package configs

import (
	"fmt"

	"github.com/hashicorp/hcl2/hcl"
)

func decodeDependsOn(attr *hcl.Attribute) ([]hcl.Traversal, hcl.Diagnostics) {
	var ret []hcl.Traversal
	exprs, diags := hcl.ExprList(attr.Expr)

	for _, expr := range exprs {
		// A dependency reference was given as a string literal in the legacy
		// configuration language and there are lots of examples out there
		// showing that usage, so we'll sniff for that situation here and
		// produce a specialized error message for it to help users find
		// the new correct form.
		if exprIsNativeQuotedString(expr) {
			diags = append(diags, &hcl.Diagnostic{
				Severity: hcl.DiagError,
				Summary:  "Invalid explicit dependency reference",
				Detail:   fmt.Sprintf("%s elements must not be given in quotes.", attr.Name),
				Subject:  attr.Expr.Range().Ptr(),
			})
			continue
		}

		traversal, travDiags := hcl.AbsTraversalForExpr(expr)
		diags = append(diags, travDiags...)
		if len(traversal) != 0 {
			ret = append(ret, traversal)
		}
	}

	return ret, diags
}