#include "lexer_utils.h"

#include <stdlib.h>
#include <string.h>

#include "../io_backend/io_backend.h"
#include "../utils/string_utils/string_utils.h"

/* @brief: if a special character is found at [begin],
 * [tok->token_type] is set accordingly
 */
static void set_token_spechar(struct token *tok, char *begin, ssize_t size)
{
    if (size != 1)
        return;
    switch (begin[0])
    {
    case EOF:
        tok->type = TOKEN_EOF;
        break;
    case ';':
        tok->type = TOKEN_SEMICOLON;
        break;
    case '\n':
        tok->type = TOKEN_NEWLINE;
        break;
    case '\'':
        tok->type = TOKEN_QUOTE;
        break;
    case '"':
        tok->type = TOKEN_DOUBLE_QUOTE;
        break;
    case '`':
        tok->type = TOKEN_GRAVE;
        break;
    case '#':
        tok->type = TOKEN_COMMENT;
        break;
    case '|':
        tok->type = TOKEN_PIPE;
        break;
    case '&':
        tok->type = TOKEN_AMPERSAND;
        break;
    case '\\':
        tok->type = TOKEN_BACKSLASH;
        break;
    case '$':
        tok->type = TOKEN_DOLLAR;
        break;
    case '(':
        tok->type = TOKEN_LEFT_PAREN;
        break;
    case ')':
        tok->type = TOKEN_RIGHT_PAREN;
        break;
    case '{':
        tok->type = TOKEN_LEFT_BRACKET;
        break;
    case '}':
        tok->type = TOKEN_RIGHT_BRACKET;
        break;
    case '<':
        tok->type = TOKEN_LESS;
        break;
    case '>':
        tok->type = TOKEN_GREATER;
        break;
    case '*':
        tok->type = TOKEN_STAR;
        break;
    default:
        break;
    }
}

/* @brief: if a keyword is found at [begin],
 * [tok->token_type] is set accordingly
 */
static void set_token_keyword(struct token *tok, char *begin, ssize_t size)
{
    if (tok->type != TOKEN_NULL || size == 0)
        return;
    if (strncmp(begin, "if", size) == 0)
    {
        tok->type = TOKEN_IF;
    }
    else if (strncmp(begin, "fi", size) == 0)
    {
        tok->type = TOKEN_FI;
    }
    else if (strncmp(begin, "then", size) == 0)
    {
        tok->type = TOKEN_THEN;
    }
    else if (strncmp(begin, "else", size) == 0)
    {
        tok->type = TOKEN_ELSE;
    }
    else if (strncmp(begin, "elif", size) == 0)
    {
        tok->type = TOKEN_ELIF;
    }

    // no keywords found.
    if (tok->type == TOKEN_NULL)
        return;

    tok->data = calloc(size + 1, sizeof(char));
    if (tok->data == NULL)
        return;
    strncpy(tok->data, begin, size);
}

/* @brief: if token_type has not yet been set, then it is a TOKEN_WORD
 *         Also allocates the data and fills it.
 */
static void set_token_word(struct token *tok, char *begin, ssize_t size)
{
    if (tok->type == TOKEN_NULL && size != 0)
    {
        tok->type = TOKEN_WORD;
        tok->data = calloc(size + 1, sizeof(char));
        if (tok->data == NULL)
            return;
        strncpy(tok->data, begin, size);
    }
}

struct token *new_token(char *begin, ssize_t size)
{
    struct token *tok = calloc(1, sizeof(struct token));
    if (tok == NULL)
        return NULL;

    set_token_spechar(tok, begin, size);
    set_token_keyword(tok, begin, size);
    set_token_word(tok, begin, size);

    return tok;
}

void destroy_lexer_context(struct lexer_context **ctx)
{
    if (ctx == NULL || *ctx == NULL)
        return;
    if ((*ctx)->previous_token != NULL)
        free((*ctx)->previous_token);
    if ((*ctx)->current_token != NULL)
        free((*ctx)->current_token);
    free(*ctx);
    *ctx = NULL;
}

void free_token(struct token **tok)
{
    if (tok == NULL || *tok == NULL)
        return;
    if ((*tok)->data != NULL)
        free((*tok)->data);
    free(*tok);
    *tok = NULL;
}

char *stream_init(struct lexer_context *ctx)
{
    char *stream;

    if (ctx->previous_token == NULL) // at the begining
    {
        ctx->remaining_chars = stream_read(&stream);
    }
    else
    {
        stream = ctx->end_previous_token;
    }

    char *trimed_stream = trim_blank_left(stream);
    ctx->remaining_chars -= trimed_stream - stream;
    stream = trimed_stream;

    return stream;
}