WIP: Refactor to read from an hcl config file and expr rules

Need to write some documentation

Makefile

@@ -8,7 +8,7 @@ default: test
 
 .PHONY: test
 test: $(BIN)
-	./$(BIN) https://duck.com/
+	./$(BIN) -config ./sample-config.hcl https://duck.com/
 
 $(BIN): *.go
 	go build .

config.go

@@ -1,129 +1,108 @@
 package main
 
 import (
-	"encoding/json"
 	"fmt"
+	"net/url"
+	"os"
+	"path/filepath"
+
+	"github.com/antonmedv/expr"
+	"github.com/hashicorp/hcl/v2/hclsimple"
 )
 
-// TODO: This is a total work in progress. It generally works execept it's ugly and regex strings aren't parsed correctly
+func fileExists(path string) bool {
+	if _, err := os.Stat(path); os.IsNotExist(err) {
+		return false
+	}
+
+	return true
+}
 
 // Config is the full set of configuration required
 type Config struct {
-	DefaultBrowserCommand []string
+	DefaultBrowserCommand []string            `hcl:"default_browser_cmd"`
-	Rules                 []BrowserRuleConfig
+	Rules                 []BrowserRuleConfig `hcl:"rule,block"`
-}
-
-func (r *BrowserRule) UnmarshalJSON(data []byte) error {
-	var values struct {
-		command         string
-		args            []string
-		matchHostname   []string
-		matchHostRegexp []string
-		matchRegexp     []string
-	}
-	if err := json.Unmarshal(data, &values); err != nil {
-		return err
-	}
-
-	return nil
 }
 
 // BrowserRuleConfig represents a BrowserRule
 type BrowserRuleConfig struct {
-	BrowserCommand []string
+	Name           string   `hcl:"name,label"`
-	Matchers       []MatcherConfig
+	BrowserCommand []string `hcl:"browser_cmd"`
+	MatchExpr      string   `hcl:"match"`
 }
 
-// MatcherConfig represents a single MatchFunc
+func MakeMatchFunc(rule string) MatchFunc {
-type MatcherConfig struct {
+	return func(dest url.URL) bool {
-	Kind    string
+		env := map[string]interface{}{
-	Targets []string
+			"matchHostname":   matchHostname,
+			"matchHostRegexp": matchHostRegexp,
+			"matchRegexp":     matchRegexp,
+			"matchAny":        matchAny,
+			// Building custom matchers
+			"MatchFunc": func(foundMatch bool) MatchFunc {
+				return func(_ url.URL) bool {
+					return foundMatch
 				}
-
+			},
-func parseConfig(jsonBytes []byte) (Config, error) {
+			"hostname": dest.Hostname(),
-	var c Config
+			"url":      dest.String(),
-	err := json.Unmarshal(jsonBytes, &c)
-	return c, err
 		}
-
+		matchFunc, err := expr.Eval(rule, env)
-// GetRules returns all rules parsed from a JSON string
-func GetRules(jsonBytes []byte) (rules []BrowserRule, err error) {
-	c, err := parseConfig(jsonBytes)
 		if err != nil {
-		return
+			panic(err)
 		}
 
-	for _, rule := range c.Rules {
+		return matchFunc.(MatchFunc)(dest)
-		if len(rule.BrowserCommand) < 1 {
-			err = fmt.Errorf("Must provide a browser command")
-			return
 	}
-		browserCommand := rule.BrowserCommand[0]
-		args := rule.BrowserCommand[1:]
-
-		matchers := []MatchFunc{}
-		for _, matcher := range rule.Matchers {
-			switch matcher.Kind {
-			case "matchHostname":
-				fmt.Println("Match hostname for ", matcher.Targets)
-				matchers = append(matchers, matchHostname(matcher.Targets...))
-			case "matchHostRegexp":
-				matchers = append(matchers, matchHostRegexp(matcher.Targets...))
-			case "matchRegexp":
-				matchers = append(matchers, matchRegexp(matcher.Targets...))
-			default:
-				err = fmt.Errorf("Unknown matcher kind %s", matcher.Kind)
-				return
-			}
-		}
-		var matcher MatchFunc
-		if len(matchers) == 1 {
-			matcher = matchers[0]
-		} else {
-			matcher = matchAny(matchers...)
 }
 
-		rules = append(
+func LoadConfig(path string) ([]BrowserRule, error) {
-			rules,
+	rules := []BrowserRule{}
-			BrowserRule{
+	var config Config
-				matcher: matcher,
+	err := hclsimple.DecodeFile(path, nil, &config)
-				command: browserCommand,
+	if err != nil {
-				args:    args,
+		return nil, err
-			},
+	}
-			BrowserRule{
+
+	for _, rule := range config.Rules {
+		rules = append(rules, BrowserRule{
+			command: rule.BrowserCommand[0],
+			args:    rule.BrowserCommand[1:],
+			matcher: MakeMatchFunc(rule.MatchExpr),
+		})
+	}
+
+	// Add default browser rule to the end
+	rules = append(rules, BrowserRule{
+		command: config.DefaultBrowserCommand[0],
+		args:    config.DefaultBrowserCommand[1:],
 		matcher: defaultBrowser,
-				command: c.DefaultBrowserCommand[0],
+	})
-				args:    c.DefaultBrowserCommand[1:],
-			},
-		)
 
+	return rules, nil
 }
 
-	return
+func DefaultConfigPath() (string, error) {
+	appName := "browser-ruler"
+
+	// Check XDG_CONFIG_HOME
+	dir, err := os.UserConfigDir()
+	if err == nil {
+		configPath := filepath.Join(dir, appName, "config.hcl")
+		if fileExists(configPath) {
+			return configPath, nil
+		}
 	}
 
-func GetTestRules() ([]BrowserRule, error) {
+	dir, err = os.UserHomeDir()
-	jsonBytes := []byte(`{
+	if err != nil {
-		"DefaultBrowserCommand": ["chromium-browser"],
+		return "", fmt.Errorf("Could not find a config dir or home dir to look for config file. Specify one with -config: %w", err)
-		"Rules": [
-			{
-				"BrowserCommand": ["firefox"],
-				"Matchers": [
-					{
-						"Kind": "matchHostname",
-						"Targets": [
-							"iamthefij.com"
-						]
-					},
-					{
-						"Kind": "matchHostRegexp",
-						"Targets": [
-							".*\.iamthefij\.com$",
-						]
 	}
-				]
+
+	configPath := filepath.Join(dir, "."+appName+".hcl")
+	if fileExists(configPath) {
+		return configPath, nil
 	}
-		]
+
-	}`)
+	return "", fmt.Errorf("no config file found in config dir or home dir")
-	return GetRules(jsonBytes)
 }

go.mod

@@ -1,3 +1,8 @@
 module git.iamthefij.com/iamthefij/browser-ruler
 
 go 1.16
+
+require (
+	github.com/antonmedv/expr v1.9.0 // indirect
+	github.com/hashicorp/hcl/v2 v2.11.1 // indirect
+)

go.sum

@@ -0,0 +1,73 @@
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main.go

@@ -100,14 +100,14 @@ func noop(dest url.URL) bool {
 	return false
 }
 
-func handleURL(urlString string) error {
+func handleURL(browserRules []BrowserRule, urlString string) error {
 	dest, err := url.Parse(urlString)
 	if err != nil {
 		return fmt.Errorf("failed to parse url: %s, %w", urlString, err)
 	}
 
 	var matched bool
-	for _, rule := range rules() {
+	for _, rule := range browserRules {
 		matched, err = rule.MaybeLaunch(*dest)
 		if err != nil {
 			return fmt.Errorf("failed launching browser: %w", err)
@@ -122,11 +122,32 @@ func handleURL(urlString string) error {
 }
 
 func main() {
+	configPath := flag.String("config", "", "Path to config file, otherwise it will default to $XDG_CONFIG_HOME/browser-ruler/config.hcl or $HOME/.browser-ruler.hcl")
 	flag.Parse()
+
+	// Read config path from option or find default
+	if *configPath == "" {
+		defaultConfigPath, err := DefaultConfigPath()
+		if err != nil {
+			fmt.Println("Failed to get a path to any config files")
+			panic(err)
+		}
+		configPath = &defaultConfigPath
+	}
+
+	// Read rules from config path
+	browserRules, err := LoadConfig(*configPath)
+	if err != nil {
+		fmt.Printf("Could not read config from path %s\n", *configPath)
+		panic(err)
+	}
+
+	// Get urls from args
 	urls := flag.Args()
 
+	// For each url, run matcher
 	for _, urlString := range urls {
-		err := handleURL(urlString)
+		err := handleURL(browserRules, urlString)
 		if err != nil {
 			panic(err)
 		}

rules.go

@@ -1,54 +0,0 @@
-package main
-
-// Update this file with your rules
-// You can either define a BrowserRule directly, or using one of the
-// pre-defined browsers in browsers.go
-
-func rules() []BrowserRule {
-	return []BrowserRule{
-		// Personal domains
-		Firefox(
-			matchHostRegexp(
-				`.*\.iamthefij\.com$`,
-				`.*\.thefij\.rocks$`,
-				`.*\.thefij$`,
-			),
-		),
-		// Work domains
-		ChromiumFlatpak(
-			matchAny(
-				matchHostname(
-					"app.signalfx.com",
-					"lever.co",
-					"work.grubhub.com",
-					"y",
-					"yelp.rimeto.io",
-					"yelp.slack.com",
-					"yelplove.appspot.com",
-					"yelp-shootie.appspot.com",
-				),
-				matchHostRegexp(
-					`.*\.lifesize\.com$`,
-					`.*\.myworkday\.com$`,
-					`.*\.salesforce\.com$`,
-					`.*\.yelpcorp\.com$`,
-				),
-			),
-		),
-		// Googly domains
-		ChromiumFlatpak(
-			matchAny(
-				matchHostname(
-					"google.com",
-					"youtube.com",
-				),
-				matchHostRegexp(
-					`.*\.google\.com$`,
-					`.*\.youtube\.com$`,
-				),
-			),
-		),
-		// Default fallback browser
-		Firefox(defaultBrowser),
-	}
-}

sample-config.hcl

@@ -0,0 +1,39 @@
+default_browser_cmd = ["firefox"]
+
+# The rule label doesn't matter
+rule "Flatpak Chromium" {
+  # Command and args, like with default
+  browser_cmd = ["flatpak", "run", "org.chromium.Chromium"]
+  # match evaluates an expr that should result in a MatchFunc where the signature
+  # is MatchFunc = func(url.URL) bool
+  # There are several functions provided that contain common rules and help construct this.
+  # provided are:
+  #   matchHostname(...string) MatchFunc
+  #   matchHostRegexp(...string) MatchFunc
+  #   matchRegexp(...string) MatchFunc
+  #   matchAny(...MatchFunc) MatchFunc
+  #
+  # For writing custom rules using expr, you can use the following two variables:
+  #   hostname: the URL hostname
+  #   url: the full string of the URL
+  #
+  # When using those, you can turn them into a MatchFunc using
+  #   MatchFunc(bool) MatchFunc
+  #
+  # For example:
+  #   MatchFunc(hostname endsWith "example.com")
+  # is equivalent to:
+  #   matchHostRegexp(".*\\example\\.com$")
+  match = "matchHostname('google.com', 'youtube.com')"
+}
+
+rule "Firefox Private" {
+  browser_cmd = ["firefox", "--private-window"]
+  # For more complex rules, rules can span multiple lines using EOF syntax
+  match = <<EOF
+  matchAny(
+    matchHostname('facebook.com'),
+    MatchFunc(hostname == 'instagram.com')
+  )
+  EOF
+}