//
//  m3_api_libc.c
//
//  Created by Volodymyr Shymanskyy on 11/20/19.
//  Copyright © 2019 Volodymyr Shymanskyy. All rights reserved.
//

#define _POSIX_C_SOURCE 200809L

#include "m3_api_libc.h"

#include "m3_env.h"
#include "m3_exception.h"

#include <time.h>
#include <errno.h>
#include <stdio.h>

typedef uint32_t wasm_ptr_t;
typedef uint32_t wasm_size_t;

m3ApiRawFunction(m3_libc_abort)
{
    m3ApiTrap(m3Err_trapAbort);
}

m3ApiRawFunction(m3_libc_exit)
{
    m3ApiGetArg     (int32_t, code)

    m3ApiTrap(m3Err_trapExit);
}


m3ApiRawFunction(m3_libc_memset)
{
    m3ApiReturnType (int32_t)

    m3ApiGetArgMem  (void*,           i_ptr)
    m3ApiGetArg     (int32_t,         i_value)
    m3ApiGetArg     (wasm_size_t,     i_size)

    m3ApiCheckMem(i_ptr, i_size);

    u32 result = m3ApiPtrToOffset(memset (i_ptr, i_value, i_size));
    m3ApiReturn(result);
}

m3ApiRawFunction(m3_libc_memmove)
{
    m3ApiReturnType (int32_t)

    m3ApiGetArgMem  (void*,           o_dst)
    m3ApiGetArgMem  (void*,           i_src)
    m3ApiGetArg     (wasm_size_t,     i_size)

    m3ApiCheckMem(o_dst, i_size);
    m3ApiCheckMem(i_src, i_size);

    u32 result = m3ApiPtrToOffset(memmove (o_dst, i_src, i_size));
    m3ApiReturn(result);
}

m3ApiRawFunction(m3_libc_print)
{
    m3ApiReturnType (uint32_t)

    m3ApiGetArgMem  (void*,           i_ptr)
    m3ApiGetArg     (wasm_size_t,     i_size)

    m3ApiCheckMem(i_ptr, i_size);

    fwrite(i_ptr, i_size, 1, stdout);
    fflush(stdout);

    m3ApiReturn(i_size);
}

static
void internal_itoa(int n, char s[], int radix)
{
    static char const HEXDIGITS[0x10] = {
        '0', '1', '2', '3', '4', '5', '6', '7',
        '8', '9', 'A', 'B', 'C', 'D', 'E', 'F'
    };

    int i, j, sign;
    char c;

    if ((sign = n) < 0) { n = -n; }
    i = 0;
    do {
        s[i++] = HEXDIGITS[n % radix];
    } while ((n /= radix) > 0);

    if (sign < 0) { s[i++] = '-'; }
    s[i] = '\0';

    // reverse
    for (i = 0, j = strlen(s)-1; i<j; i++, j--) {
        c = s[i];
        s[i] = s[j];
        s[j] = c;
    }
}

m3ApiRawFunction(m3_libc_printf)
{
    m3ApiReturnType (int32_t)

    m3ApiGetArgMem  (const char*,    i_fmt)
    m3ApiGetArgMem  (wasm_ptr_t*,    i_args)

    if (m3ApiIsNullPtr(i_fmt)) {
        m3ApiReturn(0);
    }

    m3ApiCheckMem(i_fmt, 1);
    size_t fmt_len = strnlen(i_fmt, 1024);
    m3ApiCheckMem(i_fmt, fmt_len+1); // include `\0`

    FILE* file = stdout;

    int32_t length = 0;
    char ch;
    while ((ch = *i_fmt++)) {
        if ( '%' != ch ) {
            putc(ch, file);
            length++;
            continue;
        }
        ch = *i_fmt++;
        switch (ch) {
            case 'c': {
                m3ApiCheckMem(i_args, sizeof(wasm_ptr_t));
                char char_temp = *i_args++;
                fputc(char_temp, file);
                length++;
                break;
            }
            case 'd':
            case 'x': {
                m3ApiCheckMem(i_args, sizeof(wasm_ptr_t));
                int int_temp = *i_args++;
                char buffer[32] = { 0, };
                internal_itoa(int_temp, buffer, (ch == 'x') ? 16 : 10);
                fputs(buffer, file);
                length += strnlen(buffer, sizeof(buffer));
                break;
            }
            case 's': {
                m3ApiCheckMem(i_args, sizeof(wasm_ptr_t));
                const char* string_temp;
                size_t string_len;

                string_temp = (const char*)m3ApiOffsetToPtr(*i_args++);
                if (m3ApiIsNullPtr(string_temp)) {
                    string_temp = "(null)";
                    string_len = 6;
                } else {
                    string_len = strnlen(string_temp, 1024);
                    m3ApiCheckMem(string_temp, string_len+1);
                }

                fwrite(string_temp, 1, string_len, file);
                length += string_len;
                break;
            default:
                fputc(ch, file);
                length++;
                break;
            }
        }
    }

    m3ApiReturn(length);
}

m3ApiRawFunction(m3_libc_clock_ms)
{
    m3ApiReturnType (uint32_t)
#ifdef CLOCKS_PER_SEC
    uint32_t clock_divider = CLOCKS_PER_SEC/1000;
    if (clock_divider != 0) {
        m3ApiReturn(clock() / clock_divider);
    } else {
        m3ApiReturn(clock());
    }
#else
    m3ApiReturn(clock());
#endif
}

static
M3Result  SuppressLookupFailure (M3Result i_result)
{
    if (i_result == m3Err_functionLookupFailed)
        return m3Err_none;
    else
        return i_result;
}

m3ApiRawFunction(m3_spectest_dummy)
{
    m3ApiSuccess();
}

M3Result  m3_LinkSpecTest  (IM3Module module)
{
    M3Result result = m3Err_none;

    const char* spectest = "spectest";

_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print",         "v()",      &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_i32",     "v(i)",     &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_i64",     "v(I)",     &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_f32",     "v(f)",     &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_f64",     "v(F)",     &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_i32_f32", "v(if)",    &m3_spectest_dummy)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, spectest, "print_i64_f64", "v(IF)",    &m3_spectest_dummy)));

_catch:
    return result;
}


M3Result  m3_LinkLibC  (IM3Module module)
{
    M3Result result = m3Err_none;

    const char* env = "env";

_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_debug",            "i(*i)",   &m3_libc_print)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_memset",           "*(*ii)",  &m3_libc_memset)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_memmove",          "*(**i)",  &m3_libc_memmove)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_memcpy",           "*(**i)",  &m3_libc_memmove))); // just alias of memmove
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_abort",            "v()",     &m3_libc_abort)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "_exit",             "v(i)",    &m3_libc_exit)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "clock_ms",          "i()",     &m3_libc_clock_ms)));
_   (SuppressLookupFailure (m3_LinkRawFunction (module, env, "printf",            "i(**)",   &m3_libc_printf)));

_catch:
    return result;
}