1 files changed, 164 insertions, 0 deletions
diff --git a/lib/abi.js b/lib/abi.js
new file mode 100644
index 000000000..1e3759918
--- /dev/null
+++ b/lib/abi.js
@@ -0,0 +1,164 @@
+
+var findIndex = function (array, callback) {
+    var end = false;
+    var i = 0;
+    for (; i < array.length && !end; i++) {
+        end = callback(array[i]);
+    }
+    return end ? i - 1 : -1;
+};
+
+var findMethodIndex = function (json, methodName) {
+    return findIndex(json, function (method) {
+        return method.name === methodName;
+    });
+};
+
+var padLeft = function (number, n) {
+    return (new Array(n * 2 - number.toString().length + 1)).join("0") + number;
+};
+
+var setupInputTypes = function () {
+    var prefixedType = function (prefix) {
+        return function (type, value) {
+            var expected = prefix;
+            if (type.indexOf(expected) !== 0) {
+                return false;
+            }
+
+            var padding = parseInt(type.slice(expected.length)) / 8;
+            return padLeft(value, padding);
+        };
+    };
+
+    var namedType = function (name, padding, formatter) {
+        return function (type, value) {
+            if (type !== name) {
+                return false; 
+            }
+
+            return padLeft(formatter ? value : formatter(value), padding);
+        };
+    };
+
+    var formatBool = function (value) {
+        return value ? '1' : '0';
+    };
+
+    return [
+        prefixedType('uint'),
+        prefixedType('int'),
+        namedType('address', 20),
+        namedType('bool', 1, formatBool),
+    ];
+};
+
+var inputTypes = setupInputTypes();
+
+var toAbiInput = function (json, methodName, params) {
+    var bytes = "";
+    var index = findMethodIndex(json, methodName);
+    
+    if (index === -1) {
+        return;
+    }
+
+    // it needs to be checked in WebThreeStubServer 
+    // something wrong might be with this additional zero
+    bytes = bytes + index + 'x' + '0';
+    var method = json[index];
+    
+    for (var i = 0; i < method.inputs.length; i++) {
+        var found = false;
+        for (var j = 0; j < inputTypes.length && !found; j++) {
+            found = inputTypes[j](method.inputs[i].type, params[i]);
+        }
+        if (!found) {
+            console.error('unsupported json type: ' + method.inputs[i].type);
+        }
+        bytes += found;
+    }
+    return bytes;
+};
+
+var setupOutputTypes = function () {
+    var prefixedType = function (prefix) {
+        return function (type) {
+            var expected = prefix;
+            if (type.indexOf(expected) !== 0) {
+                return -1;
+            }
+            
+            var padding = parseInt(type.slice(expected.length)) / 8;
+            return padding * 2;
+        };
+    };
+
+    var namedType = function (name, padding) {
+        return function (type) {
+            return name === type ? padding * 2: -1;
+        };
+    };
+
+    var formatInt = function (value) {
+        return parseInt(value, 16);
+    };
+
+    var formatBool = function (value) {
+        return value === '1' ? true : false;
+    };
+
+    return [
+    { padding: prefixedType('uint'), format: formatInt },
+    { padding: prefixedType('int'), format: formatInt },
+    { padding: namedType('address', 20) },
+    { padding: namedType('bool', 1), format: formatBool }
+    ];
+};
+
+var outputTypes = setupOutputTypes();
+
+var fromAbiOutput = function (json, methodName, output) {
+    var index = findMethodIndex(json, methodName);
+
+    if (index === -1) {
+        return;
+    }
+    
+    output = output.slice(2);
+
+    var result = [];
+    var method = json[index];
+    for (var i = 0; i < method.outputs.length; i++) {
+        var padding = -1;
+        for (var j = 0; j < outputTypes.length && padding === -1; j++) {
+            padding = outputTypes[j].padding(method.outputs[i].type);
+        }
+
+        if (padding === -1) {
+            // not found output parsing
+            continue;
+        }
+        var res = output.slice(0, padding);
+        var formatter = outputTypes[j - 1].format;
+        result.push(formatter ? formatter(res): res);
+        output = output.slice(padding);
+    }
+
+    return result;
+};
+
+var load = function (json) {
+    var contract = {};
+    json.forEach(function (method) {
+        contract[method.name] = function () {
+            var params = Array.prototype.slice.call(arguments);
+            return toAbiInput(json, method.name, params);
+        };
+    });
+
+    return contract;
+};
+
+module.exports = load;
+