";
}