refactor: drop writer and all unused code

Signed-off-by: Christian Stewart <christian@aperture.us>

Author: paralin

.golangci.yml

@@ -0,0 +1,66 @@
+linters:
+  enable:
+    - depguard
+    - goimports
+    - gosec
+    - gosimple
+    - govet
+    - importas
+    # - ineffassign
+    - misspell
+    - revive
+    - staticcheck
+    - typecheck
+    # - unconvert
+    - unused
+
+  disable:
+    - errcheck
+
+  run:
+    concurrency: 4
+    modules-download-mode: vendor
+
+    skip-dirs:
+      - hack
+
+linters-settings:
+  staticcheck:
+    checks:
+      - all
+      - '-SA1012' # Allow passing nil contexts.
+
+  importas:
+    # Do not allow unaliased imports of aliased packages.
+    no-unaliased: true
+
+  maligned:
+    suggest-new: true
+
+  depguard:
+    rules:
+      main:
+        deny:
+          - pkg: io/ioutil
+            desc: The io/ioutil package has been deprecated, see https://go.dev/doc/go1.16#ioutil
+          - pkg: "github.com/stretchr/testify/assert"
+            desc: Use "gotest.tools/v3/assert" instead
+          - pkg: "github.com/stretchr/testify/require"
+            desc: Use "gotest.tools/v3/assert" instead
+          - pkg: "github.com/stretchr/testify/suite"
+            desc: Do not use
+
+  revive:
+    rules:
+      - name: package-comments
+        disabled: true
+
+issues:
+  # Maximum issues count per one linter. Set to 0 to disable. Default is 50.
+  max-issues-per-linter: 0
+
+  # Maximum count of issues with the same text. Set to 0 to disable. Default is 3.
+  max-same-issues: 0
+
+  exclude:
+    - G601

Makefile

@@ -0,0 +1,49 @@
+SHELL:=bash
+GOIMPORTS=hack/bin/goimports
+GOFUMPT=hack/bin/gofumpt
+GOLANGCI_LINT=hack/bin/golangci-lint
+GOLIST=go list -f "{{ .Dir }}" -m
+
+export GO111MODULE=on
+undefine GOOS
+undefine GOARCH
+
+all:
+
+vendor:
+	go mod vendor
+
+$(GOIMPORTS):
+	cd ./hack; \
+	go build -v \
+		-o ./bin/goimports \
+		golang.org/x/tools/cmd/goimports
+
+$(GOFUMPT):
+	cd ./hack; \
+	go build -v \
+		-o ./bin/gofumpt \
+		mvdan.cc/gofumpt
+
+$(GOLANGCI_LINT):
+	cd ./hack; \
+	go build -v \
+		-o ./bin/golangci-lint \
+		github.com/golangci/golangci-lint/cmd/golangci-lint
+
+.PHONY: lint
+lint: $(GOLANGCI_LINT)
+	$(GOLANGCI_LINT) run --timeout=10m
+
+.PHONY: fix
+fix: $(GOLANGCI_LINT)
+	$(GOLANGCI_LINT) run --fix --timeout=10m
+
+.PHONY: format
+format: $(GOFUMPT) $(GOIMPORTS)
+	$(GOIMPORTS) -w ./
+	$(GOFUMPT) -w ./
+
+.PHONY: test
+test:
+	go test -v ./...

README.md

@@ -1,14 +1,30 @@
+# Brotli Decoder for Go
+
+[![Go Reference](https://pkg.go.dev/badge/github.com/aperturerobotics/go-brotli-decoder.svg)](https://pkg.go.dev/github.com/aperturerobotics/go-brotli-decoder)
+[![Go Report Card Widget]][Go Report Card]
+
+[Go Report Card Widget]: https://goreportcard.com/badge/github.com/aperturerobotics/go-brotli-decoder
+[Go Report Card]: https://goreportcard.com/report/github.com/aperturerobotics/go-brotli-decoder
+
+## Introduction
+
+This package is a brotli decompressor implemented in pure Go.
+
 This package is a brotli compressor and decompressor implemented in Go.
+
 It was translated from the reference implementation (https://github.com/google/brotli)
-with the `c2go` tool at https://github.com/andybalholm/c2go.
+with the `c2go** tool at https://github.com/andybalholm/c2go.
+
+## Upstream
+
+This package is a fork of the [upstream project] to create a more minimal
+package with just the decoder and not the encoder.
+
+This is a significantly lighter package in terms of binary size.
 
-I have been working on new compression algorithms (not translated from C)
-in the matchfinder package.
-You can use them with the NewWriterV2 function.
-Currently they give better results than the old implementation
-(at least for compressing my test file, Newton’s *Opticks*) 
-on levels 2 to 6.
+It was created by deleting the writer types and then repeatedly removing all
+unused symbols (detected with the gounused linter).
 
-I am using it in production with https://github.com/andybalholm/redwood.
+If you need the brotli compressor, see the [upstream project].
 
-API documentation is found at https://pkg.go.dev/github.com/andybalholm/brotli?tab=doc.
+[upstream project]: https://github.com/andybalholm/brotli