Added "likes" feature

contract/talk.cpp

@@ -1,5 +1,8 @@
 #include <eosio/eosio.hpp>
 
+using react_t = uint8_t;
+constexpr react_t REACT_TYPE_MAX = 5;
+
 // Message table
 struct [[eosio::table("message"), eosio::contract("talk")]] message {
     uint64_t    id       = {}; // Non-0
@@ -11,8 +14,36 @@ struct [[eosio::table("message"), eosio::contract("talk")]] message {
     uint64_t get_reply_to() const { return reply_to; }
 };
 
+uint128_t makeLikesUniqSecondary( uint64_t post_id, eosio::name user) {
+    return uint128_t{post_id} << 64 | user.value;
+}
+
+// Likes table
+struct [[eosio::table("likes"), eosio::contract("talk")]] likes {
+    uint64_t    id       = {}; // Non-0
+    uint64_t    post_id  = {}; // Non-0 
+    eosio::name user     = {};
+    react_t react        = {};  // reaction type
+
+    uint64_t primary_key() const { return id; }
+    uint128_t get_uniq_secondary() const { return makeLikesUniqSecondary(post_id, user); }
+};
+
 using message_table = eosio::multi_index<
-    "message"_n, message, eosio::indexed_by<"by.reply.to"_n, eosio::const_mem_fun<message, uint64_t, &message::get_reply_to>>>;
+    "message"_n, message, 
+    eosio::indexed_by<
+        "by.reply.to"_n, 
+        eosio::const_mem_fun<message, uint64_t, &message::get_reply_to>
+    >
+>;
+
+using likes_table = eosio::multi_index<
+    "likes"_n, likes, 
+    eosio::indexed_by<
+        "by.uniq.secondary"_n, 
+        eosio::const_mem_fun<likes, uint128_t, &likes::get_uniq_secondary>
+    >
+>;
 
 // The contract
 class talk : eosio::contract {
@@ -28,9 +59,10 @@ class talk : eosio::contract {
         require_auth(user);
 
         // Check reply_to exists
-        if (reply_to)
+        if (reply_to) {
             table.get(reply_to);
-
+        }
+
         // Create an ID if user didn't specify one
         eosio::check(id < 1'000'000'000ull, "user-specified id is too big");
         if (!id)
@@ -44,4 +76,58 @@ class talk : eosio::contract {
             message.content  = content;
         });
     }
+
+    // Like or unlike a message, or change reaction
+    // to like a message, react must be > 0 and <+ REACT_MAX
+    // to unlike a message, react must be 0 and like must exist in likes_table
+    [[eosio::action]] void likepost(uint64_t post_id, eosio::name user, react_t react) {
+        // Check user authentication
+        require_auth(user);
+
+        auto msg = message_table{get_self(), 0};
+        auto likes = likes_table{get_self(), 0};
+
+        // check for valid reaction 
+        eosio::check(react <= REACT_TYPE_MAX, "Bad value for reaction");
+
+        // post_id must be > 0
+        eosio::check(post_id > 0, "Must have valid post_id-to");
+
+        // Check reply_to exists
+        auto it_msg = msg.find(post_id);
+
+        // cannot like your own post
+        eosio::check(it_msg->user != user, "Cannot like yur own post");
+
+        // determien if user already liked this post
+        auto idx = likes.get_index<"by.uniq.secondary"_n>();
+        auto it = idx.find(makeLikesUniqSecondary(post_id, user));
+        bool likeExists = (it != idx.end());
+
+        // if reaction is 0, post must already exist (it will be deleted)
+        if(react == 0)
+            eosio::check(likeExists, "Like not found in table");
+
+        // like does not exist, so insert new record
+        if (!likeExists) {
+            likes.emplace(get_self(), [&](auto& like) {
+                like.id       = likes.available_primary_key();
+                like.post_id  = post_id;
+                like.user     = user;
+                like.react    = react;
+            });
+        }  
+        // othwerise like already exists in table, so either erase it, if reaction is 0 or update it it reaction is changed
+        else {
+            auto like_it = likes.find(it->id);
+            if (react == 0) {
+                likes.erase(like_it);
+            } else if (react != like_it->react) {
+                likes.modify(like_it, get_self(), [&](auto& like) {
+                    like.react    = react;
+                });
+            }
+        }
+
+    }
 };

talk_run.sh

@@ -0,0 +1,9 @@
+#!/bin/bash
+
+eosio-cpp contract/talk.cpp
+cleos create account eosio talk EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
+cleos create account eosio bob EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
+cleos create account eosio jane EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
+cleos create account eosio alice EOS6MRyAjQq8ud7hVNYcfnVPJqcVpscN5So8BhtHuGYqET5GDW5CV
+cleos set code talk talk.wasm
+cleos set abi talk talk.abi

tests/talk_tests.cpp

@@ -23,6 +23,7 @@ BOOST_AUTO_TEST_CASE(post) try {
     // Create users
     t.create_account(N(john));
     t.create_account(N(jane));
+    t.create_account(N(jack));
 
     // Test "post" action
     t.push_action(
@@ -50,6 +51,43 @@ BOOST_AUTO_TEST_CASE(post) try {
         ("content", "post 3: reply") //
     );
 
+
+    // jane likes johns post
+    t.push_action(
+        N(talk), N(likepost), N(jane),
+        mutable_variant_object       //
+        ("post_id", 1)               //
+        ("user", "jane")             //
+        ("react", 1)                 //
+    );
+
+    // jane changes reaction type from 'like' to 'love'
+    t.push_action(
+        N(talk), N(likepost), N(jane),
+        mutable_variant_object       //
+        ("post_id", 1)               //
+        ("user", "jane")             //
+        ("react", 2)                 //
+    );
+
+    // jack also reacts to johns post
+    t.push_action(
+        N(talk), N(likepost), N(jack),
+        mutable_variant_object       //
+        ("post_id", 1)               //
+        ("user", "jack")             //
+        ("react", 4)                 //
+    );
+
+    // jane deletes like 
+    t.push_action(
+        N(talk), N(likepost), N(jane),
+        mutable_variant_object       //
+        ("post_id", 1)               //
+        ("user", "jane")             //
+        ("react", 0)                 //
+    );
+
     // Can't reply to non-existing message
     BOOST_CHECK_THROW(
         [&] {
@@ -63,6 +101,58 @@ BOOST_AUTO_TEST_CASE(post) try {
             );
         }(),
         fc::exception);
+
+    BOOST_CHECK_THROW(
+        [&] {
+            t.push_action(
+                N(talk), N(post), N(john),
+                mutable_variant_object       //
+                ("id", 4)                    //
+                ("reply_to", 99)             //
+                ("user", "john")             //
+                ("content", "post 3: reply") //
+            );
+        }(),
+        fc::exception);        
+
+    // must have proper authorization
+    BOOST_CHECK_THROW(
+        [&] {
+            t.push_action(
+                N(talk), N(likepost), N(john),
+                mutable_variant_object       //
+                ("post_id", 1)               //
+                ("user", "jane")             //
+                ("react", 1)                 //
+            );
+        }(),
+        fc::exception);                    
+
+     // cannot like yoru own post
+    BOOST_CHECK_THROW(
+        [&] {
+            t.push_action(
+                N(talk), N(likepost), N(john),
+                mutable_variant_object       //
+                ("post_id", 1)               //
+                ("user", "john")             //
+                ("react", 1)                 //
+            );
+        }(),
+        fc::exception);     
+
+    // cannot like a post which does not exist    
+    BOOST_CHECK_THROW(
+        [&] {
+            t.push_action(
+                N(talk), N(likepost), N(john),
+                mutable_variant_object       //
+                ("post_id", 3)               //
+                ("user", "john")             //
+                ("react", 1)                 //
+            );
+        }(),
+        fc::exception);           
 }
 FC_LOG_AND_RETHROW()