/* tectonic/xetex-stringpool.c: preloaded "string pool" constants
   Copyright 2017-2018 the Tectonic Project
   Licensed under the MIT License.
*/

#include "xetex-core.h"
#include "xetex-xetexd.h"
#include <string.h>

static const char *string_constants[] = {
    // this catches code that relies on magic stringpool constants
    "this marks the start of the stringpool",
    "",
    NULL
};

int
load_pool_strings(int32_t spare_size)
{
    const char *s;
    int i = 0;
    size_t total_len = 0;
    str_number g = 0;

    while ((s = string_constants[i++]) != NULL) {
        size_t len = strlen(s);

        total_len += len;
        if (total_len >= spare_size)
            return 0;

        while (len-- > 0)
            str_pool[pool_ptr++] = *s++;

        g = make_string(); /* Returns 0 on error. */
    }

    return g;
}


int32_t
length(str_number s)
{
    if (s >= 65536L)
        return str_start[s + 1 - 65536L] - str_start[s - 65536L];
    if (s >= 32 && s < 127)
        return 1;
    if (s <= 127)
        return 3;
    if (s < 256)
        return 4;
    return 8;
}


str_number
make_string(void)
{
    if (str_ptr == max_strings)
        overflow("number of strings", max_strings - init_str_ptr);

    str_ptr++;
    str_start[str_ptr - TOO_BIG_CHAR] = pool_ptr;
    return str_ptr - 1;
}


void
append_str(str_number s)
{
    int32_t i;
    pool_pointer j;

    i = length(s);

    if (pool_ptr + i > pool_size)
        overflow("pool size", pool_size - init_pool_ptr);

    j = str_start[s - 65536L];

    while (i > 0) {
        str_pool[pool_ptr] = str_pool[j];
        pool_ptr++;
        j++;
        i--;
    }
}


bool
str_eq_buf(str_number s, int32_t k)
{
    pool_pointer j;

    j = str_start[s - 65536L];

    while (j < str_start[s + 1 - 65536L]) {
        if (buffer[k] >= 65536L) {
            if (str_pool[j] != 55296L + (buffer[k] - 65536L) / 1024) {
                return false;
            } else if (str_pool[j + 1] != 56320L + (buffer[k] - 65536L) % 1024) {
                return false;
            } else {
                j++;
            }
        } else if (str_pool[j] != buffer[k]) {
            return false;
        }

        j++;
        k++;
    }

    return true;
}


bool
str_eq_str(str_number s, str_number t)
{
    pool_pointer j, k;

    if (length(s) != length(t))
        return false;

    if (length(s) == 1) {
        if (s < 65536L) {
            if (t < 65536L) {
                if (s != t)
                    return false;
            } else {
                if (s != str_pool[str_start[t - 65536L]])
                    return false;
            }
        } else {
            if (t < 65536L) {
                if (str_pool[str_start[s - 65536L]] != t)
                    return false;
            } else {
                if (str_pool[str_start[s - 65536L]] != str_pool[str_start[t - 65536L]])
                    return false;
            }
        }
    } else {
        j = str_start[s - 65536L];
        k = str_start[t - 65536L];

        while (j < str_start[s + 1 - 65536L]) {
            if (str_pool[j] != str_pool[k])
                return false;

            j++;
            k++;
        }
    }

    return true;
}


str_number
search_string(str_number search)
{
    str_number s;
    int32_t len;

    len = length(search);

    if (len == 0) {
        return EMPTY_STRING;
    } else {
        s = search - 1;

        while (s > 65535L) {
            if (length(s) == len) {
                if (str_eq_str(s, search)) {
                    return s;
                }
            }

            s--;
        }
    }

    return 0;
}


str_number
slow_make_string(void)
{
    str_number s;
    str_number t;

    t = make_string();
    s = search_string(t);

    if (s > 0) {
        str_ptr--;
        pool_ptr = str_start[str_ptr - TOO_BIG_CHAR];
        return s;
    }

    return t;
}