Reset repo history

.github/dependabot.yml

@@ -0,0 +1,6 @@
+version: 2
+updates:
+  - package-ecosystem: "gomod"
+    directory: "/"
+    schedule:
+      interval: "daily"

.github/workflows/test.yml

@@ -0,0 +1,39 @@
+name: Test
+on: push
+jobs:
+  test:
+    name: Test
+    runs-on: ubuntu-latest
+    container: golang
+    services:
+      cache:
+        image: memcached:latest
+        ports:
+          - 11211:11211
+      database:
+        image: postgres:latest
+        ports:
+          - 5432:5432
+        env:
+          POSTGRES_USER: postgres
+          POSTGRES_PASSWORD: pass
+          POSTGRES_DB: url-shortener
+        options: >-
+          --health-cmd pg_isready
+          --health-interval 10s
+          --health-timeout 5s
+          --health-retries 5
+    steps:
+      - name: Pull repository
+        uses: actions/checkout@v3
+      - name: Set up Go
+        uses: actions/setup-go@v3
+        with:
+          cache: true
+      - name: Run tests
+        run: go test -coverprofile=coverage.txt
+        env:
+          MEMCACHED_HOST: cache
+          POSTGRES_HOST: database
+      - name: Upload test coverage report
+        uses: codecov/codecov-action@v3

Dockerfile

@@ -0,0 +1,10 @@
+FROM golang as builder
+RUN mkdir /build 
+COPY . /build/
+WORKDIR /build 
+RUN CGO_ENABLED=0 GOOS=linux go build -a -installsuffix cgo -ldflags '-extldflags "-static"' -o main .
+FROM scratch
+LABEL maintainer="Bruno Fernandes <bfdes@users.noreply.github.com>"
+COPY --from=builder /build/main /app/
+WORKDIR /app
+CMD ["./main"]

README.md

@@ -0,0 +1,47 @@
+# url-shortener
+
+![GitHub Actions](https://github.com/bfdes/url-shortener/workflows/Build/badge.svg)
+[![Codecov](https://codecov.io/gh/bfdes/url-shortener/branch/master/graph/badge.svg)](https://codecov.io/gh/bfdes/url-shortener)
+
+URL shortener and redirect service [designed for](https://www.notion.so/URL-shortening-8272c692648143698859d9f3524a8b5e#a2becb53582444cfb3e9cce1dd8978ba) low-latency, read-heavy use.
+
+## Usage
+
+### Requirements
+
+- [Go](https://golang.org/) 1.20.*
+- [Docker Engine](https://docs.docker.com/engine/) 20.*
+- [Docker Compose](https://docs.docker.com/compose/) 2.*
+
+Run the following command within the repository root to start container dependencies in the background:
+
+```shell
+docker compose up --detach cache database
+```
+
+Then, when the databases are ready to accept connections, start the server with `go run .`.
+
+### Shorten a URL
+
+```shell
+curl http://localhost:8080/api/links \
+  --request POST \
+  --data '{"url": "http://example.com"}'
+# {"url": "http://example.com", "slug": "<SLUG>" }
+```
+
+### Redirect a URL
+
+```shell
+curl http://localhost:8080/<SLUG>
+```
+
+### Testing
+
+Run unit and integration tests with `go test` after starting container dependencies.
+
+[GitHub Actions](https://github.com/bfdes/url-shortener/actions) will run tests for every code push.
+
+## Deployment
+
+This URL shortener is unsuited for production use; it does not support logging or metric collection.

base62.go

@@ -0,0 +1,49 @@
+package main
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+// Characters defines the character set for base 62 encoding
+const Characters = "0123456789abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ"
+
+const base = len(Characters)
+
+var digits = make(map[rune]int)
+
+func init() {
+	for i, char := range Characters {
+		digits[char] = i
+	}
+}
+
+// Encode a non-negative integer into a base 62 symbol string
+func Encode(id int) (string, error) {
+	if id < 0 {
+		return "", errors.New("argument to Encode must be non-negative")
+	}
+	var sb strings.Builder
+	for id > 0 {
+		rem := id % base
+		sb.WriteByte(Characters[rem])
+		id = id / base
+	}
+	return sb.String(), nil
+}
+
+// Decode a base 62 encoded string
+func Decode(str string) (int, error) {
+	id := 0
+	coeff := 1
+	for _, char := range str {
+		digit := digits[char]
+		if char != '0' && digit == 0 {
+			return 0, fmt.Errorf(`argument "%s" contains illegal character(s)`, str)
+		}
+		id += coeff * digit
+		coeff *= base
+	}
+	return id, nil
+}

base62_test.go

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+package main
+
+import (
+	"math/rand"
+	"testing"
+)
+
+type testInput struct {
+	decoded int
+	encoded string
+}
+
+var testInputs = []testInput{
+	{0, ""},
+	{1, "1"},
+	{62, "01"},
+	{1504, "go"},
+}
+
+func TestEncode(t *testing.T) {
+	for _, testInput := range testInputs {
+		actual, err := Encode(testInput.decoded)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if actual != testInput.encoded {
+			t.Errorf("%d encoded to %s, not %s", testInput.decoded, actual, testInput.encoded)
+		}
+	}
+}
+
+func TestEncodeNegative(t *testing.T) {
+	arg := -1
+	encoded, err := Encode(arg)
+	if err == nil {
+		t.Errorf("negative argument %d encoded to %s", arg, encoded)
+	}
+}
+
+func TestDecode(t *testing.T) {
+	for _, testInput := range testInputs {
+		actual, err := Decode(testInput.encoded)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if actual != testInput.decoded {
+			t.Errorf("%s decoded to %d, not %d", testInput.encoded, actual, testInput.decoded)
+		}
+	}
+}
+
+func TestDecodeIllegalCharacter(t *testing.T) {
+	arg := "!llegal"
+	decoded, err := Decode(arg)
+	if err == nil {
+		t.Errorf("malformed slug %s decoded to %d", arg, decoded)
+	}
+}
+
+func TestEncodeDecode(t *testing.T) {
+	testInputs := []int{0, 1, 62}
+	for i := 0; i < 20; i++ {
+		testInputs = append(testInputs, rand.Int())
+	}
+	for _, testInput := range testInputs {
+		encoded, err := Encode(testInput)
+		if err != nil {
+			t.Fatal(err)
+		}
+		actual, err := Decode(encoded)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if actual != testInput {
+			t.Errorf("%d does not roundtrip", testInput)
+		}
+	}
+}

docker-compose.yml

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+version: '3.8'
+services:
+  cache:
+    image: memcached:latest
+    ports:
+      - 11211:11211
+  database:
+    image: postgres:latest
+    environment:
+      - POSTGRES_USER=postgres
+      - POSTGRES_PASSWORD=pass
+      - POSTGRES_DB=url-shortener
+    volumes:
+      - data:/var/lib/postgresql/data/
+    ports:
+      - 5432:5432
+volumes:
+  data:

go.mod

@@ -0,0 +1,9 @@
+module github.com/bfdes/url-shortener
+
+go 1.20
+
+require (
+	github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b
+	github.com/google/uuid v1.3.0
+	github.com/lib/pq v1.10.9
+)

go.sum

@@ -0,0 +1,6 @@
+github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b h1:L/QXpzIa3pOvUGt1D1lA5KjYhPBAN/3iWdP7xeFS9F0=
+github.com/bradfitz/gomemcache v0.0.0-20190913173617-a41fca850d0b/go.mod h1:H0wQNHz2YrLsuXOZozoeDmnHXkNCRmMW0gwFWDfEZDA=
+github.com/google/uuid v1.3.0 h1:t6JiXgmwXMjEs8VusXIJk2BXHsn+wx8BZdTaoZ5fu7I=
+github.com/google/uuid v1.3.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/lib/pq v1.10.9 h1:YXG7RB+JIjhP29X+OtkiDnYaXQwpS4JEWq7dtCCRUEw=
+github.com/lib/pq v1.10.9/go.mod h1:AlVN5x4E4T544tWzH6hKfbfQvm3HdbOxrmggDNAPY9o=

handler.go

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+package main
+
+import (
+	"encoding/json"
+	"io/ioutil"
+	"net/http"
+	"strings"
+)
+
+func RedirectHandler(service LinkService) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodGet {
+			msg := http.StatusText(http.StatusMethodNotAllowed)
+			http.Error(w, msg, http.StatusMethodNotAllowed)
+			return
+		}
+		slug := r.URL.Path[1:]
+		url, err := service.Get(slug)
+		if err == ErrDecodeFailure {
+			msg := http.StatusText(http.StatusBadRequest)
+			http.Error(w, msg, http.StatusBadRequest)
+		} else if err == ErrNotFound {
+			http.NotFound(w, r)
+		} else {
+			// `err` must be `nil`...
+			http.Redirect(w, r, url, http.StatusPermanentRedirect)
+		}
+	})
+}
+
+func CreateLinkHandler(service LinkService) http.Handler {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != http.MethodPost {
+			msg := http.StatusText(http.StatusMethodNotAllowed)
+			http.Error(w, msg, http.StatusMethodNotAllowed)
+			return
+		}
+		if r.Body == nil || r.Body == http.NoBody {
+			msg := http.StatusText(http.StatusBadRequest)
+			http.Error(w, msg, http.StatusBadRequest)
+			return
+		}
+		payload := Link{}
+		body, err := ioutil.ReadAll(r.Body) // DOS attack vector
+		defer r.Body.Close()
+		if err == nil {
+			err = json.Unmarshal(body, &payload)
+		}
+		if err != nil {
+			msg := http.StatusText(http.StatusBadRequest)
+			http.Error(w, msg, http.StatusBadRequest)
+			return
+		}
+		url := strings.TrimSpace(payload.URL)
+		link, err := service.Create(url)
+		if err != nil {
+			msg := http.StatusText(http.StatusInternalServerError)
+			http.Error(w, msg, http.StatusInternalServerError)
+			return
+		}
+		res, _ := json.Marshal(link)
+		w.Header().Set("content-type", "application/json")
+		w.WriteHeader(http.StatusCreated)
+		w.Write(res)
+	})
+}