From 5dc45c35e64c1e5882e0c01287b36ec88dff70a7 Mon Sep 17 00:00:00 2001
From: Omar Roth <omarroth@hotmail.com>
Date: Wed, 10 Apr 2019 16:23:37 -0500
Subject: Automatically migrate database

---
 src/invidious.cr                    |  10 +-
 src/invidious/helpers/helpers.cr    | 104 +++++++++++++++++
 src/invidious/helpers/jobs.cr       | 225 ++++++++++++++++++++++++++++++++++++
 src/invidious/helpers/macros.cr     |  16 ++-
 src/invidious/helpers/signatures.cr |  70 +++++++++++
 src/invidious/jobs.cr               | 225 ------------------------------------
 src/invidious/signatures.cr         |  70 -----------
 7 files changed, 417 insertions(+), 303 deletions(-)
 create mode 100644 src/invidious/helpers/jobs.cr
 create mode 100644 src/invidious/helpers/signatures.cr
 delete mode 100644 src/invidious/jobs.cr
 delete mode 100644 src/invidious/signatures.cr

(limited to 'src')

diff --git a/src/invidious.cr b/src/invidious.cr
index 06e96a53..adc69829 100644
--- a/src/invidious.cr
+++ b/src/invidious.cr
@@ -105,10 +105,16 @@ end
 
 Kemal::CLI.new ARGV
 
+# Check table integrity
+analyze_table(PG_DB, logger, "channel_videos", ChannelVideo)
+analyze_table(PG_DB, logger, "nonces", Nonce)
+analyze_table(PG_DB, logger, "session_ids", SessionId)
+analyze_table(PG_DB, logger, "users", User)
+analyze_table(PG_DB, logger, "videos", Video)
+
+# Start jobs
 refresh_channels(PG_DB, logger, config.channel_threads, config.full_refresh)
-
 refresh_feeds(PG_DB, logger, config.feed_threads)
-
 subscribe_to_feeds(PG_DB, logger, HMAC_KEY, config)
 
 statistics = {
diff --git a/src/invidious/helpers/helpers.cr b/src/invidious/helpers/helpers.cr
index 3b53a468..f515f28a 100644
--- a/src/invidious/helpers/helpers.cr
+++ b/src/invidious/helpers/helpers.cr
@@ -1,5 +1,20 @@
 require "./macros"
 
+struct Nonce
+  db_mapping({
+    nonce:  String,
+    expire: Time,
+  })
+end
+
+struct SessionId
+  db_mapping({
+    id:     String,
+    email:  String,
+    issued: String,
+  })
+end
+
 struct ConfigPreferences
   module StringToArray
     def self.to_yaml(value : Array(String), yaml : YAML::Nodes::Builder)
@@ -483,3 +498,92 @@ def extract_shelf_items(nodeset, ucid = nil, author_name = nil)
 
   return items
 end
+
+def analyze_table(db, logger, table_name, struct_type = nil)
+  # Create table if it doesn't exist
+  if !db.query_one?("SELECT true FROM information_schema.tables WHERE table_name = $1", table_name, as: Bool)
+    db.using_connection do |conn|
+      conn.as(PG::Connection).exec_all(File.read("config/sql/#{table_name}.sql"))
+    end
+
+    logger.write("CREATE TABLE #{table_name}\n")
+  end
+
+  if !struct_type
+    return
+  end
+
+  struct_array = struct_type.to_type_tuple
+  column_array = get_column_array(db, table_name)
+  column_types = File.read("config/sql/#{table_name}.sql").match(/CREATE TABLE public\.#{table_name}\n\((?<types>[\d\D]*?)\);/)
+    .try &.["types"].split(",").map { |line| line.strip }
+
+  if !column_types
+    return
+  end
+
+  struct_array.each_with_index do |name, i|
+    if name != column_array[i]?
+      if !column_array[i]?
+        new_column = column_types.select { |line| line.starts_with? name }[0]
+        db.exec("ALTER TABLE #{table_name} ADD COLUMN #{new_column}")
+        logger.write("ALTER TABLE #{table_name} ADD COLUMN #{new_column}\n")
+        next
+      end
+
+      # Column doesn't exist
+      if !column_array.includes? name
+        new_column = column_types.select { |line| line.starts_with? name }[0]
+        db.exec("ALTER TABLE #{table_name} ADD COLUMN #{new_column}")
+      end
+
+      # Column exists but in the wrong position, rotate
+      if struct_array.includes? column_array[i]
+        until name == column_array[i]
+          new_column = column_types.select { |line| line.starts_with? column_array[i] }[0]?.try &.gsub("#{column_array[i]}", "#{column_array[i]}_new")
+
+          # There's a column we didn't expect
+          if !new_column
+            db.exec("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]} CASCADE")
+            logger.write("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]}\n")
+
+            column_array = get_column_array(db, table_name)
+            next
+          end
+
+          db.exec("ALTER TABLE #{table_name} ADD COLUMN #{new_column}")
+          logger.write("ALTER TABLE #{table_name} ADD COLUMN #{new_column}\n")
+          db.exec("UPDATE #{table_name} SET #{column_array[i]}_new=#{column_array[i]}")
+          logger.write("UPDATE #{table_name} SET #{column_array[i]}_new=#{column_array[i]}\n")
+          db.exec("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]} CASCADE")
+          logger.write("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]} CASCADE\n")
+          db.exec("ALTER TABLE #{table_name} RENAME COLUMN #{column_array[i]}_new TO #{column_array[i]}")
+          logger.write("ALTER TABLE #{table_name} RENAME COLUMN #{column_array[i]}_new TO #{column_array[i]}\n")
+
+          column_array = get_column_array(db, table_name)
+        end
+      else
+        db.exec("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]} CASCADE")
+        logger.write("ALTER TABLE #{table_name} DROP COLUMN #{column_array[i]} CASCADE\n")
+      end
+    end
+  end
+end
+
+class PG::ResultSet
+  def field(index = @column_index)
+    @fields.not_nil![index]
+  end
+end
+
+def get_column_array(db, table_name)
+  column_array = [] of String
+  db.query("SELECT * FROM #{table_name} LIMIT 0") do |rs|
+    rs.column_count.times do |i|
+      column = rs.as(PG::ResultSet).field(i)
+      column_array << column.name
+    end
+  end
+
+  return column_array
+end
diff --git a/src/invidious/helpers/jobs.cr b/src/invidious/helpers/jobs.cr
new file mode 100644
index 00000000..ad9e8ada
--- /dev/null
+++ b/src/invidious/helpers/jobs.cr
@@ -0,0 +1,225 @@
+def refresh_channels(db, logger, max_threads = 1, full_refresh = false)
+  max_channel = Channel(Int32).new
+
+  spawn do
+    max_threads = max_channel.receive
+    active_threads = 0
+    active_channel = Channel(Bool).new
+
+    loop do
+      db.query("SELECT id FROM channels ORDER BY updated") do |rs|
+        rs.each do
+          id = rs.read(String)
+
+          if active_threads >= max_threads
+            if active_channel.receive
+              active_threads -= 1
+            end
+          end
+
+          active_threads += 1
+          spawn do
+            begin
+              channel = fetch_channel(id, db, full_refresh)
+
+              db.exec("UPDATE channels SET updated = $1, author = $2, deleted = false WHERE id = $3", Time.now, channel.author, id)
+            rescue ex
+              if ex.message == "Deleted or invalid channel"
+                db.exec("UPDATE channels SET updated = $1, deleted = true WHERE id = $2", Time.now, id)
+              end
+              logger.write("#{id} : #{ex.message}\n")
+            end
+
+            active_channel.send(true)
+          end
+        end
+      end
+
+      sleep 1.minute
+    end
+  end
+
+  max_channel.send(max_threads)
+end
+
+def refresh_feeds(db, logger, max_threads = 1)
+  max_channel = Channel(Int32).new
+
+  spawn do
+    max_threads = max_channel.receive
+    active_threads = 0
+    active_channel = Channel(Bool).new
+
+    loop do
+      db.query("SELECT email FROM users") do |rs|
+        rs.each do
+          email = rs.read(String)
+          view_name = "subscriptions_#{sha256(email)[0..7]}"
+
+          if active_threads >= max_threads
+            if active_channel.receive
+              active_threads -= 1
+            end
+          end
+
+          active_threads += 1
+          spawn do
+            begin
+              db.query("SELECT * FROM #{view_name} LIMIT 1") do |rs|
+                # Drop view that doesn't contain same number of rows as ChannelVideo
+                if ChannelVideo.from_rs(rs)[0]?.try &.to_a.size.try &.!= rs.column_count
+                  db.exec("DROP MATERIALIZED VIEW #{view_name}")
+                  raise "valid schema does not exist"
+                end
+              end
+
+              db.exec("REFRESH MATERIALIZED VIEW #{view_name}")
+            rescue ex
+              # Create view if it doesn't exist
+              if ex.message.try &.ends_with?("does not exist")
+                # While iterating through, we may have an email stored from a deleted account
+                if db.query_one?("SELECT true FROM users WHERE email = $1", email, as: Bool)
+                  db.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
+                  SELECT * FROM channel_videos WHERE \
+                  ucid = ANY ((SELECT subscriptions FROM users WHERE email = E'#{email.gsub("'", "\\'")}')::text[]) \
+                  ORDER BY published DESC;")
+                  logger.write("CREATE #{view_name}\n")
+                end
+              else
+                logger.write("REFRESH #{email} : #{ex.message}\n")
+              end
+            end
+
+            active_channel.send(true)
+          end
+        end
+      end
+
+      sleep 1.minute
+    end
+  end
+
+  max_channel.send(max_threads)
+end
+
+def subscribe_to_feeds(db, logger, key, config)
+  if config.use_pubsub_feeds
+    case config.use_pubsub_feeds
+    when Bool
+      max_threads = config.use_pubsub_feeds.as(Bool).to_unsafe
+    when Int32
+      max_threads = config.use_pubsub_feeds.as(Int32)
+    end
+    max_channel = Channel(Int32).new
+
+    spawn do
+      max_threads = max_channel.receive
+      active_threads = 0
+      active_channel = Channel(Bool).new
+
+      loop do
+        db.query_all("SELECT id FROM channels WHERE CURRENT_TIMESTAMP - subscribed > interval '4 days' OR subscribed IS NULL") do |rs|
+          rs.each do
+            ucid = rs.read(String)
+
+            if active_threads >= max_threads.as(Int32)
+              if active_channel.receive
+                active_threads -= 1
+              end
+            end
+
+            active_threads += 1
+
+            spawn do
+              begin
+                response = subscribe_pubsub(ucid, key, config)
+
+                if response.status_code >= 400
+                  logger.write("#{ucid} : #{response.body}\n")
+                end
+              rescue ex
+              end
+
+              active_channel.send(true)
+            end
+          end
+        end
+
+        sleep 1.minute
+      end
+    end
+
+    max_channel.send(max_threads.as(Int32))
+  end
+end
+
+def pull_top_videos(config, db)
+  loop do
+    begin
+      top = rank_videos(db, 40)
+    rescue ex
+      next
+    end
+
+    if top.size > 0
+      args = arg_array(top)
+    else
+      next
+    end
+
+    videos = [] of Video
+
+    top.each do |id|
+      begin
+        videos << get_video(id, db)
+      rescue ex
+        next
+      end
+    end
+
+    yield videos
+    sleep 1.minute
+  end
+end
+
+def pull_popular_videos(db)
+  loop do
+    subscriptions = db.query_all("SELECT channel FROM \
+      (SELECT UNNEST(subscriptions) AS channel FROM users) AS d \
+    GROUP BY channel ORDER BY COUNT(channel) DESC LIMIT 40", as: String)
+
+    videos = db.query_all("SELECT DISTINCT ON (ucid) * FROM \
+      channel_videos WHERE ucid IN (#{arg_array(subscriptions)}) \
+    ORDER BY ucid, published DESC", subscriptions, as: ChannelVideo).sort_by { |video| video.published }.reverse
+
+    yield videos
+    sleep 1.minute
+  end
+end
+
+def update_decrypt_function
+  loop do
+    begin
+      decrypt_function = fetch_decrypt_function
+    rescue ex
+      next
+    end
+
+    yield decrypt_function
+    sleep 1.minute
+  end
+end
+
+def find_working_proxies(regions)
+  loop do
+    regions.each do |region|
+      proxies = get_proxies(region).first(20)
+      proxies = proxies.map { |proxy| {ip: proxy[:ip], port: proxy[:port]} }
+      # proxies = filter_proxies(proxies)
+
+      yield region, proxies
+    end
+
+    sleep 1.minute
+  end
+end
diff --git a/src/invidious/helpers/macros.cr b/src/invidious/helpers/macros.cr
index fda34ed7..fe1fc94e 100644
--- a/src/invidious/helpers/macros.cr
+++ b/src/invidious/helpers/macros.cr
@@ -3,10 +3,14 @@ macro db_mapping(mapping)
     end
 
     def to_a
-        return [{{*mapping.keys.map { |id| "@#{id}".id }}}]
+        return [ {{*mapping.keys.map { |id| "@#{id}".id }}} ]
     end
 
-    DB.mapping({{mapping}})
+    def self.to_type_tuple
+        return { {{*mapping.keys.map { |id| "#{id}" }}} }
+    end
+
+    DB.mapping( {{mapping}} )
 end
 
 macro json_mapping(mapping)
@@ -14,11 +18,11 @@ macro json_mapping(mapping)
     end
 
     def to_a
-        return [{{*mapping.keys.map { |id| "@#{id}".id }}}]
+        return [ {{*mapping.keys.map { |id| "@#{id}".id }}} ]
     end
 
-    JSON.mapping({{mapping}})
-    YAML.mapping({{mapping}})
+    JSON.mapping( {{mapping}} )
+    YAML.mapping( {{mapping}} )
 end
 
 macro yaml_mapping(mapping)
@@ -26,7 +30,7 @@ macro yaml_mapping(mapping)
     end
 
     def to_a
-        return [{{*mapping.keys.map { |id| "@#{id}".id }}}]
+        return [ {{*mapping.keys.map { |id| "@#{id}".id }}} ]
     end
 
     def to_tuple
diff --git a/src/invidious/helpers/signatures.cr b/src/invidious/helpers/signatures.cr
new file mode 100644
index 00000000..8b760398
--- /dev/null
+++ b/src/invidious/helpers/signatures.cr
@@ -0,0 +1,70 @@
+def fetch_decrypt_function(id = "CvFH_6DNRCY")
+  client = make_client(YT_URL)
+  document = client.get("/watch?v=#{id}&gl=US&hl=en&disable_polymer=1").body
+  url = document.match(/src="(?<url>\/yts\/jsbin\/player_ias-.{9}\/en_US\/base.js)"/).not_nil!["url"]
+  player = client.get(url).body
+
+  function_name = player.match(/^(?<name>[^=]+)=function\(a\){a=a\.split\(""\)/m).not_nil!["name"]
+  function_body = player.match(/^#{Regex.escape(function_name)}=function\(a\){(?<body>[^}]+)}/m).not_nil!["body"]
+  function_body = function_body.split(";")[1..-2]
+
+  var_name = function_body[0][0, 2]
+  var_body = player.delete("\n").match(/var #{Regex.escape(var_name)}={(?<body>(.*?))};/).not_nil!["body"]
+
+  operations = {} of String => String
+  var_body.split("},").each do |operation|
+    op_name = operation.match(/^[^:]+/).not_nil![0]
+    op_body = operation.match(/\{[^}]+/).not_nil![0]
+
+    case op_body
+    when "{a.reverse()"
+      operations[op_name] = "a"
+    when "{a.splice(0,b)"
+      operations[op_name] = "b"
+    else
+      operations[op_name] = "c"
+    end
+  end
+
+  decrypt_function = [] of {name: String, value: Int32}
+  function_body.each do |function|
+    function = function.lchop(var_name).delete("[].")
+
+    op_name = function.match(/[^\(]+/).not_nil![0]
+    value = function.match(/\(a,(?<value>[\d]+)\)/).not_nil!["value"].to_i
+
+    decrypt_function << {name: operations[op_name], value: value}
+  end
+
+  return decrypt_function
+end
+
+def decrypt_signature(fmt, code)
+  if !fmt["s"]?
+    return ""
+  end
+
+  a = fmt["s"]
+  a = a.split("")
+
+  code.each do |item|
+    case item[:name]
+    when "a"
+      a.reverse!
+    when "b"
+      a.delete_at(0..(item[:value] - 1))
+    when "c"
+      a = splice(a, item[:value])
+    end
+  end
+
+  signature = a.join("")
+  return "&#{fmt["sp"]?}=#{signature}"
+end
+
+def splice(a, b)
+  c = a[0]
+  a[0] = a[b % a.size]
+  a[b % a.size] = c
+  return a
+end
diff --git a/src/invidious/jobs.cr b/src/invidious/jobs.cr
deleted file mode 100644
index 82e58c93..00000000
--- a/src/invidious/jobs.cr
+++ /dev/null
@@ -1,225 +0,0 @@
-def refresh_channels(db, logger, max_threads = 1, full_refresh = false)
-  max_channel = Channel(Int32).new
-
-  spawn do
-    max_threads = max_channel.receive
-    active_threads = 0
-    active_channel = Channel(Bool).new
-
-    loop do
-      db.query("SELECT id FROM channels ORDER BY updated") do |rs|
-        rs.each do
-          id = rs.read(String)
-
-          if active_threads >= max_threads
-            if active_channel.receive
-              active_threads -= 1
-            end
-          end
-
-          active_threads += 1
-          spawn do
-            begin
-              channel = fetch_channel(id, db, full_refresh)
-
-              db.exec("UPDATE channels SET updated = $1, author = $2, deleted = false WHERE id = $3", Time.now, channel.author, id)
-            rescue ex
-              if ex.message == "Deleted or invalid channel"
-                db.exec("UPDATE channels SET updated = $1, deleted = true WHERE id = $2", Time.now, id)
-              end
-              logger.write("#{id} : #{ex.message}\n")
-            end
-
-            active_channel.send(true)
-          end
-        end
-      end
-
-      sleep 1.minute
-    end
-  end
-
-  max_channel.send(max_threads)
-end
-
-def refresh_feeds(db, logger, max_threads = 1)
-  max_channel = Channel(Int32).new
-
-  spawn do
-    max_threads = max_channel.receive
-    active_threads = 0
-    active_channel = Channel(Bool).new
-
-    loop do
-      db.query("SELECT email FROM users") do |rs|
-        rs.each do
-          email = rs.read(String)
-          view_name = "subscriptions_#{sha256(email)[0..7]}"
-
-          if active_threads >= max_threads
-            if active_channel.receive
-              active_threads -= 1
-            end
-          end
-
-          active_threads += 1
-          spawn do
-            begin
-              db.query("SELECT * FROM #{view_name} LIMIT 1") do |rs|
-                # View doesn't contain same number of rows as ChannelVideo
-                if ChannelVideo.from_rs(rs)[0]?.try &.to_a.size.try &.!= rs.column_count
-                  db.exec("DROP MATERIALIZED VIEW #{view_name}")
-                  raise "valid schema does not exist"
-                end
-              end
-
-              db.exec("REFRESH MATERIALIZED VIEW #{view_name}")
-            rescue ex
-              # Create view if it doesn't exist
-              if ex.message.try &.ends_with?("does not exist")
-                # While iterating through, we may have an email stored from a deleted account
-                if db.query_one?("SELECT true FROM users WHERE email = $1", email, as: Bool)
-                  db.exec("CREATE MATERIALIZED VIEW #{view_name} AS \
-                  SELECT * FROM channel_videos WHERE \
-                  ucid = ANY ((SELECT subscriptions FROM users WHERE email = E'#{email.gsub("'", "\\'")}')::text[]) \
-                  ORDER BY published DESC;")
-                  logger.write("CREATE #{view_name}\n")
-                end
-              else
-                logger.write("REFRESH #{email} : #{ex.message}\n")
-              end
-            end
-
-            active_channel.send(true)
-          end
-        end
-      end
-
-      sleep 1.minute
-    end
-  end
-
-  max_channel.send(max_threads)
-end
-
-def subscribe_to_feeds(db, logger, key, config)
-  if config.use_pubsub_feeds
-    case config.use_pubsub_feeds
-    when Bool
-      max_threads = config.use_pubsub_feeds.as(Bool).to_unsafe
-    when Int32
-      max_threads = config.use_pubsub_feeds.as(Int32)
-    end
-    max_channel = Channel(Int32).new
-
-    spawn do
-      max_threads = max_channel.receive
-      active_threads = 0
-      active_channel = Channel(Bool).new
-
-      loop do
-        db.query_all("SELECT id FROM channels WHERE CURRENT_TIMESTAMP - subscribed > interval '4 days' OR subscribed IS NULL") do |rs|
-          rs.each do
-            ucid = rs.read(String)
-
-            if active_threads >= max_threads.as(Int32)
-              if active_channel.receive
-                active_threads -= 1
-              end
-            end
-
-            active_threads += 1
-
-            spawn do
-              begin
-                response = subscribe_pubsub(ucid, key, config)
-
-                if response.status_code >= 400
-                  logger.write("#{ucid} : #{response.body}\n")
-                end
-              rescue ex
-              end
-
-              active_channel.send(true)
-            end
-          end
-        end
-
-        sleep 1.minute
-      end
-    end
-
-    max_channel.send(max_threads.as(Int32))
-  end
-end
-
-def pull_top_videos(config, db)
-  loop do
-    begin
-      top = rank_videos(db, 40)
-    rescue ex
-      next
-    end
-
-    if top.size > 0
-      args = arg_array(top)
-    else
-      next
-    end
-
-    videos = [] of Video
-
-    top.each do |id|
-      begin
-        videos << get_video(id, db)
-      rescue ex
-        next
-      end
-    end
-
-    yield videos
-    sleep 1.minute
-  end
-end
-
-def pull_popular_videos(db)
-  loop do
-    subscriptions = db.query_all("SELECT channel FROM \
-      (SELECT UNNEST(subscriptions) AS channel FROM users) AS d \
-    GROUP BY channel ORDER BY COUNT(channel) DESC LIMIT 40", as: String)
-
-    videos = db.query_all("SELECT DISTINCT ON (ucid) * FROM \
-      channel_videos WHERE ucid IN (#{arg_array(subscriptions)}) \
-    ORDER BY ucid, published DESC", subscriptions, as: ChannelVideo).sort_by { |video| video.published }.reverse
-
-    yield videos
-    sleep 1.minute
-  end
-end
-
-def update_decrypt_function
-  loop do
-    begin
-      decrypt_function = fetch_decrypt_function
-    rescue ex
-      next
-    end
-
-    yield decrypt_function
-    sleep 1.minute
-  end
-end
-
-def find_working_proxies(regions)
-  loop do
-    regions.each do |region|
-      proxies = get_proxies(region).first(20)
-      proxies = proxies.map { |proxy| {ip: proxy[:ip], port: proxy[:port]} }
-      # proxies = filter_proxies(proxies)
-
-      yield region, proxies
-    end
-
-    sleep 1.minute
-  end
-end
diff --git a/src/invidious/signatures.cr b/src/invidious/signatures.cr
deleted file mode 100644
index 8b760398..00000000
--- a/src/invidious/signatures.cr
+++ /dev/null
@@ -1,70 +0,0 @@
-def fetch_decrypt_function(id = "CvFH_6DNRCY")
-  client = make_client(YT_URL)
-  document = client.get("/watch?v=#{id}&gl=US&hl=en&disable_polymer=1").body
-  url = document.match(/src="(?<url>\/yts\/jsbin\/player_ias-.{9}\/en_US\/base.js)"/).not_nil!["url"]
-  player = client.get(url).body
-
-  function_name = player.match(/^(?<name>[^=]+)=function\(a\){a=a\.split\(""\)/m).not_nil!["name"]
-  function_body = player.match(/^#{Regex.escape(function_name)}=function\(a\){(?<body>[^}]+)}/m).not_nil!["body"]
-  function_body = function_body.split(";")[1..-2]
-
-  var_name = function_body[0][0, 2]
-  var_body = player.delete("\n").match(/var #{Regex.escape(var_name)}={(?<body>(.*?))};/).not_nil!["body"]
-
-  operations = {} of String => String
-  var_body.split("},").each do |operation|
-    op_name = operation.match(/^[^:]+/).not_nil![0]
-    op_body = operation.match(/\{[^}]+/).not_nil![0]
-
-    case op_body
-    when "{a.reverse()"
-      operations[op_name] = "a"
-    when "{a.splice(0,b)"
-      operations[op_name] = "b"
-    else
-      operations[op_name] = "c"
-    end
-  end
-
-  decrypt_function = [] of {name: String, value: Int32}
-  function_body.each do |function|
-    function = function.lchop(var_name).delete("[].")
-
-    op_name = function.match(/[^\(]+/).not_nil![0]
-    value = function.match(/\(a,(?<value>[\d]+)\)/).not_nil!["value"].to_i
-
-    decrypt_function << {name: operations[op_name], value: value}
-  end
-
-  return decrypt_function
-end
-
-def decrypt_signature(fmt, code)
-  if !fmt["s"]?
-    return ""
-  end
-
-  a = fmt["s"]
-  a = a.split("")
-
-  code.each do |item|
-    case item[:name]
-    when "a"
-      a.reverse!
-    when "b"
-      a.delete_at(0..(item[:value] - 1))
-    when "c"
-      a = splice(a, item[:value])
-    end
-  end
-
-  signature = a.join("")
-  return "&#{fmt["sp"]?}=#{signature}"
-end
-
-def splice(a, b)
-  c = a[0]
-  a[0] = a[b % a.size]
-  a[b % a.size] = c
-  return a
-end
-- 
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