3 files changed, 87 insertions, 0 deletions
diff --git a/cmd/install/fish.go b/cmd/install/fish.go
new file mode 100644
index 0000000..f04e7c3
--- /dev/null
+++ b/cmd/install/fish.go
@@ -0,0 +1,50 @@
+package install
+
+import (
+	"bytes"
+	"fmt"
+	"os"
+	"path/filepath"
+	"text/template"
+)
+
+// (un)install in fish
+
+type fish struct {
+	configDir string
+}
+
+func (f fish) Install(cmd, bin string) error {
+	completionFile := filepath.Join(f.configDir, "completions", fmt.Sprintf("%s.fish", cmd))
+	completeCmd := f.cmd(cmd, bin)
+	if _, err := os.Stat(completionFile); err == nil {
+		return fmt.Errorf("already installed at %s", completionFile)
+	}
+
+	return createFile(completionFile, completeCmd)
+}
+
+func (f fish) Uninstall(cmd, bin string) error {
+	completionFile := filepath.Join(f.configDir, "completions", fmt.Sprintf("%s.fish", cmd))
+	if _, err := os.Stat(completionFile); err != nil {
+		return fmt.Errorf("does not installed in %s", f.configDir)
+	}
+
+	return os.Remove(completionFile)
+}
+
+func (f fish) cmd(cmd, bin string) string {
+	var buf bytes.Buffer
+	params := struct{ Cmd, Bin string }{cmd, bin}
+	template.Must(template.New("cmd").Parse(`
+function __complete_{{.Cmd}}
+    set -lx COMP_LINE (string join ' ' (commandline -o))
+    test (commandline -ct) = ""
+    and set COMP_LINE "$COMP_LINE "
+    {{.Bin}}
+end
+complete -c {{.Cmd}} -a "(__complete_{{.Cmd}})"
+`)).Execute(&buf, params)
+
+	return string(buf.Bytes())
+}
diff --git a/cmd/install/install.go b/cmd/install/install.go
index 082a226..4a70624 100644
--- a/cmd/install/install.go
+++ b/cmd/install/install.go
@@ -68,9 +68,36 @@ func installers() (i []installer) {
 	if f := rcFile(".zshrc"); f != "" {
 		i = append(i, zsh{f})
 	}
+	if d := fishConfigDir(); d != "" {
+		i = append(i, fish{d})
+	}
 	return
 }
 
+func fishConfigDir() string {
+	configDir := filepath.Join(getConfigHomePath(), "fish")
+	if configDir == "" {
+		return ""
+	}
+	if info, err := os.Stat(configDir); err != nil || !info.IsDir() {
+		return ""
+	}
+	return configDir
+}
+
+func getConfigHomePath() string {
+	u, err := user.Current()
+	if err != nil {
+		return ""
+	}
+
+	configHome := os.Getenv("XDG_CONFIG_HOME")
+	if configHome == "" {
+		return filepath.Join(u.HomeDir, ".config")
+	}
+	return configHome
+}
+
 func getBinaryPath() (string, error) {
 	bin, err := os.Executable()
 	if err != nil {
diff --git a/cmd/install/utils.go b/cmd/install/utils.go
index 2c8b44c..8bcf4e1 100644
--- a/cmd/install/utils.go
+++ b/cmd/install/utils.go
@@ -36,6 +36,16 @@ func lineInFile(name string, lookFor string) bool {
 	}
 }
 
+func createFile(name string, content string) error {
+	f, err := os.Create(name)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	_, err = f.WriteString(fmt.Sprintf("%s\n", content))
+	return err
+}
+
 func appendToFile(name string, content string) error {
 	f, err := os.OpenFile(name, os.O_RDWR|os.O_APPEND, 0)
 	if err != nil {