Auto merge of #6513 - agrim123:agr-bundler-remove, r=indirect

Add `bundle remove`

Features of the command implemented:
- Multiple gems support
```bash
$ bundle remove rack rails
```
- Remove any empty block that might occur after removing the gem or otherwise present

Things yet to implement:
- Add `rm` alias. _Optional_
- [x] Add `--install` flag to remove gems from `.bundle`.
- [x] Handling multiple gems on the same line.
- [x] Handle gem spec
- [x] Handle eval_gemfile cases ([one](https://github.com/bundler/bundler/pull/6513#discussion_r195632603) case left)

Closes #6506

6 files changed, 195 insertions, 14 deletions

diff --git a/lib/bundler/cli.rb b/lib/bundler/cli.rb
index 466fb0135a..f1ff3f4554 100644
--- a/lib/bundler/cli.rb
+++ b/lib/bundler/cli.rb
@@ -166,6 +166,17 @@ module Bundler
       Check.new(options).run
     end
 
+    desc "remove [GEM [GEM ...]]", "Removes gems from the Gemfile"
+    long_desc <<-D
+      Removes the given gems from the Gemfile while ensuring that the resulting Gemfile is still valid. If the gem is not found, Bundler prints a error message and if gem could not be removed due to any reason Bundler will display a warning.
+    D
+    method_option "install", :type => :boolean, :banner =>
+      "Runs 'bundle install' after removing the gems from the Gemfile"
+    def remove(*gems)
+      require "bundler/cli/remove"
+      Remove.new(gems, options).run
+    end
+
     desc "install [OPTIONS]", "Install the current environment to the system"
     long_desc <<-D
       Install will install all of the gems in the current bundle, making them available
diff --git a/lib/bundler/cli/remove.rb b/lib/bundler/cli/remove.rb
new file mode 100644
index 0000000000..cd6a2cec28
--- /dev/null
+++ b/lib/bundler/cli/remove.rb
@@ -0,0 +1,18 @@
+# frozen_string_literal: true
+
+module Bundler
+  class CLI::Remove
+    def initialize(gems, options)
+      @gems = gems
+      @options = options
+    end
+
+    def run
+      raise InvalidOption, "Please specify gems to remove." if @gems.empty?
+
+      Injector.remove(@gems, {})
+
+      Installer.install(Bundler.root, Bundler.definition) if @options["install"]
+    end
+  end
+end
diff --git a/lib/bundler/dependency.rb b/lib/bundler/dependency.rb
index 24257bc113..ec5081dee0 100644
--- a/lib/bundler/dependency.rb
+++ b/lib/bundler/dependency.rb
@@ -7,8 +7,7 @@ require "bundler/rubygems_ext"
 module Bundler
   class Dependency < Gem::Dependency
     attr_reader :autorequire
-    attr_reader :groups
-    attr_reader :platforms
+    attr_reader :groups, :platforms, :gemfile
 
     PLATFORM_MAP = {
       :ruby     => Gem::Platform::RUBY,
@@ -87,6 +86,7 @@ module Bundler
       @platforms      = Array(options["platforms"])
       @env            = options["env"]
       @should_include = options.fetch("should_include", true)
+      @gemfile        = options["gemfile"]
 
       @autorequire = Array(options["require"] || []) if options.key?("require")
     end
diff --git a/lib/bundler/dsl.rb b/lib/bundler/dsl.rb
index 37bfe36740..7467b5a537 100644
--- a/lib/bundler/dsl.rb
+++ b/lib/bundler/dsl.rb
@@ -16,7 +16,7 @@ module Bundler
     VALID_PLATFORMS = Bundler::Dependency::PLATFORM_MAP.keys.freeze
 
     VALID_KEYS = %w[group groups git path glob name branch ref tag require submodules
-                    platform platforms type source install_if].freeze
+                    platform platforms type source install_if gemfile].freeze
 
     attr_reader :gemspecs
     attr_accessor :dependencies
@@ -93,6 +93,7 @@ module Bundler
 
     def gem(name, *args)
       options = args.last.is_a?(Hash) ? args.pop.dup : {}
+      options["gemfile"] = @gemfile
       version = args || [">= 0"]
 
       normalize_options(name, version, options)
diff --git a/lib/bundler/injector.rb b/lib/bundler/injector.rb
index 08f2ba90fd..5bbb6aeae0 100644
--- a/lib/bundler/injector.rb
+++ b/lib/bundler/injector.rb
@@ -2,13 +2,18 @@
 
 module Bundler
   class Injector
-    def self.inject(new_deps, options = {})
-      injector = new(new_deps, options)
+    def self.inject(deps, options = {})
+      injector = new(deps, options)
       injector.inject(Bundler.default_gemfile, Bundler.default_lockfile)
     end
 
-    def initialize(new_deps, options = {})
-      @new_deps = new_deps
+    def self.remove(gems, options = {})
+      injector = new(gems, options)
+      injector.remove(Bundler.default_gemfile, Bundler.default_lockfile)
+    end
+
+    def initialize(deps, options = {})
+      @deps = deps
       @options = options
     end
 
@@ -28,19 +33,18 @@ module Bundler
         builder.eval_gemfile(gemfile_path)
 
         # don't inject any gems that are already in the Gemfile
-        @new_deps -= builder.dependencies
+        @deps -= builder.dependencies
 
         # add new deps to the end of the in-memory Gemfile
-        # Set conservative versioning to false because
-        # we want to let the resolver resolve the version first
-        builder.eval_gemfile("injected gems", build_gem_lines(false)) if @new_deps.any?
+        # Set conservative versioning to false because we want to let the resolver resolve the version first
+        builder.eval_gemfile("injected gems", build_gem_lines(false)) if @deps.any?
 
         # resolve to see if the new deps broke anything
         @definition = builder.to_definition(lockfile_path, {})
         @definition.resolve_remotely!
 
         # since nothing broke, we can add those gems to the gemfile
-        append_to(gemfile_path, build_gem_lines(@options[:conservative_versioning])) if @new_deps.any?
+        append_to(gemfile_path, build_gem_lines(@options[:conservative_versioning])) if @deps.any?
 
         # since we resolved successfully, write out the lockfile
         @definition.lock(Bundler.default_lockfile)
@@ -49,7 +53,21 @@ module Bundler
         Bundler.reset_paths!
 
         # return an array of the deps that we added
-        @new_deps
+        @deps
+      end
+    end
+
+    # @param [Pathname] gemfile_path The Gemfile from which to remove dependencies.
+    # @param [Pathname] lockfile_path The lockfile from which to remove dependencies.
+    # @return [Array]
+    def remove(gemfile_path, lockfile_path)
+      # remove gems from each gemfiles we have
+      Bundler.definition.gemfiles.each do |path|
+        deps = remove_deps(path)
+
+        show_warning("No gems were removed from the gemfile.") if deps.empty?
+
+        deps.each {|dep| Bundler.ui.confirm "#{SharedHelpers.pretty_dependency(dep, false)} was removed." }
       end
     end
 
@@ -76,7 +94,7 @@ module Bundler
     end
 
     def build_gem_lines(conservative_versioning)
-      @new_deps.map do |d|
+      @deps.map do |d|
         name = d.name.dump
 
         requirement = if conservative_versioning
@@ -101,5 +119,132 @@ module Bundler
         f.puts new_gem_lines
       end
     end
+
+    # evalutes a gemfile to remove the specified gem
+    # from it.
+    def remove_deps(gemfile_path)
+      initial_gemfile = IO.readlines(gemfile_path)
+
+      Bundler.ui.info "Removing gems from #{gemfile_path}"
+
+      # evaluate the Gemfile we have
+      builder = Dsl.new
+      builder.eval_gemfile(gemfile_path)
+
+      removed_deps = remove_gems_from_dependencies(builder, @deps, gemfile_path)
+
+      # abort the opertion if no gems were removed
+      # no need to operate on gemfile furthur
+      return [] if removed_deps.empty?
+
+      cleaned_gemfile = remove_gems_from_gemfile(@deps, gemfile_path)
+
+      SharedHelpers.write_to_gemfile(gemfile_path, cleaned_gemfile)
+
+      # check for errors
+      # including extra gems being removed
+      # or some gems not being removed
+      # and return the actual removed deps
+      cross_check_for_errors(gemfile_path, builder.dependencies, removed_deps, initial_gemfile)
+    end
+
+    # @param [Dsl]      builder Dsl object of current Gemfile.
+    # @param [Array]    gems Array of names of gems to be removed.
+    # @param [Pathname] path of the Gemfile
+    # @return [Array]   removed_deps Array of removed dependencies.
+    def remove_gems_from_dependencies(builder, gems, gemfile_path)
+      removed_deps = []
+
+      gems.each do |gem_name|
+        deleted_dep = builder.dependencies.find {|d| d.name == gem_name }
+
+        if deleted_dep.nil?
+          raise GemfileError, "`#{gem_name}` is not specified in #{gemfile_path} so it could not be removed."
+        end
+
+        builder.dependencies.delete(deleted_dep)
+
+        removed_deps << deleted_dep
+      end
+
+      removed_deps
+    end
+
+    # @param [Array] gems            Array of names of gems to be removed.
+    # @param [Pathname] gemfile_path The Gemfile from which to remove dependencies.
+    def remove_gems_from_gemfile(gems, gemfile_path)
+      patterns = /gem\s+(['"])#{Regexp.union(gems)}\1|gem\s*\((['"])#{Regexp.union(gems)}\2\)/
+
+      # remove lines which match the regex
+      new_gemfile = IO.readlines(gemfile_path).reject {|line| line.match(patterns) }
+
+      # remove lone \n and append them with other strings
+      new_gemfile.each_with_index do |_line, index|
+        if new_gemfile[index + 1] == "\n"
+          new_gemfile[index] += new_gemfile[index + 1]
+          new_gemfile.delete_at(index + 1)
+        end
+      end
+
+      %w[group source env install_if].each {|block| remove_nested_blocks(new_gemfile, block) }
+
+      new_gemfile.join.chomp
+    end
+
+    # @param [Array] gemfile       Array of gemfile contents.
+    # @param [String] block_name   Name of block name to look for.
+    def remove_nested_blocks(gemfile, block_name)
+      nested_blocks = 0
+
+      # count number of nested blocks
+      gemfile.each_with_index {|line, index| nested_blocks += 1 if !gemfile[index + 1].nil? && gemfile[index + 1].include?(block_name) && line.include?(block_name) }
+
+      while nested_blocks >= 0
+        nested_blocks -= 1
+
+        gemfile.each_with_index do |line, index|
+          next unless !line.nil? && line.include?(block_name)
+          if gemfile[index + 1] =~ /^\s*end\s*$/
+            gemfile[index] = nil
+            gemfile[index + 1] = nil
+          end
+        end
+
+        gemfile.compact!
+      end
+    end
+
+    # @param [Pathname] gemfile_path   The Gemfile from which to remove dependencies.
+    # @param [Array] original_deps     Array of original dependencies.
+    # @param [Array] removed_deps      Array of removed dependencies.
+    # @param [Array] initial_gemfile   Contents of original Gemfile before any operation.
+    def cross_check_for_errors(gemfile_path, original_deps, removed_deps, initial_gemfile)
+      # evalute the new gemfile to look for any failure cases
+      builder = Dsl.new
+      builder.eval_gemfile(gemfile_path)
+
+      # record gems which were removed but not requested
+      extra_removed_gems = original_deps - builder.dependencies
+
+      # if some extra gems were removed then raise error
+      # and revert Gemfile to original
+      unless extra_removed_gems.empty?
+        SharedHelpers.write_to_gemfile(gemfile_path, initial_gemfile.join)
+
+        raise InvalidOption, "Gems could not be removed. #{extra_removed_gems.join(", ")} would also have been removed. Bundler cannot continue."
+      end
+
+      # record gems which could not be removed due to some reasons
+      errored_deps = builder.dependencies.select {|d| d.gemfile == gemfile_path } & removed_deps.select {|d| d.gemfile == gemfile_path }
+
+      show_warning "#{errored_deps.map(&:name).join(", ")} could not be removed." unless errored_deps.empty?
+
+      # return actual removed dependencies
+      removed_deps - errored_deps
+    end
+
+    def show_warning(message)
+      Bundler.ui.info Bundler.ui.add_color(message, :yellow)
+    end
   end
 end
diff --git a/lib/bundler/shared_helpers.rb b/lib/bundler/shared_helpers.rb
index 2b9fb8d6a7..93e2a35b54 100644
--- a/lib/bundler/shared_helpers.rb
+++ b/lib/bundler/shared_helpers.rb
@@ -198,10 +198,12 @@ module Bundler
     def pretty_dependency(dep, print_source = false)
       msg = String.new(dep.name)
       msg << " (#{dep.requirement})" unless dep.requirement == Gem::Requirement.default
+
       if dep.is_a?(Bundler::Dependency)
         platform_string = dep.platforms.join(", ")
         msg << " " << platform_string if !platform_string.empty? && platform_string != Gem::Platform::RUBY
       end
+
       msg << " from the `#{dep.source}` source" if print_source && dep.source
       msg
     end
@@ -224,6 +226,10 @@ module Bundler
       Digest(name)
     end
 
+    def write_to_gemfile(gemfile_path, contents)
+      filesystem_access(gemfile_path) {|g| File.open(g, "w") {|file| file.puts contents } }
+    end
+
   private
 
     def validate_bundle_path