From 75f86b4107f87489efcd7b4ebea230cb8e24dd71 Mon Sep 17 00:00:00 2001
From: Jose Marcial Vieira Bisneto <marcial.vieirab@gmail.com>
Date: Tue, 29 Nov 2016 20:55:59 -0300
Subject: [PATCH] Implemented encode and decode routines in namesys/proquint

---
 namesys/proquint.c | 163 ++++++++++++++++++++++++++++++++++++++++++++-
 1 file changed, 161 insertions(+), 2 deletions(-)

diff --git a/namesys/proquint.c b/namesys/proquint.c
index a68f90f..6f0a3df 100644
--- a/namesys/proquint.c
+++ b/namesys/proquint.c
@@ -1,18 +1,177 @@
 #include <stdlib.h>
+#include <stdint.h>
+#include <string.h>
 #include "ipfs/namesys/namesys.h"
 #include "ipfs/cid/cid.h"
 #include "ipfs/path/path.h"
 
+const uint8_t  conse[] = {'b', 'd', 'f', 'g', 'h', 'j', 'k', 'l', 'm', 'n', 'p', 'r', 's', 't', 'v', 'z'};
+const uint8_t  vowse[] = {'a', 'i', 'o', 'u'};
+
+// Find decoded number from the encoded consonant.
+static inline int consd(char c)
+{
+    int i;
+
+    for (i = 0 ; i < sizeof(conse) ; i++) {
+        if (c == conse[i]) {
+            return i;
+        }
+    }
+
+    return 0;
+}
+
+// Find decoded number of encoded vowel.
+static inline int vowsd(char c)
+{
+    int i;
+
+    for (i = 0 ; i < sizeof(vowse) ; i++) {
+        if (c == vowse[i]) {
+            return i;
+        }
+    }
+
+    return 0;
+}
+
+/**
+* Tests if a given string is a Proquint identifier
+*
+* @param {string} str The candidate string.
+*
+* @return {bool} Whether or not it qualifies.
+* @return {error} Error
+*/
+int ProquintIsProquint(char *str)
+{
+    int i, c;
+
+    // if str is null, or length isn't 11 or don't have - at middle
+    if (!str || strlen(str) != 11 || str[5] != '-') {
+        return 0; // it's not a proquint
+    }
+
+    // run every position
+    for (i = 0 ; i < 11 ; i++) {
+        if (i == 5) i++; // skip -, already tested.
+        switch (i) {
+            case 1:
+            case 3:
+            case 7:
+            case 9:
+                // compare with vowse array
+                c = vowsd(str[i]);
+                if (str[i] != vowse[c]) {
+                    return 0; // it's not a proquint
+                }
+                break;
+            default: // 0,2,4,6,8,10
+                // compare with conse array
+                c = consd(str[i]);
+                if (str[i] != conse[c]) {
+                    return 0; // it's not a proquint
+                }
+        }
+    }
+
+    return 1; // passed on every value.
+}
+
+/**
+* Encodes an arbitrary byte slice into an identifier.
+*
+* @param {[]byte} buf Slice of bytes to encode.
+*
+* @return {string} The given byte slice as an identifier.
+*/
+char *ProquintEncode(char *buf)
+{
+    // TODO: check endianness.
+    char *ret;
+    int i, c;
+    uint16_t n;
+
+    if (!buf) {
+        return NULL;
+    }
+
+    ret = malloc(12);
+    if (!ret) {
+        return NULL;
+    }
+
+    for (i = 0, c = 0; i < 4; i += 2) {
+        n = ((buf[i] & 0xff) << 8) | (buf[i + 1] & 0xff);
+
+        ret[c++] = conse[(n >> 12) & 0x0f];
+        ret[c++] = vowse[(n >> 10) & 0x03];
+        ret[c++] = conse[(n >> 6)  & 0x0f];
+        ret[c++] = vowse[(n >> 4)  & 0x03];
+        ret[c++] = conse[n         & 0x0f];
+        ret[c++] = '-';
+    }
+    ret[--c] = '\0';
+
+    return ret;
+}
+
+/**
+* Decodes an identifier into its corresponding byte slice.
+*
+* @param {string} str Identifier to convert.
+*
+* @return {[]byte} The identifier as a byte slice.
+*/
+char *ProquintDecode(char *str)
+{
+    // TODO: check endianness.
+    char *ret;
+    int i, c;
+    uint16_t x;
+
+    // make sure its a valid Proquint string.
+    if (!ProquintIsProquint(str)) {
+        return NULL;
+    }
+
+    ret = malloc(4);
+    if (!ret) {
+        return NULL;
+    }
+
+    for (i = 0, c = 0 ; i < 11 ; i += 6) {
+        x =(consd(str[i + 0]) << 12) | \
+           (vowsd(str[i + 1]) << 10) | \
+           (consd(str[i + 2]) <<  6) | \
+           (vowsd(str[i + 3]) <<  4) | \
+           (consd(str[i + 4]) <<  0);
+
+        ret[c++] = x >> 8;
+        ret[c++] = x & 0xff;
+    }
+
+    return ret;
+}
+
 // resolveOnce implements resolver. Decodes the proquint string.
 int ProquintResolveOnce (char **p, char *name)
 {
-    int err = proquintIsProquint(name);
+    int err = ProquintIsProquint(name);
+    char buf[500];
 
     if (err) {
         *p = NULL;
         err = ErrInvalidProquint;
     } else {
-        err = pathFromString(p, proquintDecode(name));
+        err = ParsePath(buf, ProquintDecode(name));
+        if (!err) {
+            *p = malloc (strlen(buf) + 1);
+            if (p) {
+                strcpy(*p, buf);
+            }
+        }
     }
     return err;
 }