feat(completion): unify shell wrappers behind task __complete

internal/complete/context.go

@@ -0,0 +1,65 @@
+package complete
+
+import (
+	"strings"
+
+	"github.com/spf13/pflag"
+)
+
+type completionContext struct {
+	toComplete string
+	prev       string
+	taskName   string
+	afterDash  bool
+}
+
+// parseContext infers the cursor position from args. fs is needed to skip the
+// word following a value-taking flag, otherwise `task --dir deploy` would
+// mistake "deploy" (the directory) for a task name.
+func parseContext(args []string, knownTasks []string, fs *pflag.FlagSet) completionContext {
+	ctx := completionContext{}
+	if len(args) == 0 {
+		return ctx
+	}
+
+	ctx.toComplete = args[len(args)-1]
+	if len(args) >= 2 {
+		ctx.prev = args[len(args)-2]
+	}
+
+	known := make(map[string]struct{}, len(knownTasks))
+	for _, t := range knownTasks {
+		known[t] = struct{}{}
+	}
+
+	skipNext := false
+	for _, w := range args[:len(args)-1] {
+		if skipNext {
+			skipNext = false
+			continue
+		}
+		if w == "--" {
+			ctx.afterDash = true
+			continue
+		}
+		if ctx.afterDash {
+			continue
+		}
+		if strings.HasPrefix(w, "-") {
+			if !strings.Contains(w, "=") {
+				if f := matchFlagName(fs, w); f != nil && flagTakesValue(f) {
+					skipNext = true
+				}
+			}
+			continue
+		}
+		if strings.Contains(w, "=") {
+			continue
+		}
+		if _, ok := known[w]; ok {
+			ctx.taskName = w
+		}
+	}
+
+	return ctx
+}