refactor: add more go linters (#970)

.golangci.yml

@@ -0,0 +1,132 @@
+linters-settings:
+  dupl:
+    threshold: 100
+  exhaustive:
+    default-signifies-exhaustive: false
+  funlen:
+    lines: 100
+    statements: 50
+  goconst:
+    min-len: 2
+    min-occurrences: 2
+  gocritic:
+    enabled-tags:
+      - diagnostic
+      - experimental
+      - opinionated
+      - performance
+      - style
+    disabled-checks:
+      - dupImport # https://github.com/go-critic/go-critic/issues/845
+      - ifElseChain
+      - octalLiteral
+      - whyNoLint
+      - wrapperFunc
+  gocyclo:
+    min-complexity: 15
+  goimports:
+    local-prefixes: github.com/filebrowser/filebrowser
+  golint:
+    min-confidence: 0
+  gomnd:
+    settings:
+      mnd:
+        # don't include the "operation" and "assign"
+        checks: argument,case,condition,return
+  govet:
+    check-shadowing: true
+  lll:
+    line-length: 140
+  maligned:
+    suggest-new: true
+  misspell:
+    locale: US
+  nolintlint:
+    allow-leading-space: true # don't require machine-readable nolint directives (i.e. with no leading space)
+    allow-unused: false # report any unused nolint directives
+    require-explanation: false # don't require an explanation for nolint directives
+    require-specific: false # don't require nolint directives to be specific about which linter is being skipped
+
+linters:
+  # please, do not use `enable-all`: it's deprecated and will be removed soon.
+  # inverted configuration with `enable-all` and `disable` is not scalable during updates of golangci-lint
+  disable-all: true
+  enable:
+    - bodyclose
+    - deadcode
+    - depguard
+    - dogsled
+    - dupl
+    - errcheck
+    - funlen
+    - gochecknoinits
+    - goconst
+    - gocritic
+    - gocyclo
+    - gofmt
+    - goimports
+    - golint
+    - gomnd
+    - goprintffuncname
+    - gosec
+    - gosimple
+    - govet
+    - ineffassign
+    - interfacer
+    - lll
+    - misspell
+    - nakedret
+    - nolintlint
+    - rowserrcheck
+    - scopelint
+    - staticcheck
+    - structcheck
+    - stylecheck
+    - typecheck
+    - unconvert
+    - unparam
+    - unused
+    - varcheck
+    - whitespace
+    - prealloc
+
+  # don't enable:
+  # - asciicheck
+  # - exhaustive (TODO: enable after next release; current release at time of writing is v1.27)
+  # - gochecknoglobals
+  # - gocognit
+  # - godot
+  # - godox
+  # - goerr113
+  # - maligned
+  # - nestif
+  # - testpackage
+  # - wsl
+
+issues:
+  exclude-rules:
+    - path: cmd/.*.go
+      linters:
+        - gochecknoinits
+    - path: .*_test.go
+      linters:
+        - lll
+        - gochecknoinits
+        - gocyclo
+        - funlen
+        - dupl
+        - scopelint
+    - text: "Auther"
+      linters:
+        - misspell
+
+run:
+  skip-dirs:
+    - frontend/
+  skip-files:
+    - http/rice-box.go
+
+# golangci.com configuration
+# https://github.com/golangci/golangci/wiki/Configuration
+service:
+  golangci-lint-version: 1.27.x # use the fixed version to not introduce new linters unexpectedly