# frozen_string_literal: true

require "helper"

RSpec.describe HTTP2::Framer do
  let(:f) { Framer.new }

  context "common header" do
    let(:frame) do
      {
        length: 4,
        type: :headers,
        flags: %i[end_stream end_headers],
        stream: 15
      }
    end

    let(:bytes) { [0, 0x04, 0x01, 0x5, 0x0000000F].pack("CnCCN") }

    it "should generate common 9 byte header" do
      expect(f.common_header(frame, buffer: "".b)).to eq bytes
    end

    it "should parse common 9 byte header" do
      expect(f.read_common_header(bytes)).to eq frame
    end

    it "should generate a large frame" do
      f = Framer.new
      f.remote_max_frame_size = (2**24) - 1
      frame = {
        length: (2**18) + (2**16) + 17,
        type: :headers,
        flags: %i[end_stream end_headers],
        stream: 15
      }
      bytes = [5, 17, 0x01, 0x5, 0x0000000F].pack("CnCCN")
      expect(f.common_header(frame, buffer: "".b)).to eq bytes
      expect(f.read_common_header(bytes)).to eq frame
    end

    it "should raise exception on invalid frame type when sending" do
      expect do
        frame[:type] = :bogus
        f.common_header(frame, buffer: "".b)
      end.to raise_error(CompressionError, /invalid.*type/i)
    end

    it "should raise exception on invalid stream ID" do
      expect do
        frame[:stream] = Framer::MAX_STREAM_ID + 1
        f.common_header(frame, buffer: "".b)
      end.to raise_error(CompressionError, /stream/i)
    end

    it "should raise exception on invalid frame flag" do
      expect do
        frame[:flags] = [:bogus]
        f.common_header(frame, buffer: "".b)
      end.to raise_error(CompressionError, /frame flag/)
    end

    it "should raise exception on invalid frame size" do
      expect do
        frame[:length] = 2**24
        f.common_header(frame, buffer: "".b)
      end.to raise_error(CompressionError, /too large/)
    end
  end

  context "DATA" do
    it "should generate and parse bytes" do
      frame = {
        length: 4,
        type: :data,
        flags: [:end_stream],
        stream: 1,
        payload: "text"
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x4, 0x0, 0x1, 0x1, *"text".bytes].pack("CnCCNC*")

      expect(f.parse(bytes)).to eq frame
    end
  end

  context "HEADERS" do
    it "should generate and parse bytes" do
      frame = {
        length: 12,
        type: :headers,
        flags: %i[end_stream end_headers],
        stream: 1,
        payload: "header-block"
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0xc, 0x1, 0x5, 0x1, *"header-block".bytes].pack("CnCCNC*")
      expect(f.parse(bytes)).to eq frame
    end

    it "should carry an optional stream priority" do
      frame = {
        length: 16,
        type: :headers,
        flags: [:end_headers],
        stream: 1,
        dependency: 15,
        weight: 12,
        exclusive: false,
        payload: "header-block"
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x11, 0x1, 0x24, 0x1, 0xf, 0xb, *"header-block".bytes].pack("CnCCNNCC*")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "PRIORITY" do
    it "should generate and parse bytes" do
      frame = {
        length: 5,
        type: :priority,
        stream: 1,
        dependency: 15,
        weight: 12,
        exclusive: true
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x5, 0x2, 0x0, 0x1, 0x8000000f, 0xb].pack("CnCCNNC")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "RST_STREAM" do
    it "should generate and parse bytes" do
      frame = {
        length: 4,
        type: :rst_stream,
        stream: 1,
        error: :stream_closed
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x4, 0x3, 0x0, 0x1, 0x5].pack("CnCCNN")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "SETTINGS" do
    let(:frame) do
      {
        type: :settings,
        flags: [],
        stream: 0,
        payload: [
          [:settings_max_concurrent_streams, 10],
          [:settings_header_table_size,      2048]
        ]
      }
    end

    it "should generate and parse bytes" do
      bytes = f.generate(frame)
      expect(bytes).to eq [0, 12, 0x4, 0x0, 0x0, 3, 10, 1, 2048].pack("CnCCNnNnN")
      parsed = f.parse(bytes)
      parsed.delete(:length)
      frame.delete(:length)
      expect(parsed).to eq frame
    end

    it "should generate settings when id is given as an integer" do
      frame[:payload][1][0] = 1
      bytes = f.generate(frame)
      expect(bytes).to eq [0, 12, 0x4, 0x0, 0x0, 3, 10, 1, 2048].pack("CnCCNnNnN")
    end

    it "should ignore custom settings when sending" do
      frame[:payload] = [
        [:settings_max_concurrent_streams, 10],
        [:settings_initial_window_size,    20],
        [55, 30]
      ]

      buf = f.generate(frame)
      frame[:payload].slice!(2) # cut off the extension
      frame[:length] = 12       # frame length should be computed WITHOUT extensions
      expect(f.parse(buf)).to eq frame
    end

    it "should ignore custom settings when receiving" do
      frame[:payload] = [
        [:settings_max_concurrent_streams, 10],
        [:settings_initial_window_size,    20]
      ]

      buf = f.generate(frame)
      buf.setbyte(2, 18) # add 6 to the frame length
      buf << "\x00\x37\x00\x00\x00\x1e"
      parsed = f.parse(buf)
      parsed.delete(:length)
      frame.delete(:length)
      expect(parsed).to eq frame
    end

    it "should raise exception on sending invalid stream ID" do
      expect do
        frame[:stream] = 1
        f.generate(frame)
      end.to raise_error(CompressionError, /Invalid stream ID/)
    end

    it "should raise exception on receiving invalid stream ID" do
      expect do
        buf = f.generate(frame)
        buf.setbyte(8, 1)
        f.parse(buf)
      end.to raise_error(ProtocolError, /Invalid stream ID/)
    end

    it "should raise exception on sending invalid setting" do
      expect do
        frame[:payload] = [[:random, 23]]
        f.generate(frame)
      end.to raise_error(CompressionError, /Unknown settings ID/)
    end

    it "should raise exception on receiving invalid payload length" do
      expect do
        buf = f.generate(frame)
        buf.setbyte(2, 11) # change payload length
        f.parse(buf)
      end.to raise_error(ProtocolError, /Invalid settings payload length/)
    end
  end

  context "PUSH_PROMISE" do
    it "should generate and parse bytes" do
      frame = {
        length: 11,
        type: :push_promise,
        flags: [:end_headers],
        stream: 1,
        promise_stream: 2,
        payload: "headers"
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0xb, 0x5, 0x4, 0x1, 0x2, *"headers".bytes].pack("CnCCNNC*")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "PING" do
    let(:frame) do
      {
        length: 8,
        stream: 1,
        type: :ping,
        flags: [:ack],
        payload: "12345678"
      }
    end

    it "should generate and parse bytes" do
      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x8, 0x6, 0x1, 0x1, *"12345678".bytes].pack("CnCCNC*")
      expect(f.parse(bytes)).to eq frame
    end

    it "should raise exception on invalid payload" do
      expect do
        frame[:payload] = "1234"
        f.generate(frame)
      end.to raise_error(CompressionError, /Invalid payload size/)
    end
  end

  context "GOAWAY" do
    let(:frame) do
      {
        length: 13,
        stream: 1,
        type: :goaway,
        last_stream: 2,
        error: :no_error,
        payload: "debug"
      }
    end

    it "should generate and parse bytes" do
      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0xd, 0x7, 0x0, 0x1, 0x2, 0x0, *"debug".bytes].pack("CnCCNNNC*")
      expect(f.parse(bytes)).to eq frame
    end

    it "should treat debug payload as optional" do
      frame.delete :payload
      frame[:length] = 0x8

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x8, 0x7, 0x0, 0x1, 0x2, 0x0].pack("CnCCNNN")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "WINDOW_UPDATE" do
    it "should generate and parse bytes" do
      frame = {
        length: 4,
        type: :window_update,
        increment: 10
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0x4, 0x8, 0x0, 0x0, 0xa].pack("CnCCNN")
      parsed_frame = f.parse(bytes)
      frame.each do |k, v|
        expect(parsed_frame[k]).to eq(v)
      end
    end

    it "should break when the increment is too large" do
      frame = {
        length: 4,
        type: :window_update,
        increment: 0x7fffffff + 1
      }

      expect { f.generate(frame) }.to raise_error(CompressionError)
    end
  end

  context "CONTINUATION" do
    it "should generate and parse bytes" do
      frame = {
        length: 12,
        type: :continuation,
        stream: 1,
        flags: [:end_headers],
        payload: "header-block"
      }

      bytes = f.generate(frame)
      expect(bytes).to eq [0, 0xc, 0x9, 0x4, 0x1, *"header-block".bytes].pack("CnCCNC*")
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "ALTSVC" do
    it "should generate and parse bytes" do
      frame = {
        length: 44,
        type: :altsvc,
        stream: 1,
        max_age: 1_402_290_402,     # 4
        port: 8080,                 # 2
        proto: "h2-13",             # 1 + 5
        host: "www.example.com",    # 1 + 15
        origin: "www.example.com" # 15
      }
      bytes = f.generate(frame)
      expected = [0, 43, 0xa, 0, 1, 1_402_290_402, 8080].pack("CnCCNNn")
      expected << [5, *"h2-13".bytes].pack("CC*")
      expected << [15, *"www.example.com".bytes].pack("CC*")
      expected << [*"www.example.com".bytes].pack("C*")
      expect(bytes).to eq expected
      expect(f.parse(bytes)).to eq frame
    end
  end

  context "Padding" do
    let(:frame) do
      {
        length: 12,
        type: type,
        stream: 1,
        payload: "example data"
      }
    end
    %i[data headers push_promise].each do |type|
      let(:type) { type }
      if type == :push_promise
        let(:frame) do
          {
            length: 12,
            type: type,
            stream: 1,
            payload: "example data",
            promise_stream: 2
          }
        end
      end
      [1, 256].each do |padlen|
        context "generating #{type} frame padded #{padlen}" do
          let(:normal) { f.generate(frame) }
          let(:padded) { f.generate(frame.merge(padding: padlen)) }
          it "should generate a frame with padding" do
            expect(padded.bytesize).to eq normal.bytesize + padlen
          end
          it "should fill padded octets with zero" do
            trailer_len = padlen - 1
            expect(padded[-trailer_len, trailer_len]).to match(/\A\0*\z/)
          end
          it "should parse a frame with padding" do
            expect(f.parse(padded)).to eq \
              f.parse(normal).merge(padding: padlen)
          end
          it "should preserve payload" do
            expect(f.parse(padded)[:payload]).to eq frame[:payload]
          end
        end
      end
    end
    context "generating with invalid padding length" do
      [0, 257, 1334].each do |padlen|
        it "should raise error on trying to generate data frame padded with invalid #{padlen}" do
          expect do
            f.generate(frame.merge(padding: padlen))
          end.to raise_error(CompressionError, /padding/i)
        end
      end
      it "should raise error when adding a padding would make frame too large" do
        frame[:payload] = "q" * (f.remote_max_frame_size - 200)
        frame[:length]  = frame[:payload].size
        frame[:padding] = 210 # would exceed 4096
        expect do
          f.generate(frame)
        end.to raise_error(CompressionError, /padding/i)
      end
    end
    context "parsing frames with invalid paddings" do
      let(:padded) { f.generate(frame.merge(padding: 123)) }
      it "should raise exception when the given padding is longer than the payload" do
        padded.setbyte(9, 240)
        expect { f.parse(padded) }.to raise_error(ProtocolError, /padding/)
      end
    end
  end

  it "should determine frame length" do
    frames = [
      [{ type: :data, stream: 1, flags: [:end_stream], payload: "abc" }, 3],
      [{ type: :headers, stream: 1, payload: "abc" }, 3],
      [{ type: :priority, stream: 3, dependency: 30, exclusive: false, weight: 1 }, 5],
      [{ type: :rst_stream, stream: 3, error: 100 }, 4],
      [{ type: :settings, payload: [[:settings_max_concurrent_streams, 10]] }, 6],
      [{ type: :push_promise, promise_stream: 5, payload: "abc" }, 7],
      [{ type: :ping, payload: "blob" * 2 }, 8],
      [{ type: :goaway, last_stream: 5, error: 20, payload: "blob" }, 12],
      [{ type: :window_update, stream: 1, increment: 1024 }, 4],
      [{ type: :continuation, stream: 1, payload: "abc" }, 3]
    ]

    frames.each do |(frame, size)|
      bytes = f.generate(frame)
      expect(bytes.slice(1, 2).unpack1("n")).to eq size
      expect(bytes.getbyte(0)).to eq 0
    end
  end

  it "should parse single frame at a time" do
    frames = [
      { type: :headers, stream: 1, payload: "headers" },
      { type: :data, stream: 1, flags: [:end_stream], payload: "abc" }
    ]

    buf = f.generate(frames[0]) << f.generate(frames[1])

    expect(f.parse(buf)).to eq frames[0]
    expect(f.parse(buf)).to eq frames[1]
  end

  it "should process full frames only" do
    frame = { type: :headers, stream: 1, payload: "headers" }
    bytes = f.generate(frame)

    expect(f.parse(bytes.slice(0...-1))).to be_nil
    expect(f.parse(bytes)).to eq frame
    expect(bytes).to be_empty
  end

  it "should ignore unknown extension frames" do
    frame = { type: :headers, stream: 1, payload: "headers" }
    bytes = f.generate(frame)
    bytes = "#{bytes}#{bytes}".b # Two HEADERS frames in bytes
    bytes.setbyte(3, 42) # Make the first unknown type 42

    expect(f.parse(bytes)[:type]).to be_nil
    expect(f.parse(bytes)).to eq frame # should generate only one HEADERS
    expect(bytes).to be_empty
  end
end