#include "lexer.h"
#include "scirpt/lexer.h"
#include "scirpt/position.h"
#include "scirpt/token.h"
#include "utils/stringmap.h"
#include <stdlib.h>
#include <string.h>

static inline void step(ScirptLexer* lexer) { scirpt_lexer_step(lexer); }
static inline ScirptToken
token(const ScirptLexer* lexer, ScirptTokenType type, ScirptPosition start)
{
	return scirpt_lexer_token(lexer, type, start);
}
static inline ScirptPosition pos(const ScirptLexer* lexer)
{
	return scirpt_lexer_pos(lexer);
}
static inline bool current_is(const ScirptLexer* lexer, char value)
{
	return scirpt_lexer_current_is(lexer, value);
}
static inline bool done(const ScirptLexer* lexer)
{
	return scirpt_lexer_done(lexer);
}
static inline char current(const ScirptLexer* lexer)
{
	return scirpt_lexer_current(lexer);
}

ScirptLexer* scirpt_lexer_new(const char* text, size_t text_length)
{
	ScirptLexer* lexer = malloc(sizeof(ScirptLexer));
	scirpt_lexer_create(lexer, text, text_length);
	return lexer;
}

void scirpt_lexer_delete(ScirptLexer* lexer) { free(lexer); }

static inline void
add_keyword(StringMap* keywords, const char* key, ScirptTokenType value)
{
	stringmap_set(keywords, key, strlen(key), value);
}

void scirpt_lexer_create(
	ScirptLexer* lexer, const char* text, size_t text_length
)
{
	StringMap* keywords = stringmap_new();
	add_keyword(keywords, "null", ScirptTokenTypeNull);
	add_keyword(keywords, "false", ScirptTokenTypeFalse);
	add_keyword(keywords, "true", ScirptTokenTypeTrue);
	add_keyword(keywords, "let", ScirptTokenTypeLet);
	add_keyword(keywords, "if", ScirptTokenTypeIf);
	add_keyword(keywords, "else", ScirptTokenTypeElse);
	add_keyword(keywords, "while", ScirptTokenTypeWhile);
	add_keyword(keywords, "for", ScirptTokenTypeFor);
	add_keyword(keywords, "in", ScirptTokenTypeIn);
	add_keyword(keywords, "break", ScirptTokenTypeBreak);
	add_keyword(keywords, "fn", ScirptTokenTypeFn);
	add_keyword(keywords, "return", ScirptTokenTypeReturn);
	*lexer = (ScirptLexer) {
		.text = text,
		.text_length = text_length,
		.index = 0,
		.line = 1,
		.col = 1,
		.keywords = keywords,
	};
}

void scirpt_lexer_destroy(ScirptLexer* lexer)
{
	stringmap_delete(lexer->keywords);
}

static inline bool is_whitespace(char value)
{
	return value == ' ' || value == '\t' || value == '\r' || value == '\n';
}

static inline bool is_id_char_excluding_numbers(char value)
{
	return (value >= 'a' && value <= 'z') || (value >= 'A' && value <= 'Z')
		|| value == '_';
}

static inline bool is_int_char(char value)
{
	return value >= '0' && value <= '9';
}

static inline bool is_id_char(char value)
{
	return is_id_char_excluding_numbers(value) || is_int_char(value);
}

ScirptToken scirpt_lexer_next(ScirptLexer* lexer)
{
	if (done(lexer)) {
		return token(lexer, ScirptTokenTypeEof, pos(lexer));
	} else if (is_whitespace(current(lexer))) {
		step(lexer);
		while (!done(lexer) && is_whitespace(current(lexer)))
			step(lexer);
		return scirpt_lexer_next(lexer);
	} else if (is_id_char_excluding_numbers(current(lexer))) {
		ScirptPosition start = pos(lexer);
		step(lexer);
		while (!done(lexer) && is_id_char(current(lexer)))
			step(lexer);
		return token(lexer, ScirptTokenTypeId, start);
	} else {
		switch (current(lexer)) {
			default: {
				ScirptPosition start = pos(lexer);
				step(lexer);
				return token(lexer, ScirptTokenTypeInvalidChar, start);
			}
		}
	}
}

void scirpt_lexer_step(ScirptLexer* lexer)
{
	lexer->index++;
	if (!done(lexer)) {
		if (current(lexer) == '\n') {
			lexer->line++;
			lexer->col = 1;
		} else {
			lexer->col++;
		}
	}
}
ScirptPosition scirpt_lexer_pos(const ScirptLexer* lexer)
{
	return (ScirptPosition) {
		.index = lexer->index,
		.line = lexer->line,
		.col = lexer->col,
	};
}

ScirptToken scirpt_lexer_token(
	const ScirptLexer* lexer, ScirptTokenType type, ScirptPosition start
)
{
	return (ScirptToken) {
		.type = type,
		.pos = start,
		.length = lexer->index - start.index,
	};
}

bool scirpt_lexer_current_is(const ScirptLexer* lexer, char value)
{
	return !done(lexer) && current(lexer) == value;
}

bool scirpt_lexer_done(const ScirptLexer* lexer)
{
	return lexer->index >= lexer->text_length;
}

char scirpt_lexer_current(const ScirptLexer* lexer)
{
	return lexer->text[lexer->index];
}