From 8d6d8cbf79c8c9ccc929e6b1b32b4b58258e720e Mon Sep 17 00:00:00 2001
From: George Dietrich <george@dietrich.app>
Date: Tue, 22 Dec 2020 00:39:12 -0500
Subject: [PATCH] Scaffold out types and start of implementation

---
 src/abstract_negotiator.cr | 57 ++++++++++++++++++++++++++++++++++++++
 src/accept.cr              | 20 +++++++++++++
 src/accept_charset.cr      |  4 +++
 src/accept_encoding.cr     |  4 +++
 src/accept_language.cr     | 29 +++++++++++++++++++
 src/accept_match.cr        |  7 +++++
 src/athena-negotiation.cr  | 22 ++++++++++++++-
 src/base_accept.cr         | 35 +++++++++++++++++++++++
 src/negotiator.cr          |  7 +++++
 9 files changed, 184 insertions(+), 1 deletion(-)
 create mode 100644 src/abstract_negotiator.cr
 create mode 100644 src/accept.cr
 create mode 100644 src/accept_charset.cr
 create mode 100644 src/accept_encoding.cr
 create mode 100644 src/accept_language.cr
 create mode 100644 src/accept_match.cr
 create mode 100644 src/base_accept.cr
 create mode 100644 src/negotiator.cr

diff --git a/src/abstract_negotiator.cr b/src/abstract_negotiator.cr
new file mode 100644
index 0000000..0a2d846
--- /dev/null
+++ b/src/abstract_negotiator.cr
@@ -0,0 +1,57 @@
+abstract class Athena::Negotiation::AbstractNegotiator
+  private abstract def create_header(header : String) : ANG::BaseAccept
+
+  def best(header : String, priorities : Array(String), strict : Bool = false) : ANG::BaseAccept?
+    raise ArgumentError.new "priorities should not be empty" if priorities.empty?
+    raise ArgumentError.new "The header string should not be empty" if header.blank?
+
+    accepted_headers = Array(ANG::BaseAccept).new
+
+    self.parse_header(header) do |h|
+      accepted_headers << self.create_header h
+    rescue ex
+      raise ex if strict
+    end
+
+    accepted_priorties = priorities.map &->create_header(String)
+
+    matches = self.find_matches accepted_headers, accepted_priorties
+
+    pp matches
+
+    nil
+  end
+
+  private def parse_header(header : String, & : String ->) : Nil
+    header.scan /(?:[^,\"]*+(?:"[^"]*+\")?)+[^,\"]*+/ do |match|
+      yield match[0] unless match[0].blank?
+    end
+  end
+
+  private def find_matches(headers : Array(ANG::BaseAccept), priorities : Array(ANG::BaseAccept)) : Array(ANG::AcceptMatch)
+    matches = [] of ANG::AcceptMatch
+
+    priorities.each_with_index do |priority, idx|
+      headers.each do |header|
+        if match = self.match(header, priority, idx)
+          matches << match
+        end
+      end
+    end
+
+    matches
+  end
+
+  private def match(header : ANG::BaseAccept, priority : ANG::BaseAccept, index : Int32) : ANG::AcceptMatch?
+    accept_type = header.type
+    priority_type = priority.type
+
+    equal = accept_type.downcase <=> priority_type.downcase
+
+    if !equal.zero? || accept_type == "*"
+      return ANG::AcceptMatch.new header.quality * priority.quality, 1 * equal, index
+    end
+
+    nil
+  end
+end
diff --git a/src/accept.cr b/src/accept.cr
new file mode 100644
index 0000000..6a6366a
--- /dev/null
+++ b/src/accept.cr
@@ -0,0 +1,20 @@
+require "./base_accept"
+
+struct Athena::Negotiation::Accept < Athena::Negotiation::BaseAccept
+  getter base_part : String
+  getter sub_part : String
+
+  def initialize(value : String)
+    super value
+
+    @type = "*/*" if @type == "*"
+
+    parts = @type.split '/'
+
+    # TODO: Use more specific exception
+    raise "Invalid media type: '#{@type}'." if parts.size != 2 || !parts[0].presence || !parts[1].presence
+
+    @base_part = parts[0]
+    @sub_part = parts[1]
+  end
+end
diff --git a/src/accept_charset.cr b/src/accept_charset.cr
new file mode 100644
index 0000000..e20a26a
--- /dev/null
+++ b/src/accept_charset.cr
@@ -0,0 +1,4 @@
+require "./base_accept"
+
+struct Athena::Negotiation::AcceptCharset < Athena::Negotiation::BaseAccept
+end
diff --git a/src/accept_encoding.cr b/src/accept_encoding.cr
new file mode 100644
index 0000000..31feae0
--- /dev/null
+++ b/src/accept_encoding.cr
@@ -0,0 +1,4 @@
+require "./base_accept"
+
+struct Athena::Negotiation::AcceptEncoding < Athena::Negotiation::BaseAccept
+end
diff --git a/src/accept_language.cr b/src/accept_language.cr
new file mode 100644
index 0000000..3277585
--- /dev/null
+++ b/src/accept_language.cr
@@ -0,0 +1,29 @@
+require "./base_accept"
+
+struct Athena::Negotiation::AcceptLanguage < Athena::Negotiation::BaseAccept
+  getter language : String
+  getter script : String? = nil
+  getter region : String? = nil
+
+  def initialize(value : String)
+    super value
+
+    parts = @value.split '-'
+
+    pp parts
+
+    case parts.size
+    when 2
+      @language = parts[0]
+      @region = parts[1]
+    when 1
+      @language = parts[0]
+    when 3
+      @language = parts[0]
+      @script = parts[1]
+      @region = parts[2]
+    else
+      raise "Invalid language: '#{@value}'."
+    end
+  end
+end
diff --git a/src/accept_match.cr b/src/accept_match.cr
new file mode 100644
index 0000000..43b9474
--- /dev/null
+++ b/src/accept_match.cr
@@ -0,0 +1,7 @@
+struct Athena::Negotiation::AcceptMatch
+  getter quality : Float32
+  getter score : Int32
+  getter index : Int32
+
+  def initialize(@quality : Float32, @score : Int32, @index : Int32); end
+end
diff --git a/src/athena-negotiation.cr b/src/athena-negotiation.cr
index 957a270..cfd24fb 100644
--- a/src/athena-negotiation.cr
+++ b/src/athena-negotiation.cr
@@ -1,6 +1,26 @@
+require "./accept"
+require "./accept_match"
+require "./accept_charset"
+require "./accept_encoding"
+require "./accept_language"
+require "./negotiator"
+
 # Convenience alias to make referencing `Athena::Negotiation` types easier.
 alias ANG = Athena::Negotiation
 
 module Athena::Negotiation
-  VERSION = "0.1.0"
 end
+
+# pp ANG::Accept.new "application/json;q=1.0"
+# pp ANG::Accept.new "application/json ;q=1.0; level=2;foo= bar"
+# pp ANG::Accept.new "text/html ; level = 2   ; q = 0.4"
+
+# puts
+# puts
+
+# pp ANG::AcceptLanguage.new "en-gb;q=0.8"
+
+n = ANG::Negotiator.new
+
+pp n.best "text/html;level=1", ["text/html"]                                                      # text/html
+pp n.best "text/*;q=0.7, text/html;q=0.3, */*;q=0.5, image/png;q=0.4", ["text/html", "image/png"] # image/png
diff --git a/src/base_accept.cr b/src/base_accept.cr
new file mode 100644
index 0000000..3066652
--- /dev/null
+++ b/src/base_accept.cr
@@ -0,0 +1,35 @@
+abstract struct Athena::Negotiation::BaseAccept
+  getter quality : Float32 = 1.0
+  getter normalized_value : String
+  getter value : String
+  getter parameters : Hash(String, String)
+  getter type : String
+
+  def initialize(@value : String)
+    # type, parameters = self.parse_accept_value value
+    parts = @value.split ';'
+    @type = parts.shift.strip.downcase
+
+    @parameters = parts.to_h do |part|
+      part = part.split '='
+
+      # TODO: Use more specific exception
+      raise ArgumentError.new "Invalid header: '#{@value}'." unless part.size == 2
+
+      {part[0].strip.downcase, part[1].strip(" \"")}
+    end
+
+    if quality = @parameters.delete "q"
+      @quality = quality.to_f32
+    end
+
+    @normalized_value = String.build do |io|
+      io << @type
+
+      unless @parameters.empty?
+        io << "; "
+        parameters.join(io, "; ") { |(k, v), io| io << "#{k}=#{v}" }
+      end
+    end
+  end
+end
diff --git a/src/negotiator.cr b/src/negotiator.cr
new file mode 100644
index 0000000..dad27bb
--- /dev/null
+++ b/src/negotiator.cr
@@ -0,0 +1,7 @@
+require "./abstract_negotiator"
+
+class Athena::Negotiation::Negotiator < Athena::Negotiation::AbstractNegotiator
+  private def create_header(header : String) : ANG::BaseAccept
+    ANG::Accept.new header
+  end
+end