#include "readline.h"
#include "shell.h"

#include <stdlib.h>
#include <string.h> /* memmove */
#include <stdio.h>

void readline_create_array(struct readline_type *readline)
{
    readline->arr = calloc(initial_size, 1);
    readline->cursor_pos = 0;
    readline->last_element_index = -1;
    readline->considered_index = 0;
    readline->allocation_size = initial_size;
}

static void readline_copy_array(struct readline_type *readline, char *new_arr)
{
    int i;
    for(i = 0; i <= readline->last_element_index; ++i)
        new_arr[i] = readline->arr[i];
}

static void readline_allocate_memory(struct readline_type *readline)
{
    char *new_arr = calloc(readline->allocation_size * 2, 1);
    readline_copy_array(readline, new_arr);
    free(readline->arr);
    readline->arr = new_arr;
    readline->allocation_size *= 2;
}

static void readline_reprint_modified_part(struct readline_type *readline,
                                           int begin_idx)
{
    int i, counter;
    for(i = begin_idx, counter = 0; i <= readline->last_element_index;
                                                            ++i, ++counter)
        putchar(readline->arr[i]);

    /* return cursor to previous position */
    for( ; counter != 0; --counter)
        putchar('\b');
    fflush(stdout);
}

void readline_add_char(struct readline_type *readline, int ch)
{
    char *begin_arr;
    int size;

    if(readline->last_element_index+1 == readline->allocation_size)
        readline_allocate_memory(readline);
    /* insert in middle position */
    if(readline->cursor_pos - 1 != readline->last_element_index) {
        begin_arr = readline->arr + readline->cursor_pos;
        size = readline->last_element_index - readline->cursor_pos + 1;
        memmove(begin_arr+1, begin_arr, size);
        readline->arr[readline->cursor_pos] = ch;
        ++readline->last_element_index;
        readline_reprint_modified_part(readline, readline->cursor_pos + 1);
    } else {
        ++readline->last_element_index;
        readline->arr[readline->last_element_index] = ch;
    }
    ++readline->cursor_pos;
}

void readline_reset_array(struct readline_type *readline)
{
    readline->last_element_index = -1;
    readline->cursor_pos = 0;
}

void readline_clear(struct readline_type *readline)
{
    free(readline->arr);
    readline->arr = NULL;
}

void readline_print(struct readline_type *readline)
{
    int i;
    for(i = 0; i <= readline->last_element_index; ++i)
        putchar(readline->arr[i]);
    readline->cursor_pos = readline->last_element_index + 1;
    fflush(stdout);
}

enum keys readline_detect_arrow_keys(int ch)
{
    char next_ch;
    if(ch == esc) {
        next_ch = getchar();
        if(next_ch != '[')
            return unknown_key;
        next_ch = getchar();

        switch(next_ch) {
        case left_arrow:
            return left_arrow;
        case right_arrow:
            return right_arrow;
        case up_arrow:
            return up_arrow;
        case down_arrow:
            return down_arrow;
        default:
            return unknown_key;
        }
    }
    return none;
}

void readline_move_along(struct readline_type *readline, enum keys found_key)
{
    switch(found_key) {
    case left_arrow:
        if(readline->cursor_pos > 0) {
            putchar('\b');
            fflush(stdout);
            --readline->cursor_pos;
        }
        break;
    case right_arrow:
        if(readline->cursor_pos <= readline->last_element_index) {
            putchar(readline->arr[readline->cursor_pos]);
            fflush(stdout);
            ++readline->cursor_pos;
        }
        break;
    default:
        ;
    }
}

void readline_character_deletion(struct readline_type *readline)
{
    char *begin_arr;
    int size;

    if(readline->cursor_pos > 0) {
        putchar('\b');
        fflush(stdout);
        begin_arr = readline->arr + readline->cursor_pos;
        size = readline->last_element_index - readline->cursor_pos + 1;
        memmove(begin_arr-1, begin_arr, size);
        readline->arr[readline->last_element_index] = ' ';
        readline_reprint_modified_part(readline, readline->cursor_pos - 1);
        --readline->last_element_index;
        --readline->cursor_pos;
    }
}