#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_GRAVE;
        break;
    case '#':
        tok->type = TOKEN_COMMENT;
        break;
    case '\\':
        tok->type = TOKEN_BACKSLASH;
        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_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 && size == 2)
    {
        tok->type = TOKEN_IF;
    }
    else if (strncmp(begin, "fi", size) == 0 && size == 2)
    {
        tok->type = TOKEN_FI;
    }
    else if (strncmp(begin, "then", size) == 0 && size == 4)
    {
        tok->type = TOKEN_THEN;
    }
    else if (strncmp(begin, "else", size) == 0 && size == 4)
    {
        tok->type = TOKEN_ELSE;
    }
    else if (strncmp(begin, "elif", size) == 0 && size == 4)
    {
        tok->type = TOKEN_ELIF;
    }
    else if (strncmp(begin, "&&", size) == 0 && size == 2)
    {
        tok->type = TOKEN_AND;
    }
    else if (strncmp(begin, "||", size) == 0 && size == 2)
    {
        tok->type = TOKEN_OR;
    }

    // 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 an operator is found at [begin],
 * [tok->token_type] is set accordingly
 */
static void set_token_operator(struct token *tok, char *begin, ssize_t size)
{
    if (tok->type != TOKEN_NULL)
        return;
    if (strncmp(begin, ">", size) == 0)
    {
        tok->type = TOKEN_REDIR_RIGHT;
    }
    else if (strncmp(begin, "<", size) == 0)
    {
        tok->type = TOKEN_REDIR_LEFT;
    }
    else if (strncmp(begin, ">>", size) == 0)
    {
        tok->type = TOKEN_REDIR_DOUBLE_RIGHT;
    }
    else if (strncmp(begin, ">&", size) == 0)
    {
        tok->type = TOKEN_REDIR_RIGHT_AMP;
    }
    else if (strncmp(begin, ">|", size) == 0)
    {
        tok->type = TOKEN_REDIR_RIGHT_PIPE;
    }
    else if (strncmp(begin, "<&", size) == 0)
    {
        tok->type = TOKEN_REDIR_LEFT_AMP;
    }
    else if (strncmp(begin, "<>", size) == 0)
    {
        tok->type = TOKEN_REDIR_LEFT_RIGHT;
    }
    else if (strncmp(begin, "|", size) == 0)
    {
        tok->type = TOKEN_PIPE;
    }
}

/* @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);
    }
}

/* @brief: Sets the token to an IO number
 *         Also allocates the data and fills it.
 */
static void set_token_ION(struct token *tok, char *begin, ssize_t size)
{
    if (tok->type == TOKEN_NULL && size != 0)
    {
        tok->type = TOKEN_IONUMBER;
        tok->data = calloc(size + 1, sizeof(char));
        if (tok->data == NULL)
            return;
        strncpy(tok->data, begin, size);
    }
}

/* @brief: check if [c] is a delimiter for end of line.
 * @return: true if [c] == '\n' or EOF. false otherwise.
 */
static bool is_end_of_line(char c)
{
    return c == EOF || c == '\n';
}

bool is_special_char(char *stream, ssize_t i)
{
    char c = stream[i];
    if (c == EOF)
        return true;
    if (i > 0 && c == '#' && stream[i - 1] == '$')
        return false; // the edge case of $#
    if (i > 0 && stream[i - 1] == '\\')
        return false; // TODO handle backslash better
                      // this doesnt work, ex : echo \\#comment
                      // (need to count the previous consequtive backslashes)

    char special_chars[] = "\n'\"`;#|&(){}<>*";
    return strchr(special_chars, c) != NULL;
}

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

    if (only_digits)
        set_token_ION(tok, begin, size);

    set_token_operator(tok, begin, size);
    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;
}

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

    if (ctx->remaining_chars == 0) // 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;

    ctx->end_previous_token = trimed_stream;
}

ssize_t len_op_sepchar(char *stream, ssize_t i)
{
    if (!is_special_char(stream, i))
        return -1; // should never happen

    if (stream[i] != '>' && stream[i] != '<')
        return 1; // special character (cannot be operator)

    // operator

    if (stream[i] == '<')
    {
        if (stream[i + 1] == '&' || stream[i + 1] == '>')
            return 2; // <&, <>
    }
    else if (stream[i + 1] == '>' || stream[i + 1] == '|'
             || stream[i + 1] == '&')
        return 2; // >>, >&, >|

    return 1; // >, <
}

void go_end_of_line(struct lexer_context *ctx)
{
    if (ctx == NULL || ctx->end_previous_token == NULL)
        return;

    ssize_t i = 0;
    while (!is_end_of_line(ctx->end_previous_token[i]))
    {
        i++;
    }
    ctx->end_previous_token += i;
    ctx->remaining_chars -= i;
}

void get_next_stream(struct lexer_context *ctx)
{
    ctx->remaining_chars = 0;
    stream_init(ctx);
}