#include "sh_emit.h"

#include "error.h"

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

/*
 * src/gen/sh_emit.c — POSIX-sh text emitter (todo 15).
 *
 * The quoting rules implemented here are the single-quote rules of the
 * POSIX Shell Command Language (XBD 2.2.2 "Single-Quotes"): everything
 * between two unescaped `'` characters is literal, and the ONLY way to
 * embed a `'` is to close the quoted region, escape the quote with a
 * backslash, and reopen it — the four-character sequence `'\''`.
 */

static struct st_error *
quote_error(const char *message)
{
    return st_error_internal(message);
}

char *
st_sh_quote_n(const char *value, size_t len, struct st_error **err)
{
    size_t i;
    size_t out_len;
    char *out;

    if (err != NULL) {
        *err = NULL;
    }
    if (value == NULL) {
        if (err != NULL) {
            *err = quote_error("st_sh_quote: value is NULL");
        }
        return NULL;
    }
    for (i = 0; i < len; i++) {
        if (value[i] == '\0') {
            if (err != NULL) {
                *err = quote_error("st_sh_quote: value contains a NUL byte");
            }
            return NULL;
        }
    }
    /* Worst case: every byte is a `'` and expands to 4. Guard the
     * size computation against hostile (huge) lengths. */
    if (len > (SIZE_MAX - 3) / 4) {
        if (err != NULL) {
            *err = quote_error("st_sh_quote: value too large to quote");
        }
        return NULL;
    }
    out_len = 1; /* opening quote */
    for (i = 0; i < len; i++) {
        out_len += (value[i] == '\'') ? 4 : 1;
    }
    out_len += 1; /* closing quote */
    out = malloc(out_len + 1);
    if (out == NULL) {
        if (err != NULL) {
            *err = quote_error("st_sh_quote: out of memory");
        }
        return NULL;
    }
    out_len = 0;
    out[out_len++] = '\'';
    for (i = 0; i < len; i++) {
        if (value[i] == '\'') {
            memcpy(out + out_len, "'\\''", 4);
            out_len += 4;
        } else {
            out[out_len++] = value[i];
        }
    }
    out[out_len++] = '\'';
    out[out_len] = '\0';
    return out;
}

char *
st_sh_quote_ex(const char *value, struct st_error **err)
{
    if (value == NULL) {
        if (err != NULL) {
            *err = quote_error("st_sh_quote: value is NULL");
        }
        return NULL;
    }
    return st_sh_quote_n(value, strlen(value), err);
}

char *
st_sh_quote(const char *value)
{
    return st_sh_quote_ex(value, NULL);
}

int
st_sh_emit_str(FILE *out, const char *s)
{
    if (out == NULL || s == NULL) {
        return -1;
    }
    return fputs(s, out) == EOF ? -1 : 0;
}

int
st_sh_emit_comment(FILE *out, const char *text)
{
    const unsigned char *p;

    if (out == NULL || text == NULL) {
        return -1;
    }
    if (fputs("# ", out) == EOF) {
        return -1;
    }
    for (p = (const unsigned char *)text; *p != '\0'; p++) {
        if (putc(*p, out) == EOF) {
            return -1;
        }
        if (*p == '\n' && fputs("# ", out) == EOF) {
            return -1;
        }
    }
    return putc('\n', out) == EOF ? -1 : 0;
}

int
st_sh_emit_assign(FILE *out, const char *var, const char *quoted_value)
{
    if (out == NULL || var == NULL || quoted_value == NULL) {
        return -1;
    }
    if (fputs(var, out) == EOF || putc('=', out) == EOF ||
        fputs(quoted_value, out) == EOF || putc('\n', out) == EOF) {
        return -1;
    }
    return 0;
}

int
st_sh_emit_assign_q(FILE *out, const char *var, const char *value)
{
    char *quoted;
    int rc;

    if (out == NULL || var == NULL) {
        return -1;
    }
    quoted = st_sh_quote(value);
    if (quoted == NULL) {
        return -1;
    }
    rc = st_sh_emit_assign(out, var, quoted);
    free(quoted);
    return rc;
}